US 5,343,139 A · Generalized fast, power flow controller

Abstract

First and second dc linked, preferably voltage sourced, inverters are connected to an electric power transmission line in shunt and in series, respectively, by coupling transformers. Firing of the GTO-thyristors of the first inverter is controlled to regulate reactive power on the transmission line and to supply real power requirements of the second inverter. The second inverter is controlled to inject into the transmission line in series a voltage which can be adjusted in magnitude and from zero through 360 degrees in phase with respect to the transmission line voltage to selectively adjust any one or more of transmission line voltage magnitude, transmission line impedance and transmission line voltage phase angle. In a high power configuration of the controller each of the inverters includes a plurality of six-pluse inverter modules connected by interstage transformers to form balanced higher order pulse groups controlled through pulse width modulation or through adjustment of the phase between opposite groups to generate the appropriate ac voltages.

Claims16

Dependent claims

A power flow controller for controlling the flow of electric power in an alternating current transmission system including a transmission line having two ends and carrying alternating current at a selected transmission line voltage and fundamental frequency between said two ends, said controller comprising:

switching power converter means generating an alternating voltage at said fundamental frequency of the said alternating current with controllable magnitude and phase angle relative to said transmission line voltage;
means coupling the alternating voltage generated by said switching power converter means in series with said transmission line voltage;
and
control means controlling the controllable magnitude and phase angle of the alternating voltage generated by said switching power converter means at said fundamental frequency to a magnitude and any phase angle relative to said transmission line voltage to selectively adjust, individually and in coordination, effective impedance of said transmission line, effective phase angle between voltages at said two ends of said transmission line, and transmission line voltage magnitude to thereby control the power flow in said transmission line.

1 more element

A generalized fast power flow controller for an ac transmission line, said controller comprising:

first dc to ac inverter means having ac terminals connected in shunt with the transmission line and having dc terminals;
second dc to ac inverter means having ac terminals connected to inject an alternating voltage in series with said transmission line and having dc terminals;
dc links means connecting the dc terminals of said first and second inverters;
and
control means controlling real and reactive power exchange between said transmission line and said first inverter to supply real power for the said second inverter at a selected power factor, said control means also controlling said second inverter means to generate said alternating voltage with a selected magnitude and selected phase angle between 0.degree. and 360.degree. to establish a selected transmission line impedance, a selected transmission angle, and a selected transmission line voltage for controlling power flow through said transmission line.

2 more elements

Dependencies are inferred from the claim text.

Generalized fast, power flow controller

Life of this patent

Generalized fast, power flow controller

Life of this patent

Abstract

Claims16