CAJ | 학술논문

#:500 kV 自耦变中性点加装小电抗是抑制电网短路电流水平的有效措施.主变中性点加装小电抗后,改变了系统的零序参数,当线路发生不对称接地故障时,故障电量所受影响不容忽视.文章基于500 kV自耦变压器建立了复杂系统环形等值模型,用广东电网500 kV站点的实际参数进行仿真.定量计算了单个站点自耦主变压器(以下简称主变)中性点加装小电抗前后,线路故障位置不同时,各零序电量的相对变化量所受的影响,结果表明当线路出口处发生接地故障时对各零序电量的影响最严重;分析了主变中性点加装小电抗后对相关继电保护整定值的影响,为满足灵敏度需求,变压器中性点零序电流保护需重新整定;多个站点主变中性点同时加装小电抗时,研究表明不同安装情形对各零序电量的影响均存在叠加效应.实际电网仿真算例验证了理论分析的正确性.
#:500 kV 자우변중성점가장소전항시억제전망단로전류수평적유효조시.주변중성점가장소전항후,개변료계통적령서삼수,당선로발생불대칭접지고장시,고장전량소수영향불용홀시.문장기우500 kV자우변압기건립료복잡계통배형등치모형,용엄동전망500 kV참점적실제삼수진행방진.정량계산료단개참점자우주변압기(이하간칭주변)중성점가장소전항전후,선로고장위치불동시,각령서전량적상대변화량소수적영향,결과표명당선로출구처발생접지고장시대각령서전량적영향최엄중;분석료주변중성점가장소전항후대상관계전보호정정치적영향,위만족령민도수구,변압기중성점령서전류보호수중신정정;다개참점주변중성점동시가장소전항시,연구표명불동안장정형대각령서전량적영향균존재첩가효응.실제전망방진산례험증료이론분석적정학성.
@@@@ To suppress short-circuit current in power grid, it is an effective measure to add small reactances to neutral points of 500 kV autotransformers. After adding small reactances to neutral points of 500 kV autotransformers, zero-sequence parameters of power grid are changed, so the influences of this measure on fault electrical quantities during unsymmetrical earth fault occurred in transmission line cannot be neglected. Based on 500 kV autotransformers a ring equivalent model of a power grid containing three 500 kV substations is built, and actual on-site parameters of Guangdong power grid is utilized in the simulation. The influences on relative variations of zero-sequence electrical parameters are quantitatively calculated under different positions, where the fault occurs, before and after adding small reactance to neutral point of autotransformer in single substation. Calculation results show that when earth fault occurs at the outlet of transmission line, the affection of adding small reactance on zero-sequence parameters is most serious. The influences of adding small reactance to neutral point of autotransformer on related protective relayings are analyzed, and it is pointed out to meet the demand on protection sensitivity the zero-sequence current protection of neutral points of autotransformers is to be anew set. For the circumstance that small reactances are added to neutral points of autotransformers in all substations at the same time, theoretical analysis shows that there is superposition effect of zero-sequence electrical parameters under various situation of adding small reactances, and such a conclusion is verified by simulation results of actual power grid.