Apparatus and method for providing differential protection for a phase angle regulating transformer in a power system
First Claim
1. An apparatus for providing differential protection for a transformer having a load side and a source side in a three-phase power system, the apparatus comprising:
- a microcontroller including a microprocessor, a memory operatively coupled to the microprocessor, a positive sequence differential element and a negative sequence differential element, the microprocessor adapted to;
calculate a first positive sequence component and a first negative sequence component associated with incoming secondary currents detected on the source side, and calculate a second positive sequence component and a second negative sequence component associated with outgoing secondary currents detected on the load side;
apply a phase angle shift to the second positive sequence component and the second negative sequence component to form a compensated positive sequence component and a compensated negative sequence component, respectively, to compensate for a phase angle shift introduced by operation of the transformer; and
determine an operate current value and a restraint current value for each of the positive and negative sequence differential elements based on the compensated positive sequence component and the compensated negative sequence component.
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Accused Products
Abstract
Provided is an apparatus and method for providing differential protection for a phase angle regulating transformer having a load side and a source side in a three-phase power system. The method includes calculating a first positive sequence component and a first negative sequence component associated with incoming secondary currents detected on the source side, calculating a second positive sequence component and a second negative sequence component associated with outgoing secondary currents detected on the load side, applying a phase angle shift to the second positive sequence component and the second negative sequence component to form a compensated positive sequence component and a compensated negative sequence component, respectively, and determining an operate current value and a restraint current value for each of a positive and negative sequence differential element of the differential protection based on the compensated positive sequence component and the compensated negative sequence component.
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Citations
25 Claims
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1. An apparatus for providing differential protection for a transformer having a load side and a source side in a three-phase power system, the apparatus comprising:
a microcontroller including a microprocessor, a memory operatively coupled to the microprocessor, a positive sequence differential element and a negative sequence differential element, the microprocessor adapted to; calculate a first positive sequence component and a first negative sequence component associated with incoming secondary currents detected on the source side, and calculate a second positive sequence component and a second negative sequence component associated with outgoing secondary currents detected on the load side; apply a phase angle shift to the second positive sequence component and the second negative sequence component to form a compensated positive sequence component and a compensated negative sequence component, respectively, to compensate for a phase angle shift introduced by operation of the transformer; and determine an operate current value and a restraint current value for each of the positive and negative sequence differential elements based on the compensated positive sequence component and the compensated negative sequence component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for providing differential protection for a transformer having a load side and a source side in a three-phase power system, the differential protection including a positive sequence differential element and a negative sequence differential element, the method comprising:
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deriving a first set of three phasors from incoming secondary currents detected on the source side and a second set of three phasors from outgoing secondary currents detected on the load side; based on the first set of three phasors, calculating a first positive sequence component and a first negative sequence component; based on the second set of three phasors, calculating a second positive sequence component and a second negative sequence component; determining a phase angle shift based on a tap position of at least one tap changer and a predetermined number of degrees per step of the transformer, the phase angle shift introduced by operation of the transformer; applying the phase angle shift to the second positive sequence component and the second negative sequence component to generate a compensated positive sequence component and a compensated negative sequence component, respectively; and determining an operate current value and a restraint current value for each of the positive and negative sequence differential elements based on the compensated positive sequence component and the compensated negative sequence component. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for providing differential protection for a transformer having a first side and a second side in a three-phase power system, the differential protection including a positive sequence differential element and a negative sequence differential element, the method comprising:
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calculating a first positive sequence component and a first negative sequence component associated with secondary currents detected on the first side, and calculating a second positive sequence component and a second negative sequence component associated with secondary currents detected on the second side; applying a phase angle shift to the second positive sequence component and the second negative sequence component to form a compensated positive sequence component and a compensated negative sequence component, respectively, to compensate for a phase angle shift introduced by operation of the transformer; and determining an operate current value and a restraint current value for each of the positive and negative sequence differential elements based on the compensated positive sequence component and the compensated negative sequence component. - View Dependent Claims (23, 24, 25)
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Specification