STUDY OF MATRIX CONVERTER BASED UNIFIED POWER FLOW CONTROLLER APPLIED PI-D CONTROLLER

Transcription

1 Journal of Engneerng Scence and Technology Specal Issue on Appled Engneerng and Scences, October (214) 3-38 School of Engneerng, Taylor s Unversty STUDY OF MATRIX CONVERTER BASED UNIFIED POWER FLOW CONTROLLER APPLIED PI-D CONTROLLER K. MOTOYAMA 1, *, T. HANAMOTO 1, H. YAMADA 1, N. F. MAILAH 2, M. NORHISAM 2 1 Department of Bologcal Functons and Engneerng, Graduate School of Lfe Scence and Systems, Engneerng, Kyushu Insttute of Technology, Kyushu , Japan 2 Department of Electrcal & Electronc, Faculty of Engneerng, Unversty Putra Malaysa, 434 UPM Serdang, Selangor, Malaysa *Correspondng Author: motoyama-kach@edu.lfe.kyutech.ac.jp Abstract In ths paper, the Unfed Power Flow Controller (UPFC) usng a matrx converter s studed. It s an adaptaton of an approxmate dfferentaton type PI-D controller. By settng approprately the values of the gan controller, t s possble to stablse the power of the transmsson lne by controllng the UPFC by a matrx converter. The matrx converter s a power converson crcut that can convert an arbtrary phase and ampltude of the AC power drectly to AC power. The prncple of creatng a swtchng pattern that adopts a Drect Duty rato Pulse Wdth Modulaton (DDPWM) scheme. The UPFC s a statonary devce to adjust the grd voltage for controllng the power flow s nserted nto the power system, and controls the transmsson power accordng to the load varatons. Ths s ntended to stablse the power system. Verfcaton s done by smulaton usng MATLAB/Smulnk for the valdty of ths proposed method. Keywords: Matrx converter, Unfed power flow controller, Drect duty rato PWM, Approxmate dfferentaton PI-D controller. 1. Introducton In recent years, hghly relable and stable power supply system s acheved nternatonal, especally n Japan. Wth the entry of Independent Power Producer (IPP), the ntroducton of small-scale dstrbuted power usng natural energy IPP and deregulaton of power, there s a possblty that the power flow s complcated and the power transmsson system s overloaded locally. 3

2 Study on Matrx Converter based Unfed Power Flow Controller Appled Nomenclatures, l MD MN, MX n,,,,, Duty rato value n each swtchng pattern Dfferental gan value Integral gan value Proportonal gan value Tme constant Medum Input voltage, V Mnmum Input voltage, V Modulaton rate n each of the axs Maxmum Input voltage, V Percentage of for Tme perod, s Tme perod, s A-phase output termnal Swtchng perod, s Integraton of the output voltage A-phase output voltage command Averaged value of Input voltage n each phase As transmsson control system uses power electroncs technology to avod these problems. Therefore, to acheve effectve use of the exstng power transmsson system, the Flexble AC Transmsson System (FACTS) concept has been proposed [1, 2]. The UPFC acts as one of FACTS devces, thereby mprovng stablty and stran transmsson power control by adjustng the phase and ampltude of the electrc lnes [3]. However, problems such as the loss of converson and small capacty of the power converter that compensates for the power stage must be resolved. So, the matrx converter s adapted as a power converter [4]. Matrx converter s able to convert the AC power to AC power drectly. Comparng wth the back to back converter, whch connected converter and nverter wth a electrolytc capactor, there s a mert of mprovng converson effcency and mnatursaton s possble because electrolytc capactors are not requred [5-8]. We use the drect duty rato pulse wdth modulaton (DDPWM) [9]. DDPWM synthesze the duty rato value drectly from the desred output voltage and have some advantages that relatvely easy mplementaton and decrease the swtchng loss compared some other swtchng methods. To accommodate fast changes n the load as the controller and performs stablsaton, the approxmate dfferentaton type PI-D controller wth a low pass flter s desgned. The smulaton results usng MATLAB/Smulnk have shown the valdty of the proposed methods. 2. Proposed Method The stablsaton of the power system by UPFC when the load current s vared s as shown n Fg. 1.

3 32 K. Motoyama et al. Fg. 1. Dagram of a Power System Inserted the UPFC. The load s to smulate a locaton that requres power plants, homes and buldngs. The varety of the current suppled to the load must be always stable, but demands for power wth tme. A method of keepng a stable power of Bus 3 s proposed where even the value of the load s changng rapdly, the UPFC can gve out a fast response, by adjustng the power of Bus 4. The need of securty of the power of the UPFC s because there s a need to convert alternatng current to drect power to securty department. So, the matrx converter had been adapted. Its advantage s that t can be mnatursed and converson effcency s mproved when usng the matrx converter. A block dagram of an electrc power system s nserted the UPFC s shown n Fg. 2. Swtchng pattern s created by usng DDPWM scheme. Transmsson lne current (Bus3) u v w uvw pq p Actve power reference V p D D PI LPF LPF M p PI q M q Reactve power reference *LPF = pq uvw M u M v M w Fg. 2. Dagram of Controller Block. In order to obtan the robustness of the UPFC system and hgh-speed response, ts control s performed by usng the model of nstantaneous power pq. Frst, the pq converts the three-phase alternatng current, whch s the output of the matrx converter and s consdered as an nstantaneous reactve current and nstantaneous actve current. Then, by addng the lne voltage, t s consdered as nstantaneous reactve power and nstantaneous actve power. To gve a command value for the power to perform the PI-D control, control of the current s done by makng an nverse transformaton pq. Fnally, t s converted nto three-phase alternatng current agan, to determne the duty rato by usng ths value.

