Electric Parameters Optimal Design Of Novel Parallel Hybrid Active Power Filter

Because of the wide-range application of nonlinear load, the harmonic pollution to power system has become more and more serious, and has brought a series of power quality problems. At the same time, higher demands on power quality are proposed by users. As a result, the problem of harmonic controlling is imminent. Novel Parallel Hybrid Active Power Filter (NPHAPF) has been paid more and more attention and become the most important harmonic eliminating device in the high voltage and big power system, because it overcomes the shortcomings of passive power filter and active power filter, and gets a better filtering effect and stability at lower cost. Under the harmonic eliminating background of lOkV power distribution network at 11OkV substation in a power company, a profound study is penetrated on the parameters design of NPHAPF.Firstly, the topology which is appropriate for high voltage and big power system is selected based on the analyses of various active power filter topology, and analysis it deeply. Furthermore, the work principles under the command mode of testing power system harmonic current, load harmonic current and a combination of them are studied.Secondly, an improved genetic algorithm is proposed to solve the problem of passive power filter capacitor parameters of NPHAPF, and the objective is set by considering invest, reactive power compensation and filtering effects. Using the threshold values to restrict these two fitness functions, on one hand, making the populations evolve gradually into the constrainted space, on the other hand, making the potential chromosomes will not be eliminated untimely. At the same time, the chromosomes selection operations are produced by different probabilities to make sure the population evolution towards the direction of the best tuning point of three targets. Besides, the chaos operator is introduced to overcome the phenomenon of premature convergence. The PPF capacitor parameters are realized by the multi-objective optimal program in MATLAB.What's more, a detail analysis is paid on the parameters design of the active part according to the optimal result of passive filter, including active filter, coupling transformer, output filter, and DC side capacitor. Based on the software of MATLAB/SIMULINK, a simulation model of hybrid filtering system is established and simulated, and the simulation results show that the designed parameters by multi-objective optimal method have a better filtering effect. Furthermore, the graphical user interface is designed based on the parameters optimal process of NPHAPF, which makes users learn and operate more conveniently.Finally, the theories of engineering design methods are deduced to obtain the filter parameters, such as minimal capacitor installed capacity and reactive power compensation capacity method. Then, using the designed parameters by multi-objective optimal method and engineering design methods, the hybrid filter performances are compared on the aspects of cost, reactive power compensation and filtering effect. The results show that the filter parameters which are designed by engineering methods only meet some demand of the design indicators. However, the multi-objective optimal method can get a good effect on the economy and harmonic elimination, as well as the reactive power compensation, thus reveals its correctness and superiority of multi-objective optimal method for NPHAPF parameters design.