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Parallel multi-energy-storage state-of-charge balance control method for island direct-current microgrid

A DC micro-grid and state-of-charge technology, applied in the direction of AC network load balancing, can solve problems such as complex control systems, poor stability, and line mismatch, so as to improve distribution accuracy, increase service life, and avoid excessive charging and discharging. Effect

Active Publication Date: 2020-02-18
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a state-of-charge balance control method for parallel connection of multiple energy storages in an isolated island DC microgrid in order to overcome the defects of line mismatch, poor stability, and complex control system in the prior art

Method used

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  • Parallel multi-energy-storage state-of-charge balance control method for island direct-current microgrid
  • Parallel multi-energy-storage state-of-charge balance control method for island direct-current microgrid
  • Parallel multi-energy-storage state-of-charge balance control method for island direct-current microgrid

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Experimental program
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Effect test

Embodiment 1

[0080]Based on the RTDS platform, build an isolated island DC microgrid system with three sets of parallel distributed energy storage units, including the first energy storage unit, the second energy storage unit and the third energy storage unit. The capacity of the energy storage unit is set to 12Ah, and other details of the system The control parameters are shown in Table 1:

[0081] Table 1 System experiment parameters based on RTDS platform

[0082]

[0083] The initial state of charge of each energy storage unit is set to be 80%. When the output power of the photovoltaic system cannot meet the power demanded by the load, in order to maintain the real-time power balance in the microgrid, the energy storage system is in a stable discharge state at this time, and its experimental waveform is shown in Figure 6(a); The energy units all operate in the traditional droop control method, as shown in Figure 6(b), due to the influence of the mismatched line impedance, the load ...

Embodiment 2

[0087] The configuration of the energy storage unit group is the same as that in Embodiment 1. As shown in Figure 8(a), the energy storage system is in a stable charging state from 0 to 8s, and operates in the traditional droop control method before 4s. The improved droop control method proposed in the present invention, the corresponding state of charge begins to converge, and the photovoltaic system is affected by external factors at 8s, resulting in a reduction in output power, and the photovoltaic power generation cannot meet the load power demand, as shown in Figure 8(b). When the power fluctuates, the energy storage system quickly switches from the charging state to the discharging state. It can be clearly observed from Figure 8(a) that under the improved droop control method proposed in the present invention, even if the photovoltaic power fluctuates, the charging state is still at Gradually balance the state, and finally reach the state of charge balance. As shown in F...

Embodiment 3

[0089] The configuration of the energy storage unit group is the same as that in Embodiment 1. As shown in Figure 9(a), from 0 to 8s, the energy storage system is in a stable discharge state, before 4s it operates in the traditional droop control method, and at 4s the energy storage unit switches to In the improved droop control method proposed by the present invention, the corresponding state of charge begins to converge, and the load power demand suddenly decreases at 8s. At this time, the photovoltaic power generation power still remains after meeting the load power demand, as shown in Figure 9(b). The energy storage system quickly switches from the discharge state to the charge state, as shown in Figure 9(a), under the improved droop control method proposed in the present invention, load power fluctuations will not affect the state of charge balance control effect between energy storage units. As shown in Figure 9(c), under the improved droop control method proposed by the ...

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Abstract

The invention relates to a parallel multi-energy-storage state-of-charge balance control method for an island direct-current microgrid. On the basis of a traditional droop control method, by introducing a sampling holder and improving the droop control method, when a power distribution error exists in a system and the state of charge does not reach a balance state, a droop coefficient is continuously and adaptively modified in each sampling period, the deviation of the state of charge is reduced, and finally, the state of charge balance between energy storage units is realized. Compared with the prior art, the method disclosed in the invention has the advantages of avoiding excessive discharge, giving full play to the use efficiency, prolonging the service life and the like.

Description

technical field [0001] The invention relates to a control method for a DC microgrid, in particular to a control method for equalizing the state of charge of an island DC microgrid connected in parallel with multiple energy storages. Background technique [0002] In order to cope with the global energy crisis and environmental pollution and realize the sustainable development of human society, in recent years, distributed generation DGs technology based on renewable energy RES has received extensive attention and development. As one of the effective solutions to integrate various distributed power sources, energy storage, loads, converters, monitoring and protection devices, microgrid has been widely studied. Compared with the traditional AC microgrid, the DC microgrid has gradually become a current research hotspot due to less energy conversion process, high efficiency, and low loss, and no need to consider voltage phase and frequency issues; Renewable energy power generati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/32
CPCH02J3/32
Inventor 韩云昊喻思米阳常俊飞伦雪莹徐怡雯
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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