Power System Islanding Detection via Time Differential Error
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Solution Overview
Problem
Inadvertent disconnection of power system elements, known as islanding, occurs due to excessive power flow or maintenance, leading to imbalanced power generation and loads, and can result in equipment damage and loss of power reliability, as existing methods for detecting islanding are slow and lack necessary response characteristics.
Innovation Solution
A system and method that compare time errors calculated from frequency-dependent parameters at discrete power system locations to determine time differential errors, which are then mapped back to their respective locations and compared to thresholds to detect power system conditions such as islanding, pole slipping, or power swings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power system frequency is monitored at various locations to detect islanding, then islanding detection capability is provided, but the detection speed is inherently slow and may fail to detect islanding before automatic or manual controls exacerbate the problem
Solution Approach 1:
The invention divides the power system into multiple discrete monitoring locations, each with its own intelligent electronic device that independently calculates time values and time errors. By segmenting the monitoring function across multiple locations rather than using a single centralized frequency monitor, the system achieves faster local detection of islanding conditions while maintaining comprehensive coverage.
Solution Approach 2:
The invention replaces traditional mechanical frequency monitoring instruments with intelligent electronic devices that perform digital calculations of time values, time errors, and rate of change of time errors. This electronic/digital substitution enables much faster processing and detection capabilities compared to conventional frequency measurement instruments.
2Loss of information
If instruments are used to view power system frequency, then frequency information is provided, but the instruments may not have the necessary response characteristic required to accurately depict the situation to the power system operator
Solution Approach 1:
The intelligent electronic devices continuously calculate time values, time errors, and rate of change of time errors in advance, maintaining a ready supply of processed information. This preliminary calculation of multiple parameters allows the system to immediately detect and report islanding conditions without waiting for frequency changes to reach threshold levels, providing both continuous information availability and rapid response.
Solution Approach 2:
The invention adds temporal dimension to frequency monitoring by calculating not just frequency itself but also time values, time errors, and the rate of change of time errors. This multi-dimensional approach provides more comprehensive information about system conditions and enables more accurate detection of islanding events.
Data Source
AI summary
Provided is a system and method for detecting a power system condition of a power system. The system includes at least a first and second intelligent electronic device (IED) operatively coupled to the power system at respective first and second power system locations. Each IED is configured to calculate a measured time value based on a frequency dependant parameter such as a secondary voltage signal at their respective locations, to compare the measured time value to a reference time value to form a time error, and to transmit the time error. The system further includes a third IED configured to compare respective time errors received from the first and second IEDs to form a time differential error, to map the time differential error back to their power system locations, and compare the time differential error to a predetermined threshold to determine the power system condition.