Analysis of reactive power in power system electrical. Effect of reactive power compensation on voltage profile. Reactive compensation enspec power renewables voltage support. Importance of reactive power in power generation and. Because underground line capacitance for power cables is far higher than overhead line capacitance. Power, as we know, consists of two components, active and reactive power. Reactive power and voltage relationship in power transmission. For a reliable and stable operation of the power syst.
Reactive power compensation for transmission and distribution. Pdf transmission lines carry bulk power from generating stations to load. The issues of reactive power compensation in highvoltage. Reactive power uncompensated transmission lines passive compensa reactivepower control in electrical power transmission systems wileyieee press books ieee websites place cookies on your device to give you the best user experience. The advantages of reactive power compensation are improved power factor, voltage balancing, and. Reactive power management by shunt and series compensation. Load compensation is the management of the reactive power to improve the quality of the supply in ac power systems 5. Tscs do not generate harmonic distortion in the transmission line. This paper is not intended to provide a comprehensive analysis of transmission lines. Reactive power inductive load and power factor calculation duration. A reactive current is injected into the line to maintain constant voltage magnitude by varying shunt impedance.
According to the operation of the yulin substation line and the load, the theoretical calculation of the reactive power compensation scheme is developed. It is generally a power electronicsbased system facts is defined by the ieee as a power electronic based system and other static equipment that. Reactive power compensation techniques in transmission. A reactive power compensation strategy for voltage. Capacitor bank reactive power compensation electrical4u. Reactive power control in electrical power transmission system. Conclusion voltage control is essential to reduce transmission losses and to maintain the ability of the system to withstand and prevent voltage collapse decreasing reactive power causing voltage to fall while increasing it causing voltage to rise raising power factor is a proven way of increasing the efficient use of electricity by utilities. In this paper the effect of line reactive power flow on transmission efficiency, voltage regulation and power factor with and without var compensation techniques are analyzed and presented. This power should be supplied from electrical generating station. Effect of series and shunt compensation on voltage stability.
Reactive power generationconsumption note that a transmission line both absorbs and generates reactive power. Lv reactive power compensation equipment serves to balance the reactive power of transmission lines when transmitting different active power to maintain terminal voltage of the uhv lines within a reasonable range. Aug 30, 2017 transmission lines signal transmission and reflection duration. Reactive power is required to maintain the voltage to deliver active power watts through transmission lines. Under light load, the line generates more reactive power than it consumes. Power factor is a measure of the relation between real and reactive power. Jan 06, 2018 lec 14 compensation technique gatematic education. Shunt compensation the device that is connected in parallel with the transmission line is called the shunt compensator. Power 345kv system springerville vail 345kv system. To know the effect of series and shunt compensation on voltage stability, first of all we will have some discussion on compensation technique. Reactive power management is defined as compensation of reactive power flow to improve the stability and reliability of the power system. Reactive power compensation in transmission line by using.
If the power demand is less than reactive power supplied, the load voltage rises to a higher level which leads to automatic tripping of transmission equipment, low power factor, insulation failures of the cables and windings of various mechanical devices to overcome this, additional reactive power available on the system must be compensated. It is meant to enhance controllability and increase power transfer capability of the network. It can be capacitive leading or inductive lagging reactive power, although in most. Reactive power compensation for grid connected distribution.
Until a few years ago, the ability to generate reactive power was largely taken for granted in pjm. Series capacitor compensation is generally applied for transmission lines to generate reactive power when it is most needed while shunt capacitors are installed at substations in load areas to generate reactive power and for keeping voltage within limits. Review of series compensation for transmission lines psc north america power networks page 2 of 65 revision table revision issue date description 1 3212014 final draft for submission to client 2 4162014 final submission. It is required to generate energy in a more efficient, reliable and cost effective way. Importance of reactive power is increasing with growing demand for electrical power by many domestic and industrial utilities, in power system network. It accomplishes useful work like lighting lamps, rotating motors, etc. Pdf reactive power compensation and voltage control. In this paper, the reactive power compensation to maintain rated voltage at the bus bars is calculated in a 4node distribution system comprising of a 220kv source transmission line connected.
