The transmission capacity of gas pipeline networks should be calculated and allocated to deal with the capacity booking with shippers. Technical capacities, which depend on the gas flow distribution at routes or inter...The transmission capacity of gas pipeline networks should be calculated and allocated to deal with the capacity booking with shippers. Technical capacities, which depend on the gas flow distribution at routes or interchange points, are calculated with a multiobjective optimization model and form a Pareto solution set in the entry/exit or point-to-point regime. Then, the commercial capacities, which can be directly applied in capacity booking, are calculated with single-objective optimization models that are transformed from the above multiobjective model based on three allocation rules and the demand of shippers.Next, peak-shaving capacities, which are daily oversupply or overdelivery amounts at inlets or deliveries,are calculated with two-stage transient optimization models. Considering the hydraulic process of a pipeline network and operating schemes of compressor stations, all the above models are mixed-integer nonlinear programming problems. Finally, a case study is made to demonstrate the ability of the models.展开更多
In short-term operation of natural gas network,the impact of demand uncertainty is not negligible.To address this issue we propose a two-stage robust model for power cost minimization problem in gunbarrel natural gas ...In short-term operation of natural gas network,the impact of demand uncertainty is not negligible.To address this issue we propose a two-stage robust model for power cost minimization problem in gunbarrel natural gas networks.The demands between pipelines and compressor stations are uncertain with a budget parameter,since it is unlikely that all the uncertain demands reach the maximal deviation simultaneously.During solving the two-stage robust model we encounter a bilevel problem which is challenging to solve.We formulate it as a multi-dimensional dynamic programming problem and propose approximate dynamic programming methods to accelerate the calculation.Numerical results based on real network in China show that we obtain a speed gain of 7 times faster in average without compromising optimality compared with original dynamic programming algorithm.Numerical results also verify the advantage of robust model compared with deterministic model when facing uncertainties.These findings offer short-term operation methods for gunbarrel natural gas network management to handle with uncertainties.展开更多
The variable and unpredictable nature of renewable energy generation(REG)presents challenges to its large-scale integration and the efficient and economic operation of the electricity network,particularly at the distr...The variable and unpredictable nature of renewable energy generation(REG)presents challenges to its large-scale integration and the efficient and economic operation of the electricity network,particularly at the distribution level.In this paper,an operational coordination optimization method is proposed for the electricity and natural gas networks,aiming to overcome the identified negative impacts.The method involves the implementation of bi-directional energy flows through power-to-gas units and gas-fired power plants.A detailed model of the three-phase power distribution system up to each phase is employed to improve the representation of multi-energy systems to consider real-world end-user consumption.This method allows for the full consideration of unbalanced operational scenarios.Meanwhile,the natural gas network is modelled and analyzed with steady-state gas flows and the dynamics of the line pack in pipelines.The sequential symmetrical second-order cone programming(SS-SOCP)method is employed to facilitate the simultaneous analysis of three-phase imbalance and line pack while accelerating the solution process.The efficacy of the operational coordination optimization method is demonstrated in case studies comprising a modified IEEE 123-node power distribution system with a 20-node natural gas network.The studies show that the operational coordination optimization method can simultaneously minimize the total operational cost,the curtailment of installed REG,the voltage imbalance of three-phase power system,and the overall carbon emissions.展开更多
The energy transfer process of natural gas network(NGN)has remarkable dynamic characteristics.However,the model of the gas network dominated by partial differential equations(PDEs)is challenging to analyse due to its ...The energy transfer process of natural gas network(NGN)has remarkable dynamic characteristics.However,the model of the gas network dominated by partial differential equations(PDEs)is challenging to analyse due to its heterogeneous properties,high dimensionality,and significant non-linearity.To cope with the dynamic characteristics of the NGN effectively and accurately,the Schur complement-based dynamic flow calcu-lation method for the NGN is proposed in the paper.Firstly,a time-domain two-port model for the dynamic characteristics of the NGN is derived based on the finite dif-ference method in the Wendroff format.The PDEs are transformed into an easily solvable time-domain linear algebraic model while ensuring the accuracy of the computational results.To alleviate the computational burden,a numerical method based on the Schur complement strategy is then developed.By reducing the dimensions of the matrix equation,the computation speed can be dramatically improved.Finally,case an-alyses are carried out to emphasise the significance of consideration of the dynamic characteristics of NGNs and confirm the validity and precision of the developed approach.展开更多
