Modeling And Control Of Supercapacitor Energy Storage System On Electric Workover Rig

In our country,the capacity of most oilfield power grids is small,the overcurrent of transformer often occurs.To solve this problem,a supercapacitor energy storge system for electric workover rigs was designed in this paper.The power compensation control was applied to prevent the overcurrent of transformer to happen.In addition,the braking energy of workover rigs could be absorbed,it effectively avoide the energy to be wasted.Firstly,the four topologies of non-isolated bidirectional DC/DC converter were compared,and the bidirectional half-bridge topology was selected as the main circuit topology of the energy storage system in this paper.The small-signal model in Buck mode and Boost mode were respectively established by adopting state-space averaging method.The parameters of the energy storage system were designed.The capacity of the supercapacitor was conformed,while the working conditions of the workover rig was taken into acco unt.Secondly,a 3-branch RC circuit model of supercapacitor was established,and the parameters of branch were identified by the Recursive Least Squares method.The structure and parameters of model was verified by simulation.According to the supercapacitor model,the state of charge was estimated by the Extended Kalman Filter algorithm.The fastness and robustness of the Extended Kalman Filter algorithm were proved by simulation.Thirdly,in order to protect the transformer not to be destroyed by ovcrcurrent,a hybrid control strategy with transformer overcurrent protection was proposed in this paper.While the workover rig was lifting,the transformer capacity was not satisfied to the motor power demand,the supercapacitor energy storage system would operate in power compensate mode.While the workover rig was in idle,it would operate in capacity adjusted mode.While the workover rig was descending,the supercapacitor energy storage system wo uld operate in absorbing the brake energy.And then feasibility of the hybrid co ntrol strategy was ve rified by simulation.Finally,the energy storage system experimental platform was built,in which TMS320F28335 DSP was regarded as the core controller.They include three parts:the control board,signal conditional board and main circuit.The relatied control program was designed.The rationality of the energy storage system and the correctness of the control strategy were verified.