GENERATOR SWITCHGEAR USED IN HYDROELECTRIC POWER PLANT

The generator circuit breaker and associated isolating disconnect switches are used to connect and disconnect the generator to and from the power system. The generator circuit breaker may be located on either the low-voltage or high-voltage side of the generator step-up transformer. In some cases, the generator is connected to the system by means of circuit breakers located in the switchyard of the generating plant. The generator circuit breaker may be of the oil filled, air magnetic, air blast, or compressed gas insulated type, depending on the specific application. The circuit breaker is closed as part of the generator synchronizing sequence and is opened (tripped) either by operator control, as part of the automatic unit stopping sequence, or by operation of protective relay devices in the event of unit fault conditions.

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CLASSIFICATION OF POWER SYSTEM STABILITY

Power system stability is a single problem, however, it is impractical to deal with it as such. Instability of the power system can take different forms and is influenced by a wide range of factors. Analysis of stability problems, including identifying essential factors that contribute to instability and devising methods of improving stable operation is greatly facilitated by classification of stability into appropriate categories. These are based on the following considerations: Ø The physical nature of the resulting instability related to the main system parameter in which instability can be observed. Ø The size of the disturbance considered indicates the most appropriate method of calculation and prediction of stability. Ø The devices, processes, and the time span that must be taken into consideration in order to determine stability. Figure 7.1 Possible classification of power system stability into various categories and subcategories. 1) ROTOR ANGLE STABILITY: Ro...

PRIMARY SECONDARY AND TERTIARY FREQUENCY CONTROL IN POWER SYSTEMS

Primary, Secondary and Tertiary Frequency Control in Power Systems Author: Engr. Aneel Kumar Keywords: frequency control, primary frequency control, automatic generation control (AGC), tertiary control, load-frequency control, grid stability. Frequency control keeps the power grid stable by balancing generation and load. When generation and demand drift apart, system frequency moves away from its nominal value (50 or 60 Hz). Grids rely on three hierarchical control layers — Primary , Secondary (AGC), and Tertiary — to arrest frequency deviation, restore the set-point and optimize generation dispatch. Related: Power System Stability — causes & mitigation Overview of primary, secondary and tertiary frequency control in power systems. ⚡ Primary Frequency Control (Droop Control) Primary control is a fast, local response implemented by generator governors (dro...

ADVANTAGES AND DISADVANTAGES OF CORONA EFFECT IN TRANSMISSION LINES | ELECTRICAL ENGINEERING GUIDE

Advantages and Disadvantages of Corona Effect in Power Systems In high-voltage overhead transmission lines , the corona effect plays a critical role in system performance. Corona occurs when the air around a conductor becomes ionized due to high electric stress. While often seen as a drawback because of power losses and interference , it also provides certain engineering benefits . This article explains the advantages and disadvantages of corona effect in detail, with examples relevant to modern electrical power systems. ✅ Advantages of Corona Effect Increase in Virtual Conductor Diameter Due to corona formation, the surrounding air becomes partially conductive, increasing the virtual diameter of the conductor. This reduces electrostatic stress between conductors and minimizes insulation breakdown risks. Related Reading: Electrostatic Fields in High Voltage Engineering Reduction of Transient Surges Corona acts like a natural cushion for sudden ...

CASCADED TRANSFORMERS METHOD FOR GENERATING AC HIGH VOLTAGE

High-Frequency AC High Voltage Generation Using Cascaded Transformers Author: Engr. Aneel Kumar Figure 1: Infographic representation of cascaded transformers method for generating high AC voltages. Introduction In high voltage engineering , generating very high alternating current (AC) voltages is essential for testing equipment like insulators, circuit breakers, power cables, and other apparatus. One common and effective method for producing such voltages is the cascaded transformers method . This technique uses a series connection of specially designed test transformers , where the secondary of one transformer feeds the primary of the next. In this way, voltages are built up step by step, achieving levels in the range of hundreds of kilovolts (kV) or even megavolts (MV). Working Principle The principle of cascaded connection relies on the fact that each...

ADVANTAGES OF INTERCONNECTED GRID SYSTEM

Interconnected Grid System: Working, Advantages, Disadvantages, and Comparison with Isolated Grids Author: Engr. Aneel Kumar Figure 1: Infographic showing key advantages of an interconnected grid system. Introduction An interconnected grid system refers to a network of multiple power generation sources, transmission lines, substations, and distribution systems that are linked across regions, states, or even countries. Unlike an isolated grid (or islanded grid) which operates independently, an interconnected grid allows electricity to flow between interconnected nodes, enabling numerous benefits and some trade-offs. In today’s energy landscape—where demand, renewable generation, reliability, and cost pressure are all increasing—understanding how an interconnected grid works, what factors are essential, and what its advantages and disadvantages are is critical for utility planners, reg...

Advantages of Per Unit System in Power System Analysis | Electrical Engineering

Advantages of Per Unit System in Power System Analysis In electrical power engineering, the per unit (p.u.) system is one of the most widely used techniques for analyzing and modeling power systems. It is a method of expressing electrical quantities — such as voltage, current, power, and impedance — as fractions of chosen base values rather than their actual numerical magnitudes. This normalization technique provides a universal language for system calculations, minimizing errors, simplifying transformer modeling, and enabling consistency across multiple voltage levels. Because of these benefits, the per unit system is essential in fault analysis, load flow studies, transformer testing, and short-circuit calculations . ⚡ What is the Per Unit System? The per unit system is defined as: Q u a n t i t y ( p u ) = A c t u a l V a l u e B a s e V a l u e Quantity_{(pu)} = \dfrac{Actual \ Value}{Base \ Value} Q u an t i t y ( p u ) = B a se ...

Factors Affecting Corona in Overhead Transmission Lines

Factors Affecting Corona in Overhead Transmission Lines Author: Engr. Aneel Kumar Figure 1: Infographic illustrating the factors influencing corona discharge in transmission lines. Introduction The corona effect in overhead transmission lines is a phenomenon that occurs when the electric field intensity around conductors exceeds a critical value, causing ionization of the surrounding air. This ionization produces bluish light, hissing sound, power loss, and ozone gas. While corona may seem undesirable, it also has a few advantages such as reducing overvoltages by absorbing surges. Corona directly impacts power system efficiency, transmission losses, equipment life, and design cost . Therefore, engineers must understand the factors affecting corona in detail to ensure efficient and reliable design of high-voltage transmission systems. 1. Conductor Size (Diameter) ...

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