Sep 25, 2014 reactive power is both obscure for nonengineers and important in the design of electricity systems, especially at the distribution level. Download reactive power compensation a practical guide pdf. The reactive power compensation and voltage control training course essentially encourages you to understand the physical importance of reactive power, basics of reactive power compensations, distinctive answers for reactive power compensation, idea of music and voltage steadiness. Reactive power q it is a consequence of an ac system. Reactive power is both the problem and solution to the power system network for several reasons. Introduction to voltage control, reactive power compensation. Electric power systems pennsylvania state university. Pdf the reactive power compensation and voltage control training. Request pdf basics of reactive power the comprehensive resource on reactive power compensation, presenting the design, application.
While it is the active power that contributes to the energy consumed, or transmitted, reactive power does not contribute to the energy. Apparent power s or total power s is the combination of active and reactive power. The reactive power is measured in kilo volt ampere reactive kvar or mvar. Reactive power does not do any work, so it is represented as the imaginary axis of the vector diagram. Recall that inductive loads, which require reactive power, caused your low power factor. One of these is the necessity of reactive power that needs to be supplied along with active power. The kvar load sharing is achieved by increasing or decreasing the field excitation to the systems alternators.
At every instant the product of voltage and current is positive or zero, the result being that the direction of energy flow does not. Ac power the behavior of ac machines and systems are often easier to understand by working with power, rather than working with voltages and currents active, reactive, and apparent power apply to steadystate ac circuits with sinusoidal waveforms only cannot be used to describe the transient behaviors. It is the power that magnetic equipment transformer, motor and relay needs to produce the magnetizing flux. It is the power that actually powers the equipment and performs useful work.
The reactive power is measured in kilo voltampere reactive kvar or mvar. This increase in required reactive power kvar causes an increase in required apparent power kva, which is what the utility is supplying. A basics to explain reactive power we need to learn some basics first. Understand the relationship between complex power, active power, reactive power, apparent power and power factor. The reactive power compensation and voltage control training course essentially encourages you to understand the physical importance of reactive power, basics of reactive power compensations. If the load is purely resistive, the two quantities reverse their polarity at the same time. Electrical energy generated by power stations or through regenerative methods is. The power which flows back and forth that means it moves in both the directions in the circuit or reacts upon itself, is called reactive power. The sizing of the lv reactive power subbanks shall meet the requirements of voltage fluctuation such that the voltage fluctuation on the mv side induced by switching is no more than 2.
Reactive power is the power required to create a magnetic field in inductive consumers like motors, transformers, ballasts, induction furnaces, etc. In a simple alternating current ac circuit consisting of a source and a linear load, both the current and voltage are sinusoidal. To better understand why the regulation of reactive power and voltage makes power systems more efficient, lets start with discussion about the structure of the power systems and their main components. Because the ul and uc are pointing in opposite directions, they are subtracted and the difference ux is the reactive component of the total system voltage. Equation 3 suggests a relationship between active power p and apparent power s using triangle known as triangle. What is active, reactive and apparent power definition. The ur is the active or real component and the phasor. What is active, reactive and apparent power definition and. Reactive power basics about us filter circuit reactors capacitor contactors and thyristor switches power capacitors reactive power controllers basics power quality measuring devices kbr system 5 current transformers and supercapacitors our brochure reducing energy costs by reactive power compensation is available as download online. Aug 20, 2019 reactive power compensation a practical guide about the book. Reactive power is both obscure for nonengineers and important in the design of electricity systems, especially at the distribution level.
