US 2004/0070278 A1 · Dual feed power supply systems with enhanced power quality

Abstract

A dual feed power supply system provides the high reliability of a dual utility feed, with minimization of interruptions in the power supplied to critical loads during switching, and compensation for voltage sags occurring on the primary power feed. First and second AC input buses are connected through a transfer switching apparatus to each of the phase lines of a distribution bus. The transfer switching apparatus has a first input terminal connected to one of the phase lines of the first input bus and a second input terminal connected to one of the phase lines of the second input bus, and an output terminal connected to one of the phase lines of the distribution bus. Input switches allow switching from one or the other of the AC input buses to the distribution bus, with a fast transfer switch used to interrupt the supply of power from the input buses to the distribution bus during switching of the input switches. Power is drawn from a DC energy storage device through an inverter to supply AC power to the distribution bus during switching events to minimize interruption of the power supplied to the distribution bus and to critical loads connected thereto. Power may also be drawn from the input buses during voltage sags on one or both of the buses and delivered through the inverter to the distribution bus at the desired nominal output voltage levels.

Claims60

Dependent claims

A transfer switching apparatus comprising:

(a) a first input terminal and a second input terminal each of which may be provided with AC power from one of the lines of two separate AC input buses, and an output terminal that is available for connection to one of the lines of a distribution bus;
(b) a first input switch connected between the first input terminal and a junction node and a second input switch connected between the second input terminal and the junction node, the input switches responsive to control signals to open and close, the first input switch being normally closed and the second input switch being normally open, and a bi-directional transfer switch connected between the junction node and the output terminal, the transfer switch responsive to control signals to open and close the transfer switch;
(c) a first rectifier connected to the first input terminal to receive AC power therefrom and provide DC output voltage to DC bus lines and a second rectifier connected to the second input terminal to receive AC power therefrom and provide DC voltage to the DC bus lines in parallel with the DC voltage provided by the first rectifier, the first and second rectifiers connected to the first and second input terminals independently of the first and second input switches;
(d) a DC electrical energy storage device connected to the DC bus lines to receive DC power therefrom and deliver DC power thereto;
and
(e) an inverter connected to the DC bus lines and having an AC output connected to the output terminal, the inverter responsive to control signals to provide AC output voltage to the output terminal.

3 more elements

A dual feed power supply system comprising:

(a) a first AC input bus and a second AC input bus each having three phase lines;
(b) an AC distribution bus having three phase lines;
(c) for each of the three phases of the input buses and the distribution bus, a transfer switching apparatus connected to receive power from phase lines of the AC input buses and connected to supply power to a phase line of the distribution bus, each transfer switching apparatus comprising:
(1) a first input terminal and a second input terminal each of which is connected to be provided with AC power from one of the phase lines of the AC input buses, and an output terminal that is connected to one of the phase lines of the distribution bus;
(2) a first input switch connected between the first input terminal and a junction node and a second input switch connected between the second input terminal and the junction node, the input switches responsive to control signals to open and close, the first input switch being normally closed and the second input switch being normally open, and a bi-directional transfer switch connected between the junction node and the output terminal, the transfer switch responsive to control signals to open and close the transfer switch;
(3) a first rectifier connected to the first input terminal to receive AC power therefrom and provide DC output voltage to DC bus lines and a second rectifier connected to the second input terminal to receive AC power therefrom and provide DC voltage to the DC bus lines in parallel with the DC voltage provided by the first rectifier, the first and second rectifiers connected to the first and second input terminals independently of the first and second input switches;
(4) a DC electrical energy storage device connected to the DC bus lines to receive DC power therefrom and deliver DC power thereto;
(5) an inverter connected to the DC bus lines and having an AC output connected to the output terminal, the inverter responsive to control signals to provide AC output voltage to the output terminal;
and
(6) controller means connected to provide control signals to the first and second input switches, to the transfer switch and to the inverter, and connected to receive signals indicating the voltage at the first and second input terminals and at the output terminal, the controller means normally controlling the first and second input switches to maintain the first input switch closed and the second input switch open and controlling the transfer switch to maintain it closed during normal availability of power at the first input terminal, and upon a fault condition of the power provided to the first input terminal controlling the transfer switch to open and controlling the inverter to provide AC output power to the output terminal, then controlling the first input switch to open, then controlling the second input switch to close, then controlling the transfer switch to close to provide AC power from the second input terminal to the output terminal while controlling the inverter to turn off and cease supplying output power to the output terminal.

7 more elements

A transfer switching apparatus comprising:

(a) a first input terminal and a second input terminal each of which may be provided with AC power from one of the lines of two separate AC input buses, and an output terminal that is available for connection to one of the lines of a distribution bus;
(b) a first input switch connected between the first input terminal and a junction node and a second input switch connected between the second input terminal and the junction node, the input switches responsive to control signals to open and close, the first input switch being normally closed and the second input switch being normally open, and a bi-directional transfer switch connected between the junction node and the output terminal, the transfer switch responsive to control signals to open and close the transfer switch;
(c) a first rectifier connected to the first input terminal to receive AC power therefrom and provide DC output voltage to DC bus lines and a second rectifier connected to the second input terminal to receive AC power therefrom and provide DC voltage to the DC bus lines in parallel with the DC voltage provided by the first rectifier, the first and second rectifiers connected to the first and second input terminals independently of the first and second input switches;
(d) a DC electrical energy storage device connected to the DC bus lines to receive DC power therefrom and deliver DC power thereto;
(e) an inverter connected to the DC bus lines and having an AC output connected to the output terminal, the inverter responsive to control signals to provide AC output voltage to the output terminal;
and
(f) a controller means connected to provide control signals to the inverter for controlling the inverter to turn on to provide AC power at the phase and frequency of the power provided from the first input terminal through the first input switch and to turn off the transfer switch when a selected level of sag occurs in the AC voltage at the first input terminal to maintain the voltage level at the output terminal at a selected nominal voltage level greater than the level of voltage available at the first input terminal.

4 more elements

A transfer switching apparatus comprising:

(a) a first input terminal and a second input terminal each of which may be provided with AC power from one of the lines of two separate AC input buses, and an output terminal that is available for connection to one of the lines of a distribution bus;
(b) a first input switch connected between the first input terminal and a junction node and a second input switch connected between the second input terminal and the junction node, the input switches responsive to control signals to open and close, the first input switch being normally closed and the second input switch being normally open, the junction node connected to the output terminal;
(c) a first rectifier connected to the first input terminal to receive AC power therefrom and provide DC output voltage to DC bus lines and a second rectifier connected to the second input terminal to receive AC power therefrom and provide DC voltage to the DC bus lines in parallel with the DC voltage provided by the first rectifier, the first and second rectifiers connected to the first and second input terminals independently of the first and second input switches, wherein the first and second rectifiers are formed as pairs of diodes, each connected together at a node and connected in series across the DC bus lines, the nodes between the pairs of diodes in the first and second rectifiers connected respectively to the first and second input terminals;
(d) a DC electrical energy storage device connected to the DC bus lines to receive DC power therefrom and deliver DC power thereto, wherein the DC electrical energy storage device comprises two capacitors connected together at a node and connected in series across the DC bus lines, and further including a neutral return line connected to the node between the capacitors to provide a current return path for power supplied to the first and second input terminals;
(e) an inverter connected to the DC bus lines and having an AC output connected to the output terminal, the inverter responsive to control signals to provide AC output voltage to the output terminal.

2 more elements

Dependencies are inferred from the claim text.

Dual feed power supply systems with enhanced power quality

Life of this patent

Dual feed power supply systems with enhanced power quality

Life of this patent

Abstract

Claims60