Lightning Fault Assessment And Protection Scheme Optimization Of 220kV Substation

The 220 kV substation is in the middle of the voltage level sequence,and is in the middle of the power transmission and distribution functions.It plays a very important role in the transmission and distribution network.Once it is damaged by lightning,the non-self-restoring insulation of the equipment in the station may be damaged.In severe cases,it will cause the substation to stop operating,affecting the safe operation of the power grid and causing economic losses.As a kind of risk,lightning disasters need to be correctly understood and evaluated.Therefore,it is particularly important to provide a formal method suitable for engineering to evaluate the lightning-related faults of power system equipment.At the same time,it is particularly important for power system equipment to be insulated from lightning.The quantification of the risk of failure under voltage conditions can better guide designers to conduct more optimized lightning protection and insulation design.First,clarify the source of lightning hazards in substations.Substations are affected by lightning in many aspects,but not every lightning strike will cause damage to the insulation of the equipment in the station.Among them,only lightning shielding strikes and lightning counter strikes produce lightning intrusion waves along the overhead incoming line.The introduction of wires into the substation will cause the risk of insulation damage.Secondly,the overvoltage amplitude generated by the lightning intrusion wave transmitted to the equipment in the station was modeled and calculated,and the electromagnetic transient program ATP-EMPT was used to simulate and analyze it.In the simulation,the incoming line and the substation in the vicinity of the lightning strike are considered as a whole to verify the rationality of the selection of the limited distance,and consider the attenuation and distortion of the lightning intrusion wave due to corona to establish a lightning model,J.MARTI transmission line model,and multi-wave impedance tower model,insulator string flashover model and main equipment models in the substation,the distribution and change law of the intrusive wave overvoltage at the transformer and various parts of the GIS under different amplitude lightning currents and the typical operation modes of single transformer with one overhead incoming line,double transformers with one overhead incoming line,double transformers with double overhead incoming lines are calculated in detail.Finally,based on the simulation data,using the interval combination method based on the statistical method,the possible lightning current amplitude and the verified limited distance are reasonably divided into several intervals,simplify random variables such as lightning current polarity,grounding resistance and power frequency voltage in the model,quantified the lightning failure rate of the substation,completed the lightning risk assessment,and based on the assessment results,gave the optimization opinions on insulation and lightning protection design.The fault assessment method used in this paper takes into account the calculation accuracy and engineering applicability,and helps to improve the best comprehensive economic benefits of insulation and overvoltage protection.