Improvement of Power System Transient Stability using Static Synchronous Series Compensator (SSSC)

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1 IJSTE - International Journal of Science Technology & Engineering Volue 3 Issue 01 July 2016 ISSN (online): X Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) halani Kaal Kuar K. Student Departent of Electrical Engineering MEFGI, Rajkot-Morbi Road, gauridad, Gujarat , India ssi Prof. Piyush Dodiya ssistant Professor Departent of Electrical Engineering MEFGI, Rajkot-Morbi Road, gauridad, Gujarat-36003, India bstract This paper describes iproveent of power transfer capability in IEEE 4 bus 2 achine syste using Static Synchronous Series opensator (SSS).It is known that series controller is always contributing a better perforance for power transfer capability through transission line. Here Static synchronous series copensator (SSS) has been used as a switching converter type series copensation. Power oscillation daping (POD) has been incorporated as a controller to dap out the oscillation. Siulation result shows after installing SSS between bus no. 1 & 2, the power flow has been iproved. The work has siulated in MTL Siulink 2010 and output has been copared with and without Static synchronous series copensator (SSS). Keywords: Static Synchronous Series opensator (SSS), POD ontroller, Stability, Transient Stability, 4-us 2 Machine Systes I. INTRODUTION Series copensation always plays a big role to iprove power transfer capability through transission line. Series controller can be applied variable Ipedance type and switching converter type. SSS coes under the faily of switching converter type. The priary purpose of a SSS is to control power flow in steady state, while it can also iprove transient stability of a power syste. The ain interest is to use the SSS for controlling power flow (active and/or reactive) in transission lines. SSS is connected at 4 buses 2 achine power systes. It is siulated using MTL and SSS has been included with Power Oscillation Daping (POD) ontroller. Series capacitive copensation was introduced decades ago to cancel a portion of the reactive line ipedance and there-by increase the transittable power. Power flow increased by inserting an additional capacitive reactance in series with the transission line, thereby decreasing the effective reactance of the transission line between its two ends. Rather than shunt controller series controller controls the coplex power so soothly. II. STTI SYNHRONOUS SERIES OMPENSTOR The SSS is generally connected in series with the transission line. SSS coprises voltage source converters Fig. 1: Static Synchronous Series opensator ll rights reserved by 170

2 Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) nd a D capacitor. The injected voltage of the coupling transforer Vs is perpendicular to the line current. SSS is used for controlling active and reactive power in transission line one side of the converter. It is connected to syste and other side is connected to a capacitor and battery. It assues D source as battery installation to allow active as well as reactive power exchanges with the syste. The voltage with V pq with respect to the transission line I line deterines exchange of real and reactive power with the syste [1]. The active and reactive power exchange between the SSS and the transission line can be calculated as follows. [9] P pq = V pq. I line cos φ Q pq = V pq. I line sin φ Where φ represents the angle between the injected SSS. The angle between the output voltage of SSS and line current is approxiately 90.It shows that SSS real power is sall copared to reactive power. The real power going in SSS is used only to cover for the losses and charging of the dc capacitor [9] P pq= P dc + P losses asic Operating Principle of The SSS. Fig. 2: SSS phasor diagra Fig 2. shows that SSS where D capacitor exchange by an high energy battery installation to allow active as well as reactive power exchanges with syste. Phase displaceent of the inserted voltage V pq with respect to line current deterines exchange of active and reactive power with the syste. Fig 2. show that line current phasor is used as reference phasor while injected SSS voltage phasor is rotate around the center of the circle defined by the axiu inserted voltage V pq ax In capacitive ode, injected SSS voltage is ade to lag the transission line current by 90 degree.in this case, the SSS operation siilar to the operation of series capacitor with variable capacitance K*Xc. where K is a variable Vpq= - jk*xciline.[9] lso possible to reverse the injected SSS voltage by 180, i.e,-v= jk*xciline. ausing an increase in the transission line reactance, which result in decrease of the line current [9] III. MULTI-MHINE POWER SYSTEM WITH SSS Fig. 2: Multi-Machine Power Syste with SSS ll rights reserved by 171

