Dr. M.Nanda Kumar Professor Department of Electrical & Electronics Engineering Govt. Engineering College, Thrissur. Dept. of EEE, GEC,Thrissur

Size: px

Start display at page:

Download "Dr. M.Nanda Kumar Professor Department of Electrical & Electronics Engineering Govt. Engineering College, Thrissur. Dept. of EEE, GEC,Thrissur"

Joleen Parrish
5 years ago
Views:

Three phase shunt Active Power Filter using P-Q (Instantaneous real and reactive power) D-Q (Synchronous Reference Frame) and S-D (Synchronous Detection)

1 Three phase shunt Active Power Filter using P-Q (Instantaneous real and reactive power) D-Q (Synchronous Reference Frame) and S-D (Synchronous Detection) method with hysteresis switching strategy Dr. M.Nanda Kumar Professor Department of Electrical & Electronics Engineering Govt. Engineering College, Thrissur

2 Contents Power quality and harmonics Causes and effects of harmonics, viable solutions Active Power Filters (APFs) Active power filter control techniques P-Q (Instantaneous real and reactive power) method D-Q (Synchronous Reference Frame) method S-D (Synchronous Detection) Method hysteresis current controller Simulink models Simulation results

3 Power quality and harmonics Power quality refers to the purity of the voltage and current waveform Power quality disturbance is a deviation from the pure sinusoidal waveform. Harmonic pollution is due to the increased number of nonlinear loads..

4 Mag (% of Fundamental) Total Harmonic Distortion ( Is I 1) s I s Total harmonic distortion, THD = = 1 2 Is 1 I s1 Fundamental (50Hz) = 35.54, THD= 28.13% Harmonic order

5 Harmonic currents 3-phase rectifier with resistive load

6 Current Current Current INPUT CURRENT OF DIFFERENT NONLINEAR LOADS TYPE OF NONLINEAR LOAD TYPICAL WAREFORM THD% 1-φ Uncontrolled Bridge Rectifier % (high 3 rd harmonic component) Time (ms) 1-φ Semi controlled Bridge Rectifier nd, 3 rd, 4 th,... harmonic components Time (ms) 6 Pulse Rectifier with output voltage filtering and without input reactor filter Time (ms) 80% 5, 7, 11,.

7 Current Current Current INPUT CURRENT OF DIFFERENT NONLINEAR LOADS (Cont.) 6 - Pulse Rectifier with output voltage filtering and with 3% reactor filter or with continues output current 6 - Pulse Rectifier with large output inductor Time (ms) Time (ms) 40% 5, 7, 11,.. 28% 5, 7, 11, Pulse Rectifier % , 13, Time (ms)

8 Nonlinear load -3-phase rectifier with resistive load

9 Nonlinear load -3-phase rectifier with R-C load

10 Total harmonic distortion and effect on input power factor ( Is I 1) s I s Total harmonic distortion, THD = = 1 2 Is 1 I s1 THD I I Is I s1 s s1 2 2 I I s1 Distortion Factor = 2 1 THD s 1THD 1 2 Displacement Power Factor, DPF=cos 1, 1 is the phase angle between fundamental Voltage and fundamental current Input power factor = Displacement Factor X Distortion Factor As THD increases Distortion factor reduces and input power factor reduces 2 I I s1 s 1 1THD 2 10

11 Power Quality Issues Power quality refers to the purity of the voltage and current waveform Power quality disturbance is a deviation from the pure sinusoidal waveform. From a customer perspective, a power quality problem is defined as Any power problem manifested in voltage, current, or frequency deviations that results in power failure or disoperation of customer equipment.

