A frequency control method and system for a transient process of a virtual synchronous generator
A virtual synchronization and transient process technology, applied in electrical components, circuit devices, AC network circuits, etc., can solve problems such as VSG disconnection, equipment damage, fluctuations, etc., achieve safe and stable operation, suppress frequency fluctuations, and speed up response speed Effect
Inactive Publication Date: 2018-07-20
QINGHAI UNIVERSITY
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Therefore, when the renewable energy is connected to the power grid through the VSG, if there is an unpredictable fluctuation on the active power input side, the frequency of the VSG will also fluctuate. If the fluctuation amplitude exceeds the safety threshold of the VSG, the inverter may Device-based devices cause damage or even cause the VSG to go off-network, thereby threatening the safe and stable operation of the system
[0004] When the frequency fluctuation of the VSG is caused by unpredictable changes in the new energy output, changing the size of the virtual inertia in the existing control method only speeds up or slows down the change process of the angular frequency, and cannot fundamentally change the frequency change nature of the VSG
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[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0044] In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0045] The basic topology of a virtual synchronous generator is as follows: figure 1 As shown, the virtual synchronous generator includes three-phase inverter, filter, grid-connected port power calculation, VSG co...
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The invention discloses a frequency control method for a transient process of a virtual synchronous generator. The method comprises the steps of: setting a frequency safety threshold; obtaining the frequency in the transient process of the virtual synchronous generator in real time; comparing the frequency with the frequency safety threshold to obtain a comparison result; when the comparison result shows that the frequency is smaller than or equal to the frequency safety threshold, determining a damping coefficient to be a stable damping coefficient; and when the comparison result shows that the frequency is greater than the frequency safety threshold, increasing the damping coefficient until the frequency is smaller than or equal to the frequency safety threshold. According to the control method, the damping coefficient can be adjusted in real time, so that frequency fluctuation in the transient process can be stabilized; the frequency change property of the VSG is fundamentally changed; and safe and stable operation of a power grid system is ensured.
Description
technical field [0001] The invention relates to the technical field of virtual synchronous generators, in particular to a frequency control method and system for the transient process of virtual synchronous generators. Background technique [0002] As the penetration rate of distributed power continues to increase, the installed capacity of traditional synchronous generators will gradually decrease, and the rotating reserve capacity and moment of inertia in the power system will be relatively reduced, which poses a serious challenge to the safe and stable operation of the power grid. Furthermore, the control strategies of grid-connected inverters are different, and the output of renewable energy is characterized by volatility and uncertainty, which makes it difficult for distributed power to achieve plug-and-play and autonomous coordinated operation. Scholars at home and abroad have proposed a virtual synchronous generator (virtual synchronous generator, VSG) technology, whi...
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IPC IPC(8): H02J3/38H02J3/24
CPCH02J3/24H02J3/382
Inventor 陈来军梅生伟司杨陈晓弢郭永庆杨艳
Owner QINGHAI UNIVERSITY