With the development of The Times, the computer automatic control technology has been applied to every corner of life and production. Many industries are beginning to use automatic or semi-automatic production lines t...With the development of The Times, the computer automatic control technology has been applied to every corner of life and production. Many industries are beginning to use automatic or semi-automatic production lines to improve production efficiency. In the manufacturing process of industrial gas, the traditional production mode has been unable to meet the needs of modern production. This design will be applied to the automatic control system for industrial gas production process. This paper first introduces the background of this design, and then briefly introduces the composition and work flow of the air separation device. Finally, the design of the measurement and control system, the design of the anti-surge control valve and the control logic design of the anti-surge control valve are introduced in three aspects of this design.展开更多
Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by...Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by analyzing the existing methods, some optimized methods are adopted. Considering safety, those methods are improved in data processing algorithms, floating threshold with multiple values, association with specific working condition, etc. These measures im- prove the nuclear instrument control system in fault tolerance and fault diagnosis, especially, the shutdown number of nucle- ar power plant decreases.展开更多
A novel distributed model predictive control scheme based on dynamic integrated system optimization and parameter estimation （DISOPE） was proposed for nonlinear cascade systems under network environment. Under the d...A novel distributed model predictive control scheme based on dynamic integrated system optimization and parameter estimation （DISOPE） was proposed for nonlinear cascade systems under network environment. Under the distributed control structure, online optimization of the cascade system was composed of several cascaded agents that can cooperate and exchange information via network communication. By iterating on modified distributed linear optimal control problems on the basis of estimating parameters at every iteration the correct optimal control action of the nonlinear model predictive control problem of the cascade system could be obtained, assuming that the algorithm was convergent. This approach avoids solving the complex nonlinear optimization problem and significantly reduces the computational burden. The simulation results of the fossil fuel power unit are illustrated to verify the effectiveness and practicability of the proposed algorithm.展开更多
A new kind of dynamic neural network--diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct...A new kind of dynamic neural network--diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.展开更多
To address the problems of torque limit and controller saturation in the control of robot arm joint,an anti-windup control strategy is proposed for a humanoid robot arm,which is based on the integral state prediction ...To address the problems of torque limit and controller saturation in the control of robot arm joint,an anti-windup control strategy is proposed for a humanoid robot arm,which is based on the integral state prediction under the direct torque control system of brushless DC motor. First,the arm joint of the humanoid robot is modelled. Then the speed controller model and the influence of the initial value of the integral element on the system are analyzed. On the basis of the traditional antiwindup controller,an integral state estimator is set up. Under the condition of different load torques and the given speed,the integral steady-state value is estimated. Therefore the accumulation of the speed error terminates when the integrator reaches saturation. Then the predicted integral steady-state value is used as the initial value of the regulator to enter the linear region to make the system achieve the purpose of anti-windup. The simulation results demonstrate that the control strategy for the humanoid robot arm joint based on integral state prediction can play the role of anti-windup and suppress the overshoot of the system effectively. The system has a good dynamic performance.展开更多
The PLC and upper computer are used in BOP control system of traditional thermal power plant to monitor the in-situ equipment. It is complicated and wastes labor and resources. It is difficult to maintain and manage t...The PLC and upper computer are used in BOP control system of traditional thermal power plant to monitor the in-situ equipment. It is complicated and wastes labor and resources. It is difficult to maintain and manage them. Beijing GuoDian ZhiShen Control Technology applied the homemade DCS (EDPF-NT System) to the integrated BOP control system of 600-MW supercritical power unit, which offers advantages in efficiency promotion, cost reduction and resource sharing. That also reflects the dominance of EDPF-NT System in performance, price, real-time DUP, network compatibility and communication. This article introduces the main characteristics, structure and configuration of EDPF-NT System, as well as the hierarchical operation, the multi-domain network structure and the private network router developed for Zhuanghe Power Plant.展开更多
