Anti-islanding protection systems for synchronous machine based distributed generators

• US 7,271,571 B2
• Filed: 02/01/2007
• Issued: 09/18/2007
• Est. Priority Date: 10/15/2004
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Ye, Zhihong, Miller, Nicholas Wright, Walling, Reigh Allen, Nelson, John Keith, Du, Pengwei
• Primary Examiner(s): Ponomarenko; Nicholas
• Application Number:
  US11/670,067
• Publication Number:
  US 20070126428A1
• Time in Patent Office: 229 Days
• Field of Search: 322/17, 322/22, 322/23, 322/24, 322/28, 322/36, 322/37, 307/31, 307/32
• US Class Current: 322/36
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network

Abstract

A system for providing anti-islanding protection of a synchronous machine based distributed generator includes a frequency sensor configured to generate a generator frequency signal, a bandpass filter configured for filtering the generator frequency signal, a governor controller configured for using the filtered frequency signal to generate a power feedback signal, and a governor summation element configured for summing the filtered frequency signal, the power feedback signal, and a reference power to provide an electrical torque signal. Another system includes a voltage sensor configured to generate a generator terminal voltage signal, a feedback power calculator configured for generating a reactive feedback power signal, a bandpass filter configured for filtering the terminal voltage signal, and a PI controller summation element configured for summing the filtered terminal voltage signal, the reactive power feedback signal, and a reference reactive power to provide an error signal.

Claims

1. A system for providing anti-islanding protection of a distributed generator with respect to a feeder connected to an electrical grid, the system comprising:

a voltage sensor configured to generate a terminal voltage signal representative of a terminal voltage of the generator;

a feedback power calculator configured for generating a reactive feedback power signal;

a bandpass filter configured for filtering the terminal voltage signal;

a proportional-integral controller summation element configured for summing the filtered terminal voltage signal, the reactive power feedback signal, and a reference reactive power to provide an error signal for use by a proportional integral controller in generating a voltage reference signal for the generator.

2. The system of claim 1 further comprising a grid controller configured for receiving the terminal voltage signal and generating a grid disconnection signal upon the terminal voltage signal becoming out of a nominal terminal voltage range.

3. The system of claim 2 wherein the bandpass filter comprises a filter gain comprising a value that is greater than or equal to a gain required to result in a disconnected grid loop gain of greater than unity.

4. The system of claim 3 wherein a range of the bandpass filter extends from about 0.1 Hz to about 100 Hz.

5. The system of claim 2 wherein the bandpass filter is configured to increase the speed of detecting a change of the terminal voltage signal upon a disruption to the electrical grid.

6. The system of claim 2 wherein the grid controller is further configured for receiving a generator frequency signal representative of the rotational speed of the generator and generating a grid disconnection signal upon the generator frequency signal becoming out of a nominal frequency range.

7. The system of claim 1 further comprising a grid controller configured for receiving a generator frequency signal representative of the rotating frequency of the generator and generating a grid disconnection signal upon the generator frequency signal becoming out of a nominal frequency range.