当虚拟同步机(VSG)孤岛运行时,不平衡负载的接入会导致其输出电压不平衡.首先分析了不平衡负载条件下VSG输出电压不平衡的机理,提出了基于PR和PI复合控制的VSG电压环路控制方法;其次,考虑到VSG输出电流的d,q轴分量在负载不平衡时含有二倍频波动分量,导致VSG定子电气方程输出电压的d,q轴指令呈现二倍频波动,提出采用电压环PI调节器输出电流指令作为定子电气方程的电流输入;再次,针对不平衡负载条件下有功功率和无功功率含有二倍频分量问题,提出一种采用电压环PI调节器输出电流指令的功率直流分量提取方法;最后,仿真和实验结果证明了所提方案的有效性.

Modbus协议是一个请求/应答协议,在工业自动化网络中应用较为广泛.本文主要阐述了Modbus协议在储能系统中的实现与应用,介绍了Modbus通信协议,描述了储能系统主从站Modbus通信协议、报文格式及实现流程,从地址域设置、功能码选择及其在微控制器上的实现,再到基于MCU的主从站软件设计,均作了详细论述.最后对该方法在工程应用中的实现及试验结果作了简要描述.本文的通信设计方法已在同里综合能源服务中心储能系统中应用,验证了Modbus协议在储能系统通信中具有良好的稳定性及正确性.

研究了大型风电场联合集中式储能系统参与电网一次调频的可行性与经济性,并提出一种风储联合调频控制策略.统计分析了正常运行与发生功率缺额事件下实际电网的频率特性,仿真验证了新能源机组参与电网一次调频的必要性;类比火电机组一次调频原理,提出了新能源机组参与一次调频的基本条件;分析了风电机组基于转子惯量、预留备用和配置储能3种调频方案的技术经济性,指出风电场装配集中式储能以承担一次调频是更为经济有效的调频方案.旨在充分利用风机转子惯量以减少配置储能容量,提出一种风储协调的调频控制策略,有效减少储能容量.

Taking the 3#microgrid in the demoretration project of multi-energy,complementary active distribution network of national energy adminsitration as the object of study,the technology of VSG in photovoltaic and energy storage microgrid systems was studied. The principle,topology and control scheme of the VSG were introduced. The power control method of the virtual power was designed,and the voltage outer loop characteristic of the stator electric equation was analyzed. In order to meet the needs of two aspects of VSG frequency modulation and dynamic performance,a parameter design constraint was proposed to ensure that VSG has good dynamic characteristics while satisfying frequency modulation performance requirements;aiming at the microgrid composed of 150 kW photovoltaic and 400 kW energy storage,100 kW VSG,experiments such as black start,planned off/grid switching,unplanned off/grid switching were carried out to verify the reliability of the VSG scheme adopted.

The grid unbalance has a great influence on the stability of devices within the distribution network. To improve the utilization of grid-connected inverter and the grid adaptability, a negative sequence reactive power control method for inverter based on SSG(Static Synchronous Generator) technology is proposed. During grid unbalance situation, according to the SSGu0027s voltage source control features, the negative sequence reactive current is calculated automatically in combination with the current decoupling control under positive and negative sequence rotated reference frame and then the negative sequence reactive power is compensated. To further realize easy expansion and redundancy, modular threelevel topology is introduced. Finally, simulation model is built based on Matlab/Simulink platform. The correctness and effectiveness of the control method are demonstrated by simulation result.