Battery energy storage system(BESS)is one of the effective technologies to deal with power fluctuation and intermittence resulting from grid integration of large renewable generations.In this paper,the system configur...Battery energy storage system(BESS)is one of the effective technologies to deal with power fluctuation and intermittence resulting from grid integration of large renewable generations.In this paper,the system configuration of a China’s national renewable generation demonstration project combining a large-scale BESS with wind farm and photovoltaic(PV)power station,all coupled to a power transmission system,is introduced,and the key technologies including optimal control and management as well as operational status of this BESS are presented.Additionally,the technical benefits of such a large-scale BESS in dealing with power fluctuation and intermittence issues resulting from grid connection of large-scale renewable generation,and for improvement of operation characteristics of transmission grid,are discussed with relevant case studies.展开更多
Transmission network expansion can significantly improve the penetration level of renewable generation.However,existing studies have not explicitly revealed and quantified the trade-off between the investment cost and...Transmission network expansion can significantly improve the penetration level of renewable generation.However,existing studies have not explicitly revealed and quantified the trade-off between the investment cost and penetration level of renewable generation.This paper proposes a distributionally robust optimization model to minimize the cost of transmission network expansion under uncertainty and maximize the penetration level of renewable generation.The proposed model includes distributionally robust joint chance constraints,which maximize the minimum expectation of the renewable utilization probability among a set of certain probability distributions within an ambiguity set.The proposed formulation yields a twostage robust optimization model with variable bounds of the uncertain sets,which is hard to solve.By applying the affine decision rule,second-order conic reformulation,and duality,we reformulate it into a single-stage standard robust optimization model and solve it efficiently via commercial solvers.Case studies are carried on the Garver 6-bus and IEEE 118-bus systems to illustrate the validity of the proposed method.展开更多
This study designs and proposes a method for evaluating the configuration of energy storage for integrated re-newable generation plants in the power spot market,which adopts a two-level optimization model of“system s...This study designs and proposes a method for evaluating the configuration of energy storage for integrated re-newable generation plants in the power spot market,which adopts a two-level optimization model of“system simulation+plant optimization”.The first step is“system simulation”which is using the power market simu-lation model to obtain the initial nodal marginal price and curtailment of the integrated renewable generation plant.The second step is“plant optimization”which is using the operation optimization model of the integrated renewable generation plant to optimize the charge-discharge operation of energy storage.In the third step,“sys-tem simulation”is conducted again,and the combined power of renewable and energy storage inside the plant is brought into the system model and simulated again for 8,760 h of power market year-round to quantify and compare the power generation and revenue of the integrated renewable generation plant after applying energy storage.In the case analysis of the provincial power spot market,an empirical analysis of a 1 GW wind-solar-storage integrated generation plant was conducted.The results show that the economic benefit of energy storage is approximately proportional to its capacity and that there is a slowdown in the growth of economic benefits when the capacity is too large.In the case that the investment benefit of energy storage only considers the in-come of electric energy-related incomes and does not consider the income of capacity mechanism and auxiliary services,the income of energy storage cannot fulfill the economic requirements of energy storage investment.展开更多
The penetration of renewable generation will affect the energy utilization efficiency,economic benefit and reliability of the active distribution network(ADN).This paper proposes a time-sequence production simulation(...The penetration of renewable generation will affect the energy utilization efficiency,economic benefit and reliability of the active distribution network(ADN).This paper proposes a time-sequence production simulation(TSPS)method for re-newable generation capacity and reliability assessments in ADN considering two operational status:the normal status and the fault status.During normal operation,an optimal dispatch model is proposed to promote the renewable consumption and increase the economic benefit.When a failure occurs,the renewable generators are partitioned into islands for resilient power supply and reliability improvement.A novel dynamic island partition model is presented based on mixed integer second-order cone programming(MISOCP).The effectiveness of the proposed TSPS method is demonstrated in a standard network integrated with historical data of load and renewable generations.展开更多
A large amount of renewable energy generation(REG)has been integrated into power systems,challenging the operational security of power networks.In a real-time dispatch,system operators need to estimate the ability of ...A large amount of renewable energy generation(REG)has been integrated into power systems,challenging the operational security of power networks.In a real-time dispatch,system operators need to estimate the ability of the power network to accommodate REG with a limited reserve capacity.The real-time dispatchable region(RTDR)is defined as the largest range of a power injection that the power network can accommodate in a certain dispatch interval for a given dispatch base point.State-of-the-art research on the RTDR adopts a DC power flow model regardless of the voltage profiles and reactive power,which can overlook potentially insecure operational states of the system.To address this issue,this paper proposes an AC power flow based RTDR model simultaneously considering the reactive power and voltage profiles constraints.The nonlinear constraints in our model are approximated using a linear power flow model together with a polytope approximation technique for quadratic constraints.An adaptive constraint generation algorithm is used to calculate the RTDR.Simulation results using the IEEE 5-bus and 30-bus systems illustrate the advantages of the proposed model.展开更多
Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents...Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents an equivalent modeling method for the AC-DC power networks with doubly-fed induction generator(DFIG)based wind farms to decrease the simulation scale and computational burden.For the AC-DC power networks,the equivalent modeling strategy in accordance with the physical structure simplification is stated.Regarding the DFIG-based wind farms,the equivalent modeling based on the sequential identification of multi-machine parameters using the improved chaotic cuckoo search algorithm(ICCSA)is conducted.In light of the MATLAB simulation platform,a two-zone four-DC interconnected power grid with wind farms is built to check the efficacy of the proposed equivalentmodelingmethod.Fromthe simulation analyses and comparative validation in different algorithms and cases,the proposed method can precisely reflect the steady and dynamic performance of the demonstrated system under N-1 and N-2 fault scenarios,and it can efficiently achieve the parameter identification of the wind farms and fulfill the equivalent modeling.Consequently,the proposed approach’s effectiveness and suitability are confirmed.展开更多
On March 19, the construction of a 10-MW photovoltaic power plant and a 1 000-kW new type geothermal power generation project were started by Guodian Longyuan Group in Yanbajing Town, Dangxiong County of Tibet.