4 Study on Matrx Converter based Unfed Power Flow Controller Appled PID controller s employed to the proposed system because t s wdely used n many ndustral applcatons to obtan the desred response. Smple PI type controller and ts controller gans desgn method was proposed by authors [7], but n some cases more robust aganst the load change s demanded so PID type controller was also consdered [8]. In ths paper, an approxmate dfferentaton type PI-D controller s composed of the PI controller and ths controller and low pass flter s appled to the dfferental. By settng the approprate gan value for the control unt to control the UPFC, t s possble to stablse the grd. 3. Drect Duty Rato PWM (DDPWM) The method of DDPWM s shown below. For ths paper, only one out of the three phases s shown here. Two other phases are also determned n a smlar manner. Frst, as shown n Fg. 3, the phases have been dvded nto ntermedate phase, the mnmum phase voltage of the power supply. The ntermedate phase s the swtchng pattern II whereas the value of the swtchng pattern I s postve f the value s negatve. Usng these phases to create a swtchng pattern, when swtchng s done, the result s as shown n Fg. 4, when the swtchng pattern s at I. The swtchng perod T S s dvded nto T 1 and T 2. T 1 s defned as n = T 1 /T S here. Dvded nto T A1, T A2, T A3, T A4 n swtchng cycle further, swtchng of the nput voltage MN, MX, MX, MD s performed to output n each secton. Fgure 5 shows the output voltage at ths tme. Input voltage Ⅱ Ⅱ Ⅰ Ⅰ Ⅱ Ⅱ Ⅰ Ⅰ Ⅱ Ⅱ Ⅰ Ⅰ MX MD MN Fg. 3. MX, MD, MN and Swtchng Pattern I, II. 1 MN MX MX MD Fg. 4. Output A-Phase Swtchng State n Swtchng Pattern-I. Fg. 5. Output A-Phase Voltage Synthess n Swtchng Pattern-I.

5 34 K. Motoyama et al. where s the average voltage. Secton T A1 to T A4 can be obtaned n the next secton as n Eqs. (1). Here, the secton of each of the T A1 ~ T A4 s n a very small range, the voltage may be a constant n the nterval. Therefore, the ntegral value of the output voltage of the swtchng perod between T S s gven by Eq. (2). Equatons (1) and (2) wheren the average value of the voltage s as shown n Eq. (3). Therefore, by usng the voltage command value and n the maxmum phase of the nput voltage, ntermedate phase and the mnmum phase, the duty rato of for A-phase s determned by the followng equaton. Therefore, by usng the voltage command value and n the maxmum phase of the nput voltage, ntermedate phase and the mnmum phase, the duty rato of for A- phase s determned by Eq. (4). It s possble n the same manner, to determne the duty rato even n swtchng pattern II. Equaton (5) shows the swtchng pattern correspondng to Fgs. 6 and 7. Fg. 6. Output A-phase Swtchng State n Swtchng Pattern-II. Fg. 7. Output A-Phase Voltage Synthess n Swtchng Pattern-II.

6 Study on Matrx Converter based Unfed Power Flow Controller Appled (5) Accordngly, the swtchng pattern for each duty rato of the A-phase s determned by Eq. (6). Ⅰ 6 Ⅱ 4. Approxmate Dfferentaton Type PI-D Controller It s desgned to approxmate dfferentaton type PI-D controller n ths study, t has been used a smple PI controller frst. The gan values have been determned by tral and error, and these were K P = 1, K I = 1. Instantaneous reactve and actve power are as shown n Fg. 8. The enlarged vew s also shown n Fg. 9. The command value of the nstantaneous actve power s 15 [VA] and of the nstantaneous reactve power s [VA]. power[va] Fg. 8. Instantaneous Power (K P =1, K I =1). power[va] Fg. 9. Enlarged Vew (K P =1, K I =1). It has not been possble from Fg. 8, the nstantaneous reactve power to follow the command value. The nstantaneous power takes long tme to settle the steady state when the load change occurs n.2 s from enlarged vew. Therefore, t s necessary to modfy the controller and gan values to enhance stablty; an approxmate dfferentaton type PI-D controller s desgned. By usng ths controller, wthout dfferentaton settngs drectly, dervatve acton s to functon only on the control varables, and a low pass flter s appled to the dfferental, thus rapd changes s seen stepwse and less senstve to the nose component t s strongly aganst. These gan values are determned by tral and error agan, and these were set to K P = 4, K I = 4, K D =.3, and tme constant s.12. Instantaneous actve and reactve power s as shown n Fg. 1. The enlarged vew s also shown n Fg. 11. From Fg. 1, t s able to follow the command value both nstantaneous actve and reactve power by usng the approxmate dfferentaton type PI-D controller. It can be seen from the enlarged vew; t s able to stably keep the actve power even when the load change occurs. So ths controller s adapted n ths study.