The power-electronics-based DC microgrid system composed of new energy sources in railway field has low inertia,weak damping characteristics,and the voltage fluctuation microgrid systems caused by the power disturbanc...The power-electronics-based DC microgrid system composed of new energy sources in railway field has low inertia,weak damping characteristics,and the voltage fluctuation microgrid systems caused by the power disturbance of solar.In order to improve the inertia of the DC microgrid system,a virtual DC generator technology is adopted in the interface converter of photovoltaic(PV)power generation unit,so that it has the external characteristics of DC generator.However,the influence of PV maximum power point tracking(MPPT)is not considered in the traditional virtual DC generator control.Therefore,an improved control strategy for virtual DC generator is proposed,and its small signal model is established to analyze the influence of inertia and damping coefficient on stability.The results show that the proposed method effectively weakens the impact on DC bus voltage when the output of PV power unit changes suddenly,which improves the stability of the microgrid.Meanwhile,the correctness and feasibility of the method are verified.展开更多
Grid-forming(GFM)converters are recognized for their stabilizing effects in renewable energy systems.Integrating GFM converters into high-voltage direct current(HVDC)systems requires DC voltage control.However,there c...Grid-forming(GFM)converters are recognized for their stabilizing effects in renewable energy systems.Integrating GFM converters into high-voltage direct current(HVDC)systems requires DC voltage control.However,there can be a conflict between GFM converter and DC voltage control when they are used in combination.This paper presents a rigorous control design for a GFM converter that connects the DC-link voltage to the power angle of the converter,thereby integrating DC voltage control with GFM capability.The proposed control is validated through small-signal and transient-stability analyses on a modular multilevel converter(MMC)-based HVDC system with a point-to-point(P2P)GFM-GFM configuration.The results demonstrate that employing a GFM-GFM configuration with the proposed control enhances the stability of the AC system to which it is connected.The system exhibits low sensitivity to grid strength and can sustain islanding conditions.The high stability limit of the system with varying grid strength using the proposed control is validated using a system with four voltage source converters.展开更多
This paper presents an analysis of the KM （Karnik-Mendel） algorithms performance under real time implementation using 3 types： the non-iterative, the iterative and the enhanced, and their feasibility for real-time ...This paper presents an analysis of the KM （Karnik-Mendel） algorithms performance under real time implementation using 3 types： the non-iterative, the iterative and the enhanced, and their feasibility for real-time interval type 2 fuzzy logic control system applications. The results are also compared against NT （Nie-Tan） method that is one of the fastest and simplest defuzzification methods. Because the DC （direct current） servo-motor is one of the most used motors in different industrial applications and the model of the motor is nonlinear, this motor was selected for validating the implementation in real time hardware. This DC motor is a perfect option for studying the real time performance of KM algorithms in order to show up its limits and possibilities for real-time control system applications. These methodologies are implemented in National Instruments LabVIEW FPGA （field programmable gate array） module hardware which is one of the most used platforms in the industry. The results show that the E-KM （enhanced KM） algorithm and the NT method present good results for implementing real-time control applications in real time hardware. Although fuzzy logic type 2 is a good option for working with nonlinear and noise from the sensors, the defuzzification method has to react in a short period of time in order to allow good control response. Hence, a complete study of defuzzification is needed for improving the real time implementations of fuzzy type 2.展开更多
There are issues with flexible DC transmission system such as a lack of control freedom over power flow.In order to tackle these issues,a DC power flow controller(DCPFC)is incorporated into a multi-terminal,flexible D...There are issues with flexible DC transmission system such as a lack of control freedom over power flow.In order to tackle these issues,a DC power flow controller(DCPFC)is incorporated into a multi-terminal,flexible DC power grid.In recent years,a multi-port DC power flow controller based on a modular multi-level converter has become a focal point of research due to its simple structure and robust scalability.This work proposes a model predictive control(MPC)strategy for multi-port interline DC power flow controllers in order to improve their steady-state dynamic performance.Initially,the mathematical model of a multi-terminal DC power grid with a multi-port interline DC power flow controller is developed,and the relationship between each regulated variable and control variable is determined;The power flow controller is then discretized,and the cost function and weight factor are built with numerous control objectives.Sub module sorting method and nearest level approximation modulation regulate the power flow controller;Lastly,theMATLAB/Simulink simulation platformis used to verify the correctness of the establishedmathematicalmodel and the control performance of the suggestedMPC strategy.Finally,it is demonstrated that the control strategy possesses the benefits of robust dynamic performance,multiobjective control,and a simple structure.展开更多
