محطات توليد الكهرباء .. الحاسبات تعمل

Power Plants .. Computers Work

Power Plants

Power plants, both thermal and nuclear, have reached a high degree of complexity in order to increase the efficiency of these plants and thus reduce the cost of producing electrical energy. One aspect of this complexity is the use of advanced control devices that require a large amount of accurate information about the main equipment in the stations such as boilers, turbines and electrical controllers. Since collecting this information from all over the vast station and coordinating it requires a large and trained human crew, the computer has also been used in this field to perform many tasks.

The computer does not need a large storage capacity or various features as in complex scientific or administrative applications, but it must be solidly made, suitable for an industrial environment and withstand the high and low temperatures to which it is exposed in this environment. Such a computer also depends on an interruption system, which enables it to respond to the requirements of a number of external devices based on the priority assigned to each of them, and makes it jump from the main program to a special program when it responds to the interruption signal.

The signals entering the computer directly must be electrical and digital, while the signals generated in the power stations may be electrical or non-electrical, analog or digital. Non-electrical signals are converted into electrical signals by suitable switches. For example, a temperature switch may be a special type of resistor whose resistance changes with temperature. Analog electrical signals are those in which the current or voltage intensity is proportional to the intensity of the original signal. If one volt represents a temperature of 100 degrees Celsius, half a volt represents a temperature of 50 degrees Celsius. As for digital signals, the current intensity is converted at certain moments into a binary number with only two symbols, “1” and “•”. One is usually represented in electrical circuits by a certain voltage and zero by another voltage. Some binary events may be represented by digital signals. For example, when the steam pressure rises to a high temperature, a safety valve opens and a stage closes. If the open phase is represented in the normal operating state by the binary zero symbol, the closed phase is represented by the binary one symbol, and this symbol is then considered in the steam pressure signal as a danger signal.

The computer must process thousands of signals from various devices in the power plant. Since the computer cannot process all of these signals at once, a converter with switched electronic circuits connects these signals to the computer, each separately and in very rapid succession. Usually, two converters are used, one for digital signals and the other for analog signals.

A special device known as a converter converts analog signals into digital signals so that the computer can process them. Some digital signals may be used to control the entire system indirectly from an operation panel in the main control room.

The computer is directly connected to television screens that quickly and clearly show the different features of numbers and letters, which inform the controller of the operating conditions of the devices and machines and the amounts of the various main measurements.

An example of a data processing system in a power plant.
The computer system kit (to the right) inside the power plant (above).

Although the screen is a television, the display method is digital and completely different from that used for a normal television image. Each digital word of the computer represents the feature to be displayed and its location on the screen, and all the features that the screen can accommodate at one time are stored in order in a storage screen throughout the display period. The logical display circuits scan this screen continuously at a speed of about 150,000 features per second. The logical display circuits or the entire screen are divided into small squares, and the shape of each number or letter is approximated by straight lines extending from one corner of these squares to another. If, for example, a Latin letter is to be displayed in a specific location on the screen, the information stored in the screen directs the electronic screen beam to the starting point shown in the opposite figure, then the intensity and deflection of the electronic beam are adjusted so that the path is lit from the beginning through points 1-2-3 ----- ...