3 Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) The power grid consists of three power generation substations and one ajor load entre at bus 1. The first power generation substation M1 has a rating of 2100 MV, and the other one M2 has a rating of 1400 MV, This syste which hase been ade in ring ode consisting of 4 buses (1 to 4) connected to each other through three phase transission lines L1, L2-1, L2-2, and L3 with the length of 280,150,150 and 5 k. The phase to phase voltage equal to 13.8 kv. IV. SSS POWER OSILLTION DMPING ONTROLLER (POD) Fig. 3: SSS POD controller SSS can be used for daping power oscillation and so enhance the overall dynaic perforance of the syste.in Fig 3 POD consists of the three blocks. 1) wash out filter blocks 2) phase copensator block 3) gain block. The washout filter block is used to avoid a POD response to the steady-state changes of the input signal. Phase copensator block provides the appropriate phase lag/lead characteristics and stabilizer gain Ks deterine the aount of daping introduced by POD. The selection of an appropriate input signal is a fundaental issue in the design of an effective and robust POD controller. Locally easurable signals are always preferred as input signal. Signal such line active power, line reactive power, line current agnitude, bus voltage agnitude and angles are considered in the selection of input signals for the POD controller in this paper bus voltage and bus current are considered for input signal. POD design ethod nuber of design ethods ay be used for POD paraeter tuning. The ost popular ones are based on frequency response [19, 20], eigenvalue sensitivities [21] as well as a cobination of these ethodologies. The phase paraeters of the phase copensator block are coputed as [18] Where φ the phase to be copensated, ω n is the frequency of the ode to dap and n the nuber of lead-lag networks usually 10% daping ratio is considered to be enough. [18] V. SIMULTION ND RESULT First power syste with two achines and four buses has been siulated in MTL environent and then powers and voltages in all buses have been obtained. The results have been given in Table 1. Using obtained result bus 2 has been selected as a candidate bus to which the SSS be installed. Therefore the siulation results have been focused on bus 2 Table 1 Siulation Result without Sssc us NO V PU I PU P PU Q PU ll rights reserved by 172

4 Voltage us2 (pu) Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) Fig. 4: Reactive power of bus-2 without SSS Tie Fig. 5: Voltage bus-2 without SSS. Fig. 6: ctive power of bus-2 without SSS ll rights reserved by 173

5 Voltage bus 2 pu Reactive power (pu) ctive power (pu) Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) hange in current, voltage, active and reactive powers of bus-2 have been obtained in real tie. The controlling systes in power plants 1,2 such as governor, PSS and other stabilizing devices are used for daping these oscillations. Oscillations aplitude for active power is ore than reactive power, and this is because the ohic parts of loads of syste are uch ore Tie Fig. 7: ctive power of bus-2 with SSS Tie Fig. 8: Reactive power of bus-2 with SSS Tie Fig. 5: Voltage bus-2 with SSS ll rights reserved by 174

6 2 2 2 ypass Vqref Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) Terinator onstant P Pref Vf Reg_M1 P Vf_ 2100 MV G1 a b c 2100 MV 13.8 kv /500 kv US 1 a b c L k US 4 L k US 3 L3-50 k a a b b c c a b c 1400 MV 13.8kv / 500 kv 1400 MV G2 P Vf_ Reg_M2 P Vf Pref onstant1 Phasors 250 MW powergui ypass 100 MW 50 MW Vabc_2 Iabc_2 Vabc Iabc Vqref Vqref * P_MW P_2 SSS 100-MV SSS POD ontroller Step Vqref US 2 a b c L1-280 k Fig. 9: Matlab/Siulink Result with SSS Fig. 10: Pod controller sub syste ll rights reserved by 175

