DC-Microgrid Droop Control Based on Double Voltage Compensation

doi:10.12204/j.issn.1000-7229.2021.03.009

Abstract

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

CLC Number:

TM732

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.

Figures/Tables 19

Fig.1 Schematic of DC microgrid structure

Fig.2 Equivalent circuit of a DC microgrid

Fig.3 Limitations of the traditional droop control

Fig.4 Principle of the improved strategy

Fig.5 Structural block diagram of the control system

Table 1 Parameters of the system

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

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

Table 2 Results of performance indicators

Fig.8 Results of traditional droop control

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

Fig.10 Results of the system with two voltage loops

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

Fig.12 Results with proposed control strategy

Table 3 Load data of the system

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

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

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

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

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