In this study,the Stokes formula is used to analyze the separation effect of three-phase separators used in a Oilfield Central Processing Facility.The considered main influencing factors include(but are not limited to...In this study,the Stokes formula is used to analyze the separation effect of three-phase separators used in a Oilfield Central Processing Facility.The considered main influencing factors include(but are not limited to)the typical size of oil and water droplets,the residence time and temperature of fluid and the dosage of demulsifier.Using the“Specification for Oil and Gas Separators”as a basis,the control loops and operating parameters of each separator are optimized Considering the Halfaya Oilfield as a testbed,it is shown that the proposed approach can lead to good results in the production stage.展开更多
This paper presents sliding mode technique associated to the direct torque control （DTC） for an isolated-loaded permanent magnet synchronous generator （PMSG）. The machine delivers an active power to a DC-load via ...This paper presents sliding mode technique associated to the direct torque control （DTC） for an isolated-loaded permanent magnet synchronous generator （PMSG）. The machine delivers an active power to a DC-load via a converter connected to a single capacitor on the DC side. Since the converter/capacitor model is nonlinear, the sliding mode technique constitutes a powerful tool to ensure the DC-bus voltage regulation. The computer simulations are provided to verify the validity of the proposed control algorithm.展开更多
Large-scale renewable energy transmission via thevoltage source converter (VSC) based high-voltage direct current(HVDC) is a crucial development direction for constructing anew-typed power system in China. However, re...Large-scale renewable energy transmission via thevoltage source converter (VSC) based high-voltage direct current(HVDC) is a crucial development direction for constructing anew-typed power system in China. However, renewable energy ischaracterized by volatility, intermittency, and randomness. Whenthe sending-end modular multilevel converter (MMC) cannotadapt to the rapid fluctuations in renewable energy output, itsenergy balance will be disrupted by the active power differencebetween the AC and DC sides, causing issues such as widebandoscillations and exacerbated circulating currents. To solve theproblem mentioned above, a novel energy balance-based controlmethod for MMCs connected to wind farms is proposed in thispaper, enabling the MMC to effectively adapt to fluctuationsin renewable energy output and naturally maintain circulatingcurrent at a relatively low level. Firstly, the evolution principleillustrating topology decomposition and reconfiguration of theMMC is revealed. Secondly, the control method for AC internalvoltage is proposed, which combines the energy balance betweenthe half MMCs and voltage amplitude support. Thirdly, the DCinternal voltage is defined, and its control method is proposedbased on the MMC’s overall energy balance. Then, independentcontrol of each bridge arm is achieved by integrating the energybalance of the bridge arms with both the AC and DC internalvoltages. Finally, an electromagnetic transient simulation modelis built with PSCAD/EMTDC, and the efficacy and practicalityof the proposed method are demonstrated through extensivesimulation experiments.展开更多
In series-connected-based offshore wind farms(SCOWFs),the bulky offshore platform,step-up transformer,and high voltage and large-scale converters can be eliminated.In SC-OWFs,grounding fault is an inevitable issue.In ...In series-connected-based offshore wind farms(SCOWFs),the bulky offshore platform,step-up transformer,and high voltage and large-scale converters can be eliminated.In SC-OWFs,grounding fault is an inevitable issue.In this study,the mathematical model of DC link in SC-OWFs is established.On this basis,this paper reveals characteristic of grounding faults in SC-OWFs and proposes a DC link current control strategy,consisting of feedback and feedforward control.Based on DC link current control and protection method,faulty part isolation from SC-OWF can be realized,and unfaulty part will operate normally.Finally,simulation and experimental results prove feasibility of the proposed DC control strategy and fault current calculation method.展开更多
An equivalent source-load MTDC system including DC voltage control units,power control units and interconnected DC lines is considered in this paper,which can be regarded as a generic structure of low-voltage DC micro...An equivalent source-load MTDC system including DC voltage control units,power control units and interconnected DC lines is considered in this paper,which can be regarded as a generic structure of low-voltage DC microgrids,mediumvoltage DC distribution systems or HVDC transmission systems with a common DC bus.A reduced-order model is proposed with a circuit structure of a resistor,inductor and capacitor in parallel for dynamic stability analysis of the system in DC voltage control timescale.The relationship between control parameters and physical parameters of the equivalent circuit can be found,which provides an intuitive insight into the physical meaning of control parameters.Employing this model,a second-order characteristic equation is further derived to investigate system dynamic stability mechanisms in an analytical approach.As a result,the system oscillation frequency and damping are characterized in a straight forward manner,and the role of electrical and control parameters and different system-level control strategies in system dynamic stability in DC voltage control timescale is defined.The effectiveness of the proposed reduced-order model and the correctness of the theoretical analysis are verified by simulation based on PSCAD/EMTDC and an experiment based on a hardware low-voltage MTDC system platform.展开更多
Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular mul...Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular multilevel converter(MMC)has become the basic building block for MTDC and DC grids due to its salient features,i.e.,modularity and scalability.Therefore,the MMC-based MTDC systems should be pervasively embedded into the present power system to improve system performance.However,several technical challenges hamper their practical applications and deployment,including modeling,control,and protection of the MMC-MTDC grids.This paper presents a comprehensive investigation and reference in modeling,control,and protection of the MMC-MTDC grids.A general overview of state-of-the-art modeling techniques of the MMC along with their performance in simulation analysis for MTDC applications is provided.A review of control strategies of the MMC-MTDC grids which provide AC system support is presented.State-of-the art protection techniques of the MMCMTDC systems are also investigated.Finally,the associated research challenges and trends are highlighted.展开更多
This paper study and solve the design and manufacture of baby care car, its unique function is the baby carriage can be used as a baby bed, when necessary, it can also become a nursing car, sensor in the vehicle can b...This paper study and solve the design and manufacture of baby care car, its unique function is the baby carriage can be used as a baby bed, when necessary, it can also become a nursing car, sensor in the vehicle can be real-time detected whether the baby bed wetting and induction time will give parents information feedback; the humidity sensing probe controlled by single chip microcomputer and with the bottle clamp flexible connecting rod, can realize the baby auxiliary nurse; remote wireless commtmication system can allow parents to monitor children＇ s state. The design of intelligent baby carriage, to enhance the technological content of products, promote the innovation of design China bassinet production, has the important practical significance to seize the smart baby car market.展开更多
The present paper addresses an advanced teaching lab consisting of setting up an islanded production unit. This teaching lab takes place in the very last semester at master level for students in electrical engineering...The present paper addresses an advanced teaching lab consisting of setting up an islanded production unit. This teaching lab takes place in the very last semester at master level for students in electrical engineering with energy specialization. The purpose of this teaching lab is to combine knowledge learned in different areas such as power electronics, control, electrical machines and networks, and make use of all of them in practice. The present paper describes in detail the different steps followed by the student to set up an islanded production unit.展开更多
The cluster DC voltage balancing control adopting zero-sequence voltage injection is appropriate for the starconnected cascaded H-bridge STATCOM because no zerosequence currents are generated in the three-phase three-...The cluster DC voltage balancing control adopting zero-sequence voltage injection is appropriate for the starconnected cascaded H-bridge STATCOM because no zerosequence currents are generated in the three-phase three-wire system.However,as the zero-sequence voltage is expressed in trigonometric form,traditional control methods involve many complicated operations,such as the square-root,trigonometric operations,and inverse tangent operations.To simplify cluster voltage balancing control,this paper converts the zero-sequence voltage to the dq frame in a DC representation by introducing a virtually orthogonal variable,and the DC components of the zero-sequence voltage in the dq frame are regulated linearly by proportional integral regulators,rather than being calculated from uneven active powers in traditional controls.This removes all complicated operations.Finally,this paper presents simulation and experimental results for a 400 V±7.5 kvar star-connected STATCOM,in balanced and unbalanced scenarios,thereby verifying the effectiveness of the proposed control.展开更多
文摘With the development of The Times, the computer automatic control technology has been applied to every corner of life and production. Many industries are beginning to use automatic or semi-automatic production lines to improve production efficiency. In the manufacturing process of industrial gas, the traditional production mode has been unable to meet the needs of modern production. This design will be applied to the automatic control system for industrial gas production process. This paper first introduces the background of this design, and then briefly introduces the composition and work flow of the air separation device. Finally, the design of the measurement and control system, the design of the anti-surge control valve and the control logic design of the anti-surge control valve are introduced in three aspects of this design.
