Fault Location Using Sparse Wide Area Measurements
Transmission line fault location allows quick repair of the damage caused by the fault and timely restoration of the line affected by the fault. Accuracy of the fault location is quite important since it affects repair crew’s ability to physically locate the damage part quickly. Typically, the desirable accuracy is to be able to locate a fault within a span of the transmission line towers. This paper presents a new fault location scheme which uses synchronized phasor measurements from different substations sparsely located near the region where the fault has occurred. When fault occurs different Intelligent Electronic Devices (IEDs) such as Phasor Measurement Units (PMUs) and Digital Fault Recorders (DFRs) connected to Global Positioning System (GPS) receivers and installed in some of the substations in the region will be automatically triggered by the change in monitored signals and will record corresponding current, voltage and status signals. Apart from these sparse measurements, the proposed method also uses SCADA PI Historian data which is utilized for tuning the power system model data with the pre-fault condition in real time information. The paper presents how the technique is implemented and shows test results using actual power system model as well as actual field data from a utility company that supported demonstration of the technique. The results are quite encouraging since the sparse measurement problem for such unique transmission line configurations does not allow any other known techniques to produce accurate and reliable results while the proposed technique produces satisfactory results.
Unified representation of data and model for sparse measurement based fault location
Transmission line fault location methods typically need measurements from at least one end of the faulted line. Sparse measurement based fault location method using phasor measurements from different substations located near the faulted line can be applied if the measurements are not available from any of the line ends. This method uses data and model described in both bus-branch and node-breaker representation. This requires use of nomenclature correlation tables to correlate between different data and model, which is a very cumbersome process as for each substation separate nomenclature correlation tables are required. The proposed solution uses standard formats of data and model (IEC 61970-CIM for describing power system model and SCADA data; IEC 61850-SCL for describing substation model and COMTRADE for describing event data triggered by IEDs) all expressed in node-breaker format, which allows for unified data and model representation by using simple rules.
A new fault location technique for two- and three-terminal lines
A method for the computation of fault location in two- and three-terminal high voltage lines is presented. It is based on digital computation of the three-phase current and voltage 60/50 Hz phasors at the line terminals. The method is independent of fault type and insensitive to source impedance variation or fault resistance. Furthermore, it considers the synchronization errors in sampling the current and voltage waveforms at the different line terminals. The method can be used online following the operation of digital relays or offline using data transferred to a central processor from digital transient recording apparatus. The authors start with a two-terminal line to explain the principles and then present the technique for a three-terminal line. The technique was first tested using data obtained from a steady-state fault analysis program to evaluate the convergence, observability, and uniqueness of the solution. The technique was then tested using EMPT-generated transient data. The test results show the high accuracy of the technique. >