Design and Control Strategy of Thyristor Voltage Regulator for Distribution Line Voltage Regulation for Expansion of Distributed Power Supply

Abstract

The power system is designed to operate within a voltage range that takes into account the line impedance from the substation's transmission voltage to the distribution and distribution loads. However, when a distributed power source such as solar or wind power is connected to an existing system, intermittent output characteristics of a renewable energy source may cause voltage instability in the distribution line.In order to stabilize the voltage with a distributed power supply line, SVR can be installed to operate the system within the stable voltage range by LDC control. However, as the distributed power sources such as PV system are connected, frequent change of output can lead to frequent tap switching of the SVR beyond the allowable voltage range, which can cause damage and shorten the lifetime of the device . Recently, researches on the voltage instability problem in the distribution line connected with the PV system are being actively carried out.In this paper, we introduce a thyristor voltage regulator (TVR) using a fast switching semiconductor switching device to compensate the shortcomings of conventional SVR. This paper proposes a control method for voltage stabilization of power distribution lines by sensing the voltage value at the substation output stage, the concentrated power source area, and the line terminal voltage.The proposed control method overcomes the voltage control limit caused by the LDC voltage control method of existing SVR. We model the proposed TVR using PSCAD / EMTDC and simulate and verify the proposed control scheme.