This paper develops a many-objective optimization model, which contains objectives representing the interests of the electricity and gas networks, as well as the distributed district heating and cooling units, to coor...This paper develops a many-objective optimization model, which contains objectives representing the interests of the electricity and gas networks, as well as the distributed district heating and cooling units, to coordinate the benefits of all parties participated in the integrated energy system(IES). In order to solve the many-objective optimization model efficiently, an improved objective reduction(IOR) approach is proposed, aiming at acquiring the smallest set of objectives. The IOR approach utilizes the Spearman’s rank correlation coefficient to measure the relationship between objectives based on the Pareto-optimal front captured by the multi-objective group search optimizer with adaptive covariance and Lévy flights algorithm, and adopts various strategies to reduce the number of objectives gradually. Simulation studies are conducted on an IES consisting of a modified IEEE 30-bus electricity network and a 15-node gas network. The results show that the many-objective optimization problem is transformed into a bi-objective formulation by the IOR. Furthermore,our approach improves the overall quality of dispatch solutions and alleviates the decision making burden.展开更多
An integrated energy system with multiple types of energy can support power shortages caused by the uncertainty of renewable energy.With full consideration of gas network constraints,this paper proposes a multi-energy...An integrated energy system with multiple types of energy can support power shortages caused by the uncertainty of renewable energy.With full consideration of gas network constraints,this paper proposes a multi-energy inertia-based power support strategy.The definition and modelling of gas inertia are given first to demonstrate its ability to mitigate power fluctuations.Since partial utilization of gas inertia can influence overall gas network parameters,the gas network is modelled with an analysis of network dynamic changes.A multi-energy inertia-based power support model and strategy are then proposed for fully using gas-thermal inertia resources in integrated energy systems.The influence of gas network constraints on strategy,economy and power outputs is analyzed.Special circumstances where the gas network can be simplified are introduced.This improves the response speed and application value.The feasibility and effectiveness of the proposed strategy are assessed using a real scenario.展开更多
This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipelin...This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipeline systems (CFD-simulator). The approach used in CFD-simulators for modeling gas mixture transmission through long, branched, multi-section pipelines is based on tailoring the full system of fluid dynamics equations to conditions of unsteady, non-isothermal processes of the gas mixture flow. Identification, in a CFD-simulator, of safe parameters for gas transmission through compressor stations amounts to finding the interior points of admissible sets described by systems of nonlinear algebraic equalities and inequalities. Such systems of equalities and inequalities comprise a formal statement of technological, design, operational and other constraints to which operation of the network equipment is subject. To illustrate the practicability of the method of numerical simulation of a gas transmission network, we compare computation results and gas flow parameters measured on-site at the gas transmission enter-prise.展开更多
An integrated dynamic model of natural gas pipeline networks is developed in this paper.Components for gas supply,e.g.,pipelines,junctions,compressor stations,LNG terminals,regulation stations and gas storage faciliti...An integrated dynamic model of natural gas pipeline networks is developed in this paper.Components for gas supply,e.g.,pipelines,junctions,compressor stations,LNG terminals,regulation stations and gas storage facilities are included in the model.These components are firstly modeled with respect to their properties and functions and,then,integrated at the system level by Graph Theory.The model can be used for simulating the system response in different scenarios of operation,and evaluate the consequences from the perspectives of supply security and resilience.A case study is considered to evaluate the accuracy of the model by benchmarking its results against those from literature and the software Pipeline Studio.Finally,the model is applied on a relatively complex natural gas pipeline network and the results are analyzed in detail from the supply security and resilience points of view.The main contributions of the paper are:firstly,a novel model of a complex gas pipeline network is proposed as a dynamic state-space model at system level;a method,based on the dynamic model,is proposed to analyze the security and resilience of supply from a system perspective.展开更多
The optimiz at ion operation of gas pipeline network is investigated in this paper. Based on th e theories of system optimization and the multi object decision, a mathematical model about the multi object optimization...The optimiz at ion operation of gas pipeline network is investigated in this paper. Based on th e theories of system optimization and the multi object decision, a mathematical model about the multi object optimization operation of gas pipeline network is established, in line with the demand of urban gas pipeline network operation. A t the same time, an effective solution of the mathematical model is presented. A calculating software about optimization operation is compiled, coupling the actual operation of gas pipeline network. It can be applied to the operation of the gas pipeline network. The software was examined by real examples. The resul ts indicated that 2.13% energy consumption and 3.12% gas supply cost can be reduced through optimization operation.展开更多
In this paper we discuss the uniqueness and existence of solution to a real gas flow network by employing graph theory. A directed graph is an efficient way to represent a gas network. We consider steady state real ga...In this paper we discuss the uniqueness and existence of solution to a real gas flow network by employing graph theory. A directed graph is an efficient way to represent a gas network. We consider steady state real gas flow network that includes pipelines, compressors, and the connectors. The pipelines and compressors are represented as edges of the graph and the interconnecting points are represented as nodes of the graph representing the network. We show that a unique solution of such a system exists. We use monotonicity property of a mapping to proof uniqueness, and the contraction mapping theorem is used to prove existence.展开更多
