Research On Overvoltage Of 66kV Straight Hanging SVC On Phase-controlled Reactor

Static reactive compensation device can play a role in complementing system reactive power and improving the power factor and stabling voltage, it is the key equipment in the power system. At present among domestic reactive power compensation device, TCR + FC is the most –used practical SVC combinations. In recent years, SF₆ circuit breaker used to cut 66 kv voltage class SVC is gradually increasing. According to the practical operation experience, however, accident that SVC phased reactor burned overvoltage, endanger the safety of electric power equipment and influence the normal operation of power system. This shows that the 66 kv straight hanging SVC phased reactor to cut off the overvoltage of the research has great significances.This paper analyzed the types and mechanism of breaking over voltage and the protection method based on circuit theory and performance characteristics of SF₆ circuit breaker. Simulation model of a 220 k V substation 66 k V straight hanging SVC device is established by PSCAD software, transient process of all sorts of possible overvoltage is simulated in the process of cutting SVC, instantaneous voltage is simulated and analysed when the lightning arrester is installed respectively in between TCR line and ground, TCR branch in parallel and the three-phase, and also the other combinations of instantaneous voltage are simulated when the absorption equipment was installed and the results were analyzed.The research results show that normal removal of SVC, due to the existence of the energy storage element, there will be a phenomenon of overvoltage, and because of SF₆ circuit breaker have phenomenon such as intercepting and resurgence, on both ends of SVC phased reactor can produce intercepting overvoltage and renewed overvoltage. These high amplitude and high frequency overvoltage seriously threats the safe operation of the reactor. Lightning arrester installed in different locations will have different inhibiting effect on overvoltage, The overvoltage suppression effect also different with RC absorption device have the different parameters. It is concluded that the overvoltage is well restrained by the lightning arrester connected to reactor in parallel, and appropriate resistance capacity of absorption device also can restrain the overvoltage, good combination device select reasonable parameters can also be very good restrain overvoltage. Finally according to the actual situation of a substation, selecting the lightning arrester connected to reactor in parallel to suppress overvoltage.