OPTIMIZE CONTROLLING OF ACTIVE FILTERS CONTROLLED BY PI CONTROLLER

Transcription

1 International Research Journal of Engineering and Technology (IRJET) eiss: Volume: 04 Issue: 12 Dec piss: OPTIMIZE OTROLLIG OF TIVE FILTERS OTROLLED Y PI OTROLLER Md. Tanwirul Hasan 1, shutosh Gupta 2 1,2 Electrical and Electronics, Engineering, ISSOM, hopal *** bstract : Due to increasing nonlinear loads arious undesirable effects and power quality problems induced. The use of power conerters, electronic equipments and other nonlinear loads are rapidly increasing in industry and also by consumers, draw nonlinear currents from the mains as compare to traditional loads such as motors and resistie heating elements. This leads to the distortion of power system oltage and other problems. This paper presents an auto tuned actie power filter for harmonic minimization and reactie power compensation of nonlinear load under fast load ariation condition. Improing dynamic behaior of shunt actie power filter is used to tune PI controller coefficients and make it robust under random load ariation. Key words: ctie filter, PI controller. 1.1 Introduction ctie power filters are more and more capturing the interest of researchers and industries owing to the decreasing quality of power supplied by the electrical distribution companies and the difficulties in fulfilling the constraints imposed by national and international standards only by using traditional compensating strategies. The use of actie systems for compensating harmonic distortion and reactie power in the supply electrical networks, both at user leel or at a higher oltage leel, is now more often preferred to the classical passie compensating methods. In fact actie filters do not present all the typical drawbacks of passie systems such as the detuning of single tuned filters due to changes of system operatie conditions and surrounding enironment or the generation of resonance at particular frequencies, between the network and filter reactance, that amplifies unwanted harmonics. In a modern electrical distribution system, there has been a sudden increase of nonlinear loads, such as power supplies, rectifier equipment, domestic appliances, adjustable speed dries (SD), etc. s the number of these loads increased, harmonics currents generated by these loads may become ery significant. These harmonics can lead to a ariety of different power system problems including the distorted oltage waeforms, equipment oerheating, malfunction in system protection, excessie neutral currents, light flicker, inaccurate power flow metering, etc. To reduce harmonic distortion and power factor improement, capacitors are employed as passie filters. ut they hae the drawback of bulky size, component aging, resonance and fixed compensation performance. These proide either oeror undercompensation of harmonics, wheneer a load change occurs [4]. In order to oercome these problems, actie power filters (PFs) hae been deeloped. The oltagesourceinerter (VSI)based shunt actie power filter has been used in recent years and recognized as a iable solution [5]. ctie filters, besides, permit the control and the compensation of distorted line currents adapting themseles to the load changes and to changing in working frequency. The most effectie and the most diffuse structure in actie filtering systems is certainly the shunt one composed by an inerter fed by a capacitor and a passie filter used to inject the compensating currents in the grid (Fig. 1). The aim of this kind of actie filters is to generate a current waeform that is equal, but with opposite phase, to the harmonic content of the load current and to inject it in the a.c. supply system. In this way the a.c. mains will approximately delier only the fundamental current component also with the possibility of a compensation of the find a mental reactie power. In order to oercome these problems, actie power filters (PFs) hae been deeloped. The oltagesourceinerter (VSI) based shunt actie power filter has been used in recent years and recognized as a iable solution [5]. The control scheme, in which the required compensating currents are determined by sensing line currents only, is gien in [6][7], which is simple and easy to implement. The scheme uses a conentional proportional plus integral (PI) controller for the generation of a reference current template. 2017, IRJET Impact Factor alue: ISO 9001:2008 ertified Journal Page 1656

