Analysis And Solution Of Abnormal Voltage When Energizing The 500kV GIS Bus In Huaneng Laiwu Power Plant

At present,Huaneng Laiwu Power Generation Co.Ltd.(2*1000MW)booster station adopts SIMENS GIS products.After the commissioning of the system in December 2015,the problem of abnormal voltage of the bus is encountered,which shows that the unbalanced three-phase voltage appears after the joint switch is passed.This situation has a certain randomness.In the process of reversing the bus with the bus line,the voltage rise of the bus II bus will occur after the start of the bus switch,sometimes B phase,the C phase voltage is high,and sometimes the voltage of B phase is high and the voltage distortion is accompanied by the voltage distortion.In several subsequent operations,the failure is random.Firstly,by analyzing the fault waveform and referring to the relevant literature,several possible causes of failure are put forward.After the calculation of various reasons.And the mechanism,characteristic and parameter range of ferroresonance over-voltage and its suppression measures are analyzed and summarized.Secondly,combined with the actual field parameters.Then the over-voltage information of the waveform is simulated by using simulink software.The simulation results show that the neutral direct grounding system produces ferroresonance overvoltage after the breaker is closed,which is a typical frequency division resonance.Then it is proposed to identify the ferroresonance overvoltage by using the multi-resolution wavelet feature recognition method so as to provide support for the suppression of ferroresonance.Finally,the parameters of the ferromagnetic resonance line are simulated by using Matlab software,and several harmonic elimination measures are simulated and verified,which has certain guiding significance for the prevention and treatment of ferromagnetic resonance of 500kV GIS bus in Huaneng Laiwu power plant.Through the research and analysis,the solution is proposed and verified in the experiment for the low occurrence rate but the serious consequences in the power plant.It has deepened the understanding of the system,and has certain engineering guiding significance.In view of the actual operation of the bus and line in our factory,three feasible solutions are put forward,the first solution is to install harmonic elimination devices,the second solution is to change the existing electromagnetic PT into the capacitance partial pressure CVT,the third solution is to modify operation procedures.At present,through the comprehensive consideration of the operation cost,the later investment and the safety,the solution is to modify the busbar related operating rules.