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Grid-connected control method and system based on virtual synchronous generator

A virtual synchronization and control method technology, applied in electrical components, circuit devices, AC network circuits, etc., can solve the problems of frequency fluctuations, not taking into account the influence, the inverter is difficult to meet the flexible and stable operation of the microgrid, and achieves suppression Current deviation, the effect of improving stability

Active Publication Date: 2017-05-31
JIANGSU UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For the pre-synchronization method based on the phase-locked loop, the pre-synchronization function is realized, but when the grid voltage is asymmetrical and distorted, the frequency will fluctuate, and the traditional phase-locked loop cannot accurately detect the voltage synchronization signal
None of the above takes into account the influence of off-grid / grid-connection on VSG frequency and voltage after loading
According to the control requirements of different operation modes of the micro-grid, it can be seen that the traditional inverter control method is difficult to meet the requirements of flexible and stable operation of the micro-grid.

Method used

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  • Grid-connected control method and system based on virtual synchronous generator
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  • Grid-connected control method and system based on virtual synchronous generator

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Embodiment 1

[0046] Embodiment 1. A grid-connected control method based on a virtual synchronous generator. Combine below Figure 1 to Figure 6 The method provided in this embodiment will be described in detail.

[0047] see Figure 1 to Figure 6 , S1, using the instantaneous power calculation method to calculate the active power and reactive power according to the collected instantaneous values ​​of the voltage and current output by the inverter.

[0048] S2. Using the VSG control algorithm to calculate the active power and reactive power to obtain a reference signal of the inverter output voltage.

[0049] Specifically, such as image 3 As shown, the virtual synchronous machine control algorithm draws on the second-order classical equation of the synchronous generator and the governor and excitation controller, so the VSG control algorithm is designed, and its mathematical equations are shown in formula (1) to formula (3):

[0050]

[0051]

[0052]

[0053] Among them, T s...

Embodiment 2

[0103] Embodiment 2. A grid-connected control system based on a virtual synchronous generator. Combine below Figure 2 to Figure 6 The system provided in this embodiment will be described in detail.

[0104] see Figure 2 to Figure 6 , a grid-connected control system based on a virtual synchronous generator, the system includes: a three-phase full-bridge inverter, a filter, an instantaneous power calculation module, a VSG control module, a synchronous impedance module, a comparator, and a quasi-proportional resonance control devices as well as PWM modulators.

[0105] The output end of the instantaneous power calculation module is electrically connected to the input end of the VSG control module, the output end of the VSG control module and the output end of the virtual impedance module are both electrically connected to the input end of the comparator, The output end of the comparator is electrically connected to the input end of the quasi-proportional resonant controller,...

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Abstract

The invention discloses a grid-connected control method and system based on a virtual synchronous generator. The method comprises the steps as follows: simulating synchronous impedance with a synchronous impedance method based on cascade connection of an order-reduced resonator and a three-order generalized integrator to improve stability of the system, inhibit current deviation formed by load disturbance and realize power equalization, and inhibiting imbalance of output voltage and harmonic component by using quasi-proportional resonance controller. An order-reduced resonator phase-locked loop is combined with a quasi-synchronous parallel algorithm, asymmetry of grid voltage and output voltage of an inverter as well as the effect of harmonic waves on detection accuracy is avoided, the frequency, amplitude and phase of the output voltage of the virtual synchronous inverter track grid voltage quickly without static errors by the aid of the quasi-synchronous parallel algorithm, so that flexible off-grid / grid-connected switching is realized, the power supply reliability of the system is improved, and the electric energy quality is improved.

Description

technical field [0001] The present invention relates to a grid-connected control method and system based on a virtual synchronous generator, in particular to a micro-grid control and off-grid switching control method and system based on a virtual synchronous generator technology, which belongs to distributed power generation micro-grid technology field. Background technique [0002] It is of great significance to vigorously develop renewable new energy mainly based on wind power and photovoltaics, improve the economics of power grid operation, optimize the operation mode of the power system, and build an environmentally friendly power system. As the interface between new energy and the large power grid, conventional grid-connected inverters have the advantages of flexible control and quick response, but there are also deficiencies such as lack of inertia and damping, especially the use of current-controlled grid-connected converters, which are compatible with synchronous pow...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J3/40H02J3/24H02J3/01
CPCH02J3/01H02J3/24H02J3/38H02J3/388H02J3/40Y02E40/40
Inventor 施凯焦龙徐培凤叶海涵孙宇新
Owner JIANGSU UNIV
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