As loads connected to active distribution network (ADN) grow, ADN’s voltage safety issues are becoming more serious. At present, the solution is mainly to build more distributed generation (DG) or to adjust the reactive power in the whole network, but the former needs a lot of investment while the latter requires a large amount of communication equipment and it takes a long time to calculate the adjustment amount of reactive power and to coordinate reactive power compensation equipment. When the loads are heavy, there will still be drawbacks of insufficient reactive power. Therefore, this paper analyzes the relationship between the active power, reactive power, and the voltage in the ADN. Through the autonomous region (AR) division, a voltage control method based on the active power variation and adjustable power in the AR is proposed. According to the relationship between the amount of active power and the adjustable amount active power, the active power control, the reactive power control, and the coordinated control of active power reactive power control are adopted to adjust the DGs’ output to stabilize the bus voltage. The simulation results show that the proposed method can effectively improve the voltage control capability of ADN and can enable it to operate normally under greater power changes. Through the control method in this paper, the communication requirements are greatly reduced and the calculation time is effectively shortened and is more adaptable.

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In order to propose reasonable method of harmonic suppression for EV charging station, three methods that are 6-pulse rectifier with APF, 12-pulse rectifier, PWM rectifiers are analyzed and compared. Firstly,the corresponding simulation model of charger and charging station are built based on the principle of EV charger and the main method of harmonic suppression. Then the harmonic content and power factor for different simulation model are researched. Meanwhile, the advantages and disadvantages of different simulation model are studied according to the results of simulation, the use of performance and economy. At last, the improvement measure and development direction for three methods are proposed.

As the energy crisis becoming more and more serious, electric vehicles has become an important way to solve this problem. The difference of Popularity, type, charge time, charge style and charge characteristics of Electric vehicles make different effect on the Regional power grid, especially quick charge technology. In this paper, through the establishment of regional power grid model and the forecast of quick charge station load curve, we analysis the impact of charge station on voltage of the user side, furthermore, we analysis voltage loss and impulse current when the large power charger connected to the power grid, and verify the analysis by simulation. In order to reduce the impact on the grid, we should rationally plan the charge station and the reactive power compensation, thus enhance stability of power system.

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