An array composed of sixteen gas sensors was constructed to analyze gas mixtures quantitatively. The data of responses from the sensor array to ethane, propane and propylene were treated by three-layer ANN with BP alg...An array composed of sixteen gas sensors was constructed to analyze gas mixtures quantitatively. The data of responses from the sensor array to ethane, propane and propylene were treated by three-layer ANN with BP algorithms and PLS. The analytical results indicated that the concentration predicted with ANN is better than that with PLS. The average prediction errors for ethane, propane and propylene were 5.11%, 8.28%, 2.64%, respectively.展开更多
In recent years, with the rapid development of economy and technology, many fields in China have been reformed and innovated and the urbanization process is advancing by leaps and bounds. Especially the intelligent ci...In recent years, with the rapid development of economy and technology, many fields in China have been reformed and innovated and the urbanization process is advancing by leaps and bounds. Especially the intelligent city construction has begun to take shape. Water network, power grid and gas network are the basic guarantee of peoples daily life. Perfecting urban infrastructure construction is an important content to improve peoples quality of life and accelerate the development of urban informatization. Urban gas pipeline network is laid in various underground cities. Intricate is an important channel for gas supply due to a series of problems such as uneven gas construction quality, difficult problem troubleshooting, complex operation of gas equipment and slow data update and scheduling. As a result, pipeline leakage and safety accidents occur frequently. Therefore, promoting the intelligentization of urban gas pipeline network operation and management is the key to current work. In the current electrical engineering field, intelligent technology shows positive advantages, mainly reflected in data collection, storage and editing and automation of gas pipeline network. This paper analyzes the advantages of intelligent management and the application of intelligent and automatic technology in the operation and management of urban gas pipeline network based on the current operation status of urban gas pipeline network.展开更多
Gas has brought convenience to people’s life at present, and gas pipeline networks and ancillary facilities play important roles in city construction. However, there are increasingly prominent safety problems in oper...Gas has brought convenience to people’s life at present, and gas pipeline networks and ancillary facilities play important roles in city construction. However, there are increasingly prominent safety problems in operation. The safe operation of gas pipeline networks in cities has been influenced by various aspects of factors, leading to frequent gas accidents, which give rise to serious influences on supply of gas. For this reason, detailed analysis has been conducted to problems related to safe operation of gas pipeline networks in cities in this article, and corresponding solutions are proposed.展开更多
The interchangeability between natural gas of different sources and LNG have been concerned and tackled to a certain extent at home,and the interconnection of gas infrastructures including LNG terminals and gas pipeli...The interchangeability between natural gas of different sources and LNG have been concerned and tackled to a certain extent at home,and the interconnection of gas infrastructures including LNG terminals and gas pipeline networks have also been lifted up to the national level since 2018.However,the research on the interoperability with overall-planning interchangeability and interconnection at a higher level is still in the blank stage at home.By extensively investigating EU's regulations and practices related to interoperability in the field of natural gas pipeline network,this paper put forward the conceptual definition of the interoperability of gas infrastructures including LNG terminals and gas pipeline networks for the first time.Then,the basic implementation framework and components of interoperability were set up.Finally,domestic latest typical cases which have presented the characteristics of interoperability in the recent two years were analyzed.And the following research results were obtained.First,interoperability and third-party access are two independent themes.Second,the target of interoperability is to realize the cross-system unimpeded flow of natural gas of all facility users between different facilities according to the uniform specification of specific technical standards,operation criteria and operation procedures of various facilities,based on interconnection,coordination and information interaction.Third,the framework of interoperability consists of 8 key elements,including gas quality standard&interchangeability,facility interconnection,facility interconnection agreement,unified measurement unit,unified electronic data exchange platform,technical capacity calculation method,approval procedure of LNG carrier entering the port and ship-shore compatibility unique to LNG terminals,and gas quality based LNG storage and tank loading rules.Fourth,it is recommended to give consideration to both target and requirement of interoperability and fully integrate 3 elements that are discussed more deeply and more crucial in EU countries(i.e.,facility interconnection agreement,unified electronic data exchange platform and technical capacity calculation method)into the practice system of treatment reform of domestic natural gas industry chain.展开更多
The transient simulation technology of natural gas pipeline networks plays an increasingly prominent role in the scheduling management of natural gas pipeline network system.The increasingly large and complex natural ...The transient simulation technology of natural gas pipeline networks plays an increasingly prominent role in the scheduling management of natural gas pipeline network system.The increasingly large and complex natural gas pipeline network requires more strictly on the calculation efficiency of transient simulation.To this end,this paper proposes a new method for the transient simulation of natural gas pipeline networks based on fracture-dimension-reduction algorithm.Firstly,a pipeline network model is abstracted into a station model,inter-station pipeline network model and connection node model.Secondlly,the pressure at the connection node connecting the station and the inter-station pipeline network is used as the basic variable to solve the general solution of the flow rate at the connection