Improving Vietnam’s transmission grid

Louise Davis

As part of a programme to ensure a reliable national power supply in Vietnam, Siemens received an order to improve the performance of the nationwide transmission grid. 

The client is the state-run energy company, Electricity of Vietnam National Load Dispatch Centre (EVN NLDC).

Siemens will supply and install products and systems for detecting and evaluating failure situations in the grid, for ensuring grid quality and for detecting and monitoring dynamic grid states.

The equipment will be installed in substations distributed throughout the country and in the grid control centres, where it will help increase the grid's failure tolerance, improve its transmission capacity and optimize the expansion of new primary plants. The goal is to make better use of the existing grid infrastructure and to be able to connect additional loads as well as prevent outages that could result from overloading.

The substations and control centres are expected to be equipped with the new technology and go into operation by mid-2018.

Fault recorders from the Siprotec 5 7KE85 series, combined with the Sicam PQS evaluation software, will be used in 73 Vietnamese substations, and the Siguard PDP wide-area monitoring system will be employed in three regional and one national grid control centre.

These fault recorders work with an integrated function for measuring synchrophasors to monitor grid dynamics and measure grid quality.

Synchrophasors are phase measured values. Both the intensity and the phase of current and voltage are measured.

With their extensive trigger and recording functions, the fault recorders were developed for medium-, high- and ultra high-voltage plants as well as for power plants.

The devices enable the event-based evaluation, analysis and documentation of processes in the grid, including critical load situations, short-circuits, power fluctuations and power swings. The integrated Sicam PQS evaluation software evaluates the fault recorders to provide a quick overview of the grid quality.

The Siguard PDP (Phasor Data Processor) wide-area monitoring system in the one national and three regional control centres will also help ensure that the transmission grid in Vietnam operates reliably. It uses synchrophasors in real time, making it easier to quickly assess the current condition of the grid.

For example, power swings and fluctuations are immediately displayed to help the control centre personnel determine the cause of the problem and immediately take corrective action.

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