In this article we will discuss about the growth of power systems in India. India is fairly rich in natural sources like coal and lignite and has immense water power resources of which only about 25% have been utilised so far. Some oil reserves have already been discovered and intense exploration is being undertaken in various states. Though India is [...]
The operation of a modern power system has become very complex. Frequency and voltage is to be maintained within limits in addition to ensuring reliability of power supply and for maintaining the frequency and voltage within limits it is essential to match the generation of active and reactive power with the load demand. For ensuring reliability of power supply it [...]
In this article we will discuss about the load frequency control in power system. In a power system, both active and reactive power demands continually vary with the rising or falling trend. Power input (steam input to turbo-generators or water input to hydro- generators) must, therefore, be continuously regulated to match the active power demand; otherwise the machine speed will [...]
Voltage control and reactive power control are interrelated and need to be therefore considered together. One of the most troublesome features associated with the operation of overhead transmission system is the inherent variation of voltage at the receiving end, due to variations in load. These fluctuations of voltage are to be kept within the reasonable limits fixed by IE rules. [...]
There are two ways in which three-phase system can be operated and they are: 1. With isolated or free or ungrounded neutral 2. With grounded neutral. Way # 1. Ungrounded Neutral System: The 3-phase 50 Hz ac power systems with neutral earthed (or grounded) at every voltage level are used for generation, transmission, distribution and utilization of electrical power. The [...]
Resistance and reactance (and consequently impedance) may be expressed in percentage or ohmic terms. In the case of rotating machines and transformers, manufacturer values are always in percentage terms while tables for cables and overhead lines are always in ohmic terms. Calculations can be made using either but not a mixture. For short-circuit calculations, generally the percentage values are employed [...]
In this article we will discuss about:- 1. Introduction to Power System 2. Description of Power Supply System 3. Single Line Representation. Introduction to Power System: Power is the basic need for the economic development of any country. Availability of electricity has been the most powerful vehicle of introducing economic development and social change throughout the world. The process of [...]
Block diagram of a typical ac electrical power supply system is shown is Fig. 1.3. Electrical power is generated by 3-phase alternators operating in parallel at the generating stations. The generation voltage is usually 11 kV. It may be 3.3, 6.6 or even 33 kV in certain cases. For economy reasons this voltage is stepped up from 11 kV to [...]
Major components of a power system are- synchronous generators, synchronising equipment, circuit breakers, isolators, earthing switches, bus-bars, transformers, transmission lines, current transformers, potential transformers, relay and protection equipment, lightning arresters, station transformer, motors for driving auxiliaries in power station. Some of the components will be discussed here as shown in Fig. 1.7 . Component # 1. Synchronous Generators: The synchronous [...]
In this article we will discuss about the general characteristics of electrical apparatus. All electrical machines, apparatus and other forms of electrical equipment must satisfy two main requirements – they must be able to operate continuously under normal service conditions and must be able to withstand short-time over-currents and over-voltages such as may arise during emergent conditions. For operation of [...]