node,reconstruct the simulation model of the inter-station pipeline network,and reduce the equation set dimension of the inter-station pipeline network model.Thirdly,the transient simulation model of the natural gas pipeline network system is constructed based on the reconstructed simulation model of the inter-station pipeline network.Fnally,the calculation accuracy and efficiency of the proposed algorithm are compared and analyzed for the two working conditions of slow change of compressor speed and rapid shutdown of the compressor.And the following research results are obtained.First,the fracture-dimension-reduction algorithm has a high calculation accuracy,and the relative error of compressor outlet pressure and user pressure is less than 0.1%.Second,the calculation efficiency of the new fracture-dimension-reduction algorithm is high,and compared with the nonlinear equations solv ing method,the speed-up ratios under the two conditions are high up to 17.3 and 12.2 respectively.Third,the speed-up ratio of the fracture-dimension-reduction algorithm is linearly related to the equation set dimension of the transient simulation model of the pipeline network system.The larger the equation set dimension,the higher the speed-up ratio,which means the more complex the pipeline network model,the more remarkable the calculation speed-up effect.In conclusion,this new method improves the calculation speed while keeping the calculation accuracy,which is of great theoretical value and reference significance for improving the calculation efficiency of the transient simulation of complex natural gas pipeline network systems.展开更多
Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system....Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system. This paper discusses the use of simulation for performance analysis of transmission PNS. A simulation model was developed for determining flow and pressure variables for different configuration of PNS. The mathematical formulation for the simulation model was derived based on the principles of energy conservation, mass balance, and compressor characteristics. For the determination of the pressure and flow variables, solution procedure was developed based on iterative Newton Raphson scheme and implemented using visual C＋＋6. Evaluations of the simulation model with the existing pipeline network system showed that the model enabled to determine the operational variables with less than ten iterations. The performances of the compressor working in the pipeline network system xvhich includes energy consumption, compression ratio and discharge pressure were evaluated to meet pressure requirements ranging from 4000-5000 kPa at various speed. Results of the analyses from the simulation indicated that the model could be used for performance analysis to assist decisions regarding the design and optimal operations of transmission PNS.展开更多
This article shows a side segment of efforts toward finding ways to successfully commercialize a high tech product in Iran. During last decades, sanctions against importing petrochemical most used and needed utilities...This article shows a side segment of efforts toward finding ways to successfully commercialize a high tech product in Iran. During last decades, sanctions against importing petrochemical most used and needed utilities caused difficulties for Iranian petrochemical production chain. Inconveniences provoked Iranian specialists to achieve technical knowledge toward finding new ways of local producing. Attempting（s） had been encompassed to complete the whole chain of production and consumption inside of the country. Concepts implicate that during recent years, Iranian specialists have taken special steps toward localizing needed catalysts as an example of important commodities. Considerable amount of analyses have been made by Iranian petrochemical community probing the problems and obstacles associated with successful producing and what it really takes for a successful commercialization. Thematic analysis has been implicated as the research method to evaluate concepts represented as interviewees＇ analyzed declarations. Themes are analyzed toward mapping a successful merging with parties involved along with focusing on national commercializing streamline. Findings show that the idea of executing venture capital agencies as a new sector in the sequence of Iranian governmental and private petrochemical network has been appraised. Also, evaluating network management between parties involved and ways of policy making by the expert individuals are considered as the foremost factors to converse. Benchmarking feels as a necessary aspect as well to consider in the merging process. It has been concluded vital for Iranian companies to assess their own efficiency with accepted international standards, while on the other hand, they can take benchmark as a coming out opportunity when they commercialize in new intact market cooperating with renowned foreign companies.展开更多
China natural gas industry is at a turning point. Growth of mid-long term natural gas consumption may maintain at about 10%, supply is sufficient or even "over-sufficient", natural gas price will be determin...China natural gas industry is at a turning point. Growth of mid-long term natural gas consumption may maintain at about 10%, supply is sufficient or even "over-sufficient", natural gas price will be determined by competition, oil and gas pipeline facilities will be opened fairly, and private enterprises will play important roles in natural gas exploration, development, storage, transportation, and trade. It can been foreseen that China natural gas industry is very likely to take a turn in next 10 years, and a modern natural gas market with consumption about 500 billion cubic meters will come into being characterized by complete supervision system, diversified market, steady supply, fairly opened pipelines, transparent trading mechanism, and competitive prices.展开更多
Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into th...Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gas-water interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oil-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.展开更多
