CN-122000976-A - Capacity optimal configuration method, device, equipment and medium of DRU-MMC serial hybrid converter

CN122000976ACN 122000976 ACN122000976 ACN 122000976ACN-122000976-A

Abstract

The invention relates to the technical field of power systems, in particular to a capacity optimization configuration method, device, equipment and medium of a DRU-MMC serial hybrid converter, wherein the method is used for configuring the reactive power support function of a wind turbine generator by establishing a topological structure of an offshore wind power transmission system and dynamically compensating reactive power requirements by adopting constant power factor control; the auxiliary MMC is configured to execute active filtering and dynamic compensation functions, absorb harmonic current generated by the DRU and compensate reactive power which is not fully compensated by the wind turbine, optimally calculate rated capacity of the auxiliary MMC according to residual reactive power demand after compensation of the wind turbine and filtering demand of the auxiliary MMC, and only needs to process a small amount of dynamic reactive power by utilizing reactive power regulation capacity of the wind turbine, so that capacity demand and direct current voltage distribution proportion are reduced, equipment investment, running loss and land occupation area of an offshore platform are reduced on the premise of ensuring reactive power balance and electric energy quality, and economy and applicability of the system are improved.

Inventors

LIN JINJIAO
HOU TIAN
WANG GUOTENG
TAO YAN
KONG XIANGPING
HUANG YING
LI PENG

Assignees

国网江苏省电力有限公司电力科学研究院
浙江大学
江苏省电力试验研究院有限公司

Dates

Publication Date: 20260508
Application Date: 20251126

Claims (11)

The capacity optimization configuration method of the DRU-MMC serial hybrid converter is characterized by comprising the following steps of: Establishing a topological structure of a DRU-MMC serial hybrid converter offshore wind power transmission system, and analyzing reactive power requirements and characteristic harmonic currents of the DRU in the topological structure; Based on the analysis of the reactive power demand, a reactive power supporting function of the wind turbine generator is configured, and the reactive power output by the wind turbine generator is dynamically compensated for the main reactive power demand of the DRU by adopting constant power factor control; based on the analysis of the characteristic harmonic current, configuring an active filtering and dynamic compensation function of an auxiliary MMC, controlling the auxiliary MMC to execute active filtering so as to absorb the characteristic harmonic current generated by the DRU, and compensating the dynamic reactive power requirement which is not fully compensated by the wind turbine generator; and calculating and optimally determining the rated capacity of the auxiliary MMC based on the compensated residual reactive power demand of the wind turbine generator and the active filtering demand required to be born by the auxiliary MMC.
2. The capacity optimizing configuration method of DRU-MMC serial type hybrid converter as claimed in claim 1, wherein the topology of the DRU-MMC serial type hybrid converter offshore wind power delivery system includes 12 pulsating DRUs and auxiliary half-bridge MMCs connected in series on a direct current side, and both alternating current sides are connected to an alternating current collection point of an offshore wind farm to form an offshore converter station.
3. The method for optimizing capacity of a DRU-MMC series hybrid converter as claimed in claim 1, wherein a characteristic harmonic set is determined to be 12k±1 times by fourier decomposition of the DRU ac side current, wherein k is a positive integer, and each subharmonic amplitude is estimated to be 1/(12 k±1) of not more than a fundamental amplitude, as an input parameter for subsequent filtering and capacity configuration.
4. The method for optimizing capacity of DRU-MMC series hybrid converters according to claim 1, wherein the configuration of the wind turbine adopts constant power factor control, and reactive power of the converters is adjusted to enable the wind turbine to provide reactive power suitable for active power of a group of wind turbines, so that main reactive power requirements of the DRU under different operation conditions are dynamically tracked and compensated.
5. The capacity optimizing configuration method of DRU-MMC serial hybrid converter as recited in claim 1, characterized in that the active filtering function of the auxiliary MMC is implemented by a harmonic extraction strategy based on synchronous rotation coordinate transformation, the harmonic extraction strategy comprising: transforming the current signal of the DRU alternating current side from a three-phase static coordinate system to a synchronous rotation coordinate system; extracting a direct current component of the current signal, and filtering high-frequency components through a low-pass filter; inputting the difference value between the obtained direct current component and the reference value into a proportional-integral controller to generate a differential mode voltage reference value for controlling the auxiliary MMC; and controlling the auxiliary MMC to actively absorb the characteristic harmonic current generated by the DRU according to the differential mode voltage reference value.
6. The method according to claim 5, wherein the differential mode voltage reference value is superimposed on a fundamental voltage command after inverse synchronous rotation coordinate transformation, so as to control the auxiliary MMC to output a harmonic compensation current having an equal amplitude and an opposite phase to the DRU harmonic current.
7. The capacity optimizing configuration method of DRU-MMC serial type hybrid converter as claimed in claim 1, wherein the rated capacity of the auxiliary MMC is determined by calculation of the following formula: ; ; Wherein S MMC is the capacity required by MMC, P MMC is the active power transmitted by MMC, Q MMC is the total reactive power output by MMC, P w is the active power output by wind farm, S f is the harmonic capacity occupied by active filtering, and delta is the power factor target value of the constant power factor control of the wind turbine generator.
8. The capacity optimizing configuration method of DRU-MMC serial hybrid converter as recited in claim 1, further comprising: and verifying the optimized capacity of the auxiliary MMC through electromagnetic transient simulation, so as to ensure that the auxiliary MMC meets reactive power balance and electric energy quality requirements when the system operation working condition changes.
9. A capacity optimizing configuration device of a DRU-MMC serial type hybrid converter, characterized by using the method as claimed in any one of claims 1 to 8, comprising: the system modeling and analyzing unit is used for establishing a topological structure of the DRU-MMC serial hybrid converter offshore wind power transmission system and analyzing reactive power requirements and characteristic harmonic currents of the DRU in the topological structure; The wind turbine generator control configuration unit is used for configuring a reactive power supporting function of the wind turbine generator based on analysis of the reactive power demand, and adopting constant power factor control to dynamically compensate the reactive power output by the wind turbine generator for the reactive power demand of the main body of the DRU; The auxiliary MMC control configuration unit is used for configuring an active filtering and dynamic compensation function of the auxiliary MMC based on the analysis of the characteristic harmonic current, controlling the auxiliary MMC to execute active filtering so as to absorb the characteristic harmonic current generated by the DRU, and compensating the dynamic reactive power requirement which is not fully compensated by the wind turbine generator; And the capacity calculation and optimization unit is used for calculating and optimizing and determining the rated capacity of the auxiliary MMC based on the compensated residual reactive power demand of the wind turbine generator and the active filtering demand required to be born by the auxiliary MMC.
10. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of any of claims 1-8 when executing the computer program.
11. A storage medium having stored thereon a computer program which, when executed by a processor, implements the method of any of claims 1-8.

