Concordia Substation inaugurated in February 2001

The transmission system operates at 110kV and 66kV, while distribution is mainly at 11kV and 400/230 volts. The supply is 50 hertz alternating current, at 230 volts single-phase or 400 volts three-phase.

CEM has now in operation 11 HV/MV substations with a total installed capacity of 500MVA in 110/66kV and 1,152 MVA in 66/11kV, and also operates more than 900 customer substations (11/0.4kV).

66kV high voltage cable installation in Coloane

Electricity is delivered by a transmission network made up of underground cables. The main transmission network operates at 66kV, although some circuits operate at 110kV. For distribution purposes, high voltage is initially converted to MV (11kV), and further reduced to 400/230 volts for customer use. As of December 2002, CEM's network comprises 165 km high voltage (110/66kV) transmission lines, 729 km 11kV distribution lines and 1,534 km low voltage distribution lines.

The first network interconnection between Zhuhai and Macau was built in 1983 with two 110 kV cables. A second interconnection with Zhuhai was constructed in 2003, by then there will be four 110kV transmission lines interconnected with China with a total capacity of 500 MVA.

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The System Dispatch Center brings about coordination of generation, transmission and distribution control into one centralized control center hence achieving optimal performance of the power network. Particularly the 11kV SCADA functions bring into direct benefits to our customers in terms of the quality of power supply service.

The computing system is based the open system architecture that uses the most updated international standards. The feature allows future expansion and integration with other systems to be realized without any barrier.

An Energy Management System is incorporated to ensure optimisation, safety and reliability of the network. Analysis is performed regularly, providing advises to Dispatchers to get the best efficiency of the Power System.

With regard to implementation of 11kV SCADA functions, firstly, the number of power interruption to our customers is reduced. The operator can monitor the whole 11kV network and the operation of power network is improved, so some faults can be suppressed beforehand.

Secondly, the duration of the power interruption is drastically shorter than before. In case of fault, without these 11kV SCADA functions, the maintenance crew must go to field to locate the fault location, to isolate the fault and then to restore the power supply to customers. With these 11kV SCADA functions, at control room the operator can locate the fault of power network easily, isolate the fault and restore the power supply to customers quickly. So the average interruption time is reduced.

In a word, with the 11kV SCADA functions, better power supply service to customers can be obtained.

For contingency and security purpose, a Backup Control Center was also implemented at CEM Headquarters.

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