In the 21st century Smart Grid and Renewable Energy technologies are an important issue with regards to global climate change problem and energy security. The evolution of current conventional or centralized generatio...In the 21st century Smart Grid and Renewable Energy technologies are an important issue with regards to global climate change problem and energy security. The evolution of current conventional or centralized generation in form of distributed generation and Smart Power Grid (SPG) has great opportunity and potentially can eradicate several issues associated with energy efficiency, energy security and the drawback of aging power system infrastructures. In order to meet the rising electrical power demand and increasing service quality as well as reducing pollution, the existing power grid infrastructure should be developed into Smart Grid (SG) that is flexible for interconnectivity with the distributed generation. However, integrating distributed generation to power system causes several technical issues especially system stability. To make the power grid become “smarter”, particularly in terms of stability, Flexible AC Transmission System (FACTS) device especially Static VAR Compensator (SVC) is used. This paper explores Smart Grid technologies and distributed generation systems. Furthermore, it discusses the impact of distributed generation on Smart Grid, particularly its system stability after installing distributed generation in the Smart Grid. This was done by examining the system stability during interconnection and faults on the system and validated with Dig-SILENT Power Factory Software V 13.2.展开更多
The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC vo...The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.展开更多
Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to loca...Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%.展开更多
In large inter connected power systems, inter-area oscillations are turned to be a severe problem. Hence inter-area oscillations cause severe problems like damage to generators, reduce the power transfer capability of...In large inter connected power systems, inter-area oscillations are turned to be a severe problem. Hence inter-area oscillations cause severe problems like damage to generators, reduce the power transfer capability of transmission lines, increase wear and tear on network components, increase line losses etc. This paper is to maintain the stability of system by damping inter-area oscillations. Implementation of new equipment consists of high power electronics based technologies such as FACTs and proper controller design has become an essential to provide better damping performance than Power System Stabilizer (PSS). With development of Wide Area Measurement System (WAMS), remote signals have become as feedback signals to design Wide Area Damping Controller (WADC) for FACTs devices. In this work, POD is applied to both SVC and SSSC. Simulation studies are carried out in Power System Analysis Toolbox (PSAT) environment to evaluate the effectiveness of the FACTs controller in a large area power system. Results show that extensive analysis of FACTs controller for improving stability of system.展开更多
利用功率注入法,建立广义统一潮流控制器(generalized unified power flow controller,GUPFC)和线间潮流控制器(interline power flow controller,IPFC)的数学模型。将GUPFC和IPFC的目标控制约束及运行约束即内部功率平衡约束和考虑等...利用功率注入法,建立广义统一潮流控制器(generalized unified power flow controller,GUPFC)和线间潮流控制器(interline power flow controller,IPFC)的数学模型。将GUPFC和IPFC的目标控制约束及运行约束即内部功率平衡约束和考虑等效功率注入模型的潮流约束嵌入到最优潮流计算模型中,得到计及GUPFC和IPFC的可用输电能力(available transfer capability,ATC)计算模型,并利用跟踪中心轨迹内点法对模型进行求解。IEEE-30节点系统的仿真计算显示GUPFC对节点电压和多条线路甚至某一子网络潮流的灵活控制能力及IPFC对线间潮流的合理分配能力;同时验证模型和算法的有效性和可行性。展开更多
研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。...研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。推导电力系统阻尼控制框架下的EOP,在此基础上建立用于多FACTS阻尼控制器分析的阻尼控制等效开环过程(damping control effective open-loop process,DCEOP)。提出基于DCEOP谱半径和多变量Nyquist推广定理的多FACTS阻尼控制器交互影响分析方法,可以判断系统中是否存在多FACTS阻尼控制器的负交互作用。进一步推导并提出基于DCEOP的多FACTS交互风险因子和交互作用因子,实现了多FACTS阻尼控制器协调控制及交互作用的量化分析。最后,通过算例分析验证了所提方法的正确性以及在实际电网中应用的可行性。展开更多