The phase-locked loop(PLL)plays an essential role for synchronizing renewable power generation to the grid.However,as per the grid-code compliance for reactive current support,the PLL output frequency fluctuates signi...The phase-locked loop(PLL)plays an essential role for synchronizing renewable power generation to the grid.However,as per the grid-code compliance for reactive current support,the PLL output frequency fluctuates significantly and exceeds the limitation,which seriously threaten the safe supply of electricity.In this paper,the underlying theoretical mechanism and dominant force behind the maximum PLL frequency deviation are revealed.Accordingly,two feasible approaches are proposed to enhance the PLL frequency stability with validations in experimental results.展开更多
This paper proposes an optimal configuration of the distributed hybrid renewable generations based on the stand-alone micro-grid system, considering the diesel as the main control source. Due to the natural sources an...This paper proposes an optimal configuration of the distributed hybrid renewable generations based on the stand-alone micro-grid system, considering the diesel as the main control source. Due to the natural sources and load of user changes randomly and the non-tinearity of the power output by renewable generations, an intelligent optimization method based on the improvement of the genetic algorithm and the control strategy are discussed. The instance analysis is compared with the optimization result of the hybrid system based on HOMER （hybrid optimization of multiple energy resources） and GA （genetic algorithm） method on Matlab software. The simulation result of the optimal configuration showed the new hybrid renewable system and would improve the power supply situation which decreased the cost of energy greatly compared with the conventional form of power supply system which was operated only by diesel. The conclusion of the comparing result between HOMER and GA method shows the advantages of the strategy for the diesel as main control sources.展开更多
Renewable energy transmission by high-voltage direct current(HVDC)has attracted increasing attention for the development and utilization of large-scale renewable energy under the Carbon Peak and Carbon Neutrality Stra...Renewable energy transmission by high-voltage direct current(HVDC)has attracted increasing attention for the development and utilization of large-scale renewable energy under the Carbon Peak and Carbon Neutrality Strategy in China.High-penetration power electronic systems(HPPESs)have gradually formed at the sending end of HVDC transmission.The operation of such systems has undergone profound changes compared with traditional power systems dominated by synchronous generators.New stability issues,such as broadband oscillation and transient over-voltage,have emerged,causing tripping accidents in large-scale renewable energy plants.The analysis methods and design principles of traditional power systems are no longer suitable for HPPESs.In this paper,the mechanisms of broadband oscillation and transient over-voltage are revealed,and analytical methods are proposed for HPPESs,including small-signal impedance analysis and electromagnetic transient simulation.Validation of the theoretical research has been accomplished through its application in several practical projects in north,northwest,and northeast region of China.Finally,suggestions for the construction and operation of the future renewable-energy-dominated power system are put forward.展开更多
The data-driven approaches have been extensively developed for multi-operation impedance modeling of the renewable power generation equipment(RPGE).However,due to the black box of RPGE,the dataset used for establishin...The data-driven approaches have been extensively developed for multi-operation impedance modeling of the renewable power generation equipment(RPGE).However,due to the black box of RPGE,the dataset used for establishing impedance model lacks theoretical guidance for data generation,which reduces data quality and results in a large amount of data redundancy.To address this issue,this paper proposes an impedance dataset optimization method for data-driven modeling of RPGE considering multi-operation conditions.The objective is to improve the data quality of the impedance dataset,thereby reflecting the overall impedance characteristics with a reduced data amount.Firstly,the impact of operation conditions on impedance is evaluated to optimize the selection of operating points.Secondly,at each operating point,the frequency distribution is designed to reveal the impedance characteristics with fewer measurement points.Finally,a serial update method for measured datasets and the multi-operation impedance model is developed to further refine the dataset.The experiments based on control-hardware-in-loop(CHIL)are conducted to verify the effectiveness of the proposed method.展开更多
A modular system of cascaded converters based on model predictive control(MPC)is proposed to meet the application requirements ofmultiple voltage levels and electrical isolation in renewable energy generation systems....A modular system of cascaded converters based on model predictive control(MPC)is proposed to meet the application requirements ofmultiple voltage levels and electrical isolation in renewable energy generation systems.The system consists of a Buck/Boost+CLLLC cascaded converter as a submodule,which is combined in series and parallel on the input and output sides to achieve direct-current(DC)voltage transformation,bidirectional energy flow,and electrical isolation.The CLLLC converter operates in DC transformer mode in the submodule,while the Buck/Boost converter participates in voltage regulation.This article establishes a suitable mathematical model for the proposed system topology,and uses MPC to control the system based on this mathematical model.Module parameters are designed and calculated,and simulation is built in MATLAB/Simulink to complete the simulation comparison experiment between MPC and traditional proportional integral(PI)control.Finally,a physical experimental platform is built to complete the physical comparison experiment.The simulation and physical experimental results prove that the control accuracy and response speed ofMPC are better than traditional PI control strategy.展开更多
