Multi-VSG inverter circulation suppression and fault processing control method and system

A circulating current suppression and inverter technology, applied in the direction of multi-phase network asymmetry reduction, multi-phase network elimination/reduction of asymmetry, single network parallel feeding arrangement, etc., can solve time-consuming, load asymmetry, inverter Problems such as damage to magnetic components of switching devices, to achieve the effects of suppressing circulating currents and troubleshooting, realizing power distribution, and realizing correct distribution

Pending Publication Date: 2021-03-30
CHINA ELECTRIC POWER RES INST +3
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  • Claims
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AI Technical Summary

Problems solved by technology

[0003] Although the VSG inverter has a certain amplitude and phase compensation ability compared with ordinary inverters, its main circuit is still composed of fragile power electronic devices, and its ability to resist overvoltage and overcurrent is weak.
If the VSG inverter still adopts the traditional method of synchronously dragging the synchronous generator into the grid, or there may be an emergency situation of load asymmetry after off-grid or grid-connected, the inrush current generated at the moment of its grid-connected may affect the inverter. Severe damage to transformer switching devices and magnetic components
In addition, the traditional grid-connected inverter needs 2 coordinate transformations in the pre-synchronization link, and 5 PI links to ensure the smooth realization of pre-synchronization, which is cumbersome and time-consuming
[0004] In the process of switching from off-grid to grid-connected multi-inverters, especially at the moment of switching from off-grid operation to grid-connected operation, or in emergency situations such as sudden load changes, there will be a large inrush current, resulting in Grid-connected current and PCC point voltage are distorted, reducing power quality and causing serious damage to electronic devices. Therefore, not only the problem of pre-synchronization needs to be considered during switching, but also serious circulating currents exist when multiple VSGs form a microgrid. However, pre-synchronous grid-connected control of multi-VSG inverters, pre-synchronized grid-connected control under off-grid load faults, power distribution and circulation suppression are particularly important

Method used

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  • Multi-VSG inverter circulation suppression and fault processing control method and system

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Embodiment 1

[0075] A multi-VSG inverter circulating inhibition and a control method of the fault processing provided by the present invention is shown figure 1 As shown, including:

[0076] Step 1: When switching from the network: The VSG inverter set for each completed power parameter is used, and the VSG inverter is compensated by the pre-control compensation method, and it is reached to the grid network requirements;

[0077] Step 2: When the network is turned steady state time: If the non-symmetrical fault of the load occurs, the VSG inverter after the current type inverter is set in parallel with the VSG inverter after the completion of the power parameter, and the unbalanced current is compensated.

[0078] Among them, the power parameters of each VSG inverter are based on the rated capacity setting of each VSG inverter.

[0079] In order to solve an emergency, multiple different capacities of inverters are quickly and accurately realized and accurately realized and accurately realizin...

Embodiment 2

[0111] A multi-VSG inverter loop suppression and method of controlling the method of controlling the method of controlling the method are described below. This control method is used to simulate the VSG parallel operation of two different capacities. Choosing the VSG1 capacity is 20kW + 10kVar, the VSG2 capacity is 10KW + 5kVAR, and the capacity ratio is 2: 1, and the common local load is 18KW + 15kVar. Figure 6 ~ 8 The phase current waveforms of the microcarrene and the output active / reactive power waveform of VSG1 and VSG2, respectively. As can be seen from the simulation results, in the microfield system in parallel in multiple VSG, the grid is also implemented without any pre-synchronous control strategy, but the microbrid bus current has a large impact, which is approximately the normal grid current 8. Double, and the output power of the two inverters produces huge spikes and oscillations, reducing the power quality.

[0112] The present patent is introduced into the syste...

Embodiment 3

[0116] Based on the same inventive concept, the present invention also provides a multi-VSG inverter circulation suppression and a control system for fault processing, since these devices solve technical problems and multi-VSG inverter circulation suppression and fault control methods are similar, The repetition is not described again.

[0117] The basic structure of this system is like Figure 16 As shown, the grid switch module and the grid fault disposal module;

[0118] among them,

[0119] The grid switch module is used to switch to the network, and the VSG inverter is used for each completion of the power parameter, and the pre-control compensation method is used to compensate each VSG inverter separately until it reaches Paper network requirements;

[0120] The grunger fault disposal module is used to run when the grid is steady-state operation: if the loaded non-symmetrical fault, the VSG inverter after the current inverter is set in parallel with the VSG inverter, compens...

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Abstract

The invention provides a multi-VSG inverter circulation suppression and fault processing control method and system, and the method comprises the steps: carrying out the compensation of each VSG inverter through employing a pre-synchronization control compensation method for each VSG inverter which completes the setting of a power parameter when the grid-connected switching is carried out through an off-grid mode until the grid-connected requirements are met; during steady-state operation after grid connection, if an asymmetric fault of a load occurs, connecting the current type inverter and the VSG inverter in parallel after power parameter setting and connecting the current type inverter and the VSG inverter into a power grid, and compensating for the unbalanced current, wherein the powerparameter of each VSG inverter is set based on the rated capacity of each VSG inverter. The multi-VSG inverter control method provided by the invention not only effectively ensures that the multi-VSGinverter can realize power distribution through parameter setting, but also can ensure synchronization with a power grid in a pre-synchronization process, can effectively suppress grid-connected impact current, improves electric energy quality, and realizes seamless switching between operation modes. And the problem of circulating current among the multiple VSG inverters is eliminated.

Description

Technical field [0001] The present invention belongs to the field of intelligent grid grid power generation, and more particularly to a multi-VSG inverter circulation inhibition and a control method and system of fault processing. Background technique [0002] In the micrometer, the two operation modes of grid and away from the network (island) are the key to reflecting the microbrid technology and economic advantages, so seamless, smooth switching technology is the key to ensuring the smooth transition of the micro-network operation mode. technology. Since the virtual synchronous generator (VSG) technology passes the operation mechanism of the simulated synchronous generator, it can be freedom to convert the process from the island to the grid, so that the cumbersome transition from V / F turning into P / Q, and has The inertial link can better achieve friendly access to distributed power supplies and improve the stability of power system. [0003] Although the VSG inverter has ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/40H02J3/26
CPCH02J3/26H02J3/40Y02E40/50
Inventor 苏剑季宇丁保迪吴鸣张颖熊雄胡转娣袁森王玥娇
Owner CHINA ELECTRIC POWER RES INST
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