Control method for virtual synchronous generator capable of being adapted to imbalanced power grid and load conditions

A technology of generator control and virtual synchronization, applied in the direction of single-network parallel feeding arrangement, etc., can solve problems such as current imbalance and power fluctuation

Active Publication Date: 2016-09-21
XI AN JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The present invention aims at the problems of power fluctuation and current unbalance of the virtual synchronous generator under the unbalanced power grid and load condit

Method used

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  • Control method for virtual synchronous generator capable of being adapted to imbalanced power grid and load conditions
  • Control method for virtual synchronous generator capable of being adapted to imbalanced power grid and load conditions
  • Control method for virtual synchronous generator capable of being adapted to imbalanced power grid and load conditions

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Embodiment

[0085] The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

[0086] The response process of the virtual synchronous generator when a step occurs in the grid frequency, and compares the control effect of the virtual synchronous generator adding the method proposed by the present invention and not adding the method proposed by the present invention. The concrete parameter setting of embodiment is referring to table 1:

[0087] Table 1 embodiment parameter

[0088]

[0089] The working condition of the implementation is that the virtual synchronous generator runs in the grid-connected mode, and the grid voltage imbalance is 5%. The grid voltage waveform is as Image 6 shown.

[0090] At the initial steady state, the grid frequency is 50Hz, and the steady state value of the virtual synchronous generator output active power is 5000W. At t=3s, the fre...

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Abstract

The invention discloses a control method for a virtual synchronous generator capable of being adapted to imbalanced power grid and load conditions. The control method comprises the following steps that 1) an active ring simulates the mechanical characteristics of a speed controller and a rotor to obtain an output positive sequence voltage frequency and a phase position instruction; 2) a reactive ring simulates a n excitation controller to obtain an output positive sequence voltage amplitude value instruction; 3) a voltage-control and virtual synchronous impedance ring simulates the electrical characteristics of a stator; 4) positive and negative sequence current rings carry out accurate tracking on the positive and negative sequence current instructions respectively, and eliminates the negative sequence current output; and 5) a modulation signal is obtained by the combination of the positive and negative sequence current rings, and then the modulation signal is subjected to PWM to obtain a switching signal. Compared with the prior art, the output active power fluctuation and frequency fluctuation caused by imbalance of the power grid can be eliminated; and in addition, it is ensured that the output current of the virtual synchronous generator is balanced constantly, so that overhigh electrical stress of a certain bridge arm of the inverter can be avoided.

Description

Technical field: [0001] The invention belongs to the field of virtual synchronous motor control, and in particular relates to a virtual synchronous generator control method adapting to unbalanced power grid and load conditions. Background technique: [0002] Renewable new energy power generation mainly based on wind power and photovoltaics mainly uses power electronic converters as grid-connected interfaces, which have the advantages of flexible control and quick response, but also have shortcomings such as lack of inertia and damping, especially at present Current converters are often connected to the grid in current source mode, which is significantly different from the synchronous generators used in traditional energy sources in terms of external characteristics. Now, with the continuous improvement of the penetration rate of distributed renewable energy, the rotating reserve capacity and moment of inertia in the power system are relatively reduced, which increases the fr...

Claims

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Application Information

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IPC IPC(8): H02J3/46
CPCH02J3/46
Inventor 王跃李明烜王文媞徐宁一王宁段国朝
Owner XI AN JIAOTONG UNIV
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