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A converter for interconnecting two electric networks to transmit electric power from one network to the other, each network being coupled to a respective power generator station. The converter, having an AC side and a DC side, includes a bridge of semiconductor switches with gate turn-off capabilit

A converter for interconnecting two electric networks to transmit electric power from one network to the other, each network being coupled to a respective power generator station. The converter, having an AC side and a DC side, includes a bridge of semiconductor switches with gate turn-off capability coupled to a control system to produce a bridge voltage waveform having a fundamental Fourier component at the frequency of the electric network coupled to the AC side of the converter. The control system includes three inputs for receiving reference signals allowing to control the frequency, the amplitude and the phase angle of the fundamental Fourier component with respect to the alternating voltage of the network coupled to the AC side of the converter. Through appropriate feedback loops, the converter may be used to maintain at a predetermined level the power flowing therethrough or to keep at a preset value the voltage across the DC terminals of the converter and, in both cases, to maintain the frequency synchronism between the fundamental Fourier component and the alternating voltage of the network coupled to the DC side of the converter.

대표청구항 ▼

A converter for interconnecting a first electric network and a second electric network to transmit electric power from one network to the other, each of said networks being coupled to a respective active power source, said first network including DC link terminals for coupling said first network to

A converter for interconnecting a first electric network and a second electric network to transmit electric power from one network to the other, each of said networks being coupled to a respective active power source, said first network including DC link terminals for coupling said first network to said converter, there being a DC voltage having a certain amplitude across the DC link terminals, said second network including AC link terminals for coupling said second network to said converter, there being an alternating voltage at a given substantially fixed frequency across said AC link terminals, said alternating voltage having an amplitude which is always lower than the amplitude of said DC voltage, said converter comprising: a bridge of valves each associated with an antiparallel diode, each valve of said bridge being capable of assuming two different states, namely an ON staten and an OFF state, in said ON state the valve allowing current to pass therethrough, in said OFF state the valve blocking the passage of current, each diode being normally reverse-biased between said DC and alternating voltage, and said bridge being capable of operating either as an inverter to enable transmission of electric power from the first network to the second one, or as a rectifier to enable transmission of electric power from the second network to the first one; inductor means interposed between said bridge and said AC link terminals for producing a boost voltage across said inductor means, said boost voltage forward-biasing said diodes to allow the same to conduct electric current to thereby enable operation of said bridge as an inverter and rectifier; capacitor means across said DC link terminals, said bridge being interposed between the inductor and capacitor means; valve control means coupled to said bridge for commanding the valves thereof to switch state to operate said bridge as an inverter or rectifier, said valve control means including: signal generating means for outputting a control signal representative of a desired valve state switching sequence to obtain a bridge voltage waveform having a fundamental Fourier component at a frequency corresponding substantially to the frequency of said alternating voltage; and frequency control means coupled to said signal generating means to adjust said control signal in accordance with adrift of the frequency of said alternating voltage to cause the frequency of said fundamental Fourier component to track the frequency of said alternating voltage.