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Offshore wind power flexible direct current converter grid-connected current tracking and circulating current prediction control method

A technology of offshore wind power and predictive control, applied in wind power generation, conversion of AC power input to DC power output, electrical components, etc., can solve problems such as small number of levels, poor adaptability to working conditions, and limited performance of grid-connected current control. Achieve the effect of small calculation burden and high precision

Active Publication Date: 2021-12-17
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the control priority of this method is fixed, and the adaptability to working conditions is poor. Generally, the grid-side current has a higher priority, and the control priority of the circulating current is low, which limits the ability of the system to suppress the circulating current. By traversing the feasible switch state, choose the number of input sub-modules that minimizes the cost function, and the computational complexity is proportional to the total number of sub-modules, which is not suitable for flexible DC converters with a large number of sub-modules
In addition, the parity of the total number of input sub-modules finally selected by this method is fixed, and the number of output levels is small, which limits the performance of grid-connected current control

Method used

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  • Offshore wind power flexible direct current converter grid-connected current tracking and circulating current prediction control method

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Embodiment 1

[0050] Embodiment 1 of the present disclosure introduces a grid-connected current tracking and circulating current prediction control method of an offshore wind power flexible DC converter.

[0051] The converter in this embodiment is a grid-connected modular multilevel converter oriented to offshore wind power collection through flexible direct integration. The main basic control objectives are: grid-connected current tracking, phase-to-phase circulating current suppression, and sub-module capacitor voltage balance; Among them, the sub-module capacitor voltage balance is usually implemented by a sorting algorithm. Grid-connected current tracking and phase-to-phase circulation suppression are coupled with each other, and phase-to-phase circulation fluctuations will cause power fluctuations, resulting in output current fluctuations. In addition, the number of modular multilevel converters for flexible direct current is very large, and how to realize grid-connected current track...

Embodiment 2

[0099] Embodiment 2 of the present disclosure introduces a grid-connected current tracking and circulating current predictive control system for offshore wind power flexible DC converters, which adopts the grid-connected current tracking and circulating current predictive control of offshore wind power flexible DC converters introduced in Embodiment 1 method.

[0100] like Figure 5 A grid-connected current tracking and circulating current predictive control method for an offshore wind power flexible DC converter includes:

[0101] The measurement module is used to measure the current of the three-phase bridge arm, the DC voltage, the grid side voltage, the grid side current and the capacitor voltage of each sub-module at the current sampling time, so as to establish the equivalent model of the DC side and the AC side of the converter;

[0102] The single-phase optimization module calculates the interaction error according to the obtained equivalent model and the preset predi...

Embodiment 3

[0106] Embodiment 3 of the present disclosure provides a computer-readable storage medium.

[0107] A computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, the steps in the grid-connected current tracking and circulating current prediction control method of an offshore wind power flexible DC converter described in Embodiment 1 of the present disclosure are implemented .

[0108] The detailed steps are the same as the grid-connected current tracking and circulating current predictive control method of the offshore wind power flexible DC converter provided in the first embodiment, and will not be repeated here.

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Abstract

The invention provides an offshore wind power flexible direct current converter grid-connected current tracking and circulating current prediction control method, which is characterized in thata converter adopts a modular multi-level converter structure comprising three phases of upper bridge arms and three phases of lower bridge arms, each phase of upper bridge arm and each phase of lower bridge arm are connected through a bridge arm inductor, and the method comprises the following steps: acquiring equivalent models of a direct current side and an alternating current side of each phase of a converter; and obtaining a control scheme with optimal comprehensive performance of grid-connected current tracking and circulating current suppression according to the obtained equivalent model and a preset prediction cost function of each phase of the converter, wherein the prediction cost function of each phase of the converter takes the minimum interaction error as a target, and is obtained by solving grid-connected current tracking and circulating current suppression by using a fair sorting algorithm. According to the invention, the fairness sorting algorithm and the prediction control theory are combined, rapid tracking of grid-connected current and effective suppression of circulating current under different working conditions are realized, and the calculation burden is reduced.

Description

technical field [0001] The disclosure belongs to the technical field of electric power converters, and in particular relates to a grid-connected current tracking and circulating current prediction control method of an offshore wind power flexible DC converter. 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] Grid-connected current tracking and circulating current suppression are two basic control objectives of modular multilevel converters. On the one hand, grid-connected current tracking requires the grid-connected current of the converter to quickly track the current reference to achieve grid power balance; on the other hand, it requires that the waveform distortion of the grid-connected current is small in steady state to ensure the power quality of users. Circulating current suppression requires that the circulating current between th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02J3/38H02M7/493
CPCH02M7/483H02J3/38H02M7/493Y02E10/76
Inventor 张祯滨尹亚飞李真孙远翔
Owner SHANDONG UNIV