Low-frequency oscillation suppression strategy of photovoltaic power station for multi-machine system based on VSG technology

Abstract

The invention provides a low-frequency oscillation suppression strategy design method for a multi-machine system by a photovoltaic power station based on the VSG technology. The method comprises the steps of establishing a multi-machine system mathematical model containing the photovoltaic power station; establishing a VSG control strategy model of the grid-connected inverter of the photovoltaic power station by simulating a rotor motion equation of a synchronous generator; designing a self-adaptive virtual inertia control strategy for the VSG control strategy model of the grid-connected inverter of the photovoltaic power station; and designing a WPSS low-frequency oscillation suppression strategy based on wide-area signal control in the VSG control strategy model of the grid-connected inverter of the photovoltaic power station according to a power system stabilizer equipped for a power generator set. According to the invention, low-frequency oscillation in the multi-machine system andpower low-frequency oscillation on a tie line are suppressed.

Description

technical field [0001] The invention belongs to the field of electric power systems and automation thereof, and specifically relates to a low-frequency oscillation suppression strategy for a multi-machine system of a photovoltaic power station based on VSG technology. Background technique [0002] With the increasing world energy crisis and environmental problems, distributed power generation technology and micro-grid technology have received more and more attention, especially with the increase of photovoltaic penetration rate, the scale of centralized photovoltaic power plants is increasing, and Conventional grid-connected inverters have fast response speed, almost no moment of inertia, and are difficult to participate in grid regulation. They cannot provide the necessary voltage and frequency support for active distribution networks with large-scale photovoltaic power plants, let alone power grids with relatively poor stability Provide the necessary damping effect. [00...

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Problems solved by technology

[0005] Different from traditional synchronous generator sets, as a static power generation unit, photovoltaics have zero moment of inertia. Therefore, large-scale photovoltaic grid connection will affect the damping characteristics of the system, especially in recent years. With the increase of transmission power, it is very easy to cause low-frequency oscillation due to lack of damping on such a large regional interconnection grid tie line with weak connection, long-distance transmission and heavy load, which seriously affects the safe and stable operation of the regional interconnection grid

[0006] For large-scale photovoltaic power plants controlled by traditional PQ, most of the current research uses active power additional damping controllers to improve system damping, but this will make the control structure more complex; a few studies further use wide-area transmission line active differential signals to achieve adaptive damping Control, has a certain effect on the low-frequency power oscillation on the interval tie line, but has a limited effect on the local oscillation in the area

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