12 Power Quality Issues (cont.) Sags and Swells are the most common types of power quality disturbances, resulting in downtime losses totalling a huge amount each year Sags (dips) are a decrease to between 10% and 90% of the normal voltage. Swells are an increase to between 110% and!80% of normal voltage

13 IEEE Standard Sag (dip) can be defined as, A decrease to between 0.1 and 0.9 pu in rms voltag or current at the power frequency for durations of 0.5 cycles to 1 minute Swell can be defined as, An increase to between 1.1 pu and 1.8 pu in rms voltage or current at the power frequency durations from 0.5 to 1 minute

14 Sag-Swell waveforms

15 Power quality and harmonics (cont.) Some major concerns of power quality problems are, Poor load power factor Harmonic contents in load Notching in load voltage DC offset in load voltage Unbalanced loads Supply voltage distortion Voltage sag/swell Voltage flicker etc

16 Main causes of Harmonics in Power System are Variable Speed Drives/ Variable Frequency Drives Arc Equipments Converters Power Electronic Devices Highly Fluxed Iron Cores Discharge Devices Generator Imperfection

17 EFFECTS OF HARMONICS Increases power system losses Causes excessive heating in rotating machinery Can create significant interference with communication circuits and neighborhood equipment with distorted voltage and EMI Reduces power handling capacity of power system equipments like transformers, circuit breakers etc. ( or equipments are to be derated) Dangerous to the safety of protection and control devices of the whole power system etc

18 Latest Power Quality Solutions Power Quality Solutions VOLTAGE ISSUES (Sag,Swell,Flicker) DVR Dynamic Voltage Restorer CURRENT ISSUES (Harmonics, VAR comp) STATCOM /APF Static Synchronous Compensator Result is Pure Sine wave with Rated Amplitude, Power Factor and low Harmonics Presented by Soman.U / S4 M- Tech - GECT

19 Viable solutions Power-factor-correction (PFC) techniques for reactive compensation Passive Power Filters (PPFs) 3-Phase Line Reactors Tuned single arm passive filter Tuned multiple arm passive filter Active Power Filters (APFs)

20 Active Power Filters (APFs) Active power filter has been proposed since 1970s. It provides functions such as reactive power compensations harmonic compensations negative-sequence current or voltage compensation voltage regulation etc.

21 APF consists of an inverter with switching control circuit. The inverter generate the desired compensating harmonics based on the switching algorithm provided by the controller. The APF injects harmonic current required by the non linear load and makes the current at the source side purely sinusoidal the line.

22 Single line diagram of Active Filter

23 Active Power Filters (cont.) Based on topology APF can be classified as (i) Shunt active power filter (ii) Series active power filter (iii) Hybrid active power filter

24 Shunt active power filter Used to compensate, current harmonics, reactive power and load current unbalance Static VAR generator in power system networks for stabilizing and improving voltage profile

25 Series active power filter Eliminates voltage unbalance, sag, swell etc

26 Concept of Dynamic Voltage Restorer

27 Hybrid active power filter Used for compensation of high power systems Power rating of active power filter can be reduced significantly

28 CLASSIFICATION BASED ON COMPENSATED VARIABLE A) Harmonic compensation Compensation of voltage harmonics Compensation of current harmonics B) Multiple compensation: Harmonic currents with Reactive power compensation Harmonic voltages with Reactive power compensation Harmonic currents and voltages with reactive-power compensation

29 SUPPLY-SYSTEM BASED CONFIGURATIONS Two-wire APF's Three-wire APF's Four-wire APF's

(i) Instantaneous real and reactive power (p-q) algorithm (ii) Synchronous rotating frame based (D-Q)

30 Active power filter classification based on reference signal generation Time domain load current detection, supply current detection and voltage detection. (i) Instantaneous real and reactive power (p-q) algorithm (ii) Synchronous rotating frame based (D-Q) algorithm (iii) Synchronous-detection (S-D) algorithm (iv) constant-active power algorithm (v) unity power factor algorithm (vi) ICOSɸ algorithm etc

31 Static Var Compensation DSTATCOM is APF used for reactive power compensation

32 Control of DSTATCOM using Instantaneous p-q Theory (Akagi -1984) reactive compensation va v v b v v c 2 2 I a I b I c p v v i q v v i q v i v i q * p v i v i q v i v i ia i i b i i c 2 2

33 Control of STATCOM using Instantaneous p-q Theory (cont.) Reference current calculation * 1 * v v p * * v v q i i 1 0 * i a * * 1 3 i ib (2 / 3) * * 2 2 i i c * p 0 * 1 v v 0 * * v v q i i * = Reference current to be injected for compensating the reactive power q (=q )