2 International Research Journal of Engineering and Technology (IRJET) eiss: Volume: 04 Issue: 12 Dec piss: Recently has generated a great deal of interest in arious applications and has been introduced in the power electronics field [8][10]. The adantages of oer the conentional PI controller are that they do not need an accurate mathematical model; they can work with imprecise inputs, can handle nonlinearity, and may be more robust than the conentional PI controller. Use of for minimization of harmonics and improement of power quality is not a new issue rather arious authors hae introduced some innoatie methodologies using these tools [11]. The most important obseration from the work reported by arious researchers for power quality improement is the design of actie power filter under fixed load conditions or for loads with slow and small ariation [12]. 2. OUT THE TIVE POWER FILTER When linear loads are connected to the supply the waeforms are linear. Whereas nonlinear loads are connected harmonic appears on electric oltage or current. The harmonics are integer multiples of system frequency. This leads to arious power quality problems like heating of the deices, mis triggering of the dries, pulsating output in the motors, etc., harmonic filter are used to eliminate the harmonics. There are three basic types of harmonics filters gien below. Passie power filters ctie power filters 2.1 Passie power filters (PPF) PPF is a type of filter, which consists of only passie components. It consists of linear elements like resistors, capacitors and inductors. They are also called as L filters, which produce series resonance or parallel resonance that forms a major drawback of this type of filter. nother drawback of PPF is the cost which increases as the oltage rating of the inductor and capacitor increases. 2.2 ctie power filter PF is a type of filter that uses either current or oltage source as its major component. They compensate oltage or current harmonics by injecting the negatie of the harmonic signal measured injected signals fed are of same magnitude but in phase opposition with the measured harmonic signals. Of these two oltage source based PF is more adantages. It is controlled to draw/supply a compensated current from/to the utility, such that it eliminates reactie and harmonic currents of the nonlinear load. Thus, the resulting total current drawn from the ac mains is sinusoidal. Ideally, the PF needs to generate just enough reactie and harmonic current to compensate the nonlinear loads in the line [12] Proposed PI control scheme Fig. 1: ctie power filter connected with transmission line Figs 2 and 3 show the actie power filter compensation system and the schematic diagram of the PI control scheme, respectiely. In order to implement the control algorithm of a shunt actie power filter, the D capacitor oltage ( ) is 2017, IRJET Impact Factor alue: ISO 9001:2008 ertified Journal Page 1657

3 International Research Journal of Engineering and Technology (IRJET) eiss: Volume: 04 Issue: 12 Dec piss: sensed and compared with the reference alue (ref ). The Input of PI controller is the alue of Error, e = ref, and its output, after a limit, is considered as the magnitude of peak reference current max I. The switching signal for the PWM conerter are obtained from comparing the actual source currents ( isa, isb,isc ) with the reference current templates ( Isa Isb Isc ) in a hysteresis current controller. The output pulses are applied to the switching deices of the PWM conerter [14]. Fig. 2. ctie filter controlling system. Since coefficients of PI controller, K p and Ki, are fixed in this model, the performance of actie power filter under random load ariation conditions is not as well as fixed load condition. To oercome this problem and make a robust controller is designed to tune K p and Ki on the base of load current alue. 3. Simulink model of ctie power filter using PI controller. Fig. 3 shows the block diagram of PI controller used for the controlling of actie power filter. Source PWM ontrol Load urrent ontroller PI / Fuzzy ontroller Fig. 3 lock Diagram of PI controlled improed power quality conerter The simulation is done using MTL for the oltage source PWM rectifier. The complete rectifier system is composed of mainly (1) three phase source, (2) oltage source PWM rectifier, (3) fuzzy controller, and (4) hysteresis controller. 2017, IRJET Impact Factor alue: ISO 9001:2008 ertified Journal Page 1658

4 International Research Journal of Engineering and Technology (IRJET) eiss: Volume: 04 Issue: 12 Dec piss: aia bib cic ia ia 1 signal THD THD Display Usa Usb Usc Usc 1 Sinchronizing & Reference urrent Generator In1 In2 Isa Isb In3 Isc g Uniersal ridge iaibic Goto 1 onstant Ism* Vact PI ontroller abc From Isa* Ig 1 Ig 2 Ig 3 Discrete, Ts = 1e006 s powergui Isb* Ig 4 Ig 5 Isc* Ig 6 Pulse Generator gate pulses Fig. 5. Simulated power circuit without controlled improed power quality conerter aia bib cic ia ia 1 signal THD THD Display In1 In2 Isa Isb In3 Isc g iaibic Usa Usb Usc Usc 1 Sinchronizing & Reference urrent Generator Uniersal ridge Goto 1 onstant Ism* Vact PI ontroller abc From Isa* Ig 1 Ig 2 Ig 3 Discrete, Ts = 1e006 s powergui Isb* Ig 4 Ig 5 Isc* Ig 6 gate pulses Pulse Generator 5. Simulation Results 6. onclusion Fig. 6. Simulated power circuit for PI controlled improed power quality conerter The current and oltage waeform of the conentional three phase rectifier without controller is shown in fig 7. The current waeform for one cycle and its harmonica spectrum is shown in fig 8 (a) & (b). The current is non sinusoidal and total harmonica distortion (THD) is ery high (88.84%). To make the current sinusoidal and THD within permissible limit current controller is used. ased on the simulation results, it can be concluded that PWM rectifier perform satisfactory for the compensation of line current. fter compensation, line current become sinusoidal, balanced and in phase with the respectie source oltage and reduces the THD of the source current below 5% limit. It is clear from simulation result that the transient performance of 2017, IRJET Impact Factor alue: ISO 9001:2008 ertified Journal Page 1659

