A microgrid system with improved operation, control and protection performance

Abstract

The invention discloses a micro-grid system with functions of improving operation control and protection performance. The micro-grid system mainly comprises a multi-inverter-parallel-operation control strategy, a micro-grid relay protection scheme and micro-grid load prediction, wherein an improved droop control algorithm is adopted for the multi-inverter-parallel-operation control strategy, region differential-motion main protection, overcurrent backup protection and fault component comprehensive impedance bus protection of normalization brake coefficients are adopted for the micro-grid relay protection scheme, and a neural network model is adopted for the micro-grid load prediction. According to the micro-grid system, the improved droop control algorithm of the multi-inverter-parallel-operation control strategy and the region differential-motion main protection, the overcurrent backup protection and the fault component comprehensive impedance bus protection of the normalization brake coefficients of the control strategy of the micro-grid relay protection and the neural network model of the micro-grid load prediction are combined together, the operation, control and protection performance and intelligent level in switching among different modes of a micro-grid are improved.

Description

technical field [0001] The invention relates to a micro-grid system with improved operation, control and protection performance, which belongs to the electrotechnical technology. Background technique [0002] From a system point of view, the microgrid combines generators, loads, energy storage devices, and control devices to form a single controllable unit that supplies electricity and heat to users at the same time. Most of the power sources in the microgrid are micro power sources, which have the characteristics of low cost, low voltage, and low pollution. The microgrid can be connected to the large power grid, and can also be disconnected from the main grid when the grid fails or needs to be operated independently. It is an autonomous system that can realize self-control, protection and management. The microgrid not only solves the problem of large-scale access to distributed power, but also gives full play to the advantages of distributed power, and brings other benefit...

AI Technical Summary

Problems solved by technology

[0003] In the parallel operation of multiple inverters, the droop control method, which is the key technology of parallel control, in the low-voltage microgrid, the impedance ratio of the connecting line is much higher than that of other voltage level lines, and the resistance value is higher when the line is longer; Due to the difference in the distance between the distributed power supply and the public connection point, there is a difference in the connection impedance, resulting in an increase in the circulation of the inverter and unbalanced power distribution; the connection of the micro-grid brings new problems to the protection of the power system. The gradual increase in power generation quantity and penetration rate may change the direction of its internal power flow, thereby affecting the entire power grid; the current micro-grid lacks an effective load forecasting model, so the randomness and nature of the access load in the micro-grid Uncertain power flow does not have a good predictive ability, so it is impossible to effectively determine the amount of micro-power access according to the various loads in the micro-grid, causing instability in the micro-grid and even the large power grid

[0004] The micro-grid with traditional control and protection strategies used in engineering can operate and work normally in occasions with low requirements, but the traditional micro-grid in occasions with relatively high requirements for operation performance, control performance, protection performance and intelligence level will not be able to meet the requirements

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