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

MEASUREMENT OF ELECTRICAL LINE PARAMETERS UNDER CONTINUOUS OPERATION

Features:

• On-line measurement of voltage and current synchrophasors.
• Simultaneous measurement on both ends of electrical line in all three phases.
• Calculation of line parameters and their transfer to all relevant applications.
• Line parameters and their meaning:
  • R - conductor temperature, line sag, active loses.
  • X - reactive losses, voltage drop, network stability
  • B - reactive losses, open circuit voltage.
  • G - active losses, line quality.
• High accuracy GPS time synchronization of measurement.
• In-place measurement under continuous line operation.
• Evaluation of trend of changes in line parameters by repeated measurement.
• PMU conforms to IEEE-C37.118 standard.

Typical measurement scheme:

Application benefits:

• Knowledge of actual values of parameters brings:
  • Better functionality of protection units.
  • Higher precision in estimation and network computation applications.
  • Higher precision in calculations of losses.
• There is need to break the electrical line during measurement process.
• Cost savings in preparation of measurement conditions.
• Minimum preparation time for customer.
• Possibility of repeated measurement under different load and atmospheric conditions with consequent time-based analysis and evaluation of changes of line parameters under various conditions.

Offline data processing:

• MS Excel® - based multistage data processing.
• Automated data filtering and sorting.
• Embedded library with functions for various asym-metry models.
• Charts for better data series filtering.

Equivalent scheme of line:

Parameters and losses in low quality line:

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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