Power System Wide-area Damping Controller Design Research

With the further implementation of the strategy of China’s power transmission from the West to the East,mutual supply between north and south and nation-wide power grid inter-connection,the power system is about to enter into the era of large units,ultra-high voltage,ultra-large-scale and long-distance Transmission. Low-frequency oscillation has become an important factor that affecting the inter-connected power grids’ stability and limits the power transmission ability of the inter-area power system. Conventional power system stabilizer (CPSS) can damp local mode low-frequency oscillation effectively, but not the inter-area mode oscillations due to local information alone.Therefore,the wide area damping control should be studied.In recent years, a phasor measurement unit was launched. The development of synchronous phasor measurements technology and wide-area measurement system can provide nearly every real time imformation of the power system under the same time frame.Using these wide-area imformation in the wide-area damping control can suppress low-frequency oscillations of the inter-regional power grid.There is time delays in the communication and process of information,which affect the performance of wide-area damping control.Therefore, in this paper, the design of WADC is considered. Firstly, the lead-lag compensation is used for offseting the time delay.It can reduce the adverse effects of time delay.Currently, the WADC cann’t be installed on every generator.So, the method of determination of the installation location and numbers of WADCs is introduced in this paper.In the communication process,because of network congestion,electromagetic interfence and other reasons,the wide-area signals can be lossesed.This is bound to affect the efficiency of the wide-area damping control.The least squares support vector machine(LS-SVM) has the advantages of simle computation,fast convergence,high precision and so on.So,LS-SVM is used to predict the continued lossed data in this paper.The lost data is replaced by the predicted result.By the computer simulation,the results show that the LS-SVM can predict the continued lossed data more accurately.Also,the LS-SVM prediction and curve fitting is used to deal with the problem of varying delay.The static synchronous compensator(STATCOM) is a new kind reactive compensator used in flexible AC transmission system recenlty.By the control of the output AC voltage phase,the reactive power of power system is adjusted fastly and flexibly.The stability of power system is improved. The bacterial foraging optimization(BFO) is studied and improved in this paper. If the number of WADC is increased,the parameters of the WADC and STATCOM controllers should be coordinated and optimizated globally in the power system installed of STATCOM.The parameters of WADC and STATCOM optimized simultaneously by using the BFO. An integral of the time-weighted squared error (ITSE) is used as performance index. And performance index would be got by solving the nonlinear differential-algebraic equations of multiple power systems.A10-machine39-bus New England system is used to as a test system.The code programming by Matlab is used to optimize the parameters of the WADC and STATCOM controllers coordinately. The test result shows that the coordinated design of these controllers can enhance the dynamic stability of power system.