虚拟直流发电机励磁补偿控制策略

虚拟直流发电机(VDCG)功率协调控制策略将直流电机算法嵌入到DC/DC变换器控制回路中,使其模拟直流发电机运行特性,提升直流微网直流母线电压的动态稳定性。该控制通过功率分配环实现不同容量储能装置间的功率协调分配,但已有的VDCG功率协调控制策略均采用固定励磁磁通作为虚拟电机励磁系数,当再生能源输出功率发生波动或负载发生投切时,直流母线电压会产生稳态电压偏移。为消除母线电压偏移,在详细分析VDCG功率协调控制工作机理的基础上,提出虚拟直流发电机励磁补偿控制策略,通过实时补偿VDCG励磁,消除母线电压偏移,稳定直流母线电压。构建储能装置双机并联光储直流微网仿真及实验平台,分别在再生能源功率波动和负载投切情况下对传统固定励磁磁通功率协调VDCG控制及所提VDCG励磁补偿控制策略进行对比仿真及实验验证,证明所提控制策略的正确性。

Excitation Compensation Control Strategy for Virtual DC Generator

The virtual DC generator(VDCG)power coordinated control strategy embeds the DC motor algorithm into the DC/DC converter control loop to simulate the DC generator operating characteristics and improve the dynamic stability of the bus voltage.The control realizes the coordinated distribution of power between different capacity energy storage devices through the power distribution ring,but the existing VDCG power coordinated control strategy uses the fixed excitation magnetic flux as the virtual motor excitation coefficient,when the regenerative energy output power fluctuates or the load occurs,the DC bus voltage produces a steady-state voltage offset.In order to eliminate the bus voltage offset,the working mechanism of VDCG power coordination control was analyzed in detail,and the virtual DC generator excitation compensation control strategy was proposed.By realtime compensation VDCG excitation,the bus voltage offset was eliminated and the DC bus voltage was stabilized.A dual-machine parallel optical storage DC micro-network simulation and experimental platform for energy storage devices were constructed.In the case of renewable energy power fluctuation and load switching,the traditional fixed excitation flux power coordinated VDCG control and the improved excitation compensation VDCG control strategy were compared and verified by simulation and experiment,which proves the correctness of the proposed control strategy.