Sensitive ground fault detection system for use in compensated electric power distribution networks
First Claim
1. A system for detecting ground faults in a compensated distribution network, comprising:
- means for determining the zero sequence voltage (V0) and zero sequence current (I0) on a power line;
a calculation system for calculating therefrom a conductance or resistance value from the real parts of said zero sequence voltage and zero sequence current;
circuitry for enabling the operation of the calculating system for only preselected power line conditions; and
means for comparing the conductance or resistance value against a first threshold value to determine a forward fault and a second threshold value to determine a reverse fault.
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Abstract
A system for detecting ground faults in a compensated electric power distribution network includes the determination of zero sequence voltage (V0) and zero sequence current (I0) on a power line and calculating the zero sequence conductance (G0) therefrom. The operation of the conductance calculation circuit occurs only under selected power line conditions involving minimum values of zero sequence voltage, zero sequence current and positive sequence voltage, to ensure the accuracy of a fault direction determination. The conductance values are processed on an adaptive basis in which the difference between the most recent conductance value and a conductance value from a selected previous point in time is determined and then compared against threshold values to make forward and reverse fault declarations.
37 Citations
31 Claims
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1. A system for detecting ground faults in a compensated distribution network, comprising:
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means for determining the zero sequence voltage (V0) and zero sequence current (I0) on a power line;
a calculation system for calculating therefrom a conductance or resistance value from the real parts of said zero sequence voltage and zero sequence current;
circuitry for enabling the operation of the calculating system for only preselected power line conditions; and
means for comparing the conductance or resistance value against a first threshold value to determine a forward fault and a second threshold value to determine a reverse fault. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method for detecting ground faults in a compensated power distribution network, comprising the steps of:
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determining the zero sequence voltage (V0) and zero sequence current (I0) on a power line;
calculating a conductance or resistance value from the real parts of said zero sequence voltage and zero sequence current;
enabling the operation of the calculating step for selected power line conditions, to assist in insuring the accuracy of a ground fault determination; and
comparing the conductance or resistance value against a first threshold value to determine a forward fault and a second threshold value to determine a reverse fault. - View Dependent Claims (27, 28, 29, 30, 31)
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Specification