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VSC harmonic modeling method based on PWM modulation principle

A modeling method and modulating wave technology, applied in harmonic reduction devices, AC networks to reduce harmonics/ripples, etc., can solve problems such as high order, multivariate, low efficiency, etc.

Inactive Publication Date: 2019-07-23
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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Problems solved by technology

[0006] For the study of the harmonics injected by VSC into the power system, the traditional technique is to deduce the time-domain analysis by establishing the switching function. This method has the disadvantages of high-order, multi-variable, and low efficiency.

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  • VSC harmonic modeling method based on PWM modulation principle
  • VSC harmonic modeling method based on PWM modulation principle
  • VSC harmonic modeling method based on PWM modulation principle

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Embodiment Construction

[0059] Below in conjunction with accompanying drawing, implementation process of the present invention is described in further detail:

[0060] The present invention is a VSC harmonic modeling method based on PWM modulation principle, see Figure 7 , including the following steps:

[0061] One, such as figure 1 is the topological structure diagram of the three-phase two-level VSC converter, assuming that there are two time variables x(t)=ω c t and y(t) = ω 0 t, where x(t) and y(t) represent the phase of the carrier wave and the phase of the modulating wave respectively; ω c =1000Hz, ω 0 =50Hz are the high-frequency carrier frequency and the fundamental frequency respectively;

[0062] Two, such as figure 2 It is the waveform of sinusoidal modulation wave and triangular carrier wave, and its time expression is as follows:

[0063] u cos (t)=M cos(ω 0 t)

[0064]

[0065] Among them, u cos (t), u Δ (t) respectively represents the sinusoidal modulation waveform an...

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Abstract

The invention discloses a VSC harmonic modeling method based on a PWM modulation principle. A harmonic model of a VSC type converter is established by adopting a time domain analysis method; the method starts from the basic concept of a pulse width modulation (PWM) technology, a commutation process of a thyristor is ignored, by establishing two time variables of a carrier phase and a modulation wave phase, a universal VSC type converter alternating current side harmonic voltage analytical expression is obtained through Fourier decomposition, a Fourier coefficient of the general VSC type converter alternating current side harmonic voltage analytical expression is further simplified through a double accumulation table expression, so that a, b and c phases of bridge arm voltages, line-line voltages and alternating current side phase voltages are obtained. Only three input data of the direct current voltage, the modulation ratio and the carrier frequency are used for solving the content ofeach harmonic of the alternating current side, and the VSC type converter is approximately regarded as a harmonic voltage source.

Description

technical field [0001] The invention belongs to the field of harmonic analysis of power systems, and in particular relates to a VSC harmonic modeling method based on a PWM modulation principle. Background technique [0002] With the development of the power system, more and more nonlinear components such as power electronic components and new energy sources are put into the power system, and the harmonic problem of the power system becomes more and more prominent. In recent years, high-voltage direct current transmission (VSC-HVDC) technology based on the principle of voltage source control and flexible direct current transmission (FACTS) technology have developed rapidly, and have excellent characteristics in many fields of power systems. Wave analysis still mainly relies on electromagnetic transient simulation of detailed models and FFT analysis of steady-state waveforms. For systems with a certain scale and complexity, the application of simulation methods is limited due...

Claims

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Application Information

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IPC IPC(8): H02J3/01
CPCH02J3/01H02J2203/20Y02E40/40
Inventor 洪潮赵勇涂亮张野袁豪陈晓雯焦在滨李建华
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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