5 International Research Journal of Engineering and Technology (IRJET) eiss: Volume: 04 Issue: 12 Dec piss: the source current and D side capacitor oltage is better for the PI controller in term of the setting time and % rise/fall in D link oltage. The steady state performance of the is comparable with that of PI controller. References [1] kagi H., ew Trends in ctie Filters, 1995, EPE, [2]. S., Malesani L., Mattaelli P., 1998, IEEE Trans. on Ind. Electron., Vol. 45, [3] W. M. Grady, M. J. Samotyj, and. H. oyola, Surey of actie power line conditioning methodologies, IEEE Trans. Power Del., ol. 5,no. 3, pp , Jul [4] V. E. Wagner, J.c. alda, D.. Griffith,. McEachern, T.M.arnes, D.P. Hartmann, D.J. Philleggi,.E. Emannuel, W.F. Hortion, W.E. Reid, R.J. Ferraro, W.T. Jewell, Effects of harmonics on equipments,ieee Trans. Power Deli. 8 (2) (1993) [5]. Singh,. handra, and K. lhaddad, omputeraided modeling and simulation of actie power filters, Elect. Mach. Power Syst., ol. 27, pp , [6] K. hatterjee,. G. Fernandes, and G. K. dubey, n instantaneous reactie oltampere compensator and harmonic suppressor system, IEEETrans. Power Electron. ol. 14, no. 2,pp , Mar [7] S. Jain, P. garwal, and H. O. Gupta, Design simulation and experimental inestigations on a shunt actie power filter for harmonics and reactie power compensation, Elect. Power ompon. Syst., ol.32, no. 7, pp , Jul [8]. K. ose, Expert Systems, Fuzzy Logic and eural etwork pplication in Power Electronics and Motion ontrol. Piscataway, J: IEEE Press, [9] V. S.. Rairaj and P.. Sen, omparatie study of proportional integral, sliding mode, and fuzzy logic controllers for power conerters, IEEE Trans. Ind. ppl., ol. 33, no. 2, pp , Mar./pr [10] Dell quila,. Lecci, and V. G. Monopoli, Fuzzy controlled actie filter drien by an innoatie current reference for cost reduction, in proc. IEEE Int. symp. Ind. Electron., ol. 3, May 2629, 2002, pp [11] J.. Momoh, X.W. Ma, K. Tomsoic, Oeriew and Literature surey of fuzzy set theory in power systems, IEEE Trans. Power Syst. 10 (ugust (3)) (1995) [12] G.K. Singh,.K. Singh, R. Mitra., a simple fuzzy logic based robust actie power filter for harmonics minimization under random load ariation Electr. Power Syst. Res. (2006). [13] Recommended Practices and Requirements for Harmonic ontrol in Electronic Power Systems, IEEE Standard , ew York, [14].. hende, S. Mishra, and S. K. Jain, TSFuzzyontrolled ctie Power Filter for Load ompensation, IEEE Transactions on Power Deliery, Vol. 21,o. 3, July [15]. Elmitwally, S. bdelkader, M. Elkateb Performance ealuation of fuzzy controlled three and four wireshunt actie power conditioners IEEE Power Engineering Society Winter Meeting, Volume 3, Issue, 2327 Jan 2000 Page(s): ol , IRJET Impact Factor alue: ISO 9001:2008 ertified Journal Page 1660