Isolated DC microgrid self-adaptive droop control method

Abstract

The invention discloses an isolated DC microgrid self-adaptive droop control method, which comprises three parts including application of a three-node DC microgrid, droop control and application of adiscrete distribution algorithm. The isolated DC microgrid self-adaptive droop control method provided by the invention exchanges voltage and current information with neighbor nodes under the action of a synchronous clock at each control node, iteratively evaluates an average voltage of the entire grid through adopting a local distributed algorithm, dynamically searches for target virtual resistance satisfying requirements of current sharing and voltage regulation, and realizes self-adaptive droop control of variable virtual resistance. Due to the absence of a central controller, the robustness and flexibility of control are increased. Meanwhile, measures for reducing or eliminating influences of communication delay are proposed from the aspects of communication media, communication protocols, system sampling intervals, network matrix optimization and the like, and the reliability of the strategies are improved.

Description

technical field [0001] The invention relates to an isolated DC microgrid, in particular to an adaptive droop control method for an isolated DC microgrid. Background technique [0002] Microgrid is a new form of power grid composed of distributed power sources, energy storage devices, and loads. It is an effective way for distributed power sources to connect to distribution networks. In order to improve the power supply reliability and capacity of the microgrid, multiple distributed generation units are often used in parallel operation mode to bear the load power. Compared with the AC micro-grid, the DC micro-grid is more suitable for the access of DC power sources and DC loads such as photovoltaic cells, fuel cells, super capacitors, and batteries. Due to the reduced use of inverters, the efficiency and controllability of the system are increased. . [0003] There are also problems such as load power distribution in the DC microgrid connected in parallel by distributed gen...

AI Technical Summary

Problems solved by technology

However, due to the uneven distribution of line impedance, droop control without interconnection line cannot meet the requirements of current sharing accuracy and bus voltage at the same time

In the secondary adjustment method, the central controller collects the voltage and current information of the entire network, and after calculation, sends the command value of the control quantity to the local controller to adjust the output. This method is simple to implement and has high adjustment accuracy, but due to the existence of central Node, poor system reliability and scalability

For example, the DC micro-grid adaptive droop control strategy based on distributed algorithms achieves the purpose of current sharing and voltage regulation, but it adopts a simple multi-machine parallel model without considering the impact of renewable energy access, and uses continuous time model analysis System performance, ignoring the influence of actual sampling time interval and communication delay, information interaction does not involve specific communication process, communication protocol, lack of support for practical application

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