7 Iproveent of Power Syste Transient Stability using Static Synchronous Series opensator (SSS) Table - 2 Siulation Result without SSS us NO V PU I PU P PU Q PU VI. ONLUSION It has been found that the SSS is capable of controlling the flow of power at a desired point on the transission line. It is also observed that the SSS injects a fast changing voltage in series with the line irrespective of the agnitude and phase of the line current. ased on obtained siulation results the perforance of the SSS has been exained in a ultiachine syste, and applications of the SSS will be extended in future to a coplex syste to investigate the probles related to the various odes of power oscillation in the power syste. REFERENES [1] K.K.Sen, SSS static syn ch ron ou s series cop ensator: theory, odeling, and applications, IEEE Trans. Power Delv., vol. 13, , Jan [2] P.Kukratug Transient Stability ssessent of a power syste with a Static Synchronous Series opensator, IEEE Trans. [3] Definition and of Power Syste Transient Stability IEEE Transactions on Power Systes, vol. 19 No.2, May [4] L. Gyugyi, Dynaic copensation of transission line by solid state Synchronous voltage sources, IEEE Trans. [5] Habibur Rahan, Jewel Rana, Harun-Or-Rashid Power Syste Stability Iproveent y Using SSS With Power Syste ontroller International Journal of Science, Engineering & Technology Research (IJSETR) Volue 1, Issue 6, Deceber [6] K.R.Padiyar Facts controllers in power transission and distribution. [7] Mr.G.V. Rajashekar, Dr.Hiani Goyal Power Syste Enhanceent using Static Synchronous Series opensator international journal of odern engineering research (IJMER) vol.3 pp [8] Swasti R.Khuntia Siulation Study of a SSS-based Neuro-Fuzzy ontroller for Iproveent of Transient Stability in a Three-Machine Power Syste /12/2012 IEEE. [9] H.Taheri, S.Shahabi, Sh.Taheri,.Gholai pplication of Synchronous Static Series opensator (SSS) on Enhanceent of voltage Stability and Power Oscillation Daping /09/2009 IEEE. [10] L.Sunil Kuar, rinda Ghosh Static synchronous series copensator design control and application ELSEVIER. [11] H.F Wang Static Synchronous Series opensator to dap power syste oscillations ELSEVIER. [12] Fawzi.Rahan L Jowder ipact of daping schee on daping characteristic of static synchronous series copensator 2011 IEEE. [13] H.M. yres, V.F. da osta ipacts of the sssc control odes on sall-signal and transient stability of a power syste ELSEVIER. [14] Dr. xay J Mehta Static Synchronous Series opensator n approach for reactive power copensation for the transission syste National onference on Recent Trends in Engineering & Technology [15] P. Kundur, Power Syste Stability and ontrol, McGraw-Hill, [16] N. G. Hingorani, and L. Gyugyi, Understanding FTS: oncepts and Technology of Flexible Transission Systes, IEEE Press, New York, [17] K.R.Padiyar Facts controllers in power transission and distribution. [18] M.S.H.M.yres,V.F. da costa, L..P.da silva Ipacts of the SSS control odes on sall-signal and transient stability of a power syste Science direct [19] N. Martins, L. Lia, Eigenvalue and frequency doain for sall-signal electroechanical stability probles, in: IEEE Syposiu on pplication of Eigenanalysis and Frequency Doain Methods for Syste Dynaic Perforance Special Publication 90TH PWR, 1990, pp [20] N. Martins, H.J..P. Pinto, J.J. Paserba, Using a TS for line power scheduling and syste oscillation daping sall-signal and transient stability studies, in: IEEE PES Winter Meeting, vol. 2, 2000, pp [21] L. Rouco, F.L. Pagola, n eigenvalue sensitivity approach to location and controller design of controllable series capacitors for daping power syste oscillations, IEEE Trans. Power Syst. 12 (4) (1997) ll rights reserved by 176