The acid gas absorption in four potassium based amino acid salt solutions was predicted using artificial neural network(ANN). Two hundred fifty-five experimental data points for CO_2 absorption in the four potassium b...The acid gas absorption in four potassium based amino acid salt solutions was predicted using artificial neural network(ANN). Two hundred fifty-five experimental data points for CO_2 absorption in the four potassium based amino acid salt solutions containing potassium lysinate, potassium prolinate, potassium glycinate, and potassium taurate were used in this modeling. Amine salt solution's type, temperature, equilibrium partial pressure of acid gas, the molar concentration of the solution, molecular weight, and the boiling point were considered as inputs to ANN to prognosticate the capacity of amino acid salt solution to absorb acid gas. Regression analysis was employed to assess the performance of the network. Levenberg–Marquardt back-propagation algorithm was used to train the optimal ANN with 5:12:1 architecture. The model findings indicated that the proposed ANN has the capability to predict precisely the absorption of acid gases in various amino acid salt solutions with Mean Square Error(MSE) value of 0.0011, the Average Absolute Relative Deviation(AARD) percent of 5.54%,and the correlation coefficient(R^2) of 0.9828.展开更多
文摘The transmission capacity of gas pipeline networks should be calculated and allocated to deal with the capacity booking with shippers. Technical capacities, which depend on the gas flow distribution at routes or interchange points, are calculated with a multiobjective optimization model and form a Pareto solution set in the entry/exit or point-to-point regime. Then, the commercial capacities, which can be directly applied in capacity booking, are calculated with single-objective optimization models that are transformed from the above multiobjective model based on three allocation rules and the demand of shippers.Next, peak-shaving capacities, which are daily oversupply or overdelivery amounts at inlets or deliveries,are calculated with two-stage transient optimization models. Considering the hydraulic process of a pipeline network and operating schemes of compressor stations, all the above models are mixed-integer nonlinear programming problems. Finally, a case study is made to demonstrate the ability of the models.
基金partially supported by the National Science Foundation of China(Grants 71822105 and 91746210)。
文摘In short-term operation of natural gas network,the impact of demand uncertainty is not negligible.To address this issue we propose a two-stage robust model for power cost minimization problem in gunbarrel natural gas networks.The demands between pipelines and compressor stations are uncertain with a budget parameter,since it is unlikely that all the uncertain demands reach the maximal deviation simultaneously.During solving the two-stage robust model we encounter a bilevel problem which is challenging to solve.We formulate it as a multi-dimensional dynamic programming problem and propose approximate dynamic programming methods to accelerate the calculation.Numerical results based on real network in China show that we obtain a speed gain of 7 times faster in average without compromising optimality compared with original dynamic programming algorithm.Numerical results also verify the advantage of robust model compared with deterministic model when facing uncertainties.These findings offer short-term operation methods for gunbarrel natural gas network management to handle with uncertainties.
基金supported by the Engineering and Physical Sciences Research Council(EPSRC,UK)in project“Street2Grid–an electricity blockchain platform for P2P energy trading”(No.EP/S001778/2).
文摘The variable and unpredictable nature of renewable energy generation(REG)presents challenges to its large-scale integration and the efficient and economic operation of the electricity network,particularly at the distribution level.In this paper,an operational coordination optimization method is proposed for the electricity and natural gas networks,aiming to overcome the identified negative impacts.The method involves the implementation of bi-directional energy flows through power-to-gas units and gas-fired power plants.A detailed model of the three-phase power distribution system up to each phase is employed to improve the representation of multi-energy systems to consider real-world end-user consumption.This method allows for the full consideration of unbalanced operational scenarios.Meanwhile,the natural gas network is modelled and analyzed with steady-state gas flows and the dynamics of the line pack in pipelines.The sequential symmetrical second-order cone programming(SS-SOCP)method is employed to facilitate the simultaneous analysis of three-phase imbalance and line pack while accelerating the solution process.The efficacy of the operational coordination optimization method is demonstrated in case studies comprising a modified IEEE 123-node power distribution system with a 20-node natural gas network.The studies show that the operational coordination optimization method can simultaneously minimize the total operational cost,the curtailment of installed REG,the voltage imbalance of three-phase power system,and the overall carbon emissions.
基金National Natural Science Foundation of China,Grant/Award Numbers:52307130,U22A6007Shanxi Province Science Foundation for Youths,Grant/Award Number:202303021212058。
文摘The energy transfer process of natural gas network(NGN)has remarkable dynamic characteristics.However,the model of the gas network dominated by partial differential equations(PDEs)is challenging to analyse due to its heterogeneous properties,high dimensionality,and significant non-linearity.To cope with the dynamic characteristics of the NGN effectively and accurately,the Schur complement-based dynamic flow calcu-lation method for the NGN is proposed in the paper.Firstly,a time-domain two-port model for the dynamic characteristics of the NGN is derived based on the finite dif-ference method in the Wendroff format.The PDEs are transformed into an easily solvable time-domain linear algebraic model while ensuring the accuracy of the computational results.To alleviate the computational burden,a numerical method based on the Schur complement strategy is then developed.By reducing the dimensions of the matrix equation,the computation speed can be dramatically improved.Finally,case an-alyses are carried out to emphasise the significance of consideration of the dynamic characteristics of NGNs and confirm the validity and precision of the developed approach.
