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US 7,453,674 B2Granted
Method for protecting an electric generator
AssigneeBattelle Energy Alliance, LLC
InventorsBarry W. Kuehnle, Jeffrey B. Roberts, Ralph W. Folkers
Life of this patent
Estimating the term…
Abstract
A method for protecting an electrical generator which includes providing an electrical generator which is normally synchronously operated with an electrical power grid; providing a synchronizing signal from the electrical generator; establishing a reference signal; and electrically isolating the electrical generator from the electrical power grid if the synchronizing signal is not in phase with the reference signal.
Claims24
A method for protecting an electrical generator, comprising:
- providing an electrical generator which is electrically coupled to and normally synchronously operated with an electrical power grid;
- providing a synchronizing signal from the electrical generator;
- deriving a periodic time function reference signal from historical system information having a time duration, and relating to the electrical generator and/or the electrical power grid;
- and
- electrically isolating the electrical generator from the electrical power grid if the synchronizing signal is not in phase with the reference signal.
2 more elements
A method for protecting an electrical generator, comprising:
- providing an electrical generator, which is electrically coupled to and normally synchronously operated with an electrical power grid;
- providing a synchronizing voltage signal from the electrical generator, and wherein the synchronizing voltage signal is sinusoidal, and which has a frequency fs;
- establishing historical system information having a time duration, and which relates to the electrical generator and/or the electrical grid;
- deriving a reference voltage signal from the historical system information, and wherein the reference voltage signal is a periodic time function having a frequency substantially similar to the frequency of the synchronizing voltage signal;
- determining a phase angle difference between the synchronizing voltage signal and the reference voltage signal;
- and
- electrically isolating the electrical generator from the electrical power grid if the magnitude of the phase angle difference is greater than a predetermined value.
4 more elements
A method for protecting an electrical generator, comprising:
- providing an electrical generator, which is electrically coupled to and normally synchronously operated with an electrical power grid;
- providing a synchronizing signal time function from the electrical generator, and wherein the synchronizing signal time function is sinusoidal, and which has a frequency fs;
- deriving a reference signal time function having a time duration of greater than about two cycles, and which is a periodic time function with a frequency substantially similar to fs, and which is calculated by multiplying the amplitude of a previously calculated reference signal time function over the time duration by (x−1)/x, and wherein x is a number that lies within a range of about 4 to about 1000, and multiplying the amplitude of the synchronizing signal time function over the time period by 1/x, and summing the synchronizing signal time function multiplied by 1/x to the previously calculated reference signal time function multiplied by (x−1)/x;
- determining a phase angle difference between the synchronizing signal time function and the reference signal time function during the time duration;
- and
- electrically isolating the electrical generator from the electrical power grid if the magnitude of the phase angle difference is greater than a predetermined value.
3 more elements
A method for protecting an electrical generator, comprising:
- providing an electrical generator which is electrically coupled to and normally synchronously operated with an electrical power grid;
- providing a synchronizing voltage signal Vs(t) from the electrical generator, and wherein the synchronizing voltage signal is sinusoidal, and which has a frequency fs, and which is derived from a single phase of the electrical generator;
- calculating a reference voltage signal Vr(t) using the formula:
- Vr(t)=[Vr(t−1)·(x−1)/x]+[Vs(t)·1/x],
- and wherein x is a number that lies within a range of about 4 to about 1000;
- detecting a zero crossing of the synchronizing voltage signal, and detecting a zero crossing of the reference voltage signal, and measuring a time difference Δt between the zero crossing of the synchronizing voltage signal and the zero crossing of the reference voltage signal;
- calculating a phase angle difference Φ between the synchronizing voltage signal and the reference voltage signal using the formula:
- Φ=360·fs·Δt;
- comparing the calculated phase angle difference to a predetermined value of about 20 to about 60 degrees;
- energizing a relay if the calculated phase angle difference is greater than the predetermined value;
- introducing a time delay of about 1/60 second to about 5 seconds following the determination that the calculated phase angle difference is greater than the predetermined value;
- and
- causing the relay to open one or more circuit breakers after the time delay so as to isolate the electrical generator from the electrical power grid.
10 more elements
Dependencies are inferred from the claim text.