基金Research Project of Hunan Province Education Department(No.14C0972)
文摘Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by analyzing the existing methods, some optimized methods are adopted. Considering safety, those methods are improved in data processing algorithms, floating threshold with multiple values, association with specific working condition, etc. These measures im- prove the nuclear instrument control system in fault tolerance and fault diagnosis, especially, the shutdown number of nucle- ar power plant decreases.
基金This work was supportedbytheNationalNaturalScienceFoundationofChina(No.60474051),theProgramforNewCenturyExcellentTalentsinUniversityofChina(NCET),andtheSpecializedResearchFundfortheDoctoralProgramofHigherEducationofChina(No.20020248028).
文摘A novel distributed model predictive control scheme based on dynamic integrated system optimization and parameter estimation （DISOPE） was proposed for nonlinear cascade systems under network environment. Under the distributed control structure, online optimization of the cascade system was composed of several cascaded agents that can cooperate and exchange information via network communication. By iterating on modified distributed linear optimal control problems on the basis of estimating parameters at every iteration the correct optimal control action of the nonlinear model predictive control problem of the cascade system could be obtained, assuming that the algorithm was convergent. This approach avoids solving the complex nonlinear optimization problem and significantly reduces the computational burden. The simulation results of the fossil fuel power unit are illustrated to verify the effectiveness and practicability of the proposed algorithm.
文摘A new kind of dynamic neural network--diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.
基金Supported by the National Natural Science Foundation of China(61175090,61703249)Shandong Provincial Natural Science Foundation,China(ZR2017MF045)
文摘To address the problems of torque limit and controller saturation in the control of robot arm joint,an anti-windup control strategy is proposed for a humanoid robot arm,which is based on the integral state prediction under the direct torque control system of brushless DC motor. First,the arm joint of the humanoid robot is modelled. Then the speed controller model and the influence of the initial value of the integral element on the system are analyzed. On the basis of the traditional antiwindup controller,an integral state estimator is set up. Under the condition of different load torques and the given speed,the integral steady-state value is estimated. Therefore the accumulation of the speed error terminates when the integrator reaches saturation. Then the predicted integral steady-state value is used as the initial value of the regulator to enter the linear region to make the system achieve the purpose of anti-windup. The simulation results demonstrate that the control strategy for the humanoid robot arm joint based on integral state prediction can play the role of anti-windup and suppress the overshoot of the system effectively. The system has a good dynamic performance.
文摘The PLC and upper computer are used in BOP control system of traditional thermal power plant to monitor the in-situ equipment. It is complicated and wastes labor and resources. It is difficult to maintain and manage them. Beijing GuoDian ZhiShen Control Technology applied the homemade DCS (EDPF-NT System) to the integrated BOP control system of 600-MW supercritical power unit, which offers advantages in efficiency promotion, cost reduction and resource sharing. That also reflects the dominance of EDPF-NT System in performance, price, real-time DUP, network compatibility and communication. This article introduces the main characteristics, structure and configuration of EDPF-NT System, as well as the hierarchical operation, the multi-domain network structure and the private network router developed for Zhuanghe Power Plant.