This research focuses on restructuring medium-level voltage(MLV)distribution systems by integrating distributed renewable energy resources(DER)at multiple feed points.It examines the impact of incorporating renewable ...This research focuses on restructuring medium-level voltage(MLV)distribution systems by integrating distributed renewable energy resources(DER)at multiple feed points.It examines the impact of incorporating renewable energy and evaluates system performance metrics such as robustness,static voltage stability,line carrying capacity,utility grid effectiveness,and losses within the conventional radial distribution framework commonly used in educational institutions.The contingency ranking of the real-time radial distribution system(RTRDS)for a typical educational institution consisting of N buses was conducted.Parameters such as the Voltage Performance Index(PIV)and Flow Performance Index(PIF)were evaluated.The results support the integration of distributed renewable energy sources within the existing radial distribution grid infrastructure.This research proposes enhanced contingency analyses through a straightforward reconfiguration process involving an additional tie line(Nþ1)for the existing N bus radial distribution system(RDS).Load flow analysis of the RDS with distributed renewable energy resources(DER)for both N bus and Nþ1 bus systems was conducted using the Gauss-Seidel and Newton–Raphson methods.Simulation results indicate that baseline loading is consistently maintained by grid sources and DER sources connected at multiple feed points.The proposed configuration of the Nþ1 bus system for the existing RTRDS was evaluated for voltage performance and compared with the Grey Wolf Optimization(GWO)algorithm.The results indicate that the Nþ1 bus configuration modeled using the MiPower tool performed comparably to the GWO results.Additionally,the contingency ranking for the proposed Nþ1 configuration was validated using the IEEE 10 and 30 bus system.展开更多
Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at t...Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at the unit-level,manifesting as local resonances.However,conventional equivalent methods can only simulate plant-level instability,but cannot consider such unit-level instability.To address this problem,the main contributions of this paper are as follows:1)Based on the impedance matrix and the eigenvalue analysis,the reason why conventional equivalent methods cannot accurately simulate unitlevel stability is studied.2)A double-machine equivalent method is proposed.The model used in this method is a minimumscale equivalent model capable of simulating plant-level and unit-level stability,simultaneously.It uses two single-machine models to represent a generation cluster containing N generation units.A single-machine model M_(1) represents N—1 generation units for simplification,while another single-machine model M_(2) represents the remaining one generation unit for simulating unitlevel stability.3)Furthermore,a practical improvement approach of the double-machine equivalent method is proposed for taking into account operating point differences and complex connection conditions.Finally,the proposed method is verified by simulations and experiments.展开更多
Energy flexibility can address the challenges of large scale integration of renewable energy resources and thereby increasing imbalance in the power system. Flexible power system can provide reliable supply, low elect...Energy flexibility can address the challenges of large scale integration of renewable energy resources and thereby increasing imbalance in the power system. Flexible power system can provide reliable supply, low electricity cost and sustainability. Various situations and factors influence the adoption of the flexibility solutions, such as flexible electricity generation, demand-response, and electricity storage. This paper tries to analyze the current energy flexibility solutions and the factors that can influence the energy flexibility adoption. This paper takes Philippines as case study to provide an overview of the current condition of the Philippines＇ power system and discuss the energy flexibility in the Philippines＇ power system. A further discussion and recommendation is conducted in the end of the paper.展开更多
Large-scale hybrid power plants, composed of two or more generation sources and with the participation of energy storage systems, have driven important electricity Market Design regulation discussions worldwide. Regul...Large-scale hybrid power plants, composed of two or more generation sources and with the participation of energy storage systems, have driven important electricity Market Design regulation discussions worldwide. Regulatory framework ought to be adapted to support technical particularities of these new generation arranges. This paper presents an assessment of the main requirements to be met by Market Design to enable hybrid power plants by means of assertive market incentives. Assessing regulatory adjustments promoted in Australia, United States, India, China, and Brazil, emphasizing the latter one, the authors presents a case study by applying specific computational simulation and optimization model to a hybrid Hydro-Solar plant, that supports the findings for the necessary evolution needed in the national regulatory framework in order to enable hybrid projects. The evaluation of international experiences indicates that the insertion of hybrid projects is associated with the design of the market they belong to and demand regulatory adjustments so that their attributes can be properly valued for the benefit of all stakeholders, especially for the electricity consumer.展开更多
