Emergency Control In The Receiving-end Under Transient Security And Stability Constraints

The inverse distribution of load centers and energy resource centers makes the destruction of UHVAC/UHVDC necessary and the received power of the eastern grid increase gradually.The faults in UHVAC/UHVDC or generators may result in the loss of huge power,then threaten the transient frequency/voltage security and cause overload,which may lead to serious results.To ensure the security and reduce the load shedding amount,it is necessary to optimize the emergency control in the receiving-end.The main content is listed as below:(1)The event-driven load shedding(EDLS)is optimized.The mathematical model is constructed,in which TFDS,TVDS and overload are optimized in a unified framework.An iterative algorithm is proposed:the linearization and the step-by-step summation method are used to solve the load shedding to ensure TFDS/TVDS and to eliminate overload,respectively;then the integrated iteration is taken to minimize the total load curtailment.The characteristic of the optimal solution is given,and that the event-driven principle is more helpful for the security is pointed.Lastly,the IEEE39 system is used to verify the effectiveness of the algorithm.It is proved that the load shedding that considering transient security and overload in a unified framework can reduce the load shedding amount.(2)The coordination of EDLS and the corrective line switching(CLS)is optimized.Considering the CLS can lighten the overload without load curtailment,therefore,the coordination of EDLS and CLS is taken to optimize the emergency control in the receiving-end grid.Firstly,the mathematical model is constructed,in which the transient security and overload,EDLS and CLS are all considered.Then,a two-loop iterative algorithm is proposed:the inner loop optimizes the EDLS,while the outer coordinates the two measures by the neighbor search.The application prospect of the algorithm is given.The improved IEEE39 system and improved provincial system are used to verify the effectiveness of the algorithm.This chapter proves that the coordination of EDLS and CLS can optimize the emergency control and reduce the load shedding amount.(3)The optimization program to guide the emergency control is developed.The main function of the program convers three points:quantitative assessment of the transient security and stability(which includes the assessment of transient frequency security,transient voltage security and transient angel stability),optimization of EDLS,coordination of EDLS and CLS.All of them are designed based on the modularization method.The EDLS module is developed based on the iterative algorithm in the Chapter 2.And on the base,the module of the coordination of EDLS and CLS is designed,according to the two-loop iterative algorithm in the Chapter 3.Lastly,the IEEE39 system,a provincial system and an improved provincial system are used to verify the effectiveness of the three modules,respectively.It proves that the program can guide the optimization of the emergency control under transient security and stability constraints in the receiving-end.