Analysis And Research Of Dynamic Voltage Restorer Based On Compound Control

As the user-side power equipment increasingly focuses on the stability and eligibility of power quality,the research and application of transient voltage problems have been invented and applied to practice by scientific research institutions and equipment manufacturers.The dynamic voltage restorer(DVR)is a new type of DFACTS device connected to the power supply and sensitive load.Its characteristics of being put into operation only when the voltage drop occurs in the power grid make it more advantageous than UPS and other devices.The dynamic characteristics make it work effectively in many situations and play an practical role in ensuring the quality of power supply.In the specific design of the DVR,many contents are included.According to its workflow,the first is to design an algorithm to detect voltage dips,which should be timely and accurate,to ensure that the DVR can effectively perform its functions.Based on this,according to user-side compensation requirements for the DVR,it is necessary to ensure the compensation accuracy and response speed of the DVR.Therefore,the design should evaluate the compensation capability that the DVR can implement from both voltage and power.The control strategy is the requirement that the DVR can quickly and accurately outputs the compensation voltage to maintain the voltage stability on the load side,which needs to be considered from the aspects of anti-load disturbance,stability and response speed.Based on the study of the working principle and topological structure of DVR as described above,this article specifies several major parameters according to a certain industrial production practice,mainly including the capacity of the inverter device,the capacity of the series coupled transformer,the parameters of the switch tube and the filter.In order to achieve rapid and accurate information of voltage dips,this paper improves the traditional dq transform.The three-phase voltage is constructed by deriving the single-phase voltage,and the rapidity of detection is improved by the derivative method.The shortcomings of the minimum energy compensation method in the compensation strategy cannot maintain the longest compensation time.The target energy optimization method is used to improve the compensation time of the minimum energy compensation method.In addition,the voltage and current double closed loops are used and the PR outer loop control is used to control the double loops.The way to achieve DVR output voltage meets the requirements of no static difference,low damping and fast response.Rooted in those work done,the DVR model was built based on the MATLAB/Simulink environment,and the single-phase and three-phase voltage system simulation experiments were performed to verify that the voltage of the simulated grid fell 20%,50%,and 70% of the single-phase voltage.With the problems of temporary dips and three-phase voltage drop,three-phase unbalance and phase angle deviation,the system’s ability to stabilize load voltage and improve power quality during grid voltage fluctuations was verified.