The role of computers in the monitoring, control and planning of power networks

Computers play a key role in the operation, management and planning of electrical power networks. Their use is on the increase due to the complexity of today's interconnected electrical networks operating under free market principles.

Energy control centres

Energy control centres have the objective to monitor and control the electrical network in real-time so that secure and economic operation is achieved round the clock, with a minimum of operator intervention. They include:

1. 'smart' monitoring equipment
2. fast communications
3. power systems application software
4. an efficient database
5. mainframe computers.

The main power systems software used for the real-time control of the network is (Wood and Wollenberg, 1984):

1. state estimation
2. security analysis
3. optimal power flows.

These applications provide the real-time means of controlling and operating power systems securely. In order to achieve such an objective they execute sequentially. Firstly, they validate the condition of the power system using the state estimator and then they develop control actions, which may be based on economic considerations while avoiding actual or potential security violations.

Fig. 1.21 Real-time environment.

Figure 1.21 shows the real-time environment where the supervisory control and data acquisition (SCADA) and the active and reactive controls interact with the real-time application programmes.

Distribution networks

Most distribution networks do not have real-time control owing to its expense and specialized nature, but SCADA systems are used to gather load data information. Data is a valuable resource that allows better planning and, in general, better management of the distribution network (Gönen, 1986). The sources of data typically found in UK distribution systems are illustrated in Figure 1.22. These range from half hourly telemetered measurements of voltage, current and power flow at the grid supply point down to the pole mounted transformer supplying residential loads, where the only information available is the transformer rating. Most distribution substations have the instrumentation needed to measure and store current information every half hour, and some of them also have provision to measure and store voltage information. Large industrial customers may have SCADA systems of their own and are able to measure electricity consumption, power factor and average load factor.

Fig. 1.22 Distribution system data sources.

Planning

At the planning level, increasingly powerful computer resources are dedicated to hosting the extensive power systems analysis tools already available (Stoll, 1989). At present, the emphasis is on corporate databases, geographic information systems and interactive graphics to develop efficient interfaces which blend seamlessly with legacy power systems software. The current trend is towards web applications and e-business which should help companies to cope with the very severe demands imposed on them by market forces.

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