Schweitzer Engineering Laboratories, Inc.

Satish Samineni

Normann Fischer

Ritwik Chowdhury

Casper A Labuschagne

Bogdan Zdzislaw Kasztenny

Armando Guzman-Casillas

Dale S Finney

Matchyaraju Alla

Rogerio Scharlach

Dereje Jada Hawaz

Jon Steinmetz

Jason Andrew Young

Protection of shunt capacitor banks in electric power delivery systems using protection settings determined by the protection device or an independent system using capacitor bank arrangement data is described herein. Capacitor bank arrangement data may be entered into an intelligent electronic device (IED). The IED may determine protection settings for the capacitor bank arrangement and for fail-open and fail-short scenarios using the arrangement data. The protection settings may be loaded into a protection element, which applies protection using signals from the power system. Upon detection of an unbalance condition, the IED may effect a protective action by opening a circuit breaker to disconnect the capacitor bank from the power system.

Unbalance protection for shunt capacitor banks

Disclosed are systems and methods to determine a direction to a ground fault of an electrical generator or motor using a known steady-state standing error referenced to a positive-sequence voltage measurement to determine a system standing error and utilizing the system standing error to determine an operating current with anomalies attributable to a fault. A ground fault may be determined using zero-sequence voltage signals from the generator or motor installation. The operating current, along with the zero-sequence voltage, may be used to determine a direction to the fault. The generator or motor may be high-impedance grounded. The systems and methods further indicate the direction to a fault where multiple generators or motors are connected to a common bus.

Selective stator ground fault protection using positive-sequence voltage reference

Systems, methods, and devices are provided for identifying multiple faults across multiple phases of a multi-phase and/or multi-section capacitor bank. A protection device may measure various voltages and currents within the capacitor bank. A phase angle of the measured voltages and currents may be used to determine a location of the faults therein. For example, a phase angle of a compensated unbalance voltage may be compared to a phase angle of a positive-sequence voltage of the capacitor bank. A logic controller may use a difference between the phase angle of the compensated unbalance voltage and the phase angle of the positive-sequence voltage to determine a location (e.g., a phase and/or a section of the capacitor bank) of the faults in the capacitor bank.

Multi-phase fault identification in capacitor banks

Detection of, and protection against faults within a restricted earth fault (REF) zone of a transformer or a generator is disclosed herein. Security of the REF protection element uses comparison of a negative-sequence reference quantity. The REF condition is only detected when there is sufficient ground involvement and a fault in the reverse detection has not been detected. Dependability of the REF protection element in low-impedance grounded systems is improved by ensuring that the element operates when a zero-sequence reference quantity and a neutral operate quantity are orthogonal to each other. The REF protection element further determines an open CT condition and blocks detection of an REF fault upon determination of the open CT condition. A tripping subsystem may issue a trip command based upon detection of the REF condition.

Secure and dependable restricted earth fault protection for electric power generators and transformers

An apparatus and method is provided for identifying a faulted phase in at least one shunt capacitor bank. The apparatus generally includes a sampling circuit for sampling current or voltage signals associated with the shunt capacitor bank. A microcontroller is coupled to the sampling circuit and programmed to measure a compensated neutral point phase angle from the sampled signal, and compare the compensated neutral point phase angle with a fixed reference phase angle to identify the faulted phase of the shunt capacitor bank. The method generally includes the steps of sampling a current or voltage signal associated with the shunt capacitor bank, determining a compensated neutral point phase angle from the sampled signal, and comparing the compensated neutral point phase angle with a fixed reference phase angle to identify the faulted phase of the shunt capacitor bank. The invention also relates to an apparatus and method for identifying the location of the fault (e.g., the section of the bank) in a double ungrounded shunt capacitor bank or double WYE shunt capacitor bank.

Apparatus and method for identifying a faulted phase in a shunt capacitor bank

A power system may comprise two or more transformers operating in parallel. A voltage differential may exist between the transformers, which may create a circulating current in the power system. The system voltage of the power system may be modified by performing a tap change operation on one or more of the transformers. The tap change operation may be configured to minimize the circulating current. The circulating current may be minimized by determining the bias between the transformers using an angular difference between the transformer currents. The angular difference may be calculated using time-aligned measurement data. A tap change operation configured to modify the system voltage, while minimizing circulating current, may be determined using the transformer bias.

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Pullman, WA, United States of America

Satish Samineni