High-voltage SVG power unit DC voltage dual control device and control method
A power unit, dual control technology, applied in the direction of output power conversion device, AC power input conversion to DC power output, high-efficiency power electronic conversion, etc., can solve the problem of SVG output voltage harmonic distortion rate increase, DC side capacitor voltage Unbalanced, affecting the safe operation of the device, etc., to achieve the effect of high sine degree, guaranteed voltage, and shortened maintenance time
Active Publication Date: 2019-07-23
辽宁拓新电力电子有限公司
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Problems solved by technology
[0003] In the cascaded SVG, the power units are independent of each other, and there are differences in the parallel loss, switching loss, modulation ratio and pulse delay of each power unit, which leads to the problem of unbalanced capacitor voltage on the DC side of each power unit.
The unbalanced DC capacitor voltage will bring many adverse effects. The unbalanced capacitor voltage will increase the harmonic distortion rate of the SVG output voltage. When the unbalanced degree is large, the capacitor voltage of some power units will be high , affecting the safe operation of the device, and in severe cases, it will cause the system to crash
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[0020] Such as figure 1 As shown, the double control device of the high-voltage SVG power unit involved in the present invention, each power unit is composed of a DC support capacitor, an inverter bridge, a main control board and a DC voltage equalizing circuit; the DC support capacitor adopts a non-polar film capacitor; the inverter bridge Two half bridges are used to form a full bridge to complete the conversion from DC to AC. Such as figure 2 As shown, the main control board is composed of a DSP, a receiving control signal circuit, a temperature measurement circuit and a DC voltage measurement circuit connected to the DSP input terminal, a PWM pulse output circuit and a discharge pulse output circuit connected to the DSP output terminal. The core control chip of the main control board adopts DSP, and completes the control of the switching tube in the inverter bridge through the PWM pulse output circuit, and realizes the function of DC voltage equalization control. The DC...
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A high-voltage SVG power unit DC voltage dual control device and control method, each power unit is composed of a DC support capacitor, an inverter bridge, a main control board and a DC voltage equalization circuit; the DC voltage equalization circuit and the DC support capacitor are connected to the inverter The DC end of the bridge is connected, and the output end of the main control board is respectively connected with the DC voltage equalizing circuit and the inverter bridge IGBT. The control method is as follows: in the high-current operating range of the power unit, each power unit superimposes the active voltage vector through the main control board to balance the control to realize the reasonable distribution of the active power of each power unit and ensure the balance of the DC capacitor voltage. When the power unit is in the low current operating range, the main control board increases the corresponding loss by discharging the DC voltage equalizing circuit to ensure the voltage balance of the DC support capacitor. The beneficial effect is: there is no problem of voltage equalization failure, the problem of software voltage equalization failure when outputting zero current is effectively solved, and the sine degree of the output waveform is higher.
Description
technical field [0001] The invention relates to a high-voltage SVG power unit DC voltage dual control device and a control method, which are widely used in cascaded SVGs. Background technique [0002] The cascaded SVG device is a dynamic reactive power compensation device based on the series connection of H-bridge high-power inverters. Each phase of it is composed of H-bridge power units connected in series with the same structure. The three-phase connection adopts a star connection. Then it is connected to the power grid through the connecting reactor. [0003] In the cascaded SVG, the power units are independent of each other, and the parallel loss, switching loss, modulation ratio, and pulse delay of each power unit are different, which leads to the problem of unbalanced DC side capacitor voltage in each power unit. The unbalanced DC capacitor voltage will bring many adverse effects. The unbalanced capacitor voltage will increase the harmonic distortion rate of the SVG o...
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IPC IPC(8): H02M7/5387H02M1/42H02M1/32
CPCH02M1/32H02M1/4233H02M7/53873H02M1/325Y02B70/10
Inventor 王凡王化勇
Owner 辽宁拓新电力电子有限公司