Power systems are moving toward a low-carbon or carbon-neutral future where high penetration of renewables is expected.With conventional fossil-fueled synchronous generators in the transmission network being replaced ...Power systems are moving toward a low-carbon or carbon-neutral future where high penetration of renewables is expected.With conventional fossil-fueled synchronous generators in the transmission network being replaced by renewable energy generation which is highly distributed across the entire grid,new challenges are emerging to the control and stability of large-scale power systems.New analysis and control methods are needed for power systems to cope with the ongoing transformation.In the CSEE JPES forum,six leading experts were invited to deliver keynote speeches,and the participating researchers and professionals had extensive exchanges and discussions on the control and stability of power systems.Specifically,potential changes and challenges of power systems with high penetration of renewable energy generation were introduced and explained,and advanced control methods were proposed and analyzed for the transient stability enhancement of power grids.展开更多
With the growing penetration of renewable energysources in power systems, it becomes increasingly important tocharacterize their inherent variability and uncertainty. Scenariogeneration is a key approach to provide a ...With the growing penetration of renewable energysources in power systems, it becomes increasingly important tocharacterize their inherent variability and uncertainty. Scenariogeneration is a key approach to provide a series of possible powerscenarios in the future for the system planner and operator tomake decisions. In this paper, a data-driven method is presentedfor renewable scenario generation using stable and controllablegenerative adversarial networks with transparent latent space(ctrl-GANs). The machine learning based algorithm can capturethe nonlinear and dynamic renewable patterns without the needfor modeling assumptions and complicated sampling techniques.The orthogonal regularization and spectral normalization areadopted to improve the training stabilization of the GAN model.To control the generation process, a relationship is built betweenfeatures of the generated scenarios and latent vectors on themanifold. Moreover, several new metrics for GANs are used toevaluate the quality of the scenarios. The proposed approachis applied to generate realistic time series data of wind andphotovoltaic power. The results demonstrate that our methodhas a better performance on numerical stabilization and is ableto control the generation process with latent space.展开更多
Due to the high penetration of renewable distributed generation(RDG),many issues have become conspicuous during the intentional island operation such as the power mismatch of load shedding during the transition proces...Due to the high penetration of renewable distributed generation(RDG),many issues have become conspicuous during the intentional island operation such as the power mismatch of load shedding during the transition process and the power imbalance during the restoration process.In this paper,a phase measurement unit(PMU)based online load shedding strategy and a conservation voltage reduction(CVR)based multi-period restoration strategy are proposed for the intentional island with RDG.The proposed load shedding strategy,which is driven by the blackout event,consists of the load shedding optimization and correction table.Before the occurrence of the large-scale blackout,the load shedding optimization is solved periodically to obtain the optimal load shedding plan,which meets the dynamic and steady constraints.When the blackout occurs,the correction table updated in real time based on the PMU data is used to modify the load shedding plan to eliminate the power mismatch caused by the fluctuation of RDG.After the system transits to the intentional island seamlessly,multi-period restoration plans are generated to optimize the restoration performance while maintaining power balance until the main grid is repaired.Besides,CVR technology is implemented to restore more loads by regulating load demand.The proposed load shedding optimization and restoration optimization are linearized to mixed-integer quadratic constraint programming(MIQCP)models.The effectiveness of the proposed strategies is verified with the modified IEEE 33-node system on the real-time digital simulation(RTDS)platform.展开更多
The competition among renewable power producers(RPPs)may cause the cleared power of RPPs to be less than the bidding power,while the impact of competition is neglected in the existing price-taker methods.To overcome t...The competition among renewable power producers(RPPs)may cause the cleared power of RPPs to be less than the bidding power,while the impact of competition is neglected in the existing price-taker methods.To overcome the above deficiency,this paper develops an optimal bidding strategy,considering the competition among RPPs.First,a bivariate stochastic optimization(BSO)model for a bidding strategy is proposed by considering the variable power output of RPPs and the competition among RPPs.Particularly,the cleared power estimated by the demand-supply ratio is a random variable in the proposed BSO model.Then,the Newton method and particle swarm optimization(PSO)are combined to solve the BSO model in which various probability distribution functions(PDFs)of renewable energy generation are considered.Finally,the effectiveness of the proposed method is verified based on the results of a case study,which shows that the proposed model performed better than the traditional chance-constrained programming(CCP)model in power market competition.展开更多
基金supported by National Natural Science Foundation of China(No.51107126 and No.512111046)the Key Projects in National Science and Technology Pillar Program(No.2011BAA07B07)+1 种基金the Beiing Nova Program(No.Z141101001814094)the Science and Technology Foundation of State Grid Corporation of China(No.DG71-14-032)
文摘Battery energy storage system(BESS)is one of the effective technologies to deal with power fluctuation and intermittence resulting from grid integration of large renewable generations.In this paper,the system configuration of a China’s national renewable generation demonstration project combining a large-scale BESS with wind farm and photovoltaic(PV)power station,all coupled to a power transmission system,is introduced,and the key technologies including optimal control and management as well as operational status of this BESS are presented.Additionally,the technical benefits of such a large-scale BESS in dealing with power fluctuation and intermittence issues resulting from grid connection of large-scale renewable generation,and for improvement of operation characteristics of transmission grid,are discussed with relevant case studies.