基金supported by the State Key Program of National Natural Science Foundation of China(No.51437006)Guangdong Innovative Research Team Program(No.201001N0104744201)
文摘This paper develops a many-objective optimization model, which contains objectives representing the interests of the electricity and gas networks, as well as the distributed district heating and cooling units, to coordinate the benefits of all parties participated in the integrated energy system(IES). In order to solve the many-objective optimization model efficiently, an improved objective reduction(IOR) approach is proposed, aiming at acquiring the smallest set of objectives. The IOR approach utilizes the Spearman’s rank correlation coefficient to measure the relationship between objectives based on the Pareto-optimal front captured by the multi-objective group search optimizer with adaptive covariance and Lévy flights algorithm, and adopts various strategies to reduce the number of objectives gradually. Simulation studies are conducted on an IES consisting of a modified IEEE 30-bus electricity network and a 15-node gas network. The results show that the many-objective optimization problem is transformed into a bi-objective formulation by the IOR. Furthermore,our approach improves the overall quality of dispatch solutions and alleviates the decision making burden.
基金supported by National Key R&D Program of China(No.2019YFE0118000).
文摘An integrated energy system with multiple types of energy can support power shortages caused by the uncertainty of renewable energy.With full consideration of gas network constraints,this paper proposes a multi-energy inertia-based power support strategy.The definition and modelling of gas inertia are given first to demonstrate its ability to mitigate power fluctuations.Since partial utilization of gas inertia can influence overall gas network parameters,the gas network is modelled with an analysis of network dynamic changes.A multi-energy inertia-based power support model and strategy are then proposed for fully using gas-thermal inertia resources in integrated energy systems.The influence of gas network constraints on strategy,economy and power outputs is analyzed.Special circumstances where the gas network can be simplified are introduced.This improves the response speed and application value.The feasibility and effectiveness of the proposed strategy are assessed using a real scenario.
文摘This article describes numerical simulation of gas pipeline network operation using high-accuracy computational fluid dynamics (CFD) simulators of the modes of gas mixture transmission through long, multi-line pipeline systems (CFD-simulator). The approach used in CFD-simulators for modeling gas mixture transmission through long, branched, multi-section pipelines is based on tailoring the full system of fluid dynamics equations to conditions of unsteady, non-isothermal processes of the gas mixture flow. Identification, in a CFD-simulator, of safe parameters for gas transmission through compressor stations amounts to finding the interior points of admissible sets described by systems of nonlinear algebraic equalities and inequalities. Such systems of equalities and inequalities comprise a formal statement of technological, design, operational and other constraints to which operation of the network equipment is subject. To illustrate the practicability of the method of numerical simulation of a gas transmission network, we compare computation results and gas flow parameters measured on-site at the gas transmission enter-prise.
基金supported by National Natural Science Foundation of China[grant number 51904316]provided by China University of Petroleum,Beijing[grant number2462021YJRC013,2462020YXZZ045]
文摘An integrated dynamic model of natural gas pipeline networks is developed in this paper.Components for gas supply,e.g.,pipelines,junctions,compressor stations,LNG terminals,regulation stations and gas storage facilities are included in the model.These components are firstly modeled with respect to their properties and functions and,then,integrated at the system level by Graph Theory.The model can be used for simulating the system response in different scenarios of operation,and evaluate the consequences from the perspectives of supply security and resilience.A case study is considered to evaluate the accuracy of the model by benchmarking its results against those from literature and the software Pipeline Studio.Finally,the model is applied on a relatively complex natural gas pipeline network and the results are analyzed in detail from the supply security and resilience points of view.The main contributions of the paper are:firstly,a novel model of a complex gas pipeline network is proposed as a dynamic state-space model at system level;a method,based on the dynamic model,is proposed to analyze the security and resilience of supply from a system perspective.
文摘The optimiz at ion operation of gas pipeline network is investigated in this paper. Based on th e theories of system optimization and the multi object decision, a mathematical model about the multi object optimization operation of gas pipeline network is established, in line with the demand of urban gas pipeline network operation. A t the same time, an effective solution of the mathematical model is presented. A calculating software about optimization operation is compiled, coupling the actual operation of gas pipeline network. It can be applied to the operation of the gas pipeline network. The software was examined by real examples. The resul ts indicated that 2.13% energy consumption and 3.12% gas supply cost can be reduced through optimization operation.