Part i fundamentals of reactive power in ac power systems. Ac power the behavior of ac machines and systems are often easier to understand by working with power, rather than working with voltages and currents active, reactive, and apparent power apply to steadystate ac circuits with sinusoidal waveforms only. Reactive power is either generated or absorbed by electric generators or, in some cases, devices known as capacitors to maintain a constant voltage level, commonly referred to as providing voltage support. It plays an important role in the electrical power system for various functions such as satisfying the reactive power requirement, improving the voltage profiles, decreasing the network loss, providing sufficient reserve to ensure system security in emergencies, and. However, we find the concept of reactive power little bit confusing because reactive power does not contribute in doing useful work. Where the real power p is along the horizontal axis, the reactive power q is along the vertical axis, and the apparent power s is the hypotenuse. Only when current is in phase with voltage is there actual work done, such as in resistive. Active, reactive and apparent power electronics hub. Reliability of power supply is a subject of a different course. In ac circuits, energy storage elements such as inductance and capacitance may result in periodic reversals of the direction of energy flow. Importance of reactive power voltage control in an electrical power system is important for proper operation for electrical power equipment to prevent damage such as overheating of generators and motors, to reduce transmission losses and to maintain the ability of the system to withstand and prevent voltage collapse. The electricity grid has a fundamental need for reactive power and, in some cases, the requirement to avoid instabilities via reactive power feedin.
Calculate current and voltage at various locations of a power system consisting generator, transfer and transmission line under threephase symmetrical fault conditions. Many dnos operate oltc and shunt capacitors locally by using conventional controllers, e. Generator basics the induction generator is similar to any other generator, as it is a device that converts mechanical energy into electrical energy. Apparent power is measured in va, kva, mva power factor cos. Superposition theorem, thevinins theorem, nortorns theorem, maximum power transfer theorem, reciprocity theorem, resonance in electrical circuits. The combination of reactive power and true power is called apparent power, and it is the product of a circuits voltage and current, without reference to phase angle. Reactive power is the resultant power in watts of an ac circuit when the current waveform is out of phase with the waveform of the voltage, usually by 90 degrees if the load is purely reactive, and is the result of either capacitive or inductive loads. Reactive power is an inherent part of the total power. Reactive power control in electrical power transmission system.
This increase in reactive and apparent power results in a larger angle. The current phasor i rotates in phase with the voltage vector ur, but it is lagging the voltage phasor ul and leading the voltage phasor uc. Optimal reactive power control of grid connected photovoltaic resources by joshua ryan trimble b. Switching shunt capacitor banks or reactors, and static. Nov 18, 2016 simple explanation of reactive power friday, november 18, 2016 reactive power is when the current flow, caused by ac voltage applied across a device, results in the current flow being either ahead or behind the applied ac voltage. Feb 19, 2019 in power transfer, there are three types of power. Shailendra jain, in modeling and control of power electronics converter system for power quality improvements, 2018. Free book reactive power compensation a practical guide first edition by wolfgang hofmann and jurgen schlabbach and wolfgang justauth pdf. Jose matias high voltage components reactive power compensation.
Power systems basic concepts and applications part i page 8 c l j c j l zc zc. To visualize the full dilemma of reactive power, figure 3 shows the efficiency of 0. So, a facilitys low power factor causes the utility to have to. Reactive power control in ac power systems springerlink. These loads include rotating and staticas induction motor and light loads. Power system structure the typical power system structure is shown in figure 1. Stability and reliability of electrical power system depends on reactive power management.
Generators providing voltage support often suffer heating losses that result in a reduced ability to generate real power. There are basically two types of loads, when talking about linear grids. Figure 2 shows that current magnitude and losses increases for nonzero reactive power despite inductive or capacitive. Reactive power control in ac power systems fundamentals and. Real, reactive, and apparent power analogy youtube. V is system voltage r is circuits resistance as we can see from equations 4 and 5 reduction of reactive power transported from generating station to the customers will lead to reduction of both active power losses and. This definitely impacts the economic operation of a power system, which eventually affects the endline customers. Instantaneous power, real power, reactive power and apparent power, concept of power factor, frequency.
