Development of High Voltage Testing Techniques for Conducting Elevated Frequency Test on Higher Rated Shunt Reactors

Abstract

Power demand in India is increasing day by day. In present scenario, power demand is more than 218 GW and in future government of India is planning to have 24 hours power supply to all. Existing transmission line up to 420kV is not sufficient to meet these growing demands. Extra High Voltage (EHV) transmission lines (more than 765kV) are imperative to fulfill the required power demands. The two major key concerns regarding EHV system are power frequency over volt- ages and obtaining the maximum power transfer limit over the long transmission line. Shunt reactors are inductive devices that are used to compensate the excess VArs in a power system. Use of shunt reactor is more apparent during light loads. Testing of shunt reactor during manufacturing is imperative to meet the design and performance criteria. To conduct the power frequency test, huge reactive power is required. Among various tests performed on shunt reactor Induced voltage test with partial discharge (IVPD) is the most stringent test as it requires high level of voltages and hence, huge reactive power is required which can be met by performing the test at elevated frequency. It is also impractical to have such a high rated generator for delivering the power. The only solution to perform the test is to increase the frequency above rated frequency and compensate the reactive power by the use of capacitor bank. To fulfill the requirement of high power a new test setup is designed and developed for testing of shunt reactors. In present work, behavior of different equipment connected in the test setup at rated and at higher frequency is studied. It is shown in the report that beyond a certain frequency, the whole system becomes unstable. Due to instability, power will flow in reverse direction. Hence, a technique for computation of capacitive power is developed such that the power system must work nearly unity power factor (lag) for stable and economical operating condition. In this report, effect of different frequencies and different rating of capacitor bank on the performance of the system is studied. To perform the test, a test setup is proposed to meet the testing techniques for three phase and single phase shunt reactor upto 795 kV class reactor.