Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into p...Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.展开更多
This paper presents a binary gravitational search algorithm (BGSA) is applied to solve the problem of optimal allotment of DG sets and Shunt capacitors in radial distribution systems. The problem is formulated as a no...This paper presents a binary gravitational search algorithm (BGSA) is applied to solve the problem of optimal allotment of DG sets and Shunt capacitors in radial distribution systems. The problem is formulated as a nonlinear constrained single-objective optimization problem where the total line loss (TLL) and the total voltage deviations (TVD) are to be minimized separately by incorporating optimal placement of DG units and shunt capacitors with constraints which include limits on voltage, sizes of installed capacitors and DG. This BGSA is applied on the balanced IEEE 10 Bus distribution network and the results are compared with conventional binary particle swarm optimization.展开更多
In real industrial microgrids(MGs),the length of the primary delivery feeder to the connection point of the main substation is sometimes long.This reduces the power factor and increases reactive power absorption along...In real industrial microgrids(MGs),the length of the primary delivery feeder to the connection point of the main substation is sometimes long.This reduces the power factor and increases reactive power absorption along the primary delivery feeder from the external network.Besides,the giant induction electro-motors as the working horse of industries requires remarkable amounts of reactive power for electro-mechanical energy conversions.To reduce power losses and operating costs of the MG as well as to improve the voltage quality,this study aims at providing an insightful model for optimal placement and sizing of reactive power compensation capacitors in an industrial MG.In the presented model,the objective function considers voltage profile and network power factor improvement at the MG connection point.Also,it realizes power flow equations within which all operational security constraints are considered.Various reactive power compensation strategies including distributed group compensation,centralized compensation at the main substation,and distributed compensation along the primary delivery feeder are scrutinized.A real industrial MG,say as Urmia Petrochemical plant,is considered in numerical validations.The obtained results in each scenario are discussed in depth.As seen,the best performance is obtained when the optimal location and sizing of capacitors are simultaneously determined at the main buses of the industrial plants,at the main substation of the MG,and alongside the primary delivery feeder.In this way,74.81%improvement in power losses reduction,1.3%lower active power import from the main grid,23.5%improvement in power factor,and 37.5%improvement in network voltage deviation summation are seen in this case compared to the base case.展开更多
各种清洁能源和电动汽车的大量接入给配电线路参数的准确性提出了更高要求,为此提出一种利用馈线补偿电容器投入产生的暂态特征测量线路参数的方法。通过对系统和电容器中性点运行方式影响下电容器同期和非同期投入序网开展时域分析,确...各种清洁能源和电动汽车的大量接入给配电线路参数的准确性提出了更高要求,为此提出一种利用馈线补偿电容器投入产生的暂态特征测量线路参数的方法。通过对系统和电容器中性点运行方式影响下电容器同期和非同期投入序网开展时域分析,确定最后一相电容器投入暂态特征与序网拓扑及参数间的耦合关系,建立基于投入暂态频率和衰减系数的线路参数单点测量模型,给出基于最小二乘-旋转不变技术(total least square-estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)的暂态特性提取方法。仿真和模拟实验结果表明,当有充足数据量支撑暂态特征提取时,该文算法对线路正序参数的测量误差在4%以内,对零序参数的测量误差略高,可用于配电线路参数经常性测量。展开更多
针对某500 kV变电站发生的一起66 kV并联电容器不平衡电流互感器炸裂故障进行调查分析,通过故障录波分析、电容器高压试验、实时数字仿真(real-time digital simulator,RTDS)试验分析了保护动作的行为及原因。经分析,故障原因为电容器...针对某500 kV变电站发生的一起66 kV并联电容器不平衡电流互感器炸裂故障进行调查分析,通过故障录波分析、电容器高压试验、实时数字仿真(real-time digital simulator,RTDS)试验分析了保护动作的行为及原因。经分析,故障原因为电容器放电线圈内部匝间短路引起电容器桥臂短路,导致不平衡电流互感器炸裂,同时指出本次故障电容器组不平衡电流互感器选型不合理。分析结果验证了仿真试验的有效性,并指出在技术规范书中明确技术参数要求,供后续电流互感器选型时参考的建议。展开更多
近年来,变电站真空断路器投切10 k V并联电容器组时发生了多起断路器或电容器炸裂事故,在更换断路器和改善保护措施后,此类事故还是屡禁不止。为减少该工况下绝缘事故的发生,重庆市某110 k V变电站采用分相控制技术的永磁机构真空断路...近年来,变电站真空断路器投切10 k V并联电容器组时发生了多起断路器或电容器炸裂事故,在更换断路器和改善保护措施后,此类事故还是屡禁不止。为减少该工况下绝缘事故的发生,重庆市某110 k V变电站采用分相控制技术的永磁机构真空断路器来抑制投切电容器组时的合闸涌流和降低分闸重燃概率。相控断路器是抑制并联电容器合闸涌流与分闸过电压的重要措施之一。为了验证该技术的有效性,首先基于电路理论分析了合闸角对合闸涌流的影响以及分闸过电压机理,之后在重庆市某110 k V变电站针对某种型号相控断路器与普通真空断路器合(分)闸10 k V并联电容器进行了一系列的现场试验研究。试验结果表明:相控断路器的控制精度高(合(分)闸误差均在±0.3 ms以内);普通真空断路器的合闸涌流高达4.5倍额定电流,而相控断路器的合闸涌流均在2.4倍额定电流以下;控制分闸技术能够保证首开相的工频续流开断时断路器断口间有足够的开距,降低重燃发生的概率,从而提高系统运行的安全性与可靠性。展开更多
文摘Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.
