Model And Control Methods Of The Doubly-fed Motor Ased Mechanical Elastic Energy Storage Unite

In recent years, with the rapid development of new energy technologies, the role ofenergy storage technologies in modern power system has become increasingly prominent,however, restricted by itself and the external conditions, the existing energy storagetechnologies also can’t meet the requirements of the rapid development of the powersystem. Therefore, on the basis of the principle of eddy spring elastic energy storage, weproposed a new type of energy storage generator set—Double-fed motor basedMechanical Elastic Energy Storage unit (DFIG-MEES).The subject of this paper is themodel and control methods of the DFIG-MEES unit, author researched the controlmethods of the DFIG-MEES unit under normal operation and grid voltage drop situation,the research has important theoretical significance and application value.The article first analyzed the composition and working principles of theDFIG-MEES, established the mathematical models of the energy storage tank,doubly-fed motor and convertor, and briefly analyzed the power of the unit; Then, built asimulation model of the whole unit on PSCAD/EMTDC simulation platform, duringnormal operation constant speed was proposed as the control objective for thecharacteristics of great quality and high inertia, and the vector control strategy was usedin the normal operation; Then, analyzed the changes in rotor voltage and current in thegrid voltage drop, revealed the fundamental reasons of the generation rotor over voltageand over current, identified the main objectives of the control and protection strategy;Finally, fixed the mathematical model of the DFIG, proposed the Low voltage ridethough control strategy by the multiple-input multiple-output feedback linearization andverified correctness and effectiveness of the proposed method by simulation.According to this study, we can reach the following conclusions: First, in constantspeed operation control target, the unit can achieve fast energy storage and stationarypower generation by vector control strategies; Second, since the stator flux can’t followthe stator voltage sudden changes when the grid voltage drop happen, results inover-voltage and over-current of the rotor, so the main object of control and protect is tolimit the rotor over-current and over-voltage of the DC link; Third, the proposed controlstrategy can effectively improve the ability of the rotor current control and the stability ofthe DC bus voltage, it proved to have good control effects, the control strategy is onlyrelated to motor parameters, thus improving the robustness of the control system.