Investigation of Processes During Single-Phase Auto Reclosing on Transmission Lines with Controlled Shunt Reactors

摘要

Magnetically controlled shunt reactors (MCSR) and CSR Systems (SCSR), which are dynamic reactive power compensators based on MCSR, are used in power systems of many countries for voltage stabilization and for increasing the throughput capacity of transmission lines. In recent years there has been a growing interest of the utilities in the application of 330 - 500 kV MCSRs as line reactors (i.e. directly connected to power lines), which is caused by the need to increase the throughput capacity to the level of uncompensated line. When MCSR are used as line reactors, they must perform all the functions of fixed shunt reactors (SR), including the extinguishing of secondary arc during single-phase auto reclosing (SPAR) cycles of transmission lines. One of the design features of MCSR is a delta-connected secondary winding, which results in strong electromagnetic coupling between MCSR phases and, consequently, increased in-feed current of the secondary arc. In order to mitigate the negative impact of MCSR on the secondary arc current during SPAR dead time, several solutions have been considered up to present. The common drawback of these solutions is that they only help exclude the in-feed of secondary arc from MCSR, but do not limit secondary arc current. In this paper, a different approach is presented, which is aimed at reduction of the secondary arc current and recovery voltage, and as a consequence reclosing dead time. The proposed approach is based reduction based on the use of neutral reactors, similar to neutral reactors used with fixed shunt reactors. The paper discusses the sizing their parameters according to the secondary arc current limitation and MCSR's required rate of response. Further, presented are analyses of MCSR phase currents during the reclosing dead time, faulted phase current dependence on the reactance of the neutral reactor and its operating modes. A mathematical expression was obtained for determining the reactance of the neutral reactor as a function of the degree of compensation of power line charging capacity. The paper also presents the results of investigation of the impact of reactance of the neutral reactor on MCSR response time, as well as comparative time-domain calculations of the SPAR mode of the typical 500 kV 400 km power line equipped with fixed and controlled reactors.