基金supported by the National Natural Science Foundation of China(No.52077136)。
文摘Transmission network expansion can significantly improve the penetration level of renewable generation.However,existing studies have not explicitly revealed and quantified the trade-off between the investment cost and penetration level of renewable generation.This paper proposes a distributionally robust optimization model to minimize the cost of transmission network expansion under uncertainty and maximize the penetration level of renewable generation.The proposed model includes distributionally robust joint chance constraints,which maximize the minimum expectation of the renewable utilization probability among a set of certain probability distributions within an ambiguity set.The proposed formulation yields a twostage robust optimization model with variable bounds of the uncertain sets,which is hard to solve.By applying the affine decision rule,second-order conic reformulation,and duality,we reformulate it into a single-stage standard robust optimization model and solve it efficiently via commercial solvers.Case studies are carried on the Garver 6-bus and IEEE 118-bus systems to illustrate the validity of the proposed method.
基金funded by the China Energy Investment Cor-poration under the program“Simulation of energy storage application scenarios in China and research on development strategy of China En-ergy Investment Corporation”(Grant No.:GJNY-21-143).
文摘This study designs and proposes a method for evaluating the configuration of energy storage for integrated re-newable generation plants in the power spot market,which adopts a two-level optimization model of“system simulation+plant optimization”.The first step is“system simulation”which is using the power market simu-lation model to obtain the initial nodal marginal price and curtailment of the integrated renewable generation plant.The second step is“plant optimization”which is using the operation optimization model of the integrated renewable generation plant to optimize the charge-discharge operation of energy storage.In the third step,“sys-tem simulation”is conducted again,and the combined power of renewable and energy storage inside the plant is brought into the system model and simulated again for 8,760 h of power market year-round to quantify and compare the power generation and revenue of the integrated renewable generation plant after applying energy storage.In the case analysis of the provincial power spot market,an empirical analysis of a 1 GW wind-solar-storage integrated generation plant was conducted.The results show that the economic benefit of energy storage is approximately proportional to its capacity and that there is a slowdown in the growth of economic benefits when the capacity is too large.In the case that the investment benefit of energy storage only considers the in-come of electric energy-related incomes and does not consider the income of capacity mechanism and auxiliary services,the income of energy storage cannot fulfill the economic requirements of energy storage investment.
基金This work was supported in part by the National Key Research and Development Program of China(Grant No.2016YFB0900100)the National Natural Science Foundation of China(Grant No.51807051)the Natural Science Foundation of Jiangsu Province(Grant No.BK20180507).
文摘The penetration of renewable generation will affect the energy utilization efficiency,economic benefit and reliability of the active distribution network(ADN).This paper proposes a time-sequence production simulation(TSPS)method for re-newable generation capacity and reliability assessments in ADN considering two operational status:the normal status and the fault status.During normal operation,an optimal dispatch model is proposed to promote the renewable consumption and increase the economic benefit.When a failure occurs,the renewable generators are partitioned into islands for resilient power supply and reliability improvement.A novel dynamic island partition model is presented based on mixed integer second-order cone programming(MISOCP).The effectiveness of the proposed TSPS method is demonstrated in a standard network integrated with historical data of load and renewable generations.
基金This work was supported in part by the Science and Technology Program of Guangzhou under Grant 201904010215the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources under Grant LAPS19011the Fundamental Research Funds for the Central Universities.
