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Low voltage ride through control method of virtual synchronous generator based on excitation state analysis

A low-voltage ride-through and excitation state technology, which is applied in the direction of single-network parallel feed arrangement, reactive power adjustment/elimination/compensation, reactive power compensation, etc. Current and other issues, to improve transient performance, suppress potential and frequency oscillation, and reduce the effect of transient process

Active Publication Date: 2020-03-31
JIANGSU UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the process of low voltage ride through, the inertia and damping design of VSG is in conflict with the requirements of transient operation. The voltage source characteristics of VSG are difficult to directly control the current. When the normal excitation state and the overexcitation state are transformed into each other, the impact current is unavoidable, and the potential oscillates. And power angle oscillation will also aggravate the inrush current during grid-connected operation

Method used

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  • Low voltage ride through control method of virtual synchronous generator based on excitation state analysis
  • Low voltage ride through control method of virtual synchronous generator based on excitation state analysis
  • Low voltage ride through control method of virtual synchronous generator based on excitation state analysis

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Embodiment 1

[0035] Embodiment 1. A virtual synchronous generator low-voltage ride-through control method based on excitation state analysis. Combine below Figure 1 to Figure 6 The method provided in this embodiment will be described in detail.

[0036] see Figure 1 to Figure 6 , a virtual synchronous generator low-voltage ride-through control method based on excitation state analysis, the method comprising:

[0037] S1. Execute the quasi-synchronization algorithm and the pre-synchronization algorithm in the VSG control module, adjust the output voltage of the inverter, and automatically select the grid-connection timing to close the grid-connection switch;

[0038] The pre-synchronization algorithm uses two integral links to cooperate with two droop coefficients to form two PIs to adjust the voltage and frequency, and a new PI is added to adjust the phase. The above quasi-synchronous algorithm is an existing algorithm. For details, please refer to the literature: Yang Liang, Wang Cong,...

Embodiment 2

[0073] Embodiment 2. Virtual synchronous generator low voltage ride through control system based on excitation state analysis. Combine below Figure 1 to Figure 6 The system provided in this embodiment will be described in detail.

[0074] see Figure 1 to Figure 6 , a virtual synchronous generator low voltage ride through control system based on excitation state analysis, said system comprising:

[0075] Inverter module, filter module, grid-connected switch, grid module, quasi-synchronous algorithm module, virtual synchronous generator control module, virtual impedance module, additional current loop module, SVPWM modulation module.

[0076] The inverter module, filter module, grid-connected switch, and grid module are electrically connected in sequence.

[0077] The output voltage signal at the front side of the circuit breaker and the voltage signal of the grid module at the rear side of the circuit breaker are collected, and the two signals are input into the quasi-sync...

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Abstract

The invention discloses an excitation state analysis-based low-voltage ride-through control method of a virtual synchronous power generator. The method comprises the steps of improving designs of droop characteristic, a reactive power ring and an active power ring by means of a reactive power adjustment principle of the synchronous power generator and a power grid which are connected in parallel,and the problems of excessive large reactive power increment, difficulty in preventing impact current and loop coupling reinforcement are effectively dealt with; and on the basis of no change on characteristic of the state analysis-based low-voltage ride-through control method of virtual synchronous power generator (VSG) system, an additional current ring is designed again, the under-excitation state running of an auxiliary system can be assisted during power grid fault period, an output current is adjusted, and a reactive power support is given out. A new directional method is employed, the transient process is accelerated, a control algorithm is not needed to be switched during the power grid fault period, a smooth switching strategy among states is also not needed to be added, and the low-voltage ride-through problem and the asymmetric drop of the power grid can be simultaneously dealt with.

Description

technical field [0001] The invention relates to a low-voltage ride-through control method for a virtual synchronous generator, in particular to a low-voltage ride-through control method for a virtual synchronous generator based on excitation state analysis, and belongs to the technical field of distributed power generation microgrids. Background technique [0002] Clean and renewable energy is of great significance to improving the energy structure and promoting ecological and environmental construction. As the main form of renewable energy application in the future, distributed power generation has many advantages such as less pollution, high reliability, high energy utilization rate, and flexible installation location. There are many disadvantages brought about by the centralized single power supply of the system. [0003] Synchronous generators have the advantage of being naturally friendly to the power grid. If we learn from the operation experience of traditional power...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02J3/18
CPCY02E40/30
Inventor 施凯叶海涵徐培凤孙宇新刘奕辰
Owner JIANGSU UNIV
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