基金supported by National Natural Science Foundation of China(No.52067013)Natural Science Foundation of Gansu Province(No.20JR5RA395)Tianyou Innovation Team of Lanzhou Jiaotong University(No.TY202010).
文摘The power-electronics-based DC microgrid system composed of new energy sources in railway field has low inertia,weak damping characteristics,and the voltage fluctuation microgrid systems caused by the power disturbance of solar.In order to improve the inertia of the DC microgrid system,a virtual DC generator technology is adopted in the interface converter of photovoltaic(PV)power generation unit,so that it has the external characteristics of DC generator.However,the influence of PV maximum power point tracking(MPPT)is not considered in the traditional virtual DC generator control.Therefore,an improved control strategy for virtual DC generator is proposed,and its small signal model is established to analyze the influence of inertia and damping coefficient on stability.The results show that the proposed method effectively weakens the impact on DC bus voltage when the output of PV power unit changes suddenly,which improves the stability of the microgrid.Meanwhile,the correctness and feasibility of the method are verified.
基金developed during the DICIT project sponsored by a public grant overseen by the French National Research Agency(No.ANR-20-CE05-0034 DICIT)。
文摘Grid-forming(GFM)converters are recognized for their stabilizing effects in renewable energy systems.Integrating GFM converters into high-voltage direct current(HVDC)systems requires DC voltage control.However,there can be a conflict between GFM converter and DC voltage control when they are used in combination.This paper presents a rigorous control design for a GFM converter that connects the DC-link voltage to the power angle of the converter,thereby integrating DC voltage control with GFM capability.The proposed control is validated through small-signal and transient-stability analyses on a modular multilevel converter(MMC)-based HVDC system with a point-to-point(P2P)GFM-GFM configuration.The results demonstrate that employing a GFM-GFM configuration with the proposed control enhances the stability of the AC system to which it is connected.The system exhibits low sensitivity to grid strength and can sustain islanding conditions.The high stability limit of the system with varying grid strength using the proposed control is validated using a system with four voltage source converters.
文摘This paper presents an analysis of the KM （Karnik-Mendel） algorithms performance under real time implementation using 3 types： the non-iterative, the iterative and the enhanced, and their feasibility for real-time interval type 2 fuzzy logic control system applications. The results are also compared against NT （Nie-Tan） method that is one of the fastest and simplest defuzzification methods. Because the DC （direct current） servo-motor is one of the most used motors in different industrial applications and the model of the motor is nonlinear, this motor was selected for validating the implementation in real time hardware. This DC motor is a perfect option for studying the real time performance of KM algorithms in order to show up its limits and possibilities for real-time control system applications. These methodologies are implemented in National Instruments LabVIEW FPGA （field programmable gate array） module hardware which is one of the most used platforms in the industry. The results show that the E-KM （enhanced KM） algorithm and the NT method present good results for implementing real-time control applications in real time hardware. Although fuzzy logic type 2 is a good option for working with nonlinear and noise from the sensors, the defuzzification method has to react in a short period of time in order to allow good control response. Hence, a complete study of defuzzification is needed for improving the real time implementations of fuzzy type 2.
基金funded by National Natural Science Foundation of China (52177074).
文摘There are issues with flexible DC transmission system such as a lack of control freedom over power flow.In order to tackle these issues,a DC power flow controller(DCPFC)is incorporated into a multi-terminal,flexible DC power grid.In recent years,a multi-port DC power flow controller based on a modular multi-level converter has become a focal point of research due to its simple structure and robust scalability.This work proposes a model predictive control(MPC)strategy for multi-port interline DC power flow controllers in order to improve their steady-state dynamic performance.Initially,the mathematical model of a multi-terminal DC power grid with a multi-port interline DC power flow controller is developed,and the relationship between each regulated variable and control variable is determined;The power flow controller is then discretized,and the cost function and weight factor are built with numerous control objectives.Sub module sorting method and nearest level approximation modulation regulate the power flow controller;Lastly,theMATLAB/Simulink simulation platformis used to verify the correctness of the establishedmathematicalmodel and the control performance of the suggestedMPC strategy.Finally,it is demonstrated that the control strategy possesses the benefits of robust dynamic performance,multiobjective control,and a simple structure.
