Transmission Network Risk Assessment Considering The Impact Of Multiple Factors In Substation

As the key link of power grid,the substation is assumed to undertake the power supply task from the transmission network to customers,which directly affects the security and stability of power grid and the continuity of power supply.Therefore,it is necessary to consider the mutual influence between the substation and power grid when assessing the risk of transmission network.Aiming at the deficiency of the current research,this paper focuses on the risk assessment method of transmission network considering the impact of substation.Firstly,this paper summarizes the influence factors on the risk level of transmission network in substation,and the influence factor s include the substation main connection,the element parameter uncertainty and the reliability of relay protection.The substation main connection influence mainly includes the effect of the substation bus arrangement form and the number of transmission l ines.Meanwhile,the connection number theory is introduced to deal with the uncertainty of element parameters,and the hidden fault model of relay protection is established by using the method of functional group decomposition.Secondly,in view of the above factors,this paper presents a method of transmission network risk assessment considering the influence of substation based on Monte Carlo simulation.In order to reflect the influence of multiple factors on transmission network in substation and improve the speed of risk assessment,this method is improved from the following aspects: a Latin hypercube sampling method is employed to improve the speed and efficiency of the non sequential Monte Carlo simulation method;a Monte Carlo simulation method base d on extreme scenario set is proposed to take the uncertainty of component parameters into account,which realizes the stratified sampling of substation components and the grid elements;the Warshall algorithm is employed to analyze the topology of the sub station main connection in power grid.Then on the basis of the above,an optimal load shedding model based on the DC power flow is utilized to evaluate the risk of load shedding under different system states.Finally,taking the IEEE-RTS79 system and a regional power grid in Guangdong for example;this paper calculates the transmission network risk indicators considering the substation main connection,the uncertainty of element parameters and the reliability of relay protection respectively.The influence of the above factors on the risk level of power grid is analyzed and compared through the risk indicators.At the same time,the numerical examples varify the validity and correctness of the transmission network risk assessment method considering the impact of substation.