为实现配电网的柔性互联,提出一种基于多绕组变压器的直接式AC-AC型智能软开关(direct AC-AC soft open point,AC-SOP)拓扑结构,可在四象限内独立控制输出电压的幅值及相位,且无直流环节,拓扑灵活性较高。建立AC-SOP互联馈线环网的数学...为实现配电网的柔性互联,提出一种基于多绕组变压器的直接式AC-AC型智能软开关(direct AC-AC soft open point,AC-SOP)拓扑结构,可在四象限内独立控制输出电压的幅值及相位,且无直流环节,拓扑灵活性较高。建立AC-SOP互联馈线环网的数学模型,并结合所提出的AC-SOP的等效占空比算法,给出AC-SOP在潮流控制模式和恢复供电模式下的闭环解耦控制策略。最后,通过仿真验证所提AC-SOP在控制互联馈线环网潮流和恢复供电方面的有效性;通过搭建单相1kW子模块,验证了所提拓扑结构可实现电压幅值与相位的独立控制。展开更多
柔性交流输电（flexible AC transmission system,FACTS）设备能有效实现对电力系统参数及网络结构的灵活控制,以降低功率损耗,提高系统稳定性。由于FACTS设备成本较高,因此,建立综合考虑其配置费用和系统运行性能的多目标优化模型具有...柔性交流输电（flexible AC transmission system,FACTS）设备能有效实现对电力系统参数及网络结构的灵活控制,以降低功率损耗,提高系统稳定性。由于FACTS设备成本较高,因此,建立综合考虑其配置费用和系统运行性能的多目标优化模型具有重要研究意义。该文以系统有功网损最小、设备补偿费用最低、系统电压稳定性最好为目标函数,建立了晶闸管控制串联电容器和静止同步补偿器的多目标优化配置模型。提出了一种改进差分和声搜索算法求解该非线性多目标优化问题,研究结果表明,提出的改进算法比多目标自适应和声搜索算法获得的解集更优,且得到的最优折衷解,在较低的补偿费用下具有更好的电压稳定性和更低的有功损耗。该文提出的多目标优化模型和求解算法能有效指导实际电力系统中FACTS设备的优化配置,具有良好的应用前景。展开更多
柔性交流输电装置(flexible AC transmission system,FACTS)在提升电网安全稳定和运行效率方面发挥着重要的作用。随着柔性交流输电装置在电力系统中的广泛应用,研究系统中多FACTS的协调控制机理对于实现系统的协调阻尼控制具有重要的...柔性交流输电装置(flexible AC transmission system,FACTS)在提升电网安全稳定和运行效率方面发挥着重要的作用。随着柔性交流输电装置在电力系统中的广泛应用,研究系统中多FACTS的协调控制机理对于实现系统的协调阻尼控制具有重要的理论价值和现实意义。针对实现多FACTS协调控制过程中遇到的交互影响问题,提出基于选择模式分析(selective modal analysis,SMA)和多变量频域控制理论的多FACTS交互作用机理分析方法,通过SMA实现多FACTS交互作用的有效特征量提取,进而通过多变量频域控制理论推导出多FACTS间的交互作用关系和发生条件,并在此基础上揭示多FACTS间交互作用机理。研究结果表明:处于多机系统同一电力区域中的多台FACTS阻尼控制器间存在相互制约的关系,当控制器参数满足负交互条件时会发生比较明显的负交互作用,严重时甚至威胁系统的安全运行,当控制器参数满足协调运行条件时才能保证多FACTS间的协调运行与控制。通过仿真验证了文中机理研究的正确性以及在实际电网中应用的可行性。展开更多
文摘In the 21st century Smart Grid and Renewable Energy technologies are an important issue with regards to global climate change problem and energy security. The evolution of current conventional or centralized generation in form of distributed generation and Smart Power Grid (SPG) has great opportunity and potentially can eradicate several issues associated with energy efficiency, energy security and the drawback of aging power system infrastructures. In order to meet the rising electrical power demand and increasing service quality as well as reducing pollution, the existing power grid infrastructure should be developed into Smart Grid (SG) that is flexible for interconnectivity with the distributed generation. However, integrating distributed generation to power system causes several technical issues especially system stability. To make the power grid become “smarter”, particularly in terms of stability, Flexible AC Transmission System (FACTS) device especially Static VAR Compensator (SVC) is used. This paper explores Smart Grid technologies and distributed generation systems. Furthermore, it discusses the impact of distributed generation on Smart Grid, particularly its system stability after installing distributed generation in the Smart Grid. This was done by examining the system stability during interconnection and faults on the system and validated with Dig-SILENT Power Factory Software V 13.2.
基金This work was supported in part by the National Nature Science Foundation of China(51977142)。
文摘The concept of a flexible power electronics substation(FPES)was first applied in the Zhangbei DC distribution network demonstration project.As a multi-port power electronics transformer(PET)with different AC and DC voltage levels,the FPES has adopted a novel topology integrating modular multilevel converter(MMC)and four-winding medium frequency transformer(FWMFT)based multiport DC-DC converter,which can significantly reduce capacitance in each sub-module(SM)of a MMC and also save space and cost.In this paper,in order to accelerate speed of electromagnetic transient(EMT)simulations of FPES based hybrid AC/DC distribution systems,an averaged-value model(AVM)is proposed for efficient and accurate representation of FPES.Assume that all SM capacitor voltages are perfectly balanced in the MMC,then the MMC behavior can be modeled using controlled voltage sources based on modulation voltages from control systems.In terms of the averaged current transfer characteristics among the windings of the FWMFT,we consider that all multiport DC-DC converters are controlled with the same dynamics,a lumped averaged model using controlled current and voltage sources has been developed for these four-port DC-DC converters connected to the upper or lower arms of the MMC.The presented FPES AVM model has been tested and validated by comparison with a detailed IGBT-based EMT model.Results show that the AVM is significantly more efficient while maintaining its accuracy in an EMT simulation.
文摘Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%.
文摘In large inter connected power systems, inter-area oscillations are turned to be a severe problem. Hence inter-area oscillations cause severe problems like damage to generators, reduce the power transfer capability of transmission lines, increase wear and tear on network components, increase line losses etc. This paper is to maintain the stability of system by damping inter-area oscillations. Implementation of new equipment consists of high power electronics based technologies such as FACTs and proper controller design has become an essential to provide better damping performance than Power System Stabilizer (PSS). With development of Wide Area Measurement System (WAMS), remote signals have become as feedback signals to design Wide Area Damping Controller (WADC) for FACTs devices. In this work, POD is applied to both SVC and SSSC. Simulation studies are carried out in Power System Analysis Toolbox (PSAT) environment to evaluate the effectiveness of the FACTs controller in a large area power system. Results show that extensive analysis of FACTs controller for improving stability of system.
文摘利用功率注入法,建立广义统一潮流控制器(generalized unified power flow controller,GUPFC)和线间潮流控制器(interline power flow controller,IPFC)的数学模型。将GUPFC和IPFC的目标控制约束及运行约束即内部功率平衡约束和考虑等效功率注入模型的潮流约束嵌入到最优潮流计算模型中,得到计及GUPFC和IPFC的可用输电能力(available transfer capability,ATC)计算模型,并利用跟踪中心轨迹内点法对模型进行求解。IEEE-30节点系统的仿真计算显示GUPFC对节点电压和多条线路甚至某一子网络潮流的灵活控制能力及IPFC对线间潮流的合理分配能力;同时验证模型和算法的有效性和可行性。
文摘研究多变量系统等效开环过程(effective open-loop process,EOP)理论在电力系统多柔性交流输电装置(flexible AC transmission system,FACTS)协调控制量化分析中的应用,并提出基于EOP的多FCATS阻尼控制器交互作用分析方法及量化指标。推导电力系统阻尼控制框架下的EOP,在此基础上建立用于多FACTS阻尼控制器分析的阻尼控制等效开环过程(damping control effective open-loop process,DCEOP)。提出基于DCEOP谱半径和多变量Nyquist推广定理的多FACTS阻尼控制器交互影响分析方法,可以判断系统中是否存在多FACTS阻尼控制器的负交互作用。进一步推导并提出基于DCEOP的多FACTS交互风险因子和交互作用因子,实现了多FACTS阻尼控制器协调控制及交互作用的量化分析。最后,通过算例分析验证了所提方法的正确性以及在实际电网中应用的可行性。
文摘为实现配电网的柔性互联,提出一种基于多绕组变压器的直接式AC-AC型智能软开关(direct AC-AC soft open point,AC-SOP)拓扑结构,可在四象限内独立控制输出电压的幅值及相位,且无直流环节,拓扑灵活性较高。建立AC-SOP互联馈线环网的数学模型,并结合所提出的AC-SOP的等效占空比算法,给出AC-SOP在潮流控制模式和恢复供电模式下的闭环解耦控制策略。最后,通过仿真验证所提AC-SOP在控制互联馈线环网潮流和恢复供电方面的有效性;通过搭建单相1kW子模块,验证了所提拓扑结构可实现电压幅值与相位的独立控制。
文摘柔性交流输电（flexible AC transmission system,FACTS）设备能有效实现对电力系统参数及网络结构的灵活控制,以降低功率损耗,提高系统稳定性。由于FACTS设备成本较高,因此,建立综合考虑其配置费用和系统运行性能的多目标优化模型具有重要研究意义。该文以系统有功网损最小、设备补偿费用最低、系统电压稳定性最好为目标函数,建立了晶闸管控制串联电容器和静止同步补偿器的多目标优化配置模型。提出了一种改进差分和声搜索算法求解该非线性多目标优化问题,研究结果表明,提出的改进算法比多目标自适应和声搜索算法获得的解集更优,且得到的最优折衷解,在较低的补偿费用下具有更好的电压稳定性和更低的有功损耗。该文提出的多目标优化模型和求解算法能有效指导实际电力系统中FACTS设备的优化配置,具有良好的应用前景。
