Multiple generator ground fault detection
AssigneeSchweitzer Engineering Laboratories, Inc.
InventorsRitwik Chowdhury, Dale S. Finney
Life of this patent
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Abstract
Detection and protection against electric power generator stator ground fault conditions in multiple-generator high-impedance grounded installations is provided herein. In one embodiment, a generator protection element may block a determination of a fault using third harmonic voltages when the third harmonic voltage from the generator is less than a factor of the maximum third harmonic voltage from all of the generators on the common bus. A tripping subsystem may issue a trip command based upon detection of a stator ground fault condition.
Claims20
A system, comprising:
- a generator configured to generate electrical energy for an electric power delivery system, in electrical communication with common bus for providing the electrical energy to the common bus;
- an intelligent electronic device (IED), comprising:
- a generator monitoring subsystem configured to measure a neutral voltage value and a terminal voltage value of the generator;
- a stator ground fault detection subsystem in communication with the generator monitoring subsystem and configured to determine a stator ground fault using a neutral voltage and terminal voltage value from the generator monitoring subsystem, and to block a determination of the stator ground fault when a factor of the third harmonic voltage from the generator is less than a maximum third harmonic voltage from another generator in electrical communication with the common bus;
- a tripping subsystem configured to issue a trip command based upon satisfaction of the stator ground fault detection and absence of the block;
- and,
- an electrical interrupter configured to securely and selectively interrupt an electrical connection between the generator and the electric power generation and transmission system based on the trip command.
A method of monitoring an electrical generator using a generator protection element, comprising:
- measuring a neutral voltage and a terminal voltage of a generator;
- determining a generator third harmonic voltage value using the neutral and terminal voltages;
- calculating a ratio of a generator neutral third harmonic voltage value and the generator third harmonic voltage value;
- when the ratio is less than a predetermined threshold, determining a stator ground fault condition;
- blocking the stator ground fault detection based at least in part on:
- a factor of the generator third harmonic voltage value being less than a maximum third harmonic voltage value from another generator in electrical communication with a common bus of the generator;
- a communication channel of the bus being not healthy;
- a fundamental ground fault protection system detecting a fault on the generator;
- or
- any combination thereof;
- and
- issuing a trip command based upon the declared stator ground fault condition.
An intelligent electronic device (IED) for monitoring a generator on a common bus of an electric power delivery system, comprising:
- a memory;
- a processor operatively connected to the memory, wherein the processor is configured to execute instructions stored on the memory to cause the processor to:
- receive voltage measurements of the generator;
- determine that a stator ground fault has occurred based on the voltage measurements;
- determine a biasing factor associated with a likelihood that the stator ground fault has occurred at the generator;
- receive at least one other biasing factor associated with a likelihood that the stator ground fault has occurred on an at least one other generator on the common bus;
- determine an order in which to trip a circuit breaker of the generator and an at least one other circuit breaker of the at least one other generator based at least in part on the biasing factor and the at least one other biasing factor;
- and
- send a signal to cause the circuit breaker of the generator to trip based on the order.
Dependencies are inferred from the claim text.