文摘This paper presents a binary gravitational search algorithm (BGSA) is applied to solve the problem of optimal allotment of DG sets and Shunt capacitors in radial distribution systems. The problem is formulated as a nonlinear constrained single-objective optimization problem where the total line loss (TLL) and the total voltage deviations (TVD) are to be minimized separately by incorporating optimal placement of DG units and shunt capacitors with constraints which include limits on voltage, sizes of installed capacitors and DG. This BGSA is applied on the balanced IEEE 10 Bus distribution network and the results are compared with conventional binary particle swarm optimization.
文摘In real industrial microgrids(MGs),the length of the primary delivery feeder to the connection point of the main substation is sometimes long.This reduces the power factor and increases reactive power absorption along the primary delivery feeder from the external network.Besides,the giant induction electro-motors as the working horse of industries requires remarkable amounts of reactive power for electro-mechanical energy conversions.To reduce power losses and operating costs of the MG as well as to improve the voltage quality,this study aims at providing an insightful model for optimal placement and sizing of reactive power compensation capacitors in an industrial MG.In the presented model,the objective function considers voltage profile and network power factor improvement at the MG connection point.Also,it realizes power flow equations within which all operational security constraints are considered.Various reactive power compensation strategies including distributed group compensation,centralized compensation at the main substation,and distributed compensation along the primary delivery feeder are scrutinized.A real industrial MG,say as Urmia Petrochemical plant,is considered in numerical validations.The obtained results in each scenario are discussed in depth.As seen,the best performance is obtained when the optimal location and sizing of capacitors are simultaneously determined at the main buses of the industrial plants,at the main substation of the MG,and alongside the primary delivery feeder.In this way,74.81%improvement in power losses reduction,1.3%lower active power import from the main grid,23.5%improvement in power factor,and 37.5%improvement in network voltage deviation summation are seen in this case compared to the base case.
文摘各种清洁能源和电动汽车的大量接入给配电线路参数的准确性提出了更高要求,为此提出一种利用馈线补偿电容器投入产生的暂态特征测量线路参数的方法。通过对系统和电容器中性点运行方式影响下电容器同期和非同期投入序网开展时域分析,确定最后一相电容器投入暂态特征与序网拓扑及参数间的耦合关系,建立基于投入暂态频率和衰减系数的线路参数单点测量模型,给出基于最小二乘-旋转不变技术(total least square-estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)的暂态特性提取方法。仿真和模拟实验结果表明,当有充足数据量支撑暂态特征提取时,该文算法对线路正序参数的测量误差在4%以内,对零序参数的测量误差略高,可用于配电线路参数经常性测量。
文摘针对某500 kV变电站发生的一起66 kV并联电容器不平衡电流互感器炸裂故障进行调查分析,通过故障录波分析、电容器高压试验、实时数字仿真(real-time digital simulator,RTDS)试验分析了保护动作的行为及原因。经分析,故障原因为电容器放电线圈内部匝间短路引起电容器桥臂短路,导致不平衡电流互感器炸裂,同时指出本次故障电容器组不平衡电流互感器选型不合理。分析结果验证了仿真试验的有效性,并指出在技术规范书中明确技术参数要求,供后续电流互感器选型时参考的建议。
文摘近年来,变电站真空断路器投切10 k V并联电容器组时发生了多起断路器或电容器炸裂事故,在更换断路器和改善保护措施后,此类事故还是屡禁不止。为减少该工况下绝缘事故的发生,重庆市某110 k V变电站采用分相控制技术的永磁机构真空断路器来抑制投切电容器组时的合闸涌流和降低分闸重燃概率。相控断路器是抑制并联电容器合闸涌流与分闸过电压的重要措施之一。为了验证该技术的有效性,首先基于电路理论分析了合闸角对合闸涌流的影响以及分闸过电压机理,之后在重庆市某110 k V变电站针对某种型号相控断路器与普通真空断路器合(分)闸10 k V并联电容器进行了一系列的现场试验研究。试验结果表明:相控断路器的控制精度高(合(分)闸误差均在±0.3 ms以内);普通真空断路器的合闸涌流高达4.5倍额定电流,而相控断路器的合闸涌流均在2.4倍额定电流以下;控制分闸技术能够保证首开相的工频续流开断时断路器断口间有足够的开距,降低重燃发生的概率,从而提高系统运行的安全性与可靠性。
