Detection system and detection method of distributed generation islanding based on power frequency carrier

Patent metadata

Field	Value
Publication number	US-9614364-B2
Application number	US-201113885686-A
Country	US
Kind code	B2
Filing date	Oct 31, 2011
Priority date	Nov 17, 2010
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A detection system of distributed generation islanding based on power frequency carrier, the detection system comprising: a power frequency carrier signal generating device; a power frequency carrier signal detection device; a signal coupling transformer; a substation bus; a distribution power generator (DG); and a safety isolation breaker, wherein the power frequency carrier signal generating device comprises a voltage and current monitor circuit, the power frequency carrier signal generating device is connected with the signal coupling transformer through four three phase four line power cables, and the signal coupling transformer is connected with substation bus through 3 power cables.

First claim

What is claimed is:

1. A detection system of distributed generation islanding based on power frequency carrier, the detection system comprising:
a power frequency carrier signal generating device ( 1 ),
a power frequency carrier signal detection device ( 2 ),
a signal coupling transformer ( 3 ),
a substation bus ( 4 ),
a distribution power generator (DG) ( 5 ) and
a safety isolation breaker ( 6 ),
wherein said power frequency carrier signal generating device comprises a voltage and current monitor circuit, the power frequency carrier signal generating device ( 1 ) is connected with said signal coupling transformer ( 3 ) through four three phase four line power cables, said signal coupling transformer ( 3 ) is connected with substation bus ( 4 ) through 3 power cables, wherein said substation bus ( 4 ) is connected with 10kV/400V substation and the safety isolation breaker ( 6 ) through feeder;
wherein the power frequency carrier signal detection device ( 2 ) is installed between the safety isolation breaker ( 6 ) and the DG ( 5 ), wherein the power frequency carrier signal detection device ( 2 ) is connected with the lower voltage power network though phase A, B and C live wires and the N middle wire, or through one of the phase A, B and C live wires and the N middle wire to detect signal;
wherein the power frequency carrier signal generating device ( 1 ) sends one signal at a frequency cycle when the power frequency carrier signal detection device ( 2 ) does not detect signal within five continue frequency cycles, the connection between substation bus ( 4 ) and the DG ( 5 ) will be turned off,
wherein the power frequency carrier signal detection device ( 2 ) sends a tripping signal to the safety isolation breaker ( 6 ) triple to ensure the DG ( 5 ) isolate from a major network;
wherein the power frequency carrier signal generating device is connected with said signal coupling transformer though phase A, B C live wires and the N middle wire so that the signal can be send by anyone signal phase, any two phases parallel way or three phases parallel way;
wherein the power frequency carrier signal generating device is connected with said signal coupling transformer though phase A, B, C live wires and the N middle wire, or through one of the phase A, B and C live wires and the N middle wire; and
wherein the power frequency carrier signal detection device contains a hardware signal synthesis circuit, and the hardware signal synthesis circuit includes 3 voltage transformers: the first voltage transformer ( 41 ), the second voltage transformer ( 42 ) and the third voltage transformer ( 43 ), and the transformation ratio of the first and the second voltage transformer are same.

2. The detection system of claim 1 , which is characterized in that: a high voltage side of a signal coupling transformer ( 3 ) that is 10 kV side which is connected with a substation bus through 3 high-voltage fuses ( 21 , 22 , 23 ), a low voltage side of the signal coupling transformer ( 3 ) that is 400V side is connected with a power frequency carrier signal generating device through 3 molded case circuit breakers ( 24 , 25 , 26 ), the power frequency carrier signal generating device exchanges information with a remote control system through communication interface ( 27 ).

3. The detection system of claim 1 , which is characterized in that: a power frequency carrier signal is sent by said power frequency carrier signal generating device and coupled to the substation bus by the signal coupling transformer, the signal is transformed though medium power network, distribution transformer and low voltage power network, to monitor the power frequency carrier signal by real-time monitoring of power carrier signal detection device installed in the distributed generation.

4. The detection system of claim 3 , which is characterized in that: it uses self-monitor transmit power method to control a peak of a transmit current of power frequency carrier signal greater than 300 A and less than 600 A.

5. The detection system of claim 4 , which is characterized in that: a power frequency carrier signal generating device sends the carrier signal to substation bus by the signal coupling transformer, a capacity of the signal coupling transformer is from 200 kVA to 600 kVA, and the signal detection period is 40 ms, and an effective range of the signal is 6 ms.

6. The detection system of claim 5 , which is characterized in that: a power frequency carrier signal detection device is installed the distribution generating side of a safety isolation breaker, the signal detection period is 40 ms of a signal detection device, if it didn't detect signal within 200 ms continuously, the safety isolation breaker will send tripping signal.

7. The detection system of claim 6 , which is characterized in that: the power frequency carrier signal generating device monitors transmission signal voltage and current, and adjust transmission power itself to ensure a driving signal point being less 30 electrical degrees before crossing zero from positive to negative of a voltage of power frequency, that is 3.33 ms.

8. The detection system of claim 7 , which is characterized in that: the power frequency carrier signal detection device contains hardware synthesis circuit; the circuit adopts RC full bridge all-pass filter circuit, there is no effective frequency loss of the signal, and it strengthen the signal receiving energy double.

9. The detection system of claim 8 , which is characterized in that: the power frequency carrier signal detection device makes a safety isolation breaker trip by outputting tripping signal; when a tripping signal line is shorter, less than 10 m, it can adopt plus output, and when longer than 10 m it will adopt bus communication.

10. The detection system of claim 9 , which is characterized in that: the distribution generation includes photovoltaic power, small wind power and energy storage power generation.

Assignees

• Huang Biyao
• Li Jianqi
• Liu Guojun
• Wang Zhihui
• Quan Nan
• Qu Xiaofeng
• Zhao Tao
• Wang Licheng
• State Grid Corp China
• China Electric Power Res Inst

Inventors

• Huang Biyao
• Li Jianqi
• Liu Guojun
• Wang Zhihui
• Quan Nan
• Qu Xiaofeng
• Zhao Tao
• Wang Licheng

Classifications

• H02J13/1313

  using pulsed signals · CPC title

• H02J3/388

  Arrangements for the handling of islanding, e.g. for disconnection or for avoiding the disconnection of power · CPC title

• Y02P80/14

  District level solutions, i.e. local energy networks · CPC title

• H02H1/0061

  concerning transmission of signals (transmission of measured quantities or switching orders; sectionalised protection involving signal transmission between at least two stations H02H7/261; comparison of the voltage or current values at two spaced portions of a single system H02H3/28; transferring the output of a sensing member to another variable G01D5/00; electrical measuring arrangements using modulation of electromagnetic waves, e.g. light beams G01R15/24, G01R15/26) · CPC title

• Y04S10/20

  using protection elements, arrangements or systems · CPC title