Faulted phase decision method between current and voltage based delta phase selectors
AssigneeABB Technology AG
InventorFlorin Peter Selejan
Life of this patent
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Abstract
A method of identifying fault conditions in a three phase power system includes monitoring the changes of both the current and voltage properties on a three phase power network. A maximum phase change value of both the current and voltage is determined. Either the voltage or the current values are selected, whichever includes the largest maximum phase change. Thereafter, the selected set of measurements is analyzed to determine whether a fault condition exists on any phase of the three phase power.
Claims14
A protective relay for providing protective control to a power system carrying three-phase power, the protective relay comprising:
- a processor;
- at least one computer readable medium;
- program instructions stored on the at least one computer readable medium and executable by the processor to perform a fault detection method comprising:
- receiving a first set of signal values representative of the voltage properties of each phase of the three-phase power system and a second set of signal values representative of the current properties of each phase of the three-phase power system;
- processing said first set of signal values to produce a first set of processed signals representing the current change for each respective phase of the three phase power;
- processing said second set of signal values to produce a second set of processed signals representing the voltage change for each respective phase of the three phase power;
- determining a maximum value of said first set of processed signals and a maximum value of said second set of processed signals;
- dividing said maximum value of said first set of processed signals by a first threshold value resulting in a first quality value;
- dividing said maximum value of said second set of processed signals by a second threshold value resulting in a second quality value;
- selecting the set of processed signals having the larger quality value;
- and
- using said selected set of processed signals to determine whether a fault condition exists on any phase of the three phase power.
A method of identifying faulted phases in a three phase power system comprising:
- receiving a first set of signal values representative of the voltage properties of each phase of the three-phase power system and a second set of signal values representative of the current properties of each phase of the three-phase power system;
- processing said first set of signal values to produce a first set of processed signals representing the current change for each respective phase of the three phase power;
- processing said second set of signal values to produce a second set of processed signals representing the voltage change for each respective phase of the three phase power;
- determining a maximum value of said first set of processed signals and a maximum value of said second set of processed signals;
- selecting the set of processed signals having the larger maximum value;
- and
- using said selected set of processed signals to determine whether a fault condition exists on any phase of the three phase power.
Dependencies are inferred from the claim text.