MAJOR FACTORS CONTRIBUTING TO POWER QUALITY ISSUES

The three major factors contributing to the problems associated with power quality are:

USE OF SENSITIVE ELECTRONIC LOADS

The electric utility system is designed to provide reliable, efficient, bulk power that is suitable for the very large majority of electrical equipment. However, devices like computers and digital controllers have been widely adopted by electrical end-users. Some of these devices can be susceptible to power line disturbances or interactions with other nearby equipment.

THE PROXIMITY OF DISTURBANCE-PRODUCING EQUIPMENT

Higher power loads that produce disturbances – equipment using solid state switching semiconductors, arc furnaces, welders and electric variable speed drives – may cause local power quality problems for sensitive loads.

SOURCE OF SUPPLY

Increasing energy costs, price volatility and electricity related reliability issues are expected to continue for the foreseeable future. Businesses, institutions and consumers are becoming more demanding and expect a more reliable and robust electrical supply, particularly with the installation of diverse electrical devices. Compatibility issues may become more complex as new energy sources and programs, which may be sources of power quality problems, become part of the supply solution. These include distributed generation, renewable energy solutions, and demand response programs Utilities are regulated and responsible for the delivery of energy to the service entrance, i.e., the utility meter. The supply must be within published and approved tolerances as approved by the regulator. Power quality issues on the “customer side of the meter” are the responsibility of the customer. It is important therefore, to understand the source of power quality problems, and then address viable solutions.

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...

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...

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...

TYPES OF ELECTRIC LOADS

Devices that are connected to the power system are referred to as electrical loads. Toasters, refrigerators, bug zappers, and so on are considered electrical loads. There are three types of electrical loads. They vary according to their leading or lagging time relationship between voltage and current. The three load types are resistive, inductive, and capacitive. Each type has specific characteristics that make them unique. Understanding the differences between these load types will help explain how power systems can operate efficiently. Power system engineers, system operators, maintenance personnel, and others try to maximize system efficiency on a continuous basis by having a good understanding of the three types of loads. They understand how having them work together can minimize system losses, provide additional equipment capacity, and maximize system reliability. The three different types of load are summarized below. 1) RESISTIVE LOAD: The resistance in a wire (i.e., cond...

SOLIDLY GROUNDED NEUTRAL SYSTEMS

Solidly grounded systems are usually used in low voltage applications at 600 volts or less. In solidly grounded system, the neutral point is connected to earth. Solidly Neutral Grounding slightly reduces the problem of transient over voltages found on the ungrounded system and provided path for the ground fault current is in the range of 25 to 100% of the system three phase fault current.. However, if the reactance of the generator or transformer is too great, the problem of transient over voltages will not be solved. While solidly grounded systems are an improvement over ungrounded systems, and speed up the location of faults, they lack the current limiting ability of resistance grounding and the extra protection this provides. To maintain systems health and safe, Transformer neutral is grounded and grounding conductor must be extend from the source to the furthest point of the system within the same raceway or conduit. Its purpose is to maintain very low impedance to ground faults so...

ESSENTIAL ELEMENTS OF DIESEL POWER PLANT

FUEL SUPPLY SYSTEM OF DIESEL POWER PLANT It consists of storage tank, strainers, fuel transfer pump and all day fuel tanks. The fuel oil is supplied at the plant site by rail or road. The oil is stored in the storage tank. From the storage tank, oil is pumped to smaller all day tank at daily or short intervals. From this tank, fuel oil is passed through strainers to remove suspended impurities. The clean oil is injected into the engine by fuel injection pump. AIR INTAKE SYSTEM OF DIESEL POWER PLANT This system supplies necessary air to the engine for fuel combustion. It consists of pipes for the supply of fresh air to the engine manifold. Filters are provided to remove dust particles from air which may act as abrasive in the engine cylinder. Because a diesel engine requires close tolerances to achieve its compression ratio, and because most diesel engines are either turbocharged or supercharged, the air entering the engine must be clean, free of debris, and as cool as possible. ...

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 ...

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