并网型退役动力电池储能系统优化控制策略

Optimised Control Strategy for Grid-connected Decommissioned Power Battery Energy Storage System

为实现并网型退役动力电池储能系统的安全可靠运行,基于长短期记忆网络(long short-term memory,LSTM)、模型预测控制(model predictive control,MPC)和载波移相调制,提出了一种LSTM-MPC耦合控制与载波移相调制方法相结合的退役动力电池储能系统优化控制策略。首先,利用实时电流电压,通过LSTM网络和离散模型持续预测下一时刻不同开关状态下的各相的荷电状态(state of charge,SOC)、电压、电流、输出功率;其次,计算变换器所有开关状态下对应的成本函数,建立成本函数最小的优化控制目标,将成本函数值最小的变换器状态作为下一时刻的输入状态;再次,利用系统离散模型计算出最优输出电压与系统单相总电压之比,并将其作为载波移相调制算法的占空比,生成子模块开关信号,在一个调度周期内不断迭代此过程,进行反馈校正,从而实现最优控制。最后,针对电网电压平衡和不平衡工况,从功率跟踪、SOC跟踪、负序电流抑制、功率波动抑制等方面验证了所提控制策略的有效性。仿真结果表明:所提控制策略能够有效实现并网型退役动力电池储能系统的功率跟踪、SOC跟踪。

In order to achieve the safe and reliable operation of grid-connected decommissioned power battery energy storage system,based on long short-term memory(LSTM),model predictive control(MPC)and carrier phase-shift modulation,a coupled LSTM-MPC control and carrier phase-shift modulation method was proposed as an optimal control strategy for decommissioned power battery energy storage system by combining LSTM-MPC coupled control and carrier phase-shift modulation method.Firstly,the real-time current and voltage were used to continuously predict the state of charge(SOC),voltage,current,and output power of each phase under different switching states at the next moment by using LSTM network and discrete model.Secondly,the cost functions corresponding to all the switching states of the converter were calculated,and the optimal control objective with the smallest cost function was established,so that the converter state with the smallest cost function value was used as the input state at the next moment.The converter state with the smallest cost function value was taken as the input state at the next moment.Thirdly,the ratio of the optimal output voltage to the total single-phase voltage of the system was calculated by using the system discrete model,which is used as the duty cycle of the carrier phase-shift modulation algorithm to generate the submodule switching signals,and the process was continuously iterated in a scheduling cycle to perform the feedback correction,so as to realise the optimal control.Finally,the effectiveness of the proposed control strategy was verified in terms of power tracking,SOC tracking,negative sequence current suppression,and power fluctuation suppression for both balanced and unbalanced grid voltage conditions.The simulation results show that the control strategy proposed can effectively achieve the power tracking and SOC tracking of the grid-connected retired power battery energy storage system.