Sensitive directional element for generator protection
AssigneeSchweitzer Engineering Laboratories, Inc.
InventorsRitwik Chowdhury, Dale S. Finney
Life of this patent
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Abstract
Disclosed are systems and methods to determine a direction to a fault of an electrical generator using sensitive current. A ground fault is determined using voltage signals from the generator installation. Incremental residual values of the sensitive current, along with the voltage, are used to determine a direction to the fault. The generator may be high-impedance grounded. The systems and methods further indicate the direction to a fault where multiple generators are connected using a common generation bus.
Claims20
A system for protecting an electric power generation installation in an electric power delivery system, comprising:
- a first protective device in electrical communication with a first generator of the generation installation, comprising:
- a first voltage sensor component in electrical communication with a potential transformer of the electric power delivery system, obtaining a voltage signal corresponding with a voltage of the first generator;
- a first sensitive current sensor component in electrical communication with a current transformer, obtaining a sensitive current signal of the first generator;
- a first processor;
- a first non-transitory computer-readable storage medium in communication with the processor, the first voltage sensor component, and the sensitive current sensor component, comprising instructions that when operated cause the processor to:
- detect a ground fault of the generator installation using voltage signals from the voltage sensor component;
- calculate sensitive current values of the first generator using the sensitive current signal, and store the sensitive current values;
- when the ground fault is detected,
- calculate an incremental residual current of the first generator as a difference between a present sensitive current value and a previous sensitive current values from the stored sensitive current values of the first generator;
- calculate an admittance of the first generator using the incremental residual current of the first generator;
- and
- determine a direction to the ground fault as forward to the first generator by comparing the admittance of the first generator against a forward admittance threshold;
- and
- upon determination of a forward fault, effect a protective action of the first generator.
A method for protecting an electric power generation installation in an electric power delivery system, comprising:
- obtaining from a first voltage sensor component, a first voltage signal proportional to a voltage of a first generator of the electric power generation installation;
- obtaining from a first sensitive current component, a sensitive current signal of the first generator;
- detect a generator ground fault using the first voltage signal
- calculate sensitive current values from the sensitive current signal, and store the sensitive current values;
- calculate an incremental residual current as a difference between a present sensitive current value and a previous sensitive current value from the stored sensitive current values;
- calculate an admittance of the first generator using the incremental residual current;
- determine a direction to the ground fault as forward by comparing the admittance against a forward admittance threshold;
- when a forward fault is determined, effect a protective action.
Dependencies are inferred from the claim text.