The Research On The Stepped Controllable Shunt Reactor For UHV Power Transmission System

The development of Ultra-high Voltage (UHV) power grid faces many major technological breakthroughs, the root of many problems consists of high charging reactive power per unit length of UHV AC transmission line, which is four or five times comparing with transmission line of 500kV. In order to withstand overvoltage, high-voltage reactors with high compensation should be installed on the long UHV transmission lines. However, high-voltage reactors with high compensation bring great burden to the system, affect the ability of UHV transmission line and increase the cost burden on the power grid operation. According to principles of controllable reactors, problems mentioned above could be solved to a certain extent if we properly put controllable reactors in UHV power grid.As important part in long UHV/EHV transmission systems, controlled shunt reactors have multifunction such as reduce the line loss of power grid, compensate for the capacitive effects of long transmission line, prevent resonance overvoltage, reduce the risk of arc flash, control frequency voltage and operate overvoltage suppression, etc. According to changes in the power transmission lines, they can automatically adjust their capacity, smoothly adjust the reactive power in grid system.This thesis made introduction about the research status of stepped controlled shunt reactors, analyzed the characteristics of UHV transmission system, made a detailed description of the operating methods and principles of stepped controlled shunt reactors with calculations of corresponding reactive power capacity. The thesis summarized the characteristics of stepped controlled shunt reactors and pointed out that stepped controlled shunt reactors will be the major choice for the selection of controllable reactors in UHV/EHV transmission systems. Integrating with the power grid structure in East China, in this thesis it takes PSCAD Simulation Software to build a model for simulation analysis, to verify the correctness and validity of CSR functions and the simulation model and analyze the inhibitory effect of CSR on power frequency overvoltage and arc current. Based on the power grid structure in East China, carry out the data analysis and select the appropriate CSR control strategy and compensation mode.