Improved master-slave control method for DC distribution network

Abstract

The invention relates to an improved master-slave control method for a DC distribution network. The invention is technically characterized in that the method comprises the following steps: Step 1, designing an adaptive droop controller with a dead zone; and 2, setting one MMC converter station as the main station with the working mode being a constant voltage control mode, and setting the other MMC converter stations as slave stations with the working mode being the control mode of the adaptive droop controller with the dead zone in the Step 1. According to the invention, seamless switching ofoperation modes can be realized and the stability of DC voltage can be ensured when communication failure occurs.

Description

technical field [0001] The invention belongs to the technical field of direct current distribution networks, and relates to a control method for a converter station, in particular to an improved master-slave control method for a direct current distribution network. Background technique [0002] With the rapid development of renewable energy, more and more new energy power generation and energy storage are connected to the distribution network in large quantities, and the power flow of the distribution network has become a two-way flow, which affects the capacity, reliability and power of the distribution network. Higher requirements are put forward for quality, etc., but the current traditional AC distribution network is not designed for bidirectional power flow, and cannot meet the requirements of some users. In addition, with the great progress of power electronics technology and DC load technology, the DC distribution network has attracted extensive attention from scholar...

AI Technical Summary

Problems solved by technology

DC voltage droop control means that all converter stations with power regulation capabilities use the given slope relationship between each DC power (or current) and DC voltage to realize DC voltage control shared by multiple stations. This control method does not require an upper-level controller And communication, with good modularity and scalability, but there are deviations in steady-state operation, and the DC distribution network load changes complex, frequent and large load changes will cause voltage fluctuations, and even voltage deviations exceed the rated range during stable operation, It is difficult to select the slope of this control method

Voltage margin control means that when the main converter station fails or the power exceeds the limit and cannot continue to maintain a constant DC voltage, another converter station will switch to the constant DC voltage control mode and run at the new DC voltage reference value. The method does not require inter-station communication, but the structure of the DC distribution network is complex, the load changes greatly, and the voltage fluctuates violently, which makes the selection of voltage margin more complicated, and at the same time it is difficult to determine the priority of multiple backup constant voltage converter stations

It can be seen that compared with the flexible DC transmission system, the DC distribution network has more nodes and the power flow is more complex, and the master-slave control method is easier to achieve stable operation of the DC distribution network than other methods, but the existing DC distribution network The master-slave control method still has the disadvantages that the master-slave control cannot realize the switching of the operating mode and the DC voltage stability control is difficult when the communication fails.

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