多模块化逆变器直接并联控制及效率分析研究

摘要/Abstract

摘要：

微网中大功率分布式电源并网逆变器采用模块化结构,输出功率的随机性和波动性不仅容易造成逆变器的过载或轻载,而且工作效率不高。本文根据逆变器效率随传输功率的变化在低功率区间成正比例、高功率区间普遍较高的规律,制定基于模糊控制理论的逆变模块投切控制策略,通过其并联数目的调整,维持系统的高效运行;同时设计同步控制器,实现模块的平滑投切;并提出零序环流抑制策略,解决多直接并联模块零序环流突出的问题。仿真分析表明,所采用的控制策略能够实现并网逆变器始终工作在效率最佳工作区间,为分布式电源高效安全并网提供参考。

关键词: 模块化逆变器, 逆变器效率, 零序环流抑制, 投切控制策略, 改进同步控制器

Abstract:

Inverters connecting distributed power generators and micro-grid use modular structure, which is not safe and efficient because of the randomness and volatility of transmission power. This article builds the grid inverter system based on directly paralleled inverter structure. According to the DC side model and efficiency model of inverter, relationships between transmission power and efficiency are analyzed. For a changing transmission power, the efficient and reliable switching strategies are developed. Besides, synchronous controller and circulating current restraining controller are designed. The simulation and analysis show that the control strategies can not only switch the grid inverters smoothly, but also make the distributed generators connect to grid safely and efficiently.

Key words: Modular inverters, efficiency of inverter, restraining of zero-sequence circulating current, switching control strategies, improved synchronous controller

中图分类号:

TM711

张明锐,谢青青,林显琦,欧阳丽. 多模块化逆变器直接并联控制及效率分析研究[J]. 电气工程学报, 2015, 10(7): 48-56.

Zhang Mingrui,Xie Qingqing,Lin Xianqi,Ouyang Li. Researches on Control Strategies of Modular Inverters Paralleling in the Power Grid[J]. Journal of Electrical Engineering, 2015, 10(7): 48-56.

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状态	P_sys	P_sys变化程度	P_in
1	不变	恒定值	=P_ratedn
2	不变	小范围波动	=P_ratedn
3	增大	未引起逆变系统超载	=P_ratedn
4	增大	导致逆变系统超载	>P_ratedn
5	减小	未引起逆变系统轻载	=P_ratedn
6	减小	导致逆变系统轻载	<P_ratedn

	参数	数值
高压直流	V_dc/V	18 000
滤波器	R/Ω	0.01
	L/mH	22.27
	C/μF	31
下垂系数	m/(10^-6rad/kW)	6
下垂系数	n/(10^-2rad/kvar)	6
双环控制	k_i_p	[115,0.057 7]
双环控制	k_i_i	[205 944,333]
零序环流控制	k_0p	10
零序环流控制	k_0i	1 000
载波频率	f_z/Hz	3 000

			工况
	1	2	3	4	5
时间/s	0~0.5	0.5~1.0	1.0~1.5	1.5~2.0	2.0~2.5
P_in/kW	500	700	600	200	1 000