There are various organizations on the national and international levels working in concert with engineers, equipment manufacturers, and research organizations to come up with standards governing guidelines, recommended practices, and harmonic limits. The primary objective of the standards is to provide a common ground for all involved parties to work together to ensure compatibility between end-use equipment and the system [...]
The following points highlight the four main methods used for controlling harmonic distortion in power system. The methods are: 1. Constant Frequency Control 2. Constant Tolerance Band Control 3. Variable Tolerance Band Control 4. Discontinuous Current Control. Method # 1. Constant Frequency Control: A usage of frequency controlled drives with AC motors (like asynchronous or synchronous) increased in last few [...]
There are a number of devices available to control harmonic distortion. They can be as simple as a capacitor bank or a line reactor, or as complex as an active filter. A simple mitigation action such as adding, resizing, or relocating a shunt capacitor bank can effectively modify an unfavorable system frequency response, and thus bring the harmonic distortion to [...]
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. [...]
In this article we will discuss about:- 1. Introduction to Power Factor 2. Causes of Low Power Factor 3. Disadvantages. Introduction to Power Factor: The cosine of the angle between voltage and current in an ac circuit is known as power factor. In an ac circuit, there is generally a phase difference between voltage and current. In an inductive circuit, [...]
In this article we will discuss about:- 1. Methods of Power Factor Improvement 2. Advantages of Power Factor Improvement 3. Economics 4. Economical Comparison of the Two Methods of Increasing the Power Supplied. Methods of Power Factor Improvement: The low power factor is almost invariably due to inductive nature of load and, therefore, the logical corrective is to connect such [...]
Air switches are classified as air-break switches and isolators (or disconnect switches). (i) Air-Break Switches: The air-break switch has both the blade and the contact equipped with arcing horns. Arcing horns are pieces of metal between which the arc resulting from opening a circuit carrying current is allowed to form. As the switch opens, these horns are spread farther and [...]
The following points highlights the sixteen equipment required for substations and switchgear installations. The equipment are: 1. Main Bus-Bars 2. Current Limiting Reactors 3. Station Insulators 4. Switchgear 5. Switches 6. Fuses 7. Circuit Breakers 8. Protective Relays 9. Power Transformers 10. Instrument Transformers 11. Lightning Arresters 12. Indicating and Metering Instruments 13. Batteries and others. 1. Main Bus-Bars: Bus-bar [...]