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 a wavelet transformation to the signal read in step a to form high and low frequency components of the transformed signal, a time versus high-frequency component window for the high frequency component and a time versus low-frequency component window for the low frequency component for detecting a perturbation in a transient time domain of said read signal;
c. determining whether an absolute amplitude value of the high-frequency component is greater than an amplitude threshold value and whether the amplitude threshold value is exceeded for a duration longer than a time 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.
1 Assignment
0 Petitions
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.
-
Citations
13 Claims
-
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 a wavelet transformation to the signal read in step a to form high and low frequency components of the transformed signal, a time versus high-frequency component window for the high frequency component and a time versus low-frequency component window for the low frequency component for detecting a perturbation in a transient time domain of said read signal; c. determining whether an absolute amplitude value of the high-frequency component is greater than an amplitude threshold value and whether the amplitude threshold value is exceeded for a duration longer than a time 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)
-
-
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 a public electric power grid, said detection system comprising:
-
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 read signal, which is either a voltage signal or a frequency signal, in said independent power distribution system; and a calculating processing device for performing a wavelet transformation of said read 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;
wherein;said, calculating processing device includes means for decomposing said read signal into a high-frequency component and a low frequency component by the wavelet transformation for observation of a perturbation, and means for determining a stand-alone operation to be occurring in said distributed generating system if an absolute amplitude value of the high-frequency component is greater than an amplitude threshold value for a duration greater than a time threshold value. - View Dependent Claims (9, 10, 11, 12, 13)
-
Specification