The demand for active power is expressed in kilowatts kw or mega watts mw. Shunt compensation an overview sciencedirect topics. Yongan deng, masc student at concordia university 1. Reactive power compensation reactive power can be stated as the amount of unused power that is developed by reactive components, such as inductors or capacitors in an ac circuits. Such interfaces measure power flows across select high voltage transmission lines into remote load centers to indicate when additional local generation within the load center is necessary to maintain voltage levels. It is almost universal for some of the reactive load to be compensated locally as power factor correction. Voltage and loss control for long range 10kv power. Power factor improvement reactive power compensation. It is usually necessary to site reactive power devices very near to or at the location that is deficient. Pdf reactive power compensation of transmission lines.
It can be provided by either a current source, voltage source or a capacitor. Compensation should be provided as close as possible to the consumption point to avoid having to distribute this power in the other part of network. Reactive power loads must be supplied either locally from customerowned devices or from the system itself. If the power factor of the system is poor, the ampere burden of the transmission, distribution network, transformers, alternators and other types of equipment connected to the system, becomes high for required active power. Reactive power is essential to move active power through the transmission and distribution system to the customer. Why do underground cables require a higher degree of reactive power compensation than overhead lines. There are two aspects to the problem of reactive power compensation. What is the importance of reactive power in transmission lines.
Although in alternating power system, reactive power always comes in to picture. 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. Reactivepower control in electrical power transmission. Reactive power compensation in transmission systems also improves the stability of the ac system by increasing the maximum active power that can be transmitted. Reactive compensation enspec power renewables voltage. The issues of reactive power compensation in highvoltage transmission lines article pdf available in acta energetica 2323. Motor loads and other loads require reactive power to convert the flow of electrons into useful work. An ideal shunt compensator provides the reactive power. Facts controls on the reactive power compensation, which supports voltage recovery. Fundamental concepts of reactive compensation hvdc. For improving the performance of a ac power system, the reactive is to be managed in a efficient way, this is known as reactive power compensation.
Since most loads are inductive and consume lagging reactive power, the compensation required is usually supplied by leading reactive power. So, this inverter will exchange active and reactive power with the line. The issues of reactive power compensation in highvoltage transmission lines authors zbigniew lubosny jacek klucznik krzysztof dobrzynski keywords reactive power compensation, overhead lines, shunt reactor abstract this paper discusses the selection of compensation shunt reactors for a doublecircuit 400 kv transmission line using the example. Real power or active power is the true power given to any load. Reactive power compensation rpc offers the most economic mean s to do so. Construct two new 500 kv transmission lines from the willow 500 kv substation to the existing pinal central substation near coolidge, az approximately 161 miles with 50% series compensation. The reactive power generated by the compensator, q p, is generally given by the relation q p i c v c i c v. Reactive power q var is needed for a proper functioning ac power system to keep the voltage up and is related to the active power p kw and apparent power s kva through the power triangle. Transmission and distribution reactive power compensation for. Transmission and distribution reactive power compensation. Reactive power compensation of transmission lines by.
Power factor is nothing but the ratio of real power to apparent power. To improve the performance of ac power systems, we need to manage this reactive power in an efficient way and this is known as reactive power compensation. More power plants, substations, and transmission lines need to be constructed. Dynamic reactive compensation and hvdc transmission brian k. Reactive power var compensation is nothing but the control of reactive power to enhance the performance of ac system. The configuration of reactive power compensation equipment shall follow the principles as detailed below. Also generally induction load consists of two current one is load. Therefore, the transmittable active power is increased but at the expense of increasing the. Jose matias high voltage components reactive power compensation. A shunt compensator is always connected in the middle of the transmission line. Reactive power compensation is essential for safe and efficient performance of.
The shunt inverter is operated in such a way as to demand this dc. Why is reactive power compensation needed in a power. Install shunt compensation and reactance as required. If reactive power is in excess in power system than voltage may go up and in case of shortage of reactive power voltage may be low. Pdf transmission system performance improvement through. In this article, we will explain various aspects of reactive power, what its role is in power system and how it can be injected.
