Virtual synchronous generator low-voltage ride-through method and system based on virtual voltage drop

A technology of low-voltage ride-through and virtual synchronous machine, applied in the direction of AC network voltage adjustment, electrical components, circuit devices, etc., can solve the problems of system stability, dependence on grid voltage stability, long adjustment time, etc., to ensure frequency stability , Suppress transient current and help recovery effect

Pending Publication Date: 2021-09-03
XI AN JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] One way for VSG to realize LVRT is to switch from the normal VSG control mode to the traditional inverter control mode during a fault, but this method depends on the stability of the grid voltage, which is not conducive to the operation in a weak grid
Some literature proposes that by changing the current command value of the current loop, the introduction of the current loop in the VSG control algorithm may cause low-frequency oscillation and affect the stability of the system
There are also literat

Method used

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  • Virtual synchronous generator low-voltage ride-through method and system based on virtual voltage drop
  • Virtual synchronous generator low-voltage ride-through method and system based on virtual voltage drop
  • Virtual synchronous generator low-voltage ride-through method and system based on virtual voltage drop

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Example Embodiment

[0097] Embodiment:

[0098] See Table 1, which is set for the specific parameters of the present embodiment, such as image 3 , By setting T 0 Time grid voltage falls 60%, lasting 2S, in the event of a moment of failure, the virtual fault voltage can suppress the transient current after the failure, and the steady state current is 1.1pu, and VSG You can output reactive power to meet the requirements of the national standard. t 1 Time, fault clearance, grid voltage recovery is normal, the power loop is re-adjusted to recovery mode, and the virtual recovery voltage is added to suppress the transient current when the fault is cleared. From image 3 As can be seen in this policy, this policy can realize the low voltage crossing of the virtual synchronous generator.

[0099] Table 1

[0100]

[0101]

[0102] The present invention also provides a system based on virtual synchronizing a virtual synchronizing machine, including grid operation, frozen module, virtual fault pressure drop...

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Abstract

The invention discloses a virtual synchronous generator low-voltage ride-through method and system based on virtual voltage drop. The method comprises the steps of: enabling a power control loop to be converted into a freezing mode from a conventional virtual synchronous mode when a power grid voltage drops, guaranteeing the stability of a system, through adding virtual fault voltage drop, enabling modulation waves to be equal to a difference value between the internal potential and the virtual fault voltage drop, suppressing an overcurrent when the fault occurs, and outputting reactive power meeting the national standard requirement by an inverter, thereby facilitating the recovery of the power grid voltage; and when the voltage returns to normal, converting the power control loop into a recovery mode from the freezing mode, and in order to suppress transient current during fault recovery, adding virtual recovery voltage drop, so that the modulation waves are equal to a difference value between the internal potential and the virtual recovery voltage drop. The strategy is suitable for a control structure with or without a current inner loop, and low voltage ride through of a virtual synchronous generator can be realized without mode switching.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverter control, and in particular relates to a virtual synchronous machine low-voltage ride-through method and system based on a virtual voltage drop. Background technique [0002] With the extensive use of new energy sources such as wind energy and solar energy, power electronic devices are used more and more widely in power systems as the interface connecting the grid and distributed power sources. Virtual synchronous generator (virtual synchronous generator, VSG) is a control algorithm for grid-connected inverters. By introducing the rotor motion equation and increasing the inertia and damping of the system, it can provide voltage and frequency support for the grid and avoid rapid fluctuations in loads. The frequency is unstable, and it participates in the voltage and frequency regulation of the power grid at the same time, so that the power grid has high stability. Since the VSG cont...

Claims

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Application Information

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IPC IPC(8): H02J3/16H02J3/48H02J3/50H02J3/24
CPCH02J3/16H02J3/48H02J3/50H02J3/24H02J3/241H02J2203/20Y02E40/30
Inventor 王跃刘航刘永慧彭阳徐何凡余鹏舒思睿郜凯杰
Owner XI AN JIAOTONG UNIV
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