Photovoltaic microgrid power equalization control method based on three-end cooperative control

Abstract

The invention discloses a photovoltaic microgrid power equalization control method based on three-end cooperative control, and the method comprises the steps: A) judging the current operation mode of a photovoltaic microgrid according to a DC bus voltage value of hte photovoltaic microgrid, a DC bus rated voltage value, an energy storage unit SOC, a photovoltaic power supply output power, and AC load power; B) carrying out the cooperative control of the working conditions of a photovoltaic power supply, an energy storage device and a grid-connected inverter in the photovoltaic microgrid according to the current operation model of the photovoltaic microgrid; C) controlling the current operation mode of the photovoltaic microgrid to be switched to an adjacent operation mode when the corresponding operation conditions are met; D) and enabling the converted operation mode to be updated to the current operation mode of the photovoltaic microgrid; and then switching to the step B). The method can enable the photovoltaic microgrid to be quickly switched to the corresponding operation mode in a seamless manner, thereby quickly eliminating the operation deviation, balancing the flow of an internal energy of the microgrid, reducing impact on the operation of the microgrid from power fluctuation, maintaining the stability of the voltage of a DC bus of the microgrid, and achieving the dynamic balance of the internal power of the microgrid.

Description

Technical field [0001] The invention belongs to the field of electrical technology, and in particular relates to a photovoltaic microgrid power balance control method based on three-terminal cooperative control. Background technique [0002] The microgrid organically combines distributed power sources, energy storage devices, loads and power electronic devices to form a controllable power generation and power consumption system with strong self-healing properties. Compared with the public grid, the microgrid can be used as a highly controllable power supply unit to effectively supplement the public grid, and provide reliable and high-quality power for the important loads of the grid when the public grid loses power. [0003] However, there are still many problems to be solved urgently in the process of microgrid operation and control. At present, the main problems in the operation and control of the micro-grid are as follows: First, due to the existence of a large number of...

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Problems solved by technology

[0003] However, there are still many problems to be solved urgently in the process of microgrid operation and control.

At present, the main problems in the operation and control of the micro-grid are as follows: First, due to the existence of a large number of intermittent power generation units such as wind energy and solar energy, and the capacity and inertia of the micro-grid are generally relatively small, resulting in the randomness and fluctuation of electric energy in the micro-grid The relatively large resistance causes fluctuations in the voltage, frequency and power of the micro-grid, which leads to the unstable operation of the micro-grid.

Second, the microgrid has the characteristics of a complex network, and the real-time interaction of multiple sources and loads in each subnet leads to unbalanced distribution of load power in the microgrid, making it difficult to accurately control and manage

Third, the microgrid has multiple operating scenarios such as grid-connected operation, island operation, and black start. When these operating scenarios switch to each other, it will cause two-way energy flow and impact, which seriously affects the safe and reliable operation of the microgrid.

Fourth, most distributed power sources in the micro-grid are connected to the micro-grid through power electronic devices, which can easily cause harmonic problems and circulation problems

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