Research On Uninterrupted Dynamic Voltage Restorer

With the development of science and technology, electrical equipment and power users have higher power requirements of power quality. Although for the improvement of power quality can be set in all aspects of transmission and distribution, but it is more direct and effective way that use compensation.According to statistics, 92% of the power quality problems caused by voltage sags, and its high frequency, resulting in serious economic losses, while the dynamic voltage restorer (DVR) is the most economic and effective means to current problem solving voltage sag. Through real-time monitoring of network and load node voltage state, when the voltage sag occurs, DVR inject energy into the system, to compensate for the normal voltage and the voltage difference between the system in real time. Based on this, dynamic voltage restorer can be used to solve the voltage sag, swell and other dynamic voltage power quality problems, and can also compensate three-phase unbalance, filter voltage harmonics. Today the main research on the DVR is to enhance the dynamic performance and its ability to compensate and also ensure that DVR's economy. In this paper, the working principle of the DVR, device analysis and study of the basic structure of the basis of continuous compensation structure proposed, and the voltage sag fault detection algorithms and voltage compensation strategy, DVR control strategy for the corresponding research. The main results include the following aspects:The design of DVR is considered to compensate for DVR capabilities, installed capacity, cost and other factors. Different topologies are used for different voltage levels, capacity levels occasions. And for the failure actual characteristics of voltage sags, the use of continuous compensation structures, the main circuit design using non-controlled rectifier to provide energy, and by three single-phase H-bridge inverter output to compensate, the last series transformer used for coupling.Start and stop times, the amplitude and duration for the voltage sag is the three current volume. They are ccommonly used to analyze the current-voltage fault detection algorithm performance, and taking into account the harmonic detection algorithm on the accuracy of the noise cancellation based on the principle of voltage fault detection algorithm simulation, and proposed based on sliding integrator voltage fault detection algorithm. And verify that the method can accurately and quickly isolate the fundamental and harmonic voltage information for fault detection.Taking into account the compensation UDVR performance and dynamic response speed, the voltage compensation for both discussion Design a fast and stable double-loop combined with feed forward control system, and model single-phase H-bridge inverter analysis, and select unipolar double frequency SPWM modulation .Finally, based on DSP2812 chip as the control, programming the voltage fault detection, compensation strategy, control strategy of the software, and build a 150KVA test prototype to achieved on the theory. Experimental results demonstrate the effectiveness of the design.