摘要
针对下垂系数大难以保证微电网稳定性,下垂系数取值小则反应速度慢的不足,提出了一种基于类似磁滞曲线的非线性下垂特性的逆变器下垂控制策略,通过实时改变下垂系数,提高负荷功率分配精度,有效抑制电微网频率和电压的大幅度波动,改善系统稳定性;并通过在功率控制环节中增加前馈环节进一步提高微电网稳定性。建立了简化的逆变器接口的微网小扰动分析数学模型,仅考虑功率环等慢动态过程。各微源接口先在各自本地坐标轴上建模,然后通过网络方程将各微源接口和负荷变换到统一旋转坐标轴,最后将方程线性化得到微电网小扰动分析模型,分析了下垂系数和前馈环节对微电网小扰动稳定性的影响。采用PSCA/EMTDC搭建了基于此控制策略的微电网仿真模型,仿真结果验证了此控制策略的有效性。
Big droop coefficients tend to reduce stability of micro-grid,while small droop coefficients result in slow responding of inverter.In order to overcome the disadvantage,the paper proposes a kind of droop control strategy based on nonlinear droop characteristic similar to that of magnetic hysteresis,which real-timely changes droop gain to improve load power distribution accuracy,effectively suppress the wide fluctuations of frequency and voltage,and improve stability of the system.At the same time,a feed forward path is added on the power droop block to further improve the stability.Then the small-signal mathematical model of micro-grid with inverter is developed.Only the outer power loop of the inverter is considered.Each DG units is modeled in statespace form on own reference frame and are combined together on a common reference frame by network equations.The complete model is linearized around an operating point,resulting in the system matrix.The effect of the droop coefficient and the feed forward path on the small disturbance stability is analyzed.The strategy-based simulation model of microgrid is established with PSCAD/ EMTDC,and the results verify the effectiveness of the control strategy.
出处
《陕西电力》
2013年第1期6-10,47,共6页
Shanxi Electric Power
基金
国家高技术研究发展项目(863计划)资助项目(2007AA052249)
(2008AA052216)
关键词
微网
下垂控制
非线性特性
前馈环节
小干扰分析
microgrid
droop control
nonlinear characteristics
feed forward path
small-signal analysis