文摘In this paper we discuss the uniqueness and existence of solution to a real gas flow network by employing graph theory. A directed graph is an efficient way to represent a gas network. We consider steady state real gas flow network that includes pipelines, compressors, and the connectors. The pipelines and compressors are represented as edges of the graph and the interconnecting points are represented as nodes of the graph representing the network. We show that a unique solution of such a system exists. We use monotonicity property of a mapping to proof uniqueness, and the contraction mapping theorem is used to prove existence.
文摘An array composed of sixteen gas sensors was constructed to analyze gas mixtures quantitatively. The data of responses from the sensor array to ethane, propane and propylene were treated by three-layer ANN with BP algorithms and PLS. The analytical results indicated that the concentration predicted with ANN is better than that with PLS. The average prediction errors for ethane, propane and propylene were 5.11%, 8.28%, 2.64%, respectively.
文摘In recent years, with the rapid development of economy and technology, many fields in China have been reformed and innovated and the urbanization process is advancing by leaps and bounds. Especially the intelligent city construction has begun to take shape. Water network, power grid and gas network are the basic guarantee of peoples daily life. Perfecting urban infrastructure construction is an important content to improve peoples quality of life and accelerate the development of urban informatization. Urban gas pipeline network is laid in various underground cities. Intricate is an important channel for gas supply due to a series of problems such as uneven gas construction quality, difficult problem troubleshooting, complex operation of gas equipment and slow data update and scheduling. As a result, pipeline leakage and safety accidents occur frequently. Therefore, promoting the intelligentization of urban gas pipeline network operation and management is the key to current work. In the current electrical engineering field, intelligent technology shows positive advantages, mainly reflected in data collection, storage and editing and automation of gas pipeline network. This paper analyzes the advantages of intelligent management and the application of intelligent and automatic technology in the operation and management of urban gas pipeline network based on the current operation status of urban gas pipeline network.
文摘Gas has brought convenience to people’s life at present, and gas pipeline networks and ancillary facilities play important roles in city construction. However, there are increasingly prominent safety problems in operation. The safe operation of gas pipeline networks in cities has been influenced by various aspects of factors, leading to frequent gas accidents, which give rise to serious influences on supply of gas. For this reason, detailed analysis has been conducted to problems related to safe operation of gas pipeline networks in cities in this article, and corresponding solutions are proposed.
文摘The interchangeability between natural gas of different sources and LNG have been concerned and tackled to a certain extent at home,and the interconnection of gas infrastructures including LNG terminals and gas pipeline networks have also been lifted up to the national level since 2018.However,the research on the interoperability with overall-planning interchangeability and interconnection at a higher level is still in the blank stage at home.By extensively investigating EU's regulations and practices related to interoperability in the field of natural gas pipeline network,this paper put forward the conceptual definition of the interoperability of gas infrastructures including LNG terminals and gas pipeline networks for the first time.Then,the basic implementation framework and components of interoperability were set up.Finally,domestic latest typical cases which have presented the characteristics of interoperability in the recent two years were analyzed.And the following research results were obtained.First,interoperability and third-party access are two independent themes.Second,the target of interoperability is to realize the cross-system unimpeded flow of natural gas of all facility users between different facilities according to the uniform specification of specific technical standards,operation criteria and operation procedures of various facilities,based on interconnection,coordination and information interaction.Third,the framework of interoperability consists of 8 key elements,including gas quality standard&interchangeability,facility interconnection,facility interconnection agreement,unified measurement unit,unified electronic data exchange platform,technical capacity calculation method,approval procedure of LNG carrier entering the port and ship-shore compatibility unique to LNG terminals,and gas quality based LNG storage and tank loading rules.Fourth,it is recommended to give consideration to both target and requirement of interoperability and fully integrate 3 elements that are discussed more deeply and more crucial in EU countries(i.e.,facility interconnection agreement,unified electronic data exchange platform and technical capacity calculation method)into the practice system of treatment reform of domestic natural gas industry chain.
