| In recent years, with rapid development of power electronic technology and wide application of power electronic devices, the problem of harmonic pollution and dynamic reactive power compensation is becoming increasingly severe. It causes potential threat to the safe and stable operation of power grid and devices, and influences the quality of power seriously. It has become a research hotspot to study the basic theory of harmonic and reactive power and analyze the elimination technology nowadays. In order to solve the problems of voltage and cu.rent distortion in power system, the paper proposes a method of voltage and current comprehensive compensation. Aiming at the current quality problem, it mainly studies the computing method of compensating current in shunt compensation, and analyzes its validity and usability seperately and in comprehensive compensation.The paper firstly analyzes the main power theories in nonsinusoidal condition, and summarizes their contributions, defects and applications in power quality condition. Considering the interrelationship between voltage and current disturbance, the paper puts forward the comprehensive compensation. The optimization method combines the energy and wave quality characteristic, the optimal current can be obtained by setting optimal target and solving optimization problem, and calculate the compensating current afterwards. The paper derives the expressions of optimal current under different constrain conditions, puts forward the current compensation algorithm based on optimization method, and confirms the validity of it in various cases of load.In order to prove the effectiveness of the algorithm in harmonic and reactive power compensation, the paper applies the proposed method in active power filter, and builds the simulation model based on PSCAD. The influence of different parameters in filter main circuit is also analyzed. After that, the proposed method is compared with pq method, and the results show that the optimization method can decrease more the RMS value of source current, and control the compensator not generate active power. According to the defects of the method when voltage distorted, a improved method is proposed and verified by simulation results.Finally, combined with the voltage compensation method of dq transformation, the paper builds the simulation model of comprehensive compensation based on PSCAD. The validity of current conpensation algorithm in comprehensive compensation is verified. And the results also show that comprehensive compensation can solve the power quality problems in both source and load side, and help to realize the optimization target of circuit. |
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