Visit to Seeboard Control Centre. Wealden House, East Grinstead
Tuesday 3Qth March, 1993.
A group of some twelve members visited the Seeboards system control centre on the outskirts of East Grinstead on Tuesday the 30th March.
We were welcomed by the engineer in charge Mr. Chris Mortley, who gave a brief history of the development of both the control and management of the national grid and Seeboards own high voltage networks. He explained that at the present time the control of the National grid was in a period of transition, with the present control room at Wealden House being closed and the role that it plays being transferred to St. Albans. However, Seeboards two control rooms, one dealing with the eastern side of the Seeboard area and the other with the west, would remain on site, together with their extensive communications network.
The main reasons for having a centralised control were:
1. Safety. To ensure that personel working on the network were
protected.
2. Economics. To Minimise losses in the system by ensuring that
loads were routed in the most economical way.
3. Planning. To identify load growth and plan for eventual
reinforcement.
4. Maintenance. Develop a stratagey for planned maintenance
which minimised the loss of supply to customers.
5. Maintain Supply. Under fault conditions ensure that supplies
are restored as quickly as possible.
Mr. Mortley explained that the Control Centre dealt with all high voltage supplies from 132kV downwards.
We were than split into three groups to view the establishment.
The western control room has it’s walls covered with a diagram showing the whole of the HV network. Switching points are marked by magnetic indicators which are moved as appropriate by the engineers-in-charge; no work can be done on any part of the network by the Divisional staff, without the sanction of the Control Engineer. The development of CADEC enables all HV substations to be monitored on VDU’s, as well as switching to be carried out remotely. The Cadec display was demonstrated to show the range of information that was available to manage the network.
We were then shown how a computer programme is used to monitor the performance of the 132kV system. particularly when planned maintenance is to be undertaken, with power being re-routed. The computer produces load flows to indicate likely points of stress on the network, thus showing whether any corrective action is needed. Previously, many man hours of desk work was necessary to provide this information.
Telecommunications and Computer Systems.
Our party was shown round by the Engineer-in-charge which broadly consists of the following sections: computer and data processing, interfacing with the outside world such as British Telecom and special data cables, PRN (Private Radio Network) and the Microwave link.
In the computer room. Digital Equipment Co. mainframes were installed, though time and possibly security implications did not allow a detailed explanation to be given of the system and the associated telecom equipment.
We saw an impressive array of printed circuit boards mounted in large vertical racks and were told that most of these were modems (modulators – demodulators) which transmit and receive computer data modulated onto carrier frequencies suitable for transmission over telephone lines. The continually flickering led’s indicated that they were busy talking to other modems elsewhere.
We were shown a map of the British Isles overlaid by a honeycomb pattern of hexagonal cells which represented the PRN (Private Radio Network) used by the Electricity authorities. This is used for mobile communications and is similar to Vodaphone but operates on a different band of radio frequencies.
The microwave link was apparent outside the building by the dish aerials mounted on a tall mast. The frequencies used are 7 and 13 GHz or in microwave terms, wavelengths of approximately 4 cm and 2.5 cm respectively. These ultra short wavelengths can only be used over 1ine-of-sight links between fixed stations about 30 miles apart and signal reception can be adversely affected by large atmospheric particles relative to the wavelength such as heavy rain and snow flakes.
