Method for inter-phase balance control over direct current side capacitor voltage of cascade h-bridge STATCOM based on modulating wave translation
A technology of DC side capacitance and control method, applied in the field of power system, can solve the problems of large power unit loss, complex control process, low control accuracy, etc., and achieve the effects of small power unit loss, simple control process, and high control accuracy.
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specific Embodiment approach 1
[0025] Specific implementation mode 1: see figure 2 and 3 This embodiment will be described. The H-bridge cascaded STATCOM DC-side capacitor voltage in-phase balance control method based on modulation wave translation described in this embodiment is implemented based on multiple power units. The power units include capacitors C, No. 1 power switch S1, No. 2 power switch S2, No. 3 power switch S3, No. 4 power switch S4, No. 1 diode D1, No. 2 diode D2, No. 3 diode D3 and No. 4 diode D4;
[0026] One end of the capacitor C is simultaneously connected to the power input terminal of the No. 1 power switch S1, the cathode of the No. 1 diode D1, the power input terminal of the No. 3 power switch S3 and the cathode of the No. 3 diode D3 at the same time,
[0027] The other end of the capacitor C is simultaneously connected to the power output terminal of the No. 2 power switch S2, the anode of the No. 2 diode D2, the power output terminal of the No. 4 power switch S4 and the anode o...
specific Embodiment approach 2
[0034] Specific implementation mode two: see figure 2 , 3 , 4 and 5 illustrate this embodiment. The difference between this embodiment and the H-bridge cascaded STATCOM DC side capacitance voltage in-phase balance control method based on modulation wave translation described in Embodiment 1 is that in step 1, according to each power The polarity of the voltage and current output by the unit, and the specific process of judging the charging and discharging of the capacitor C in each power unit are as follows:
[0035] At a certain moment, the current direction flows from the grid to the converter,
[0036] When the output voltage of the power unit is positive, the No. 1 power switch S1 and the No. 4 power switch S4 are turned on, and the capacitor C is in the charging state;
[0037] When the output voltage of the power unit is negative, the No. 2 power switch S2 and the No. 3 power switch S3 are turned on, and the capacitor C is in a discharging state.
[0038] At a certai...
specific Embodiment approach 3
[0041] Specific implementation mode three: see figure 2 , 3 , 4 and 5 illustrate this embodiment. The difference between this embodiment and the H-bridge cascaded STATCOM DC side capacitor voltage phase internal balance control method based on modulation wave translation described in the second embodiment is that in the second step, According to the relative size of the terminal voltage of the capacitor C in each power unit, the adjustment direction of the duty ratio is given, so that the specific process of making the terminal voltage of the capacitor C in each power unit tend to be consistent is as follows:
[0042] When (i a × v ani )>0, if V dc_a_i dc_a , then increase the conduction duty cycle of the i-th power unit, that is, for the power unit in the charging process, when V dc_a_i less than V dc_a , the conduction time of the power unit should be extended;
[0043] When (i a × v ani )>0, if V dc_a_i >V dc_a , then reduce the conduction duty cycle of the i-th ...
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