文摘A large amount of renewable energy generation(REG)has been integrated into power systems,challenging the operational security of power networks.In a real-time dispatch,system operators need to estimate the ability of the power network to accommodate REG with a limited reserve capacity.The real-time dispatchable region(RTDR)is defined as the largest range of a power injection that the power network can accommodate in a certain dispatch interval for a given dispatch base point.State-of-the-art research on the RTDR adopts a DC power flow model regardless of the voltage profiles and reactive power,which can overlook potentially insecure operational states of the system.To address this issue,this paper proposes an AC power flow based RTDR model simultaneously considering the reactive power and voltage profiles constraints.The nonlinear constraints in our model are approximated using a linear power flow model together with a polytope approximation technique for quadratic constraints.An adaptive constraint generation algorithm is used to calculate the RTDR.Simulation results using the IEEE 5-bus and 30-bus systems illustrate the advantages of the proposed model.
基金supported by the Science and Technology Project of Central China Branch of State Grid Corporation of China under 5214JS220010.
文摘Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents an equivalent modeling method for the AC-DC power networks with doubly-fed induction generator(DFIG)based wind farms to decrease the simulation scale and computational burden.For the AC-DC power networks,the equivalent modeling strategy in accordance with the physical structure simplification is stated.Regarding the DFIG-based wind farms,the equivalent modeling based on the sequential identification of multi-machine parameters using the improved chaotic cuckoo search algorithm(ICCSA)is conducted.In light of the MATLAB simulation platform,a two-zone four-DC interconnected power grid with wind farms is built to check the efficacy of the proposed equivalentmodelingmethod.Fromthe simulation analyses and comparative validation in different algorithms and cases,the proposed method can precisely reflect the steady and dynamic performance of the demonstrated system under N-1 and N-2 fault scenarios,and it can efficiently achieve the parameter identification of the wind farms and fulfill the equivalent modeling.Consequently,the proposed approach’s effectiveness and suitability are confirmed.
文摘On March 19, the construction of a 10-MW photovoltaic power plant and a 1 000-kW new type geothermal power generation project were started by Guodian Longyuan Group in Yanbajing Town, Dangxiong County of Tibet.
基金supported by the National Natural Science Foundation of China under Grant 52407069the Science and Technology Project of Zhejiang Province under Grant 2024C01254the China Postdoctoral Science Foundation under Grant 2024T170766 and 2024M762824。
文摘The phase-locked loop(PLL)plays an essential role for synchronizing renewable power generation to the grid.However,as per the grid-code compliance for reactive current support,the PLL output frequency fluctuates significantly and exceeds the limitation,which seriously threaten the safe supply of electricity.In this paper,the underlying theoretical mechanism and dominant force behind the maximum PLL frequency deviation are revealed.Accordingly,two feasible approaches are proposed to enhance the PLL frequency stability with validations in experimental results.
文摘This paper proposes an optimal configuration of the distributed hybrid renewable generations based on the stand-alone micro-grid system, considering the diesel as the main control source. Due to the natural sources and load of user changes randomly and the non-tinearity of the power output by renewable generations, an intelligent optimization method based on the improvement of the genetic algorithm and the control strategy are discussed. The instance analysis is compared with the optimization result of the hybrid system based on HOMER （hybrid optimization of multiple energy resources） and GA （genetic algorithm） method on Matlab software. The simulation result of the optimal configuration showed the new hybrid renewable system and would improve the power supply situation which decreased the cost of energy greatly compared with the conventional form of power supply system which was operated only by diesel. The conclusion of the comparing result between HOMER and GA method shows the advantages of the strategy for the diesel as main control sources.
基金This work is funded by National Key Research and Development Program of China(2021 YFB2400500).The authors would like to thank Guoqing He,Haijiao Wang,Yuntao Xiao,and Yuqi Duan for their contributions in research review,field test verification,and data analysis.
文摘Renewable energy transmission by high-voltage direct current(HVDC)has attracted increasing attention for the development and utilization of large-scale renewable energy under the Carbon Peak and Carbon Neutrality Strategy in China.High-penetration power electronic systems(HPPESs)have gradually formed at the sending end of HVDC transmission.The operation of such systems has undergone profound changes compared with traditional power systems dominated by synchronous generators.New stability issues,such as broadband oscillation and transient over-voltage,have emerged,causing tripping accidents in large-scale renewable energy plants.The analysis methods and design principles of traditional power systems are no longer suitable for HPPESs.In this paper,the mechanisms of broadband oscillation and transient over-voltage are revealed,and analytical methods are proposed for HPPESs,including small-signal impedance analysis and electromagnetic transient simulation.Validation of the theoretical research has been accomplished through its application in several practical projects in north,northwest,and northeast region of China.Finally,suggestions for the construction and operation of the future renewable-energy-dominated power system are put forward.
基金supported by the National Natural Science Foundation of China(No.52325702)。
文摘The data-driven approaches have been extensively developed for multi-operation impedance modeling of the renewable power generation equipment(RPGE).However,due to the black box of RPGE,the dataset used for establishing impedance model lacks theoretical guidance for data generation,which reduces data quality and results in a large amount of data redundancy.To address this issue,this paper proposes an impedance dataset optimization method for data-driven modeling of RPGE considering multi-operation conditions.The objective is to improve the data quality of the impedance dataset,thereby reflecting the overall impedance characteristics with a reduced data amount.Firstly,the impact of operation conditions on impedance is evaluated to optimize the selection of operating points.Secondly,at each operating point,the frequency distribution is designed to reveal the impedance characteristics with fewer measurement points.Finally,a serial update method for measured datasets and the multi-operation impedance model is developed to further refine the dataset.The experiments based on control-hardware-in-loop(CHIL)are conducted to verify the effectiveness of the proposed method.