文摘The transient simulation technology of natural gas pipeline networks plays an increasingly prominent role in the scheduling management of natural gas pipeline network system.The increasingly large and complex natural gas pipeline network requires more strictly on the calculation efficiency of transient simulation.To this end,this paper proposes a new method for the transient simulation of natural gas pipeline networks based on fracture-dimension-reduction algorithm.Firstly,a pipeline network model is abstracted into a station model,inter-station pipeline network model and connection node model.Secondlly,the pressure at the connection node connecting the station and the inter-station pipeline network is used as the basic variable to solve the general solution of the flow rate at the connection node,reconstruct the simulation model of the inter-station pipeline network,and reduce the equation set dimension of the inter-station pipeline network model.Thirdly,the transient simulation model of the natural gas pipeline network system is constructed based on the reconstructed simulation model of the inter-station pipeline network.Fnally,the calculation accuracy and efficiency of the proposed algorithm are compared and analyzed for the two working conditions of slow change of compressor speed and rapid shutdown of the compressor.And the following research results are obtained.First,the fracture-dimension-reduction algorithm has a high calculation accuracy,and the relative error of compressor outlet pressure and user pressure is less than 0.1%.Second,the calculation efficiency of the new fracture-dimension-reduction algorithm is high,and compared with the nonlinear equations solv ing method,the speed-up ratios under the two conditions are high up to 17.3 and 12.2 respectively.Third,the speed-up ratio of the fracture-dimension-reduction algorithm is linearly related to the equation set dimension of the transient simulation model of the pipeline network system.The larger the equation set dimension,the higher the speed-up ratio,which means the more complex the pipeline network model,the more remarkable the calculation speed-up effect.In conclusion,this new method improves the calculation speed while keeping the calculation accuracy,which is of great theoretical value and reference significance for improving the calculation efficiency of the transient simulation of complex natural gas pipeline network systems.
文摘Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system. This paper discusses the use of simulation for performance analysis of transmission PNS. A simulation model was developed for determining flow and pressure variables for different configuration of PNS. The mathematical formulation for the simulation model was derived based on the principles of energy conservation, mass balance, and compressor characteristics. For the determination of the pressure and flow variables, solution procedure was developed based on iterative Newton Raphson scheme and implemented using visual C＋＋6. Evaluations of the simulation model with the existing pipeline network system showed that the model enabled to determine the operational variables with less than ten iterations. The performances of the compressor working in the pipeline network system xvhich includes energy consumption, compression ratio and discharge pressure were evaluated to meet pressure requirements ranging from 4000-5000 kPa at various speed. Results of the analyses from the simulation indicated that the model could be used for performance analysis to assist decisions regarding the design and optimal operations of transmission PNS.
文摘This article shows a side segment of efforts toward finding ways to successfully commercialize a high tech product in Iran. During last decades, sanctions against importing petrochemical most used and needed utilities caused difficulties for Iranian petrochemical production chain. Inconveniences provoked Iranian specialists to achieve technical knowledge toward finding new ways of local producing. Attempting（s） had been encompassed to complete the whole chain of production and consumption inside of the country. Concepts implicate that during recent years, Iranian specialists have taken special steps toward localizing needed catalysts as an example of important commodities. Considerable amount of analyses have been made by Iranian petrochemical community probing the problems and obstacles associated with successful producing and what it really takes for a successful commercialization. Thematic analysis has been implicated as the research method to evaluate concepts represented as interviewees＇ analyzed declarations. Themes are analyzed toward mapping a successful merging with parties involved along with focusing on national commercializing streamline. Findings show that the idea of executing venture capital agencies as a new sector in the sequence of Iranian governmental and private petrochemical network has been appraised. Also, evaluating network management between parties involved and ways of policy making by the expert individuals are considered as the foremost factors to converse. Benchmarking feels as a necessary aspect as well to consider in the merging process. It has been concluded vital for Iranian companies to assess their own efficiency with accepted international standards, while on the other hand, they can take benchmark as a coming out opportunity when they commercialize in new intact market cooperating with renowned foreign companies.
文摘China natural gas industry is at a turning point. Growth of mid-long term natural gas consumption may maintain at about 10%, supply is sufficient or even "over-sufficient", natural gas price will be determined by competition, oil and gas pipeline facilities will be opened fairly, and private enterprises will play important roles in natural gas exploration, development, storage, transportation, and trade. It can been foreseen that China natural gas industry is very likely to take a turn in next 10 years, and a modern natural gas market with consumption about 500 billion cubic meters will come into being characterized by complete supervision system, diversified market, steady supply, fairly opened pipelines, transparent trading mechanism, and competitive prices.
文摘Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gas-water interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oil-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.
文摘The acid gas absorption in four potassium based amino acid salt solutions was predicted using artificial neural network(ANN). Two hundred fifty-five experimental data points for CO_2 absorption in the four potassium based amino acid salt solutions containing potassium lysinate, potassium prolinate, potassium glycinate, and potassium taurate were used in this modeling. Amine salt solution's type, temperature, equilibrium partial pressure of acid gas, the molar concentration of the solution, molecular weight, and the boiling point were considered as inputs to ANN to prognosticate the capacity of amino acid salt solution to absorb acid gas. Regression analysis was employed to assess the performance of the network. Levenberg–Marquardt back-propagation algorithm was used to train the optimal ANN with 5:12:1 architecture. The model findings indicated that the proposed ANN has the capability to predict precisely the absorption of acid gases in various amino acid salt solutions with Mean Square Error(MSE) value of 0.0011, the Average Absolute Relative Deviation(AARD) percent of 5.54%,and the correlation coefficient(R^2) of 0.9828.
