Reliability Non-coherence And Sensitivity Analysis Of Power System With TCSC

Thyristor controlled series compensation(TCSC)is widely used in the modern power system.Reliability non-coherence means adding(or reducing)components reduces(or improves)power system reliability.Reliability sensitivity is the derivation of power system reliability to components parameters.In this paper,reliability non-coherence and sensitivity of power system with TCSC are researched,which is shown as follows:(1)TCSC reliability models are derived.Firstly,TCSC is regared as impedance in parallel with a bypass breaker,and its simplified model is derived.Then,inner components of TCSC are detailedly considered,and its detailed model is proposed with hierarchical equivalence method.(2)Non-coherence of power system is analyzed based on the simplified model.Firstly,analytical models of expected load and reliability indices about TCSC are proposed,which is coherent.Then,analytical models of indices errors are proposed,with which coherence condition,margin and non-coherence critical condition are defined to analyse component non-coherence.Finally,impacts of reliability parameters,load level,compensation degree and loading constraint on non-coherence are analyzed.Results show: the system is non-coherent when the parameter is larger than its critical value;less compensation degree,lower load level,or higher loading constraint yields higher possibility of non-coherence;non-coherence is more sensitive to bypass breaker.(3)The sensitivity decomposition of power system to TCSC components is proposed based on the detailed model.Firstly,the sensitivity of power system to the compensated line is derived,and that of the line to TCSC is proposed.Therefore,the sensitivity of power system to TCSC is proposed,whose absolute value helps to find vulnerable components,and positive or negative value means conherence or non-coherence.Finally,impacts of wind power on vulnerable components are analyzed.Results show: the proposed method is feasible and accurate,which helps to find and improve vulnerable components of the flexible transmission equipment.The sensitivity of expected demand not supplied is less sensitive to wind power fluctuation than loss of load probability,because of the small capacity of wind power.