Apparatus for protection of power-electronics in series compensating systems

In an active power-line conditioner of the transformer coupled type that includes at least one transformer winding coupled to an inverter, said inverter being further coupled to a dc power source, an improved inverter-circuit protection arrangement, wherein the improvement comprises:

• shorting means for providing a current path across said winding in response to a fault condition, said shorting means comprising a current rectifying arrangement of diodes and no more than one triggerable semiconductor device.

An apparatus for protection of voltage-source inverter electronics in an electrical power distribution network, said inverter electronics being coupled to a dc power source, comprising:

• fault condition detection circuitry coupled to an input to the inverter electronics at said dc power source, said detection circuitry monitoring a first voltage across said input and generating a fault condition detect signal if said first voltage exceeds a predetermined threshold voltage;
• and
• a current bypass circuit, said bypass circuit providing an alternative current path across an ac output of the inverter electronics in response to said fault condition detect signal.

An apparatus for protection of voltage-source inverter electronics in an electrical power distribution network, comprising:

• a solid-state shorting switch means connected across an ac output of said voltage-source inverter electronics for shorting said ac output in response to a detected fault condition;
• and
• fault condition detection switching logic means for detecting a fault condition occurring in said electrical power distribution network and triggering conduction of said shorting switch, said fault condition detection switching logic responsive to a voltage measured at a dc power source input to said voltage-source inverter power electronics.

An active power-line conditioner for three-phase power distribution systems, said power-line conditioner of the type having an electrical power series compensation arrangement that includes a series transformer coupled to an inverter circuit, said inverter circuit being further coupled to a dc power source, said power-line conditioner comprising:

• a solid-state fault-condition current bypass circuit coupled across said transformer, said current bypass circuit comprising a three-phase diode rectifying bridge and a single active (triggerable) semiconductor device connected across a dc side of said diode bridge, said active semiconductor device having a trigger input coupled to a fault condition detection circuit, wherein the active semiconductor device is triggered into conduction by said fault condition detection circuit so as to short said first transformer winding via said diode bridge thereby protecting said inverter circuit during occurrence of a fault condition.

A method for the protection against electrical damage of a voltage-source inverter in a power compensation circuit for an electrical power distribution network, said method comprising:

• (a) monitoring a voltage at a dc power source input interface to said voltage-source inverter to detect a fault condition of said electrical power distribution network;
• and
• (b) providing an electrical current path across an ac output interface of said voltage-source inverter to said electrical power distribution network in response to a voltage indicative of a fault condition.

An active power-line conditioner of the type having a power compensation circuit that includes an inverter coupled to a dc power source, comprising:

• a thyristor-switched MOV electrical current path bypass arrangement connected in parallel with said dc source across a dc input to said inverter, said thyristor-switched MOV arrangement comprising an MOV connected in series with a thyristor;
• and
• MOV gating logic circuit connected to a trigger input of said thyristor, a voltage sensing device across said dc input to said inverter, said MOV gating logic generating a signal for triggering conduction of said thyristor in response to a predetermined voltage sensed by said voltage sensing device.

A method for the protection against electrical damage of voltage-source inverter (VSI) components of a power compensating circuit for an electrical power distribution network, said method comprising the steps of:

• (a) monitoring voltage at a dc power source input interface to a voltage-source inverter of said power compensating circuit;
• and
• (b) providing an electrical current bypass path at said dc power source input interface for shorting said dc input to said inverter in response to a voltage indicative of an overcurrent condition.