Mutual Power Support Strategy for Isolated Hybrid AC/DC Microgrid

doi:10.12204/j.issn.1000-7229.2021.01.009

Abstract

Abstract:

Hybrid AC/DC microgrid can effectively coordinate the power distribution of microgrid through mutual power support between two sub-grids, and improve the system’s ability to suppress power fluctuations. In order to realize the reasonable mutual power support between the two sub-grids, this paper proposes a mutual power support strategy for hybrid AC/DC microgrid used in island operation mode. Firstly, in order to avoid the power loss caused by the frequent actions of inter-linking converter, a hierarchical control strategy is proposed, which includes power autonomy model and power interaction model, and the changing between system operating models is designed reasonably. Then the goal of mutual power support based on the conditions of the sub-grids and the state of charge (SOC) of the battery is proposed. Meanwhile, a power cooperation control algorithm, which gives consideration to both AC frequency and DC voltage, is designed to achieve the goal. A simulation model is built in PSCAD/EMTDC. The simulation results show that, with the mutual power support strategy, the AC and DC sub-grids can bear the power fluctuations of the system according to their own conditions. And reasonable SOC of the battery can be maintained.

Key words: hybrid AC / DC microgrid, hierarchical control, inter-linking converter, mutual power support strategy, state of charge (SOC)

CLC Number:

TM732

WANG Zhi, MA Zhen, HU Pengtao, ZHU Yongqiang. Mutual Power Support Strategy for Isolated Hybrid AC/DC Microgrid[J]. ELECTRIC POWER CONSTRUCTION, 2021, 42(1): 76-84.

Figures/Tables 10

Fig.1 Structure of a hybrid microgrid in island operation mode

Table 1 System operation modes

Fig.2 Changing between system operating models

Fig.3 State division of battery’s SOC

Fig.4 Active power control of ILC

Table 2 Simulation parameters

Fig.5 Simulation results in case 1

Fig.6 Simulation results in case 2

Fig.7 Simulation results in case 3

Fig.8 Simulation results in case 4

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