Pdf reactive power compensation and voltage control. The reactive power is mandatory for operating a power system as different types of loads require reactive power to function. Simple explanation of reactive power friday, november 18, 2016 reactive power is when the current flow, caused by ac voltage applied across a device, results in the current flow being either ahead or behind the applied ac voltage. Fundamentals of reactive power and voltage regulation in. Reactive power basics about us filter circuit reactors capacitor contactors and thyristor switches power capacitors reactive power controllers basics power quality measuring devices kbr system 7 current transformers and supercapacitors inductance and capacitance is the same at the resulting res. Sunny central cp xt inverters by sma solar technology ag satisfy this requirement and make reactive power available outside of the feedin periods. Introduction reactive power var compensation is defined as the management of reactive power to improve the performance of ac systems. Apparent power is measured in the unit of voltamps va and is symbolized by the capital letter s.
However, the circulation of the reactive power influences the operation of different power system components and subsystems such as transmission. Concepts of reactive power control and voltage stability methods in power system network. Pdf concepts of reactive power control and voltage. Reactive power kvar required by inductive loads increases the amount of apparent power kva in your distribution system figure 4. The portion of power due to stored energy, which returns to the source in each cycle, is known as reactive power. Basic power systems v volts e kva kilo voltamperes, apparent power as measured by product of v a kw kilowatts, real consumed power kvar kilo voltamps reactive, imaginary power i a amperes current flow. Importance of reactive power in power generation and. Reactive power kvar load sharing when generator sets operate in parallel the alternator field excitation system of each generator set controls the proportional sharing of the total reactive power requirements kvar of the system. Why is it desirable to inject reactive power into a. In a transmission system, there is a strong correlation between reactive power and voltage magnitude, whereas the active power is mainly dependent on the voltage angle. Reactive power control in ac power systems fundamentals. Importance of reactive power is increasing with growing demand for electrical power by many domestic and industrial utilities, in power system network. Note that the compensation might be both positive and negative reactive power in, or reactive power out.
Here is a sending a package analogy for understanding these types of power. In this paper, an understanding of reactive power associated with power transmission networks is developed. It is the power that magnetic equipment transformer, motor and relay needs to. This textbook explores reactive power control and voltage stability and explains how they relate to different forms of power generation and transmission. Ac power basics power in an electric circuit is the rate of flow of energy past a given point of the circuit. To make transmission networks operate within desired voltage limits, methods of making up or taking away reactive power hereafter called reactivepower controlare discussed. As apparent power is made up of two parts, the resistive power which is the inphase power or real power in watts and the reactive power which is the outofphase power in voltamperes, we can show the vector addition of these two power components in the form of a power triangle. Bringing together international experts in this field, it includes chapters on electric power analysis, design and operational strategies. For the love of physics walter lewin may 16, 2011 duration. Importance of reactive power in power generation and transmission. While understanding reactive power requires knowledge of integral calculus, the basic intuitions can be understood without rigorous mathematical study. In our case, we want to compensate inductive with capacitive reactive power.
Lv reactive power compensation capacity shall be no more than the capacity of the tertiary winding of the main transformer. Reduce your reactive power improves efficiency and saves costs. Certain loads such as ups systems, cause both inductive and distortive reactive power. This unique guide discusses the effects of reactive energy on generation, transmission and distribution, and considers compensation for existing installations in detail. Reactive power outside of feedin operation with sunny. It is required to generate energy in a more efficient, reliable and cost effective way.
Apparent, active and reactive power electrical academia. Request pdf basics of reactive power the comprehensive resource on reactive power compensation, presenting the design, application and operation of reactive power equipment and. Reactive power are used to build up magnetic fields. The product of root mean square rms value of voltage and current is known as apparent power.
Kw is working power also called actual power or active power or real power. Power systems basic concepts and applications pdh online. Apparent power is often expressed in voltamperes va since it is the product of rms voltage and rms current. Introduction to power system operation and control. The power delivered by a transmission line when it is terminated by its surge impedance is known as the surge impedance load sil, c 2 l,rated z v sil mw. The power which flows back and froth that mean it moves in both the direction in the circuit or react upon itself, is called reactive power.
1346 1085 293 1463 742 1468 626 897 1568 353 78 120 828 36 170 570 843 19 387 688 965 863 708 131 1062 792 721 69 1391 214 106 1429 249 576 107 758 1424 137