基于双电压环补偿的直流微网下垂控制

doi:10.12204/j.issn.1000-7229.2021.03.009

摘要/Abstract

摘要：

针对直流微网传统下垂控制中分布式电源(distributed generation,DG)输出功率分配精度和电压维持额定值间的矛盾,提出了一种基于双电压环补偿的直流微网下垂控制方法。该方法基于集中式二级控制和对等下垂控制策略,在二级控制中引入双电压环控制,其中,第一电压环保证负载功率的高精度分配,第二电压环抬高系统电压,使其更接近额定值。该策略使直流微网系统具有良好的稳态和动态分流特性,能够实现不同容量等级变换器间输出功率的精准分配,且同样适用于本地负荷不匹配的情况。仿真结果表明该控制方法可以保证良好的功率分配精度,维持电压在较高水平,并兼顾系统的动态响应。

关键词: 直流微网, 下垂控制, 功率分配精度, 电压降落

Abstract:

In view of the contradiction between the distribution accuracy of distributed generation (DG) output powers and high voltage level in the traditional droop control of DC microgrid, a DC-microgrid droop control based on double voltage compensation is proposed in this paper. The method is based on the centralized secondary control and the peer-to-peer droop control strategy, and double voltage loop control is designed into the secondary control. The first voltage loop ensures high accuracy distribution of load power, and the second voltage loop raises the system voltage closer to the rated value. The strategy makes DC microgrid system have good steady state and dynamic characteristics, can realize the accurate distribution of output power among converters with different capacity, and can deal with local load mismatch. The simulation results show that the proposed control method can ensure good power distribution accuracy, maintain the voltage at a high level, and take into account the dynamic response of the system.

Key words: DC microgrid, droop control, accuracy of power distribution, voltage drop

中图分类号:

TM732

张小莲, 汪麒, 张仰飞, 郝思鹏, 刘海涛, 陈凡. 基于双电压环补偿的直流微网下垂控制[J]. 电力建设, 2021, 42(3): 72-80.

ZHANG Xiaolian, WANG Qi, ZHANG Yangfei, HAO Sipeng, LIU Haitao, CHEN Fan. DC-Microgrid Droop Control Based on Double Voltage Compensation[J]. ELECTRIC POWER CONSTRUCTION, 2021, 42(3): 72-80.

图/表 19

图1 直流微网结构示意图

Fig.1 Schematic of DC microgrid structure

图2 直流微网的等效电路

Fig.2 Equivalent circuit of a DC microgrid

图3 传统下垂控制的局限性原理图

Fig.3 Limitations of the traditional droop control

图4 改进策略原理

Fig.4 Principle of the improved strategy

图5 控制系统的结构框图

Fig.5 Structural block diagram of the control system

表1 系统参数

Table 1 Parameters of the system

图6 第一电压环传递函数的伯德图

Fig.6 Bode diagram of the transfer function of the first voltage loop

图7 第二电压环传递函数的伯德图

Fig.7 Bode diagram of the transfer function of the second voltage loop

表2 性能指标分析结果

Table 2 Results of performance indicators

图8 传统下垂控制的仿真结果

Fig.8 Results of traditional droop control

图9 系统引入第一电压环的仿真结果

Fig.9 Results of the system with the first voltage loop

图10 系统引入双电压环的仿真结果

Fig.10 Results of the system with two voltage loops

图11 文献[20]所提增量式下垂控制的仿真结果

Fig.11 Results with the incremental droop control method in Ref.[20]

图12 本文所提控制策略的仿真结果

Fig.12 Results with proposed control strategy

表3 系统负载的分布情况

Table 3 Load data of the system

图13 存在本地负载时传统下垂控制的仿真结果

Fig.13 Results of traditional droop control in the presence of local load

图14 存在本地负载时改进算法的仿真结果

Fig.14 Results of the improved droop control in the presence of local load

图15 DG容量不同时传统下垂控制的仿真结果

Fig.15 Results of traditional droop control under different DG capacities

图16 DG容量不同时改进算法的仿真结果

Fig.16 Results of the improved droop control under different DG capacities

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