Description

Capacity optimal configuration method, device, equipment and medium of DRU-MMC serial hybrid converter Technical Field The invention relates to the technical field of power systems, in particular to a capacity optimization configuration method, device, equipment and medium of a DRU-MMC serial hybrid converter. Background With the development of global energy transformation and offshore wind power to deep open sea and high capacity, high-voltage direct current transmission has become a preferred scheme for long-distance offshore wind power transmission, wherein a DRU-MMC serial hybrid converter scheme remarkably reduces the number of submodules of an offshore platform MMC by connecting a low-cost and high-reliability diode rectifying unit with a fully-controlled MMC on a direct current side, effectively reduces the equipment cost and occupied area of an offshore converter station, and shows good application prospect, however, in the hybrid converter scheme, the capacity configuration of an auxiliary MMC is directly determined by reactive power balance and harmonic suppression requirements of an offshore alternating current system, and the capacity of the MMC is a key factor affecting the economy of the system. At present, the traditional capacity allocation method mainly has two ideas, and has obvious limitations. The first is a mode that the MMC bears all reactive power compensation and active filtering, and the scheme requires the auxiliary MMC to be simultaneously responsible for compensating the full reactive power required by the DRU operation and actively restraining characteristic harmonic waves generated by the DRU. In the mode, although a passive filter is avoided, the auxiliary MMC needs extremely high capacity to meet the two functional requirements simultaneously, and as a result, the initial equipment investment is huge, high operation loss is brought, and the economical efficiency of the whole system is greatly reduced; the second mode is that MMC reactive compensation combines passive filter, this scheme is mainly responsible for reactive compensation by supplementary MMC, dispose passive filter simultaneously and absorb the harmonic, although this has alleviateed the capacity pressure of MMC on active filter, passive filter itself is bulky, heavy, greatly increased offshore platform's weight and area, this is contrary with offshore platform's light-duty, the design objective of compactification, more troublesome, passive filter can output fixed capacitive reactive power under different operating modes, MMC still needs extra compensation its surplus reactive power that produces, especially under low wind speed, light load operating mode, lead to the system operation flexibility poor, whole economic nature is still unsatisfactory. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. Disclosure of Invention The invention provides a capacity optimization configuration method, device, equipment and medium of a DRU-MMC serial hybrid converter, so that the problems in the background technology are effectively solved. In order to achieve the purpose, the invention adopts the technical scheme that the capacity optimizing configuration method of the DRU-MMC serial type hybrid converter comprises the following steps: Establishing a topological structure of a DRU-MMC serial hybrid converter offshore wind power transmission system, and analyzing reactive power requirements and characteristic harmonic currents of the DRU in the topological structure; Based on the analysis of the reactive power demand, a reactive power supporting function of the wind turbine generator is configured, and the reactive power output by the wind turbine generator is dynamically compensated for the main reactive power demand of the DRU by adopting constant power factor control; based on the analysis of the characteristic harmonic current, configuring an active filtering and dynamic compensation function of an auxiliary MMC, controlling the auxiliary MMC to execute active filtering so as to absorb the characteristic harmonic current generated by the DRU, and compensating the dynamic reactive power requirement which is not fully compensated by the wind turbine generator; and calculating and optimally determining the rated capacity of the auxiliary MMC based on the compensated residual reactive power demand of the wind turbine generator and the active filtering demand required to be born by the auxiliary MMC. Further, the topology of the DRU-MMC serial hybrid converter offshore wind power delivery system comprises 12 pulsating DRUs and auxiliary half-bridge MMCs connected in series on the direct current side, and the alternating current sides of the DRU-MMC serial hybrid converter offshore win