Study On Power System Emergency Control Based On Principle Of Power Balance Protection

With the development of electricity industry and scale of interconnect grid, more and more loss is caused by the large scale of black out in power system leaded by cascade failure which happens usually, higher and higher requests of rapid responsibility and control validity are advanced on the principle and method of emergency control after the failure.It shows the shortage of calculation complexity and the control policy table is unsuitable for complicated system that the traditional emergency control method based on transient stability calculation it also shows shortage of long delay time and system unstable situation is worsen by over-shedding and short-sheeting that emergency control connected with frequency and voltage. According to those reasons the Power Balance Emergency Control (PBEC) is presented. By this method, the control volume of load and generator emergency control is calculated according by the principle of power balance protection, the unbalance power is erased before large scale fluctuate of frequency or voltage shows up, it is maintaining stable that the basic flow direction and power volume of system nodes before and after failure occurred, the impact are reduced preparing for the stability control method next and the system recover operation.Firstly it is introduced that the principle of power balance protection, the mathematics formula of active power balance protection and the related situation of reactive power balance protection. The method of PBEC is presented and the difference between PBEC and other emergency control methods. It is also presented that the appliance area, the failure condition for PBEC acting and technological process. The application of WAMS for PBEC is generalized.It is analyzed that the relationship and control effection among PBEC with system transient power angle stability, transient frequency stability, facility heat-stable and overload of power line, and transient voltage stability after system failure, then it is introduced that the method of emergency load control and emergency generator control can be used by PBEC. The coordinated methods of them are also discussed. Based on the generalize of transient stability analysis and dynamic security assessment, it is used for the transient frequency stability analysis that the methods of step integration and transient energy function based on dynamic flow calculation, and the formulas of them are deduced. With the example of simulation and calculation on the system after PBEC acted, it is also processed that the transient frequency stability analysis of the system. It is the major priority research areas of this paper that the choice of control time point and control location. It is deduced that the linearity equivalent transient energy after emergency control processed by the analysis on the formula of transient energy function. It is compared in the same frame of axes that the unbalance power caused by continued failure, the failure node shedding and PBEC. By anglicizing the relationship of transient energy among them, the formula of control time point of PBEC can be deduced. Then it is presented that the measure of stratified control of load and generator based on electrical proximity between controllable node and failure node, and the creating means of dynamic control game table, and the calculate formula of PBEC real control volume based on emergency load and generator control. At last it is certificated by simulation examples that the calculated result of the PBEC time point and the method of stratified load and generator control.In the end the summarization of whole paper and the forecast of future works are presented.