Application Of Statistical Simulation In Power Scheme Evaluation

Power system is a huge and complex man-made system.Scientific and effective evaluation of power related schemes can maintain the safe and stable operation of the power system and ensure the reliable use of electricity in the whole society.The power system will contain many stochastic factors,such as stochastic faults and measurement noise,which will affect the evaluation of relevant schemes.Statistical simulation technology is widely used in the modeling of random factors,and it can also be used to explore the impact of different factors on evaluation indicators.Based on the above background,this paper carries out the research and achieves the following results and conclusions:1)The scope of application of two on-line monitoring schemes for short-circuit impedance of transformer windings based on power flow information is evaluated.Firstly,two short-circuit reactance estimation models are established based on equivalent circuit of double-winding transformer.Then the adaptability of the corresponding algorithms of the two schemes is evaluated from the perspectives of information redundancy and algorithm stability.Then,by analyzing the generation process of power flow measurement information,it is concluded that the factors affecting the stability of the algorithm are load size and power factor.Finally,according to the off-line test results,the appropriate scheme is selected when facing the specific power flow characteristics online.2)One distribution network often has several kind of protection configuration schemes because of loose requirements for distribution system protection.An evaluation method based on energy loss as performance evaluation index is proposed to quantitatively compare the performance of different protection configuration schemes.First of all,the calculation and comparison model of energy loss is established by analyzing four basic requirements ofprotective relaying and the concept of long-term and short-term outage.Then,random variables used to form fault scenarios are determined according to different protection configurations.Monte Carlo method is used to generate random fault scenarios.After that,energy loss of different schemes under different fault scenarios can be calculated.Finally,the average energy loss of each protection scheme is calculated,and the scheme with the smallest average energy loss is selected as the best one.The validity of this method is verified by two cases of distribution network protection with different setting values and hybrid lines with or without automatic reclosing.