7 36 K. Motoyama et al. Fg. 1. Instantaneous Power (K P =4, K I =4, K D =.3). Fg. 11. Enlarged Vew (K P =4, K I =4, K D =.3). 5. Results and Dscussons These smulatons accordng to the proposed method, s carred out by MATLAB/Smulnk, the smulaton was performed by varyng load condtons as shown n Table 1. The result s shown n the Fgs The parameter of the control block s shown n Table 2. RLC load value Table. 1. Value of RLC Load. Tme [s] ~.2.2~.4.4~.5 R[W] L[var] 2 C[var] 3 Table. 2. Parameter of Control Block. Reference (actve) Value.5[p.u.] Reference (reactve) Value K P 4 PI-D Controller K I 4 (actve and reactve) K D.3 l.12 Fgures 12 and 13 respectvely ndcates a modulaton rate of the reactve component and actve component. Fg. 12. Instantaneous Power (K P =1, K I =1). Fg. 13. Enlarged Vew (K P =1, K I =1). Fgures 14 and 15 show the voltage and current of Bus 4 whch s the output of the matrx converter. The voltage and current of Bus 3 s a system that s to undergo stablsaton s shown n Fgs. 16 and 17.

8 Study on Matrx Converter based Unfed Power Flow Controller Appled Current[A] Fg. 14. Bus 4 Current. Voltage[V] Fg. 15. Bus 4 Voltage. Voltage[V] Fg. 16. Bus 3 Current. Fg. 17. Bus 3 Voltage. It s found that the output of the matrx converter s changed from Fg. 14, wth varyng value of the load. From Fg. 16, the power of the system that s ntended to be stablsed when changng the value of the load s changed momentarly. It can be seen that both the phase and ampltude s back to ts regulated value nstantly. Havng sad that, t can be seen that n Fgs. 14 and 16, changng the value of the load are controlled by the UPFC power of the system so as to mantan a stable value. The nstantaneous power of Bus3 s shown n Fg. 18. It s found that the power of the system s stablsed by UPFC from the waveform. Therefore, the gan value set from these results s approprate and t was possble to control the power of the system. 6. Conclusons In ths paper, t has been descrbed that the UPFC can be used onto the PV dervatve type PI-D control usng a matrx converter. The controller s desgned successfully from the smulaton results that are bult as a smulaton model. The system also revealed the effectveness and feasblty of the PV dervatve type PI-D control of the UPFC matrx converter based as had been proposed. The smulaton results show the valdty of the proposed controller. Furthermore, t can be studed usng the actual smulaton for further understandng n the future. 15 power[va] Fg. 18. Instantaneous Powers of Bus 3.

9 38 K. Motoyama et al. Acknowledgement Ths work was supported by JSPS KAKENHI Grant Number References 1. Hngoran, N.G. (2). Role of FACTS n a deregulated market. IEEE Power Engneerng Socety Summer Meetng, 3, Gyugy, L.; Schauder, C.; Wllams, S.; Retman, T.; Torgerson, D.; and Edrs, A. (1995). The unfed power low controller: A new approach to power transmsson control. IEEE Transacton on Power Delvery, 1(2), Malah, N.F.; Bash, S.M.; Ars, I.; and Marun, N. (21). Effect of UPFC's seres converter phase shft on output voltage and current's total harmoncs dstorton. Proceedng of APSAEM, Itoh, J.; Sato, I.; and Odaka, A. (25). A control method for the matrx converter based on vrtual AC/DC/AC converson usng carrer comparson method. Electrcal Engneerng n Japan, 152(3), Carbone, R. (211). Energy storage n the emergng era of smart grds. InTech. 6. Monterro, J.; Slva, J.F.; Pnto, S.F.; and Palma, J. (211). Matrx converterbased unfed power-flow controllers: advanced drect power control method. IEEE Transactons on Power Delvery, 26(1), Hanamoto, T.; and Yamada, H. (212). Controller desgn usng coeffcent dagram methods for matrx converter based unfed power flow controllers. Proceedngs of APSAEM, Kawabe, S.; Hanamoto, T.; and Yamada, H. (27). Controller desgn of matrx converter for Unfed Power Flow Controller. Proceedngs of JCEEE, 4-1P-7 (n Japanese). 9. L, Y.; Cho, N.S.; Han, B.M.; Km, K.M.; Lee, B.; and Park, J.H. (28) Drect duty rato pulse wdth modulaton method for matrx converters. Internatonal Journal of Control, Automaton, and Systems, 6(5),