Impacts of shunt reactors on transmission line protection eithar nashawati, oncor electric delivery normann fischer, bin le, and douglas taylor, schweitzer engineering laboratories, inc. A variable shunt reactor vsr is a shunt reactor where the inductance can be varied in steps. The main difference is the reactor core limbs, which have nonmagnetic gaps inserted between packets of core steel. The need for large shunt reactors appeared when long power transmission lines for system. For these cases, the parallel surge arrester is normally giving a proper shunt reactor switching overvoltage protection even for aged shunt reactors. It can be directly connected to the power line or tertiary winding of three winding transformer. The shunt reactor is installed in a threephase system as.
Shunt capacitors as it was mentioned before, shunt capacitors may be used to provide a local source of capacitive reactive power q c to reduce a value of inductive reactive power q l carried by the line usually, an overhead line. This surplus reactive power is present when lines are lightly loaded or there is a sudden drop in load due to a failure somewhere in the system. Reactors are normally switched off for times of heavy load and are switched onto the lines at periods of low load. Practical ehv reactor protection faridul katha basha and michael thompson, schweitzer engineering laboratories, inc. Core of shunt reactor gapped core is generally used in shunt reactor. Power transformers shunt reactors proven history for future. These can be stressful to the shunt reactor and cause internal turn to turn overvoltages. The world shunt reactor market is segmented based on types, region and applications. A traditional shunt reactor has a fixed rating and is either connected to the power line all the time or switched in and out depending on the load. Thus a shunt reactor may also be constructed without iron aircore. The other grounding methods adopted are solidly grounded and high impedance grounding of neutral. Shunt reactor switching transients at high compensation levels. There might be cases when a testing laboratory can not perform. Variable shunt reactors are therefore economical means to improve voltage stability and power quality under timevarying load conditions.
The shunt reactor was shifted from 500 kv nokhar grid station district gujranwala through heavy transport. Investigation of circuit breaker switching transients for shunt reactors and shunt capacitors m. Shunt reactor reactive power compensation designed with the. Shunt capacitor banks are installed for a variety of reasons in industrial, distribution and transmission systems. Shunt capacitor banks design, application and protection. For oilimmersed shunt reactors, the ambient temperatures are usually specified within the range of 25c to 40c. Shunt reactor market size, share analysis industry forecast. A method of changing the connection of motors from series to parallel in which one motor, or group of motors, is first shortcircuited, then disconnected, and finally. Gilbert electrical systems oil filled shunt reactor.
The abb shunt reactor is the most cost efficient piece of equipment for maintaining voltage stability on the transmission lines. Shunt reactors are widely used in transmission and distribution networks. Eng thesis, qut, 2008 page ii abstract switching of shunt reactors and capacitor banks is known to cause a very high rate of rise of transient recovery voltage across the circuit breaker contacts. A shunt reactor is a piece of electrical equipment used in high voltage power transmission systems to stabilize the voltage during load variations. Shunt reactors are used in order to compensate capacitive reactive power generated by long and lightly loaded transmission lines as well as underground cables, thus allowing the flow of more act. Claes bengtsson the variable shunt reactor vsr is an interesting. The solution is to install shunt reactors manufactured by partner technologies. In this paper, a proposed hybrid topology based on diode rectifier units dru and voltage source. Fixed shunt reactors traditional shunt reactors have a fixed rating. Gilbert electrical systems is a leader in the industry with shunt reactors, which includes oilfilled shunt reactors. Shunt transition article about shunt transition by the free.
Differences between shunt reactor and power transformer. Pdf application of numerical relays for hv shunt reactor. The usage of our oilfilled shunt reactors and other shunt reactors will increase the efficiency of your power system by allowing the transmission of more active energy, reducing losses. Since a shunt reactor magnetizing current is large, if it is designed with iron alone as a power transformer, there will be large hysteresis loss. Shunt reactor current is mainly inductive and it is small 10%15% of nominal currents shunt reactors are frequently switched and during the periods of the system operations with low loads it is energized. Ironcore reactor the inductance value of the ironcore reactor figure 2 is defined by its winding geometry as well as number of turns and its core design. The other effect of shunt reactors is to control excessive voltage rise. Reactor banks play an important role in mitigating the voltage rise, otherwise known as ferranti rise, which is characteristic to long lightly loaded transmission lines having high capacitive charging current. Impacts of shunt reactors on transmission line protection. The reason for the differentiation of the bus shunt versus normal fixed control is that the bus shunt control type is intended to identify the difference between a bus shunt and a switched shunt that may have controllability, but is currently turned of off control by being set to a fixed value. Abstractshunt reactors are applied to long, highvoltage transmission lines to offset the impact of line charging capacitance to prevent high voltage during lightly loaded conditions.
