The precise value of the fault location on Utility’s assets is critical for reducing the blackout duration, with fault elimination and grid energization. Within a few minutes after a fault, IVPower provides a graphical tolerance of the fault position, through a red rectangular region, but also a geographical position. This time-sensitive and crucial information is immediately sent for remedial actions to operators and experts by email. IVPower application makes sure that only reliable and accurate information is provided to repair teams. If fault analysis improves due to additional data coming in COMTRADE records, the users receive an update.
IVPower algorithms for transmission lines
IVPower includes three fault locator algorithms which use estimates of the voltage and current phasors:
- A two-ended fault locator (TEFL), based on a voltage balance principle.
- A single-ended fault locator (SEFL), based on apparent loop impedance.
- A basic fault locator (BFL), similar to SEFL but used as an indicative method when the line topology is not known, and as a back- up method to SEFL.
Fault location methods
Depending on the level of grid automation and investment choices, Utilities may obtain fault location through various means:
- by collecting the fault indications (fault type, fault distance in km, fault current, loop resistance, loop reactance) from distance or differential protection relays, through the SCADA
- from traveling-wave fault locators, either as independent IEDs or as integrated functions in protection relays
- from digital fault recorder systems/ software or from data collectors like SICAM PQS
- by manual calculation using a tool like SIGRA, after manual, automated or semi- automated selection and retrieval of the record(s)
- from a reflectometry measurement performed by a crew on site (typical solution for accurate FL on a cable section)
- from fault indicators (“targets”) installed in the grid (typical solution for MV distribution networks).
Advantages of IVPower fault locator for Utilities
The advantages of IVPower fault locator with respect to IEDs are:
- Very accurate fault location, more precise than IEDs.
- IVPower provides an uncertainty region around the provided fault location, IEDs don’t. This is valuable information for dispatching and repair crews inspecting the lines, because they have a zone of confidence giving the % the fault is within this region (e.g., 98% confidence level).
- Fault correlation with its cause, such as lightning strikes, through links with meteorological systems.
- Supported line topologies include shunt reactors, series capacitors, parallel overhead or cable sections.
- Configuring IVPower is a central process, easily updated in case of a change in the power system, whilst IEDs would need to be reconfigured.
- Fault location and all the automated analysis is totally independent of the IED vendor.
- Measurements from traveling wave devices can be fully integrated into the sequence of events and IVPower fault location.
Accuracy of IVPower fault locator
The achievable accuracy is dependent on numerous sources of error and inaccuracies.
With normally-achievable assumptions on line parameters and voltage/current measurements accuracy, for lines > 10km long:
- Fault location accuracy is better than 2% of the line length in >50% of the low-resistance short-circuits (<40 Ohm apparent fault resistance);
- Fault location accuracy is better than 5% of the line length in >98% of the low-resistance short-circuits.
If IVPower receives and processes records from all line feeders, the situation improves further because multiple-ended fault location will usually apply and the accuracy then approaches 1% of the line length in >50% of the cases.