34 Schematic diagram of a 3-phase hysteresis controller di dt V L VL slope of inductor current L Voltage across inductor Error = Actual current-reference current Electrical & Electronics Dept. GEC, TCR 34

35 Active Power filter for harmonic and reactive compensation-instantaneous p-q Theory (Akagi -1984) (proposed by Barbosa P.G (1998), for reactive and harmonic power injection) p v i vi p v v i q v v i q v i v i va v v b v v c 2 2 p harmonic real power q = (fundamental+harmonic) reactive power 1 0 * i a * * 1 3 i i (2 / 3) b * * 2 2 i i * * * c i a i b i c * * * iac, ibc, icc are given to hysteresis controller as reference signal

36 Instantaneous p-q Theory (cont.) ia i i b i i c va v v b v v c 2 2 Reactive power = q v i v i = reference reactive power p harmonic real power q = (fundamental+harmonic) reactive power * q i, i, i are given to hysteresis controller * * * ac bc cc as reference signal

37 Schematic diagram of a 3-phase hysteresis controller di dt V L VL slope of inductor current L Voltage across inductor Error = Actual current-reference current Electrical & Electronics Dept. GEC, TCR 37

38 Reference current, actual current and switching pulses (ap & an) in hysteresis control scheme (cont.) 38

39 Simulink Models p-q theory

40 Test system data MATLAB/SimPowerSystems environment. The system parameters: Phase voltage 230 V Frequency 50Hz. Interface reactor used is 6.5 mh Dc-link capacitor is 2000µF Dc-link reference voltage being 680 V. Harmonic currents have been extracted and used as reference current signal using P-Q/D-Q Methods.

41 Non linear load modelling Three phase diode bridge rectifier with R,R-L and R-C loads 1 A A + 2 B B - 3 C C

42 System without APF A A + N B B C C -

43 System without APF(cont.) Source voltage and current 400 Souce voltage and current voltage current (V), (A) t(sec)

44 System without APF(cont.) Load current 8 Load current (A) t(sec)

45 Mag (% of Fundamental) System without APF(cont.) THD of Source current 28.13% Fundamental (50Hz) = 35.54, THD= 28.13% Harmonic order

46 System with APF Harmonic extraction method: Instantaneous real and reactive power (p-q) Theory

47 REFERENCE CURRENT GENERATION USING PQ CONTROL ALGORITHM

48 Complete model p* q* 1 ap_an_bp_bn_cp_cn 3 ic 2 ib 1 ia v + - Voltage Measurement z 1 z 1 icalpha* icbeta* ica* icb* icc* Subsystem4 p* q* Vsbeta Vsalpha icalpha* icbeta* Subsystem3 Vsaipha Vsbbeta ilalpha ilbeta p q Subsystem2 Vabc sin_cos Uabc Va Vb Vc ila ilb ilc Vsalpha Vsbeta ilalpha ilbeta Subsystem A B C A B C Smoothening Reactor Scope4 Scope3 Scope2 Scope PID Fo= 80Hz N= 1 LPF g A B C + - Inverter Iabc Iabc* Pulses Hysteresis pulse generator ican Goto4 Icref Goto3 Ibref Goto2 Iaref Goto1 Vdc Goto ilc Va ilb ila Vc Vb DC link Capcitot i + - i + - i Constant 2 pulses 1 Vabc

49 abc to (α-β) 2 Vb 3 Vc 1 Va 4 ila Vsalpha 2 Vsbeta va v v b v v c ilalpha ilb ilbeta 6 ilc.707

50 Model to obtain instantaneous real and reactive power (p-q) 1 Vsaipha 2 Vsbbeta 3 ilalpha 4 ilbeta Product Product1 Product2 Product3 1 p 2 q p v i v i q v i v i p v v i q v v i

51 Model to obtain reference currents i α* and i β * 3 Vsbeta 4 Vsalpha 1 1 p* 1 Product icalpha* * * i v v p * * i v v q 2 q* Product1 Product2 2 icbeta* u(1)*u(1) Product3 Fcn u(1)*u(1) 1/(u(1)+u(2)) Fcn2 Fcn1