Two design procedures for shunt reactor with discretely distributed gaps are developed within the scope of this thesis. Shunt reactors are used to stabilize the voltage during load variations in high voltage networks. However, the main drawback is the high converter cost. Variable shunt reactor, usa three phase variable shunt reactor 3460mvar with oltc 345kv 500kv transmission network, peru single phase shunt reactor 66. Air gaps in iron core are provided in a shunt reactor to reduce this loss and to minimize the remanent flux in the core. The other grounding methods adopted are solidly grounded and high impedance grounding of. Shunt reactors are applied to regulate the reactive power balance of a system by compensating for the surplus reactive power generation of transmission lines or cables. Another driver making variable reactors normally expressed in mvar. Shunt reactor article about shunt reactor by the free. Pdf an integrated transformershunt reactor operation device. Whats more, voltage regulated shunt reactors can keep the voltage constant within certain limits and stabilize grids affected by seasonal or daily load fluctuations. The main driver behind these investments is the need to lower and control the voltage in the 300 kv and 420 kv grids which are connected with 800 mva. Shunt reactor neutral currents during synchronized switching in order to obtain such disturbance free shunt reactor switching, circuit breaker poles must be precisely closed in three consecutive phase voltage peaks as shown in the following figure. When a line is disconnected from the system, the line reactor is also disconnected from the system.
Variable shunt reactors variable shunt reactors vsr have a variable. Shunt reactors an investment for today and for the future increased revenue. Excessive turn to turn stresses can lead to premature failure of the shunt reactor. Ntdc installs three shunt reactors to prevent system failure for the transformer and shunt reactor energization study, this paper uses a harmonic index which can calculate overvoltages for the worst case of switching time and remanent flux. Riiot2 engineering justification papers sp energy networks. A shunt reactor is an absorber of reactive power, thus increasing the energy efficiency of the system. An investigation on flux density of three phase distrubuted airgap 35 legged shunt reactor proceedings of the ires 21st international conference, amsterdam, netherland, 25 th december 2015, isbn. A line reactor is placed in line at the point of use or just after a transformer to maintain a stable amperage to the user. Shunt reactor reactive power compensation designed. These stresses cannot be controlled with terminal connected surge arresters. One is drytype reactor of an air core or coreless design. Abstractshunt reactors are installed to offset the capacitive effect of transmission lines and therefore improve the voltage profiles of transmission lines. What is the difference between a shunt reactor and a series. Reactors must be sized to closely match the capacitive kvar of the cable it is connected to and be strategically located along the cable length.
Exceeding the specified ambient temperature may reduce both the reliability and the life of the shunt reactor. A traditional shunt reactor has a fixed rating and is either connected to the transmission line all the time or switched in and out depending on the load. In that case, to reduce the receiving end voltage, shunt reactor is used. The shunt reactor shr1 is modelled as a nonlinear inductance with a high knee point linear up to 1.
Shunt reactor switching shunt reactors are used to regulate the reactive power balance of a system by compensating for the surplus reactive power generation of transmission lines or cables. Moving strip method for discretely distributed gapped shunt reactors is recommended. Other advantages of shunt reactors include the prevention of generator selfexcitation on leading power factor loads and the reduction of overvoltages on sound phases following a single linetoground fault. Shunt reactors trench is a supplier of specialized electrical products and a recognized world leader in the design and manufacture of dry type air core reactors. Shunt reactors contain the same components as power transformers, like windings, core, tank, bushings and insulating oil and are suitable for manufacturing in transformer factories. Sen 3706 k v single phase shunt reactor for chesf, brazil magnetic shield structure. That is, sending end voltage will be less than receiving end voltage due to linecable capacitance. C p is the breaker stray inductance and capacitance l is the shunt reactor inductance this paper considers the case of ungrounded reactor bank neutral. Since they decrease the voltage level, they are typically used during light load conditions. A method of changing the connection of motors from series to parallel in which one motor, or group of motors, is first shortcircuited, then disconnected, and finally connected in parallel with the other motor or motors. Due to their inductive nature of the shunt reactor, it is used whenever there is need for compensation of capacitive reactance. Shunt reactors abb variable shunt reactors applications. Design of 25 mva shunt reactor for 230 kv transmission line.
