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Direct current receiving end power grid distributed photovoltaic high permeability frequency deviation prediction method

A distributed photovoltaic and power grid frequency technology, which is applied to the prediction of power generation in the AC network, the AC network circuit, and the voltage adjustment of the AC network. It can solve the problems of large prediction errors and overly optimistic prediction results, and achieve comprehensive and accurate results. Effect

Active Publication Date: 2021-05-28
SICHUAN UNIV +2
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a frequency offset prediction method under the high penetration of distributed photovoltaic in the DC receiving-end power grid, which solves the problems that the traditional prediction results are too optimistic and the prediction error is large, so that the result of the power grid frequency prediction more comprehensive and accurate

Method used

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  • Direct current receiving end power grid distributed photovoltaic high permeability frequency deviation prediction method
  • Direct current receiving end power grid distributed photovoltaic high permeability frequency deviation prediction method
  • Direct current receiving end power grid distributed photovoltaic high permeability frequency deviation prediction method

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Embodiment

[0025] Such as Figure 1 to Figure 5 As shown, step (S1): Based on the average system frequency model, replace all the models of the speed control system with the first-order equivalent model to obtain the expression of the grid frequency response;

[0026] The average system frequency model applies the mechanical output of the governor prime mover system of all generator sets in the system to an equivalent rotor, which is obtained by the rotor equivalent aggregation of all generators in the system. The calculation formula is:

[0027]

[0028] In the formula, N is the number of generators, S i is the rated capacity of unit i, H i is the inertia time constant of unit i.

[0029] The action of photovoltaic off-grid and low-frequency load shedding mainly depends on the lowest point of system frequency and the time of occurrence of the lowest frequency. A first-order equivalent model is adopted to describe the frequency drop process after the large power loss of the receivin...

specific Embodiment

[0055] by figure 2 The proposed method is verified by the 39 busbar system of No. 10 machine, assuming that No. 31 node is a balanced node, and the G2 generator is regarded as an equivalent unit fed by DC, such as figure 2 shown. Assuming that the spinning reserve is about 15% of the maximum output of the unit at the original system load level, the rated capacity of each unit is obtained. The original total generating power of the system is maintained at 6297MW, of which the generating power of conventional units is 5297MW, the rated active power is 7300MW, and the generating capacity of distributed photovoltaic units reaches 1000MW. The inertia time constants of all generating units obtained from the data and the parameters of the first-order equivalent model of the speed control system are shown in Table 1.

[0056] Table 1 The inertia time constant of the generating set and the parameters of the first-order equivalent model after the speed control system is equivalent ...

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Abstract

The invention discloses a direct current receiving end power grid distributed photovoltaic high permeability frequency deviation prediction method, which comprises the following steps of (S1) based on an average system frequency model, replacing models of all speed regulation systems with first-order equivalent models, and obtaining an expression of power grid frequency response, (S2) solving the frequency response expression obtained in the step (S1) to obtain a power grid frequency response initial curve, (S3) judging whether the power-off grid frequency triggers a distributed photovoltaic low-frequency protection setting value or not, (S4) judging whether the power grid frequency triggers low-frequency load shedding or not, and (S5) correcting the power grid frequency response initial curve, and outputting a result. By means of the scheme, the purpose that the power grid frequency prediction result is more comprehensive and accurate is achieved, and the high practical value and popularization value are achieved.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic testing, and in particular relates to a frequency offset prediction method under distributed photovoltaic high penetration of a direct current receiving end power grid. Background technique [0002] In recent years, my country's distributed photovoltaics have developed rapidly. However, the distributed photovoltaic unit does not have the ability of primary frequency regulation. The photovoltaic unit is a non-rotating static component. It is connected to the grid through a converter and has no moment of inertia. After a large number of conventional power sources are replaced, the equivalent moment of inertia of the system is reduced, which will deteriorate The ability of the receiving end grid to cope with the shortage of active power, the system frequency may drop even lower under the same boundary conditions. In addition, photovoltaics have poor tolerance to system frequency and voltage flu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/00H02J3/24H02J3/38H02J3/46H02J3/48H02J3/14
CPCH02J3/004H02J3/241H02J3/381H02J3/46H02J3/48H02J3/144H02J2203/20Y04S20/222Y02B70/3225Y02E10/56
Inventor 许立雄贺心达刘洋吴迪贺静波汤伟杨铖
Owner SICHUAN UNIV
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