A Pseudo-Hierarchical Control Method for DC Microgrid System under High Photovoltaic Penetration Rate

Abstract

The invention discloses a pseudo-hierarchical control method for a direct current microgrid system under photovoltaic high permeability. A photovoltaic panel is connected to a direct current microgridthrough a Buck circuit. The method comprises the following steps: adding a proportional scheduling part, a voltage regulation part and a droop control part into the microgrid system; actively collecting the actual active power Ppcc at the port of the power distribution network; calculating a power difference delta P between the port reference active power and the actual active power Ppcc, and transmitting the power difference delta P to each photovoltaic power supply; carrying out proportional scheduling control, voltage regulation control and droop control on each photovoltaic power supply to obtain a photovoltaic power supply output dp / dv reference value; and enabling each photovoltaic power supply to control actual output according to the dp / dv reference value. By means of the method,the photovoltaic generator keeps certain hot standby power to participate in mitigation of power fluctuation, equal-proportion schedulable control over the photovoltaic generator in the microgrid system is achieved, the stability and robustness of the direct-current microgrid system are improved, and reliable control over grid connection-island operation and switching of the direct-current microgrid system is achieved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic networking, and in particular relates to a pseudo-layered control method for a DC microgrid system under high photovoltaic permeability. Background technique [0002] Photovoltaic power generation has gradually become an ideal substitute for fuel generators due to its advantages of no pollution, no noise, and low overhead. In addition, the DC characteristics of photovoltaics can be used more efficiently in DC microgrids with other DC loads, so DC microgrids based on photovoltaic networking have received more and more attention. Due to the randomness and discontinuity of photovoltaic power generation, unstable power output will cause random voltage fluctuations, so an additional voltage source is needed to provide bus voltage support. [0003] Generally, DC microgrids have two operating modes: networking and islanding: in the networking mode, the microgrid is connected to the main grid and ob...

AI Technical Summary

Problems solved by technology

However, as the penetration rate of photovoltaics increases, the intermittent power generation will lead to greater power fluctuations, which will have a greater impact on the main grid in the grid-connected state, and greater demand for energy storage capacity in the isolated state. The stability of the microgrid also poses a greater threat

[0004] The Chinese patent document with the publication number CN104065099A discloses a hybrid energy storage-based AC-DC hybrid modular microgrid networking structure and method, which realizes the modularization of multi-type loads and multi-type distributed power sources in the AC-DC hybrid microgrid Encapsulation, the modular micro-grid actively participates in the dispatching operation of the large power grid as an independently controllable power supply / load unit; through the reasonable design of the hybrid energy storage system structure and access mode, the seamless switching of the grid-connected / island dual mode becomes a modular micro-grid. The natural properties of the power grid, but there is no specific analysis of the internal control methods and composition

[0005] The Chinese patent document with the publication number CN103280844A discloses an AC-DC hybrid multi-level micro-grid system. The invention has a flexible structure and a modular structure, and can form a variety of system structures and research on grid-connection and off-grid switching of systems at all levels, but its It solves the problem of distributed power generation access, and cannot fully utilize the adjustment ability of controllable resources in the microgrid

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