基金This study was supported by the Natural Science Foundation of Shandong Province(Grant No.ZR2021QE030).
文摘In this study,the Stokes formula is used to analyze the separation effect of three-phase separators used in a Oilfield Central Processing Facility.The considered main influencing factors include(but are not limited to)the typical size of oil and water droplets,the residence time and temperature of fluid and the dosage of demulsifier.Using the“Specification for Oil and Gas Separators”as a basis,the control loops and operating parameters of each separator are optimized Considering the Halfaya Oilfield as a testbed,it is shown that the proposed approach can lead to good results in the production stage.
文摘This paper presents sliding mode technique associated to the direct torque control （DTC） for an isolated-loaded permanent magnet synchronous generator （PMSG）. The machine delivers an active power to a DC-load via a converter connected to a single capacitor on the DC side. Since the converter/capacitor model is nonlinear, the sliding mode technique constitutes a powerful tool to ensure the DC-bus voltage regulation. The computer simulations are provided to verify the validity of the proposed control algorithm.
基金supported by the National NaturalScience Foundation of China (No. 52277075), and Postgraduate ScientificResearch Innovation Project of Changsha University of Science & Technology(No. CSLGCX23062).
文摘Large-scale renewable energy transmission via thevoltage source converter (VSC) based high-voltage direct current(HVDC) is a crucial development direction for constructing anew-typed power system in China. However, renewable energy ischaracterized by volatility, intermittency, and randomness. Whenthe sending-end modular multilevel converter (MMC) cannotadapt to the rapid fluctuations in renewable energy output, itsenergy balance will be disrupted by the active power differencebetween the AC and DC sides, causing issues such as widebandoscillations and exacerbated circulating currents. To solve theproblem mentioned above, a novel energy balance-based controlmethod for MMCs connected to wind farms is proposed in thispaper, enabling the MMC to effectively adapt to fluctuationsin renewable energy output and naturally maintain circulatingcurrent at a relatively low level. Firstly, the evolution principleillustrating topology decomposition and reconfiguration of theMMC is revealed. Secondly, the control method for AC internalvoltage is proposed, which combines the energy balance betweenthe half MMCs and voltage amplitude support. Thirdly, the DCinternal voltage is defined, and its control method is proposedbased on the MMC’s overall energy balance. Then, independentcontrol of each bridge arm is achieved by integrating the energybalance of the bridge arms with both the AC and DC internalvoltages. Finally, an electromagnetic transient simulation modelis built with PSCAD/EMTDC, and the efficacy and practicalityof the proposed method are demonstrated through extensivesimulation experiments.
基金supported by the NARI Group Technology Projects under Grant SGNRPG00YFJS2000393B.
文摘In series-connected-based offshore wind farms(SCOWFs),the bulky offshore platform,step-up transformer,and high voltage and large-scale converters can be eliminated.In SC-OWFs,grounding fault is an inevitable issue.In this study,the mathematical model of DC link in SC-OWFs is established.On this basis,this paper reveals characteristic of grounding faults in SC-OWFs and proposes a DC link current control strategy,consisting of feedback and feedforward control.Based on DC link current control and protection method,faulty part isolation from SC-OWF can be realized,and unfaulty part will operate normally.Finally,simulation and experimental results prove feasibility of the proposed DC control strategy and fault current calculation method.
基金This work was supported in part by the National Natural Science Foundation of China under Grant No.51977142.