52 Model to obtain reference currents i a *, i b * and i c * 1 icalpha*.816 Gain ica* 1 0 * i a * * 1 3 i ib (2 / 3) * * 2 2 i i c icbeta* Gain1.707 Gain2 2 icb* icc* Gain3.707 Gain4

53 Load current and Injected harmonic current (A) (A) t(sec) 53

54 Harmonic compensation considering a non-linear load of 3-phase diode bridge with R load Source voltage and current (V), (A) t(sec) 54

55 Total harmonic distortion and effect on input power factor ( Is I 1) s I s Total harmonic distortion, THD = = 1 2 Is 1 I 2 s1 2 I s THD 1 Is1 I I Is I s1 s s1 2 1 THD 1THD Distortion Factor = 2 2 I I s1 s 1 1THD 2 Displacement factor, DPF=cos 1, where 1 is the phase angle between fundamental Voltage and fundamental current Input power factor = Displacement Factor X Distortion Factor As THD increases Distortion factor reduces and input power factor reduces 55

56 STEPS TO PLOT THD Make sure that scope has one axes only Double click the scope to open the window Click parameters Click general to make number of axes is equals to 1 Click data history and enable save data to workspace Put variable name, say sv Make format as Structure with time Simulate the model After simulation, double click the power gui block Click on FFT analysis Select the signal sv from the available signals Give the start time, number of cycles and fundamental frequency for calculating the THD (for selecting the FFT window).make sure that number of cycle that we selected as FFT window should be inside the simulation time. Select the axis (frequency or harmonic order) Click on Display to view the THD plot.

57 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation with R load (THD=6.69%) Fundamental (50Hz) = 30.85, THD= 6.69% Harmonic order

58 Load currents 11/12/

59 Load current and Injected harmonic current for a non-linear load of 3-phase diode bridge with RL load 8 (A) (A) t(sec) 59

60 Harmonic compensation considering a non-linear load of 3-phase diode bridge with RL load (V), (A) t(sec) 60

61 Capacitor voltage (V) t(sec) 61

62 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation with RL load(thd=5.41%) Fundamental (50Hz) = 35.7, THD= 5.41% Harmonic order 62

63 Harmonic compensation considering a non-linear load of 3-phase diode bridge with RC load (V), (A) t(sec) 63

64 Load current and Injected harmonic current (A) (A) t(sec) 64

65 Capacitor voltage (V) t(sec) 65

66 Dynamic response under sudden change in load Sudden change in load at time t=0.15sec Load current and injected harmonic current (A) (A) t(sec)

67 Harmonic extraction method: Synchronous rotating frame method (D-Q Method)

68 From unit vector generator GRID SUPPLY Reference current generation using Synchronous rotating frame method (D-Q Method) a b c NON LINEAR LOAD Inverter i ac i cc i bc switching pulses V dcref Unit vector generator 3-phase hysteresis controller PI Controller cos sin 3 (i ac *, i bc *, i cc *) 3 3-phase unit voltage generator d i d * a-b-c to - - to d - q LPF d-q to a-b-c 3 i q * cos sin ia i i b i i c 2 2 d cos sin q sin cos cos sin d sin cos q 1 0 * i a * * 1 3 i ib (2 / 3) * * 2 2 i i c

69 Reference current generation using Synchronous reference frame method (Cont.) This is also called D-Q method D Direct axis Q Quadrature axis The strategy used is the Synchronous Reference Frame (SRF) strategy. Finding the components of the load current along the direction of the voltage space vector and at quadrature to it. Uses co-ordinate transformations to generate the current reference Clarke s Transformation and Park s Transformation

70 Waveforms - isa, isb & isc isα & isβ isd & isq

71 Clarke s Transformation and Inverse Clarke s transformation Three phase balanced system(a,b,c) to a two axis system (α-β). 1 (2 / 3) a 2 b 3 c * i a * * 1 3 i ib (2 / 3) * * 2 2 i i c