Shunt reactor is same as power transformer but it has only one winding per phase as compared to power transformer. Shunt reactor and shunt capacitor compensate the effect of capacitive inductive currents shunt capacitors raise the system voltage shunt reactors lower the bus voltage during light load periods, shunt reactors are used to control the system voltage during heavy load periods, shunt capacitors are. The shunt reactor is either connected to the network or not connected to the network depending on the load. Mar 10, 2020 shunt reactor is used to compensate capacitive reactive power of a long transmission line.
The results achieved by the application of shunt capacitors are shown in figure 3. Shunt reactor switching 25 january 2011 page 5 reactor circuits. Voltage regulated shunt reactors ensure a stable line voltage and improve operational reliability in the event of weatherrelated power fluctuations in particular. Department of electrical and computer engg, houghton, mi 49931. High voltage shunt reactor trench group pdf catalogs. Presentation made during the ieee transformers committee. The usage of our shunt reactors and other varieties of reactors will increase the efficiency of your power system by allowing the transmission of more active energy. The large coils of the shunt reactor provide inductive compensation to guard against this effect. Fundamentals of reactive power and voltage regulation in. However, shunt reactors can reduce line loadability if they are not removed under fullload conditions. Multiple small air gaps like polygap design annihilate the stray field and lead to a robust frequency behavior of the inductor. Line reactors are often used to compensate line capacitance, mitigate voltage transients due to switching, and to limit. Shunt reactor market global industry analysis, size and. Learn about the benefits of reactor switching southern.
Application fields and control principles of variable shunt. Shunt reactor function, calculation, and compensation. Ironcore reactor the inductance value of the ironcore reactor figure 2 is defined by its winding geometry as. Shunt reactor is used to compensate capacitive reactive power of a long transmission line.
A common thread to all installations is the question of what, if any series reactor should be in stalled with the capacitor bank. The global shunt reactor market foresees promising growth prospects in emerging economies in asiapacific such as india and china. The constructional features of a shunt reactor may vary manufacturer to manufacturer but basic of construction is more or less same. Variable shunt reactors are used in high voltage energy transmission systems to stabilize the voltage during load variations. Since early 1991, pti has been designing and producing shunt reactors that have out performed customer expectations. These variable shunt reactors are 3phase units, oilimmersed and designed. A simple and practical design approach is also developed which. It does this by compensating for the capacitive charging of the high voltage aclines and cables, which are the primary generators of reactive power. They absorb consume reactive power by connecting them to the transmission line. Single and threephase shunt reactors loss measurement.
Voltage regulated shunt reactors ensure a stable line voltage and improve operational reliability in the event of. Application of numerical relays for hv shunt reactor protection conference paper pdf available december 2004 with 2,302 reads how we measure reads. The test for shunt reactors loss measurement is done by using large capacitors which are very expensive because of their large number and also for their large maintenance expenses. Iron core shunt reactors act as an absorber of reactive power to increase energy efficiency of the power system.
Shunt reactors are inductive device commonly used in hv and ehv systems for compensating the excess capacitive vars in a power system. Since produced a number of shunt reactors, including 275k v 150mva for tokvo power co. Gilbert electrical systems is a leader in the industry with oilfilled shunt reactors. On the basis of reactor types, the shunt reactors are segmented into oilimmersed shunt reactor and aircore dry shunt reactor. It is the most compact device commonly used for reactive power compensation in long highvoltage transmission lines and in cable systems.
43 658 1283 322 1543 1288 644 1057 910 752 1137 532 33 267 1100 1278 819 670 1367 1066 89 673 303 315 1035 1465 1020 32 551 1409 1002 626 390