Research On Operation Risk Assessment And Optimal Dispatching Model Of Power Grid With Thyristor Controlled Series Capacitor

This thesis is supported by National Natural Science Foundation of China(50977094) and Natural Science Foundation of Chongqing Municipal Science andTechnology Commission (CSTC,2011BB6047).Operational risk assessment is a short-term reliability evaluation because of itsrelatively short evaluation period, and components’ reliability level will be affectedwhen the external environment and operating conditions changes. Then the systemoperational risk under time-varying operating conditions can not be evalueedaccurately by the average parameter values using statistical in traditional riskassessment. Therefore, it is necessary to handle the relationships between real-timeconditions and components’ operational reliability correctly for components’ operationalreliability modeling under real-time conditions. Thyristor controlled series capacitorcompensation (TCSC) can change power grid operating conditions through thetransmission network parameter adjustment to achieve flow control, which will impactreliability of itself and the other components in system. Therefore, to researchthe reliability model of TCSC is beneficial to analyze the influence of TCSC on powersystem operation risk.Power system operation risk assessment is based on a certain dispatching mode.However, changes in generation dispatching will have an impact on system operationalreliability, and the economic cost of power system caused by operation risk can not beignored when develop generation dispatching scheme. Therefore generation dispatchingoptimization and operation risk assessment is a process which is mutual restraint, thatdispatching mode determines the system operational reliability level and operation riskindex guides dispatching decision-making. Thus generation dispatching optimizationconsidering the operational risk is an important subject of research needed.Therefore this paper constructs TCSC’s reliability model and operation riskassessment model of power system with TCSC based on the operational risk theory andexplores the effect of load fluctuation, temperature variation and component aging andTCSC on system operational reliability. An optimal generation dispatching model basedon condition-dependent operation risk is builded with combination of operation risktheory and optimal dispatching theory, so as to realize coordinated control betweenpower system operation risk and dispatching mode. The main contents are as follows: A reliability block diagrams of TCSC and that of its submodule are constructedbased on the analysis of the TCSC’s structure and fault mode, then the reliabilityanalysis of submodule with redundant configuration for its components are alsoconducted.A line reliability model considering TCSC’s apparent reactance limitation arepresented after thorough analysis of the operation characteristics of TCSC reactancewhich varies with electric current. And the state probability of TCSC’s core componentsand that of the entire line are calculated based on Markov theory, taking thetime-varying characteristic of failure rate under real-time operation condition intoaccount. Besides, a condition related failure rate model, which considers the effect ofload fluctuation, temperature variation and component aging on component reliability, isestablished based on the operation risk theory.An optimal generation dispatching model based on condition-dependent operationrisk is builded considering the impact of real-time operating conditions on the reliabilityof components and grid. With Combination of generation dispatching optimization andcondition-dependent operation risk assessment and using unified monetary to quantifygenerator dispatching and risk costs, the optimal dispatching scheme can be obtainedwith the objective of minimum expected total cost and security constraints under normaland fault condition. It also takes the response characteristics of spinning reserve andTCSC into account for the impact of operation risk on the grid, and unit ramping andTCSC compensation constraints have been included in the constraint-set.On the basis of considering mutual influence of load level, real-time dispatching, powerflow distribution and operation risk in this model, the optimal dispatching decisions tocoordinate operation risk and generation cost is achieved.The Matlab is used for calculation and analysis of RBTS test system, and theresults verify the correctness and effectiveness of the proposed model. System operationrisk index are calculated in different load levels, element equivalent service time andweather conditions, and TCSC’s influence on the reliability of the system operation arealso analyzed in detail. The optimal dispatching schemes and operation risk level atdifferent dispatching time under different operation conditions are obtained usinggenetic tabu hybrid algorithm.