基金supported by the National Key Research and Development Plan,Grant/Award Number:2018YFB1503005.
文摘A modular system of cascaded converters based on model predictive control(MPC)is proposed to meet the application requirements ofmultiple voltage levels and electrical isolation in renewable energy generation systems.The system consists of a Buck/Boost+CLLLC cascaded converter as a submodule,which is combined in series and parallel on the input and output sides to achieve direct-current(DC)voltage transformation,bidirectional energy flow,and electrical isolation.The CLLLC converter operates in DC transformer mode in the submodule,while the Buck/Boost converter participates in voltage regulation.This article establishes a suitable mathematical model for the proposed system topology,and uses MPC to control the system based on this mathematical model.Module parameters are designed and calculated,and simulation is built in MATLAB/Simulink to complete the simulation comparison experiment between MPC and traditional proportional integral(PI)control.Finally,a physical experimental platform is built to complete the physical comparison experiment.The simulation and physical experimental results prove that the control accuracy and response speed ofMPC are better than traditional PI control strategy.
文摘This research focuses on restructuring medium-level voltage(MLV)distribution systems by integrating distributed renewable energy resources(DER)at multiple feed points.It examines the impact of incorporating renewable energy and evaluates system performance metrics such as robustness,static voltage stability,line carrying capacity,utility grid effectiveness,and losses within the conventional radial distribution framework commonly used in educational institutions.The contingency ranking of the real-time radial distribution system(RTRDS)for a typical educational institution consisting of N buses was conducted.Parameters such as the Voltage Performance Index(PIV)and Flow Performance Index(PIF)were evaluated.The results support the integration of distributed renewable energy sources within the existing radial distribution grid infrastructure.This research proposes enhanced contingency analyses through a straightforward reconfiguration process involving an additional tie line(Nþ1)for the existing N bus radial distribution system(RDS).Load flow analysis of the RDS with distributed renewable energy resources(DER)for both N bus and Nþ1 bus systems was conducted using the Gauss-Seidel and Newton–Raphson methods.Simulation results indicate that baseline loading is consistently maintained by grid sources and DER sources connected at multiple feed points.The proposed configuration of the Nþ1 bus system for the existing RTRDS was evaluated for voltage performance and compared with the Grey Wolf Optimization(GWO)algorithm.The results indicate that the Nþ1 bus configuration modeled using the MiPower tool performed comparably to the GWO results.Additionally,the contingency ranking for the proposed Nþ1 configuration was validated using the IEEE 10 and 30 bus system.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U23A20655)the Science and Technology Tackling Plan Project of Anhui Province(202423h08050008)the Science and Technology Project of State Grid Anhui Electric Power Co.,Ltd.(SGAHDK00CNJS2500397).
文摘Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at the unit-level,manifesting as local resonances.However,conventional equivalent methods can only simulate plant-level instability,but cannot consider such unit-level instability.To address this problem,the main contributions of this paper are as follows:1)Based on the impedance matrix and the eigenvalue analysis,the reason why conventional equivalent methods cannot accurately simulate unitlevel stability is studied.2)A double-machine equivalent method is proposed.The model used in this method is a minimumscale equivalent model capable of simulating plant-level and unit-level stability,simultaneously.It uses two single-machine models to represent a generation cluster containing N generation units.A single-machine model M_(1) represents N—1 generation units for simplification,while another single-machine model M_(2) represents the remaining one generation unit for simulating unitlevel stability.3)Furthermore,a practical improvement approach of the double-machine equivalent method is proposed for taking into account operating point differences and complex connection conditions.Finally,the proposed method is verified by simulations and experiments.
文摘Energy flexibility can address the challenges of large scale integration of renewable energy resources and thereby increasing imbalance in the power system. Flexible power system can provide reliable supply, low electricity cost and sustainability. Various situations and factors influence the adoption of the flexibility solutions, such as flexible electricity generation, demand-response, and electricity storage. This paper tries to analyze the current energy flexibility solutions and the factors that can influence the energy flexibility adoption. This paper takes Philippines as case study to provide an overview of the current condition of the Philippines＇ power system and discuss the energy flexibility in the Philippines＇ power system. A further discussion and recommendation is conducted in the end of the paper.
