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Low-voltage ride-through dynamic evaluation method and system for two-stage photovoltaic grid-connected system

A low-voltage ride-through and dynamic evaluation technology, which is applied in the direction of AC network voltage adjustment, single-network parallel feeding arrangement, reactive power compensation, etc., can solve problems such as not considering the impact, and achieve the effect of improving analysis efficiency and feasibility

Active Publication Date: 2020-06-23
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The inventors of the present disclosure found that in the existing photovoltaic low-voltage ride-through assessment, there is a lack of theoretical support and a certain assessment accuracy, and a method that provides analytical expressions to achieve higher efficiency
Moreover, most of the existing methods do not consider the influence of the reactive power generated by photovoltaics on the AC grid during the ride-through process.

Method used

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  • Low-voltage ride-through dynamic evaluation method and system for two-stage photovoltaic grid-connected system

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Embodiment 1

[0043] Embodiment 1 of the present disclosure provides a two-stage photovoltaic grid-connected system low-voltage ride-through dynamic evaluation method, which covers the main dynamic links of photovoltaics, and considers the impact of reactive power generated by photovoltaics on the AC grid during the ride-through process, reflecting Interaction between PV and grid. In order to verify the method proposed in this paper, this embodiment also combines typical cases and compares it with the simulation results of PSCAD / EMTDC. The results all prove the feasibility of the analytical expression of photovoltaic low voltage ride-through proposed in this paper. The specific steps are as follows:

[0044] Obtain the grid-connected point parameters of the two-stage photovoltaic grid-connected system;

[0045] Considering the dynamic link of photovoltaic low voltage ride through and the control response process of photovoltaic inverter unit, the analytical expression of DC bus voltage is con...

Embodiment 2

[0121] Embodiment 2 of the present disclosure provides a low-voltage ride-through capability evaluation system of a two-stage photovoltaic grid-connected system.

[0122] include:

[0123] The data acquisition module is configured to: acquire grid-connected point parameters of a two-stage photovoltaic grid-connected system;

[0124] The data processing module is configured to: consider the photovoltaic low-voltage ride-through dynamic link and the control response process of the photovoltaic inverter unit, construct an analytical expression of the DC bus voltage, and obtain a calculated value of the DC bus voltage during the low-voltage ride-through period of the photovoltaic system;

[0125] The low-voltage ride-through capability evaluation module is configured to: evaluate the low-voltage ride-through capability of the two-stage photovoltaic grid-connected system according to the obtained calculated value of the DC bus voltage.

[0126] The specific analytical expression o...

Embodiment 3

[0128] Embodiment 3 of the present disclosure provides a medium on which a program is stored, which is characterized in that, when the program is executed by a processor, the two-stage photovoltaic grid-connected system low-voltage ride-through dynamic evaluation method as described in Embodiment 1 is implemented. A step of.

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Abstract

The invention provides a low-voltage ride-through dynamic evaluation method and system for a two-stage photovoltaic grid-connected system, and relates to the technical field of photovoltaic low-voltage ride-through evaluation. The method comprises: obtaining grid-connected point parameters of the two-stage photovoltaic grid-connected system; considering a photovoltaic low-voltage ride-through dynamic link and a control response process of a photovoltaic inversion unit, constructing analytic expression of the direct-current bus voltage, and obtaining a calculated value of the direct-current busvoltage in a low-voltage ride-through period of the photovoltaic system; and evaluating the low-voltage ride-through capability of the two-stage photovoltaic grid-connected system according to the obtained calculation value of the direct-current bus voltage. The problem that an existing two-stage photovoltaic grid-connected system lacks an excellent analysis and evaluation method in the low-voltage ride-through process is solved, main dynamic links of photovoltaic are covered, meanwhile, the influence of reactive power emitted by photovoltaic on an alternating-current power grid in the ride-through process is considered, and the interaction effect of photovoltaic and the power grid is reflected. And on the premise of ensuring certain accuracy, the analysis efficiency and feasibility are improved.

Description

technical field [0001] The present disclosure relates to the field of photovoltaic low-voltage ride-through assessment technology, and in particular to a dynamic assessment method and system for low-voltage ride-through of a two-stage photovoltaic grid-connected system. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] In recent years, with the rapid development of renewable energy power generation technology and the increasing demand for energy cleanliness, the grid-connected scale of photovoltaics has continued to increase, and the impact of its dynamic characteristics on the power system cannot be ignored. When the power grid fails or is disturbed, if a large-scale disconnection of photovoltaics occurs, the impact on the system will be further aggravated, and in severe cases, the system will even collapse. Therefore, many countries have...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J3/16
CPCH02J3/16Y02E40/30
Inventor 王晓辉高峰张强李昌明
Owner SHANDONG UNIV