Low-voltage ride through method and device of power grid following type inverter
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A low-voltage ride-through and inverter technology, which is applied in the electric power field, can solve problems such as phase voltage over-limit of the power grid system, and achieve the effects of reducing voltage unbalance, improving stability and dynamic control performance
Active Publication Date: 2021-04-02
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1
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[0006] The embodiment of this application provides a method and device for low-voltage ride-through of a grid-following inverter, which is used to solve the problem of not injecting negative-sequence reactive power at the same time in the prior art current, which leads to technical problems that the grid system is prone to phase voltage violations
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Embodiment 1
[0056] see figure 1 , Embodiment 1 of a low-voltage ride-through method for a grid-following inverter provided in an embodiment of the present application, including:
[0057] Step 101 , when an asymmetrical fault occurs in the power grid, acquire the three-phase voltage signals of the common coupling points of the inverters.
[0058] It should be noted that when an asymmetrical fault occurs in the power grid, the voltage at the PCC point is unbalanced, and the three-phase voltage signal at the PCC point (common coupling point) is obtained through a measuring device.
[0059] Step 102, decompose the three-phase voltage signal into positive sequence component and negative sequence component by symmetrical component method, and transform the positive sequence component and negative sequence component into positive sequence voltage and negative sequence voltage in αβ coordinate system respectively by Clark transform.
[0060] Then use the symmetrical component method (SCM) to de...
Embodiment 2
[0067] see figure 2 , Embodiment 2 of a low-voltage ride-through method for a grid-following inverter provided in an embodiment of the present application, including:
[0068] Step 201, when an asymmetrical fault occurs in the grid, acquire the three-phase voltage signals of the common coupling points of the inverters.
[0069] Step 201 is the same as the description of step 101 in Embodiment 1, please refer to the description of step 101, and details are not repeated here.
[0070] Step 202, decompose the three-phase voltage signal into positive sequence component and negative sequence component by symmetrical component method, and transform the positive sequence component and negative sequence component into positive sequence voltage and negative sequence voltage in αβ coordinate system respectively by Clark transform.
[0071] Step 202 is the same as the description of step 102 in Embodiment 1, please refer to the description of step 102, and details are not repeated here...
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Abstract
The invention discloses a low-voltage ride-through method and device for a power grid following inverter. The method comprises steps that a three-phase voltage signal of a common coupling point of theinverter is obtained when an asymmetric fault happens to a power grid, the three-phase voltage signal is converted, and a three-phase voltage signal of the common coupling point of the inverter is obtained ; positive-sequence reactive power and negative-sequence reactive power needing to be injected into the power grid are calculated respectively, namely, positive-sequence reactive current and negative-sequence reactive current are injected into the power grid at the same time and used for supporting the voltage of the power grid, the voltage of the power grid is supported, and therefore thevoltage unbalance degree at the common coupling point of the inverter is remarkably reduced, and stability of the inverter is improved; stability and the dynamic control performance of the inverter during low-voltage ride through are improved, and the technical problem that in the prior art, negative-sequence reactive current is not injected at the same time, so the phase voltage of a power grid system is prone to out-of-limit is solved.
Description
technical field [0001] The present application relates to the field of electric power technology, in particular to a method and device for low-voltage ride-through of a grid-following inverter. Background technique [0002] As the penetration rate of distributed energy such as photovoltaics, wind power, and energy storage devices gradually increases, power electronic grid-connected inverters, as an important component of energy exchange, have increasingly significant interactions with the grid. As the last link of the power system, the distribution network has a very complex operating environment. Asymmetrical faults such as single-phase grounding and two-phase grounding often cause unbalanced bus voltage drops, which affect the safety of the grid-connected inverter system and the grid. Stable operation. [0003] Wind power and photovoltaic grid-connected inverters are mostly grid-following inverters, and the operating voltage of grid-following inverters usually needs to be...
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