文摘Large-scale hybrid power plants, composed of two or more generation sources and with the participation of energy storage systems, have driven important electricity Market Design regulation discussions worldwide. Regulatory framework ought to be adapted to support technical particularities of these new generation arranges. This paper presents an assessment of the main requirements to be met by Market Design to enable hybrid power plants by means of assertive market incentives. Assessing regulatory adjustments promoted in Australia, United States, India, China, and Brazil, emphasizing the latter one, the authors presents a case study by applying specific computational simulation and optimization model to a hybrid Hydro-Solar plant, that supports the findings for the necessary evolution needed in the national regulatory framework in order to enable hybrid projects. The evaluation of international experiences indicates that the insertion of hybrid projects is associated with the design of the market they belong to and demand regulatory adjustments so that their attributes can be properly valued for the benefit of all stakeholders, especially for the electricity consumer.
文摘Power systems are moving toward a low-carbon or carbon-neutral future where high penetration of renewables is expected.With conventional fossil-fueled synchronous generators in the transmission network being replaced by renewable energy generation which is highly distributed across the entire grid,new challenges are emerging to the control and stability of large-scale power systems.New analysis and control methods are needed for power systems to cope with the ongoing transformation.In the CSEE JPES forum,six leading experts were invited to deliver keynote speeches,and the participating researchers and professionals had extensive exchanges and discussions on the control and stability of power systems.Specifically,potential changes and challenges of power systems with high penetration of renewable energy generation were introduced and explained,and advanced control methods were proposed and analyzed for the transient stability enhancement of power grids.
基金the National Key Research and Development Program of China under Grant 2018AAA0101505.
文摘With the growing penetration of renewable energysources in power systems, it becomes increasingly important tocharacterize their inherent variability and uncertainty. Scenariogeneration is a key approach to provide a series of possible powerscenarios in the future for the system planner and operator tomake decisions. In this paper, a data-driven method is presentedfor renewable scenario generation using stable and controllablegenerative adversarial networks with transparent latent space(ctrl-GANs). The machine learning based algorithm can capturethe nonlinear and dynamic renewable patterns without the needfor modeling assumptions and complicated sampling techniques.The orthogonal regularization and spectral normalization areadopted to improve the training stabilization of the GAN model.To control the generation process, a relationship is built betweenfeatures of the generated scenarios and latent vectors on themanifold. Moreover, several new metrics for GANs are used toevaluate the quality of the scenarios. The proposed approachis applied to generate realistic time series data of wind andphotovoltaic power. The results demonstrate that our methodhas a better performance on numerical stabilization and is ableto control the generation process with latent space.
基金This work was supported in part by the National Key R&D Program of China(No.2017YFB0902900)the National Natural Science Foundation of China(No.51707136)the Natural Science Foundation of Hubei Province(No.2018CFA080).
文摘Due to the high penetration of renewable distributed generation(RDG),many issues have become conspicuous during the intentional island operation such as the power mismatch of load shedding during the transition process and the power imbalance during the restoration process.In this paper,a phase measurement unit(PMU)based online load shedding strategy and a conservation voltage reduction(CVR)based multi-period restoration strategy are proposed for the intentional island with RDG.The proposed load shedding strategy,which is driven by the blackout event,consists of the load shedding optimization and correction table.Before the occurrence of the large-scale blackout,the load shedding optimization is solved periodically to obtain the optimal load shedding plan,which meets the dynamic and steady constraints.When the blackout occurs,the correction table updated in real time based on the PMU data is used to modify the load shedding plan to eliminate the power mismatch caused by the fluctuation of RDG.After the system transits to the intentional island seamlessly,multi-period restoration plans are generated to optimize the restoration performance while maintaining power balance until the main grid is repaired.Besides,CVR technology is implemented to restore more loads by regulating load demand.The proposed load shedding optimization and restoration optimization are linearized to mixed-integer quadratic constraint programming(MIQCP)models.The effectiveness of the proposed strategies is verified with the modified IEEE 33-node system on the real-time digital simulation(RTDS)platform.
基金supported by National Key R&D Program of China(Technology and application of wind power/photovoltaic power prediction for promoting renewable energy consumption,2018YFB0904200)Eponymous Complement S&T Program of State Grid Corporation of China(SGLNDKOOKJJS1800266)。
文摘The competition among renewable power producers(RPPs)may cause the cleared power of RPPs to be less than the bidding power,while the impact of competition is neglected in the existing price-taker methods.To overcome the above deficiency,this paper develops an optimal bidding strategy,considering the competition among RPPs.First,a bivariate stochastic optimization(BSO)model for a bidding strategy is proposed by considering the variable power output of RPPs and the competition among RPPs.Particularly,the cleared power estimated by the demand-supply ratio is a random variable in the proposed BSO model.Then,the Newton method and particle swarm optimization(PSO)are combined to solve the BSO model in which various probability distribution functions(PDFs)of renewable energy generation are considered.Finally,the effectiveness of the proposed method is verified based on the results of a case study,which shows that the proposed model performed better than the traditional chance-constrained programming(CCP)model in power market competition.