A thyristor switched capacitor tsc is used to inject capacitive reactive power step by step, if called for by transient phenomena during switchon. How reactive power is helpful to maintain a system healthy. Var compensation near load centre has gained more importance in recent times. The ability to control or compensate reactive power has many benefits. Reactive power is power that is stored during one part of the ac waveform, and returned a few milliseconds later during another part of the waveform. Importance of reactive power in power generation and transmission. Dec 09, 2019 this ratio is alternatively known as the electrical power factor, and a lower ratio indicates a poor power factor of the system. Power loss and dispersion transmission lines may also be dispersive, which means the propagation velocity on the line is not constant with frequency for example the frequency components of square wave recall odd harmonics only each propagate at a different velocity.
Unlike real power, reactive power cannot be transferred long distances across the bps. By artificial injection of reactive power to the loads relieves the transmission network from reactive power flow and improves both the transmission efficiency and operating power. Stability and reliability of electrical power system depends on reactive power management. Reactive power is an imaginary power, but still, it is needed in the power system. Voltage support is generally required to reduce voltage fluctuation at a given terminal of a transmission line. The voltage can be controlled by providing reactive power control margin to modulate the supply needs through the following compensations as given below. Shunt compensation of reactive power can be employed either at load level, substation level, or at transmission level. Pdf the issues of reactive power compensation in high. Rather, its objective is to examine those aspects that enhance the understanding of the interplay between voltages on the line and the resulting reactive power flows. Reactive power is an essential component of ac electric power systems. In shunt compensation, facts are connected in parallel with the power system transmission line. Nov 21, 2012 conclusion voltage control is essential to reduce transmission losses and to maintain the ability of the system to withstand and prevent voltage collapse decreasing reactive power causing voltage to fall while increasing it causing voltage to rise raising power factor is a proven way of increasing the efficient use of electricity by utilities.
Pdf reactive power compensation in a distribution system. Thus, it improves the power transfer capability of the line. Reactive power compensation techniques in transmission lines. The maximum transmissible power is 2 v 2 x, twice the steadystate limit of the uncompensated line. The reactive power is electronically provided by the series inverter, and the active power is transmitted to the dc terminals.
Reactive power compensation by appropriate means has become the most economically attractive and effective solution technically for both traditional and new problems at different voltage levels in a power system. In other words, in series compensation, reactive power is inserted in series with the transmission line for improving the impedance of the system. The reactive power compensation problem prevalent in modern power systems makes the power distribution performance not fully utilized and the load power consumption of the equipment increases. Planning reactive power control for transmission enhancement. Review of series compensation for transmission lines. If the transmitted power is above sk, the line will introduce additionally inductive reactive power, and if it is below sk, the line will introduce capacitive reactive power. Importance of reactive power for system electrical notes. Sometime for sinusoidal wave the power factor is defined as the cosine of angle between voltage and current in this article we are going to see entire study about power factor. Mar 21, 2011 reactive power is essential to move active power through the transmission and distribution system to the customer. Until a few years ago, the ability to generate reactive power. Instead of being controlled continuously, they are switched on and off when needed. Reactive power compensation technologies accessscience. Inadequate reactive power support has led to voltage instability and has been a cause of several recent major power outages worldwide.
The total sum of active and reactive power is called as apparent power. A technique is known as reactive compensation is used to reduce apparent power flow to a load by reducing reactive power supplied from transmission lines and providing it locally. Reactive power var compensation is defined as the management of reactive power to improve the performance of ac systems. All the arrangements in electrical pomes system are done to meet up this basic requirement. Under surge impedance loading, the line generates and consumes the same amount of reactive power. Reactive power should be supplied locally because of its dependence on voltage difference. Pdf reactive power compensation in power transmission. A flexible alternating current transmission system facts is a system composed of static equipment used for the ac transmission of electrical energy. What are the advantages, disadvantages and applications of. Ac power supply systems produce and consume two types of powers. Static var compensators svc portfolio siemens global. Voltage levels and reactive power flow must be carefully controlled to allow a power system to be operated within acceptable limits. The convention for assigning signs to reactive power is different for sources and loads, for which reason readers are urged to use a consistent notation of voltage and current, to rely on the resulting sign of q, and to not be confused by absorbers or suppliers of reactive power.
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