System for mitigating voltage disturbances and interruptions for power distribution applications

• US 6,175,166 B1
• Filed: 06/14/1999
• Issued: 01/16/2001
• Est. Priority Date: 06/14/1999
• Status: Expired due to Term

• Current Assignee: ABB Incorporated (ABB Limited)
• Original Assignee: ABB Power T&D Limited (ABB Limited)
• Inventors: Bapat, Vinod N.
• Primary Examiner(s): Ballato, Josie
• Assistant Examiner(s): Deberadinis, Robert L.
• Application Number:
  US09/332,718
• Time in Patent Office: 582 Days
• Field of Search: 307/64, 307/66, 307/67, 307/80, 307/81, 307/85, 307/86, 307/87, 216/121, 363/34
• US Class Current: 307/64
• CPC Class Codes: H02J 9/062 for AC powered loads

Abstract

A low cost voltage disturbance mitigation system is capable of providing continuous power to a load despite short interruptions or sag disturbances of the utility power. The interruption and sag mitigation system makes use of a combination of unique thermal and electrical properties of magnetic components, power semiconductor devices, and high-discharge-rate energy storage devices. It also facilitates a modular solution that can be easily and economically scaled up or down for use over a wide range of voltage and power levels, e.g., 480 V to 36 kV and 500 kVA to 10,000 kVA.

Claims

1. A system for mitigating disturbances and interruptions in unregulated, disturbance-prone electrical input power for energizing a load coupled to an output terminal, comprising:

(a) a plurality of back-up energy modules, each back-up energy module comprising a DC energy source operatively coupled to a charging circuit and a DC-AC inverter;

(b) a first electronically controllable switch for conducting current from an input terminal to the load coupled to the output terminal;

(c) a second electronically controllable switch operatively coupled to the back-up energy module for conducting current from the back-up energy module to the load; and

(d) a system control module operatively coupled to the first and second switches and to the back-up energy module, wherein the system control module controls the operation of the first and second switches and the back-up energy module, whereby current is deliverable from the input terminal to the load during normal operations and from the back-up energy module to the load during an occurrence of an interruption or disturbance of a short duration in the unregulated input power;

wherein the first electronically controllable switch comprises a normally open switching device and a normally closed switching device (S2A) coupled in parallel to the normally open switching device.

2. A system as recited in claim 1, wherein the DC energy source comprises at least one battery.

3. A system as recited in claim 1, wherein the DC energy source comprises at least one DC bus capacitor.

4. A system as recited in claim 3, wherein the DC energy source comprises a flywheel energy storage system.

5. A system as recited in claim 1, wherein the charging circuit comprises a rectifier circuit.

6. A system as recited in claim 1, wherein the DC-AC inverter comprises a pulse width modulation (PWM) inverter circuit.

7. A system as recited in claim 1, wherein the first electronically controllable switch comprises a combination of gate commutable devices.

8. A system as recited in claim 7, wherein the gate commutatable devices are selected from a group consisting of Insulated Gate Bipolar Transistors (IGBTs), Gate Turn Off thyristors (GTOs), Insulated Gate Commutated Thyristors (IGCTs) and forced commutated Silicon Controlled Rectifiers (SCRs).

9. A system as recited in claim 1, further comprising a vacuum circuit breaker operatively coupled between the input and outputs terminals.

10. A system as recited in claim 1, wherein the short duration is less than 5 seconds.

11. A system for mitigating disturbances and interruptions in unregulated, disturbance-prone electrical input power for energizing a load coupled to an output terminal, comprising:

(a) a back-up energy module comprising a DC energy source operatively coupled to a charging circuit and a DC-AC inverter;

(b) a first electronically controllable switch for conducting current from an input terminal to the load coupled to the output terminal;

(c) a second electronically controllable switch operatively coupled to the back-up energy modules for conducting current from the back-up energy module to the load; and

(d) a system control module operatively coupled to the first and second switches and to the back-up energy modules, wherein the system control module controls the operation of the first and second switches and the back-up energy modules, whereby current is deliverable from the input terminal to the load during normal operations and from the back-up energy modules to the load during an occurrence of an interruption or disturbance of a short duration in the unregulated input power;

wherein the first electronically controllable switch comprises a normally open switch device and a normally closed switching device coupled in parallel to the normally open switching device.

12. A system for mitigating disturbances and interruptions in unregulated, disturbance-prone electrical input power for energizing a load coupled to an output terminal, comprising:

(a) a back-up energy module comprising a DC energy source operatively coupled to a charging circuit and a DC-AC inverter;

(b) a first electronically controllable switch for conducting current from an input terminal to the load coupled to the output terminal;

(c) a second electronically controllable switch operatively coupled to the back-up energy module for conducting current from the back-up energy module to the load;

(d) a system control module operatively coupled to the first and second switches and to the back-up energy module, wherein the system control module controls the operation of the first and second switches and the back-up energy module, whereby current is deliverable from the input terminal to the load during normal operations and from the back-up energy module to the load during an occurrence of an interruption or disturbance of a short duration in the unregulated input power; and

a first transformer coupling the first switch to the input terminal.

13. A system as recited in claim 12, further comprising a second transformer coupling the first switch to the output terminal.

14. A system for mitigating disturbances and interruptions in unregulated, disturbance-prone electrical input power for energizing a load coupled to an output terminal, comprising:

(a) a back-up energy module comprising a DC energy source operatively coupled to a charging circuit and a DC-AC inverter;

(b) a first electronically controllable switch for conducting current from an input terminal to the load coupled to the output terminal;

(c) a second electronically controllable switch operatively coupled to the back-up energy module for conducting current from the back-up energy module to the load; and

(d) a system control module operatively coupled to the first and second switches and to the back-up energy module, wherein the system control module controls the operation of the first and second switches and the back-up energy module, whereby current is deliverable from the input terminal to the load during normal operations and from the back-up energy module to the load during an occurrence of an interruption or disturbance of a short duration in the unregulated input power;

wherein;

the DC energy source comprises at least one DC bus capacitor;

the charging circuit comprises a rectifier circuit;

the DC-AC inverter comprises a pulse width modulation (PWM) inverter circuit;

the first electronically controllable switch comprises a combination of gate commutable devices, including a normally open switching device and a normally closed switching device coupled in parallel to the normally open switching device; and

further comprising a vacuum circuit breaker operatively coupled between the input and output terminals, a first transformer coupling the first switch to the input terminal and a second transformer coupling the first switch to the output terminal.

15. A system as recited in claim 14, wherein the short duration is less than 5 seconds.