Modular multilevel converter active thermal control method based on hybrid modulation strategy
A modular multi-level, hybrid modulation technology, applied in the direction of single-network parallel feed arrangement, etc., can solve problems such as increasing system complexity, affecting system power quality, increasing system operating costs, etc., achieving strong portability, reducing heat Loss, ease and understanding of implementation effects
Active Publication Date: 2020-03-13
SOUTHEAST UNIV
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Problems solved by technology
[0004] Aiming at the problem of active heat loss control of the MMC sub-module power switch tube, the existing technology effectively reduces the system switching loss by changing the MMC topology, adding control links, and adjusting the switching frequency. However, the above methods will increase the system operating cost and improve the system efficiency. The complexity of the system even affects the power quality of the system output
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[0026] Embodiments of the invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.
[0027] Aiming at the problem of active heat loss control of MMC sub-module power switch tubes, the present invention proposes an active heat control method for modular multilevel converters based on a hybrid modulation strategy. In the present invention, the MMC topology adopts a three-phase six-arm structure, like figure 1 As shown, each bridge arm uses n half-bridge sub-modules and a bridge arm inductance L s , each sub-module consists of two power switch tubes T 1 , T 2 , two diodes D 1 、D 2 and an electrolytic capacitor.
[0028] Such as figure 2 As shown, the active thermal control method of modular multilevel converters based on the hybrid modulation strate...
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The invention discloses a modular multilevel converter active thermal control method based on a hybrid modulation strategy. The method specifically comprises the steps of real-timely detecting the wind speed of a wind power plant; comparing the wind speed with the critical wind speed to switch a modulation strategy of a wind power conversion system in real time; then, detecting the bridge arm current of a modular multilevel converter; detecting the capacitor voltage of each sub-module on a bridge arm, sorting the capacitor voltage of each sub-module, finally determining the number of the sub-modules needing to be conducted according to a modulation result, and obtaining a driving signal of each sub-module on the bridge arm in combination with the current direction of the bridge arm and thecapacitor voltage sorting result of the sub-modules, thereby reducing the thermal loss of the wind power conversion system. Compared with an existing thermal control method, the method has the advantages that the structure of the converter is not changed, the grid-connected electric energy quality of the converter is not affected, the control algorithm is simple, and the understanding and implementation are easy.
Description
technical field [0001] The invention relates to an active thermal control method for a modular multilevel converter based on a hybrid modulation strategy, and belongs to the technical field of multilevel power electronic converters. Background technique [0002] Modular Multilevel Converter (MMC) has become the core of medium-high voltage and large-capacity power electronic converters due to its highly modular structure, flexible expansion of voltage and power levels, and flexible control. technology. At present, this technology has been widely used in flexible direct current transmission, energy storage, motor drive, etc. [0003] At present, many projects in the field of wind power generation have used MMC as converters, so it is of great significance to ensure the reliable operation of MMC-based wind power systems. The fault sources of MMC mainly include power semiconductor device faults, capacitor faults, wiring and terminal faults, and other faults. Among them, power ...
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IPC IPC(8): H02J3/38
Inventor 王宝安邓富金吕泳庆
Owner SOUTHEAST UNIV