Method and system for detecting stand-alone operation of a distributed generating system
First Claim
1. A method for detecting stand-alone operation of a distributed generating system, said distributed generating system having a generating source connected in shunt with an independent power distribution system via a first branch breaker, said method comprising the steps of:
- a. reading a voltage signal or a frequency signal on said independent power distribution system;
b. performing the wavelet transformation to said voltage or frequency signal to form a time versus high-frequency component window and a time versus low-frequency component window for conveniently detecting the perturbation in a transient time domain of said signal;
c. determining whether an absolute value of the high-frequency component is greater than a threshold value and whether a duration is longer than another threshold value and deciding that a stand-alone operation occurs if both answers are yes; and
d. generating an alarm signal and sending said alarm signal to said first branch breaker to drive said first branch breaker to release a parallel connection between said generating source and said power distribution system.
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Accused Products
Abstract
A method and a system for detecting stand-alone operation of a distributed generating system having a generating source connected in shunt with an independent power distribution system via a first branch breaker are proposed. A voltage or a frequency signal on the independent power distribution system is read. The wavelet transformation is performed on the voltage or frequency signal to form a time versus high-frequency component window and a time versus low-frequency component window for conveniently detecting the perturbation in the time domain of the signal. Next, whether the absolute value of the high-frequency component is greater than a threshold value and whether the duration is longer than another threshold value are determined. If both answers are yes, a stand-alone operation occurs. An alarm signal is immediately generated and sent to the first branch breaker to release the connection between the generating source and the power distribution system.
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Citations
15 Claims
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1. A method for detecting stand-alone operation of a distributed generating system, said distributed generating system having a generating source connected in shunt with an independent power distribution system via a first branch breaker, said method comprising the steps of:
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a. reading a voltage signal or a frequency signal on said independent power distribution system;
b. performing the wavelet transformation to said voltage or frequency signal to form a time versus high-frequency component window and a time versus low-frequency component window for conveniently detecting the perturbation in a transient time domain of said signal;
c. determining whether an absolute value of the high-frequency component is greater than a threshold value and whether a duration is longer than another threshold value and deciding that a stand-alone operation occurs if both answers are yes; and
d. generating an alarm signal and sending said alarm signal to said first branch breaker to drive said first branch breaker to release a parallel connection between said generating source and said power distribution system. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for detecting stand-alone operation of a distributed generating system, said distributed generating system forming an independent power distribution system connected in shunt with the public electric power grid, said detection system comprising:
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a generating source for providing power for said independent power distribution system;
a first branch breaker connected between said generating source and said independent power distribution system;
a voltage/frequency input device connected to said independent power distribution system and used to input a voltage signal or a frequency signal in said independent power distribution system; and
a calculating processing device for performing the wavelet transformation of said voltage or frequency signal on said independent power distribution system to determine whether stand-alone operation occurs on said independent power distribution system, said first branch breaker being controlled to release a parallel connection between said generating source and said independent power distribution system if stand-alone operation occurs on said independent power distribution system. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification