A method used for determining the number of equivalent π sections oftransmission line model according to the frequency range of interest and the model accura-cy defined herein is proposed.Factors influencing the disc...A method used for determining the number of equivalent π sections oftransmission line model according to the frequency range of interest and the model accura-cy defined herein is proposed.Factors influencing the discrepancies between continuous ordistributed parameter and multiple π or lumped parameter models are discussed.Generalconclusions concerning the π section lengths of line models used in transient stability,faulttransient and switching over-voltage studies are drawn.Time-domain simulation resultsconfirm the effectiveness of this method.展开更多
This article presents an extensive examination and modeling of Capacitor Coupled Substations (CCS), noting some of their inherent constraints. The underlying implementation of a CCS is to supply electricity directly f...This article presents an extensive examination and modeling of Capacitor Coupled Substations (CCS), noting some of their inherent constraints. The underlying implementation of a CCS is to supply electricity directly from high-voltage (HV) transmission lines to low-voltage (LV) consumers through coupling capacitors and is said to be cost-effective as compared to conventional distribution networks. However, the functionality of such substations is susceptible to various transient phenomena, including ferroresonance and overvoltage occurrences. To address these challenges, the study uses simulations to evaluate the effectiveness of conventional resistor-inductor-capacitor (RLC) filter in mitigating hazardous overvoltage resulting from transients. The proposed methodology entails using standard RLC filter to suppress transients and its associated overvoltage risks. Through a series of MATLAB/Simulink simulations, the research emphasizes the practical effectiveness of this technique. The study examines the impact of transients under varied operational scenarios, including no-load switching conditions, temporary short-circuits, and load on/off events. The primary aim of the article is to assess the viability of using an established technology to manage system instabilities upon the energization of a CCS under no-load circumstances or in case of a short-circuit fault occurring on the primary side of the CCS distribution transformer. The findings underscore the effectiveness of conventional RLC filters in suppressing transients induced by the CCS no-load switching.展开更多
基于输电线路等传变理论分析可知,电容式电压互感器(capacitive voltage transformer,CVT)的暂态特性会造成参与距离保护计算的电压和电流经过的传变环节不一致,是引起距离保护暂态超越的重要因素。因此提出一种等传变快速距离保护方案...基于输电线路等传变理论分析可知,电容式电压互感器(capacitive voltage transformer,CVT)的暂态特性会造成参与距离保护计算的电压和电流经过的传变环节不一致,是引起距离保护暂态超越的重要因素。因此提出一种等传变快速距离保护方案,使保护安装处的三相电压和电流与故障点电压经过相同的传变环节,新方法主要包括3个步骤,即故障点电压的重新构造、虚拟数字传变以及求解R-L模型微分方程。ATP仿真结果表明,所提方法能有效地减小了CVT引起的暂态误差,故障后15 ms左右测距误差不超过5%,明显优于基于CVT暂态误差估计或系统线路阻抗比的各种自适应保护算法(测距误差不超过5%一般需要30 ms以上)。展开更多
文摘A method used for determining the number of equivalent π sections oftransmission line model according to the frequency range of interest and the model accura-cy defined herein is proposed.Factors influencing the discrepancies between continuous ordistributed parameter and multiple π or lumped parameter models are discussed.Generalconclusions concerning the π section lengths of line models used in transient stability,faulttransient and switching over-voltage studies are drawn.Time-domain simulation resultsconfirm the effectiveness of this method.
文摘This article presents an extensive examination and modeling of Capacitor Coupled Substations (CCS), noting some of their inherent constraints. The underlying implementation of a CCS is to supply electricity directly from high-voltage (HV) transmission lines to low-voltage (LV) consumers through coupling capacitors and is said to be cost-effective as compared to conventional distribution networks. However, the functionality of such substations is susceptible to various transient phenomena, including ferroresonance and overvoltage occurrences. To address these challenges, the study uses simulations to evaluate the effectiveness of conventional resistor-inductor-capacitor (RLC) filter in mitigating hazardous overvoltage resulting from transients. The proposed methodology entails using standard RLC filter to suppress transients and its associated overvoltage risks. Through a series of MATLAB/Simulink simulations, the research emphasizes the practical effectiveness of this technique. The study examines the impact of transients under varied operational scenarios, including no-load switching conditions, temporary short-circuits, and load on/off events. The primary aim of the article is to assess the viability of using an established technology to manage system instabilities upon the energization of a CCS under no-load circumstances or in case of a short-circuit fault occurring on the primary side of the CCS distribution transformer. The findings underscore the effectiveness of conventional RLC filters in suppressing transients induced by the CCS no-load switching.
文摘基于输电线路等传变理论分析可知,电容式电压互感器(capacitive voltage transformer,CVT)的暂态特性会造成参与距离保护计算的电压和电流经过的传变环节不一致,是引起距离保护暂态超越的重要因素。因此提出一种等传变快速距离保护方案,使保护安装处的三相电压和电流与故障点电压经过相同的传变环节,新方法主要包括3个步骤,即故障点电压的重新构造、虚拟数字传变以及求解R-L模型微分方程。ATP仿真结果表明,所提方法能有效地减小了CVT引起的暂态误差,故障后15 ms左右测距误差不超过5%,明显优于基于CVT暂态误差估计或系统线路阻抗比的各种自适应保护算法(测距误差不超过5%一般需要30 ms以上)。
