Method for evaluating stability of modular multilevel converter under multi-frequency cross coupling
A modular multi-level, cross-coupling technology, applied in the conversion of AC power input to DC power output, AC network circuit, power transmission AC network, etc., can solve the problem of not being able to accurately reflect the dynamic process of MMC
Active Publication Date: 2020-08-11
SHANGHAI JIAO TONG UNIV
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Therefore, these models cannot accurately reflect the dynamic process of MMC
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[0063] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0064] Table 1 is the calculation formula of the MMC small interference transfer function matrix involved in the present invention;
[0065] Table 2 is the concise code of the MMC small interference transfer function matrix involved in the present invention.
[0066] Simulation system see figure 1 , figure 2 ,details as follows.
[0067]...
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The invention discloses a method for evaluating the stability of a modular multilevel converter under multi-frequency cross coupling. The method is mainly composed of an impedance modeling calculationpart and an impedance measurement and evaluation part. The impedance modeling calculation part provides a theoretical calculation model of the impedance of the modular multilevel converter, and can reflect dynamic processes such as bridge arm circulation, capacitor voltage fluctuation and phase-locked loop influence. According to the impedance measurement and evaluation part, dq-axis excitation does not need to be directly applied, indirect measurement is carried out through response of phase domain excitation, and finally, based on an impedance theoretical value and an actual measurement value, a generalized Nyquist criterion is applied to evaluate the stability of the converter. According to the method, the electromagnetic analysis and impedance measurement process can be simplified toa great extent while it is guaranteed that the proposed model can accurately analyze electromagnetic transient calculation of the whole power transmission system, an effective method is provided for stability research of an actual system, and the subsuper-synchronous oscillation problem of an actual converter station can be solved.
Description
technical field [0001] The invention relates to the technical field of electromagnetic transient analysis of power systems, in particular to an evaluation method for the stability of a modular multi-level converter (Modular multi-level converter, MMC) under multi-frequency cross-coupling. Background technique [0002] At present, the penetration of flexible direct current transmission based on MMC in the power system is gradually deepening, and the stability problem of MMC caused by it is gradually highlighted, which seriously threatens the safe and stable operation of the power system. For example, about 25Hz subsynchronous oscillation occurred on the DC side of Fujian Xiamen Soft Straight Project. [0003] Although the impedance analysis method has been widely used in the study of MMC stability, the existing analysis methods generally have problems such as the oversimplification of the MMC model, the neglect of the internal harmonics of the converter, and the neglect of th...
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Login to View More IPC IPC(8): H02J3/00H02J3/36H02J3/24H02M7/00G06F30/20
CPCH02J3/00H02J3/36H02J3/24H02M7/00G06F30/20H02J2203/20G06F2113/04Y02E60/60
Inventor 舒德兀侍凡宋钊
Owner SHANGHAI JIAO TONG UNIV