PULSE WIDTH MODULATION INVERTER

Switching techniques of pulse width modulation (PWM) have been popular in the area of power electronics and drive systems. PWM is commonly used in applications like motor speed control, converters audio amplifiers etc. PWM is used to adjust voltage applied to the motor. There is no single PWM method which can suite for all applications. As per the advanced technology in solid state power electronic devices and microprocessors, various pulse-width modulation (PWM) techniques have been developed for different industrial applications. For the above reasons, the PWM techniques have been the subject of intensive research since 1970s. The main objective of the PWM is to control the inverter output voltage and to reduce the harmonic content in the output voltage. The pulse width modulation (PWM) techniques are mainly used for voltage control. These techniques are most efficient and they control the drives of the switching devices. The different PWM techniques are Single pulse width modulation, Multiple pulse width modulation, Phase displacement control, Sinusoidal pulse width modulation, Harmonic Injection modulation, Space Vector pulse width modulation, Hysteresis (Delta) pulse width modulation, Selective Harmonic Elimination and Current Controlled pulse width modulation. Hysteresis controller is used for Current source inverter and all the remaining PWM techniques are used for Voltage source inverter. Sinusoidal and Space Vector PWM techniques are most widely used. They control the output voltage as well as reduce the harmonics.

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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...

Breaker Schemes in Substations

Breaker Schemes in Substations — Types, Design, Advantages, Disadvantages, and Comparison Author: Engr. Aneel Kumar Figure 1: Infographic overview of breaker schemes commonly used in substations. Introduction The breaker scheme or busbar arrangement in a substation defines how incoming feeders, outgoing feeders, and power transformers are connected to the bus. The choice of scheme has a direct impact on system reliability, maintainability, safety, and cost . A simple bus scheme is economical but vulnerable to outages, while advanced schemes such as breaker-and-a-half or double-bus/double-breaker provide very high reliability but at much higher cost and design complexity. Engineers select breaker schemes considering fault tolerance, maintenance needs, space requirements, expansion possibilities, protection coordination, and capital investment . Below, we explain eac...

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 ...

SYMMETRICAL COMPONENT ANALYSIS

Unbalanced three phase systems can be split into three balanced components, namely Positive Sequence (balanced and having the same phase sequence as the unbalanced supply), Negative Sequence (balanced and having the opposite phase sequence to the unbalanced supply) and Zero Sequence (balanced but having the same phase and hence no phase sequence). These are known as the Symmetrical Components or the Sequence Components and are shown in figure 2.10. The phase components are the addition of the symmetrical components and can be written as follows. a = a 1 + a 2 + a 0 b = b 1 + b 2 + b 0 c = c 1 + c 2 + c 0 The unknown unbalanced system has three unknown magnitudes and three unknown angles with respect to the reference direction. Similarly, the combination of the 3 sequence components will also have three unknown magnitudes and three unknown angles with respect to the reference direction. Thus the original unbalanced system effectively has 3 complex unknown quan...

Comprehensive Guide to Static Var Compensators (SVC): Mechanisms, Configurations, and Applications

Introduction In modern power systems, voltage stability and reactive power management are critical for ensuring efficient and reliable operation. Static Var Compensators (SVCs), a key component of Flexible AC Transmission Systems (FACTS), address these challenges by dynamically controlling reactive power in AC transmission networks. This article explores SVCs in-depth, including their mechanisms, configurations, applications, and impact on power systems. Keywords: Static Var Compensator Applications, SVC Voltage Regulation Systems, Reactive Power Management Solutions, Harmonic-Free Power Systems, Dynamic Voltage Stabilization Technologies. Understanding Static Var Compensators (SVC) What is an SVC? A Static Var Compensator is a shunt-connected device used to regulate voltage by controlling reactive power in AC systems. Unlike traditional solutions like synchronous condensers, SVCs leverage power electronics for faster and more precise responses to voltage fluctuations. How SVC Wo...

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