摘要
500 kV变压器通常为单相式,当其中一相故障时,可考虑用备用相替换恢复运行。但备用相通常与原设备参数不一致,导致主变压器三相参数不对称,需分析其运行时对可靠性的影响,并研究提高可靠性的方法。为此,提出一种适用于研究三相参数不对称系统静态运行的方法,通过附加电源解耦三相电路,从相电路求不平衡电压初值,从序电路求不平衡电流初值,再用迭代原理修正附加电源逐步逼近实际值,同时研究附加电源法的收敛特性、电路特征等内容。通过仿真计算验证该方案的正确性,分析主变压器单相置换在独立运行情况下的一般性规律及负载能力。针对主变压器单相置换并列运行,研究了并列运行时零序回路的差异以及其对主变压器负载能力的影响,以及主变压器中性点加装小电抗的原理和作用,结合电网当前实践基础,计算不同电抗值抑制零序电流的效果,找出优选值。
500 kV transformer is usually single-phase,when one of the phases fails,it can be considered to replace the backup phase to resume operation.However,the standby phase is usually inconsistent with the original equipment parameters,which leads to the asymmetry of the three-phase parameters of the main transformer.Therefore,it is necessary to study the influence of operation on the reliability and the methods to improve the reliability.This paper puts forward an applicable method to analyze the static parameters of the asymmetric three-phase system,which adds the additional power supply for decoupling three-phase circuit,solves the unbalanced initial voltage value from the phase circuit and the unbalanced initial current value from the sequence circuit.Then this method uses iteration principle to correct the additional power supply gradually close to the actual value,and studies the convergence property of the additional power supply method as well as the circuit features.The correctness of the scheme is verified by simulation,and the general rule and load capacity of single-phase displacement of the main transformer in independent operation are analyzed.In view of the parallel operation of single-phase displacement of the main transformer,the differences of zero sequence loop and its influence on the load capacity during parallel operation are studied.The principle and effect of adding small reactance at the neutral point of the main transformer are also analyzed.Combining with current practice basis of the power grid,the paper calculates the effect of restraining zero sequence current with different reactance values so as to find out the optimal value.
作者
叶烜荣
杨帆
招国浩
林明伟
YE Xuanrong;YANG Fan;ZHAO Guohao;LIN Mingwei(CSG Guangdong Yunfu Power Supply Bureau,Yunfu,Guangdong 527300,China)
出处
《广东电力》
2023年第2期109-119,共11页
Guangdong Electric Power
关键词
静态运行
附加电源
迭代原理
单相置换
零序电流
static operation
additional power supply
iteration principle
single-phase replacement
zero sequence current
