AIS spol. s r.o. Measuring and information technology for power engineering

SUPPORT OF SWITCHING IN DISTRIBUTION POWER NETWORKS

Features:

• Continuous measurement of voltage and current synchrophasors by Phasor Measurement Units (PMUs).
• Possibility to set an arbitrary node as reference measurement.
• Continuous supervision on exceeding of the angle limit.
• Generation of warning in the case of angle difference above limit.
• Estimation of the balancing current in the case of switching.
• Immediate transfer of data to central station via LAN.
• Visualization of data by client software.
• Data presentation in graphical, tabular or trend form.
• On-line comparison of phase angles in various places of distribution network.

Typical measurement scheme:

Application benefits:

• On-line support for dispatcher switching decisions in distribution network.
• Exclusion of faulty switching caused by big difference of voltage angles.
• Limitation on non-delivery occurrence.
• Reduction of time required for power supply renewal after power cut.
• Improved economy of power supply.
• Flexible and user-oriented solution.
• Database data archive for later analysis of events in network.

Typical SW application characteristics:

• On-line comparison of voltage phasors (amplitudes, angles, frequencies) in the location of switching elements.
• Optional combination of table, graph, trend or map views.
• User definable levels for secure and insecure switching operation.
• Data trends for later analysis.

Terminal – Phasor Measurement Unit (PMU) specification:

• Stand alone unit with in-place compute functions, storage option and remote parameterization.
• Fast parallel measurements — typically 10 kHz.
• Various measurement inputs for range of instrument transformers.
• 8 inputs per terminal.
• GPS time synchronization - phase precision < 0.1°, voltage and currents precisions < 1%.
• Wide range of communication options on physical layer (Ethernet, RS-232, GSM/GPRS) and standard protocols (e.g. IEC-68570-5-101/103/104, IEEE-C37.118) implemented.
• Conforms to EMC standards for industrial environment.

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