文摘An equivalent source-load MTDC system including DC voltage control units,power control units and interconnected DC lines is considered in this paper,which can be regarded as a generic structure of low-voltage DC microgrids,mediumvoltage DC distribution systems or HVDC transmission systems with a common DC bus.A reduced-order model is proposed with a circuit structure of a resistor,inductor and capacitor in parallel for dynamic stability analysis of the system in DC voltage control timescale.The relationship between control parameters and physical parameters of the equivalent circuit can be found,which provides an intuitive insight into the physical meaning of control parameters.Employing this model,a second-order characteristic equation is further derived to investigate system dynamic stability mechanisms in an analytical approach.As a result,the system oscillation frequency and damping are characterized in a straight forward manner,and the role of electrical and control parameters and different system-level control strategies in system dynamic stability in DC voltage control timescale is defined.The effectiveness of the proposed reduced-order model and the correctness of the theoretical analysis are verified by simulation based on PSCAD/EMTDC and an experiment based on a hardware low-voltage MTDC system platform.
基金funded by SGCC Science and Technology Program under project Research on Electromagnetic Transient Simulation Technology for Large-scale MMC-HVDC Systems.
文摘Multi-terminal direct current(MTDC)grids provide the possibility of meshed interconnections between regional power systems and various renewable energy resources to boost supply reliability and economy.The modular multilevel converter(MMC)has become the basic building block for MTDC and DC grids due to its salient features,i.e.,modularity and scalability.Therefore,the MMC-based MTDC systems should be pervasively embedded into the present power system to improve system performance.However,several technical challenges hamper their practical applications and deployment,including modeling,control,and protection of the MMC-MTDC grids.This paper presents a comprehensive investigation and reference in modeling,control,and protection of the MMC-MTDC grids.A general overview of state-of-the-art modeling techniques of the MMC along with their performance in simulation analysis for MTDC applications is provided.A review of control strategies of the MMC-MTDC grids which provide AC system support is presented.State-of-the art protection techniques of the MMCMTDC systems are also investigated.Finally,the associated research challenges and trends are highlighted.
文摘This paper study and solve the design and manufacture of baby care car, its unique function is the baby carriage can be used as a baby bed, when necessary, it can also become a nursing car, sensor in the vehicle can be real-time detected whether the baby bed wetting and induction time will give parents information feedback; the humidity sensing probe controlled by single chip microcomputer and with the bottle clamp flexible connecting rod, can realize the baby auxiliary nurse; remote wireless commtmication system can allow parents to monitor children＇ s state. The design of intelligent baby carriage, to enhance the technological content of products, promote the innovation of design China bassinet production, has the important practical significance to seize the smart baby car market.
文摘The present paper addresses an advanced teaching lab consisting of setting up an islanded production unit. This teaching lab takes place in the very last semester at master level for students in electrical engineering with energy specialization. The purpose of this teaching lab is to combine knowledge learned in different areas such as power electronics, control, electrical machines and networks, and make use of all of them in practice. The present paper describes in detail the different steps followed by the student to set up an islanded production unit.
基金supported by National Key R&D Program of China(No.2021YFB2401100)the Science and Technology Project of State Grid Corporation of China(No.5211DS22002C).
文摘The cluster DC voltage balancing control adopting zero-sequence voltage injection is appropriate for the starconnected cascaded H-bridge STATCOM because no zerosequence currents are generated in the three-phase three-wire system.However,as the zero-sequence voltage is expressed in trigonometric form,traditional control methods involve many complicated operations,such as the square-root,trigonometric operations,and inverse tangent operations.To simplify cluster voltage balancing control,this paper converts the zero-sequence voltage to the dq frame in a DC representation by introducing a virtually orthogonal variable,and the DC components of the zero-sequence voltage in the dq frame are regulated linearly by proportional integral regulators,rather than being calculated from uneven active powers in traditional controls.This removes all complicated operations.Finally,this paper presents simulation and experimental results for a 400 V±7.5 kvar star-connected STATCOM,in balanced and unbalanced scenarios,thereby verifying the effectiveness of the proposed control.
