The Research On Optimized Compensation Strategy Of Dynamic Voltage Restorer

With the widespread application of high-precision load, the requirements of load for voltage quality have increased. Even a short voltage drop will cause varying degrees of impact on sensitive loads. Dynamic Voltage Restorer(DVR) is a kind of power electronic device which can effectively prevent voltage drop and protect the load from voltage drop of network. Because of its low cost compared to other UPS devices and its excellent characteristics of preventing voltage drop, DVR is widely used in the power system.The compensation ability of DVR depends on the capacity of energy storage devices in the system and adopted compensation strategy. Energy storage devices are usually supper capacitors, which are expensive. In order to lower the total cost, the compensation strategy for DVR has been studied comprehensively. Now there are some different strategies proposed to utilize energy stored in DC bus. These traditional voltage compensation strategies has different compensation effect. Some just reduce the load voltage distortion and restore the voltage before voltage drop. Some just produce a small DVR compensation voltage, making the DC bus release more energy. Some make the DC bus selectively release minimum energy to reach the compensation effect for voltage drop. Also there are some strategies try to make full use of the DC bus energy to achieve compensation effect with a long-lasting compensation time as long as possible. A new compensation strategy is proposed in this paper combining the application of two traditional strategies. The minimum energy compensation method is adopted to make DVR produce minimum energy when a voltage drop is detected. While the maximum time compensation method is switched to if the voltage of DC bus lower to the limit of minimum energy compensation method. The time optimal compensation method can make full use of energy stored in DC bus.The optimized compensation strategy can make the DVR compensation effect last a time as long as possible. The simulations using MATLAB verify that the proposed strategy can extend the compensation time and only produce a small load voltage distortion. It is verified by experiments that, with the new strategy, the energy storage devices can have a smaller capacity under the same load condition. In this article, the traditional voltage compensation strategies will be analyzed, and new compensation strategy will be proposed and explained theoretically. Then the validity and practical value of the proposed strategy will be verified by some experiments.In this peper,the DVR's output side of the filter capacitor location is also studied.The three different topologies' s disturbance rejection and voltage feedback outer objects were analyzed.