72 Calculation of voltage space vector From v a, v b, v c calculate v and v using Clark's transformation v V sint a m v V sin( t 120) b m v V sin( t 240) c m Then voltage vector V v jv va v 2 2 (2 / 3) v b v v c v 2 sin V t 3 m V V V 2 2 v V cost 2 m tan d-axis is chosen along voltage vector and q-axis along its quadrature 1 v v

73 Calculation of voltage and current space vector 3 3 V v jv Vmsint j Vmcos t V j Vme V e 2 2 jt j( t90 ) m o 3 o I Ime 2 j( t 90 )

74 Decomposition of current space vector into its component vectors d-component and q-component of fundamental current would directly give the active and reactive components respectively The equations of transformation can be arrived at easily by decomposition of α and β components along the d and q axis.

75 Park s transformation & Inverse Park s transformation Voltage space vector is taken as d-axis and an axis quadrature the d-axis is Taken as q-axis. The d-q axis is rotating in counter clockwise direction at synchronous speed ( 2f) with respect to stationary ( - ) axis, where f is the line frequency d cos sin q sin cos cos sin d sin cos q

76 Reference current generation in d-q plane Fundamental component appears as DC in the d-q plane. Harmonics appear as ripples in the d and q axis The dc component in the q-axis will serve as the reference for fundamental reactive current compensation. The ac (ripple) component in the d and q axis will serve as the reference for the harmonic current compensation.

77 cos θ and sin θ which are generally referred to as cos and sin unit vectors respectively cos sin V V V V Unit vector generation Unit vectors are required to transform the - quantities to synchronously rotating d-q reference frame 3 Vm sin( t) 2 sin( t). 3. Vm 2 3 Vm cos( t) 2 cos( t) 3 Vm V v jv Vmsint j Vmcos t 2 2 Magnitude of the space vector is V V V 2 2

78 From unit vector generator GRID SUPPLY APF with synchronous rotating reference method using hysteresis current control method a b c NON LINEAR LOAD i cc i ac i bc a-b-c to - Unit vector generator cos sin d - to d - q LPF 3 (i ac *, i bc *, i cc *) Inverter switching pulses 3-phase hysteresis controller PI Controller i d * d-q to a-b-c i q * cos sin 3 3 V dcref 3-phase unit voltage generator

79 Nonlinear load current, injected current, source voltage and current

80 3-PHASE HARMONIC CURRENTS Electrical & Electronics Dept. Dept. of GEC, EEE, TCR GEC,Thrissur

81 Simulink Models D-Q Method

82 Simulink model for reference current generation using D-Q Method abc_to_dq0 Transformation 1 abc Fo= 80Hz N= 1 dq ilabc 2 sin-cos sin_cos dq LPF sin_cos abc 1 Out1 dq0_to_abc Transformation

83 Freq wt Vabc (pu) Sin_Cos Model for Unit vector generation 1 Vabc 1/Vam -K- -K- 1/Vbm -K- 1/Vcm 1 sin_cos 2 Uabc

84 SIMULATION RESULTS

85 Harmonic compensation considering a non-linear load of 3-phase diode bridge with R load Source voltage and current, load current and injected harmonic current (V), (A) (A) (A) t(sec) 85

86 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation with R load(thd=4.9%) Fundamental (50Hz) = 30.79, THD= 4.90% Harmonic order 86

87 Harmonic compensation considering a non-linear load of 3-phase diode bridge with R-L load Source voltage and current, load current and injected harmonic current (V), (A) (A) (A) t(sec) 87

88 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation with R-L load(thd=4.83%) 1.8 Fundamental (50Hz) = 35.67, THD= 4.83% Harmonic order 88

89 Load current and injected harmonic current (A) (A) t(sec) 89

90 Dynamic response under sudden change in load Sudden change in load at time t=0.15sec Source voltage and current (V), (A) t(sec) 90

91 Harmonic compensation with unbalanced source Va=240V,phase=0 deg Vb=280V,phase=-125deg Vc=300V,phase=115deg Source current after compensation (A) t(sec) 91

92 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation(thd=4.46%) 1.8 Fundamental (50Hz) = 28.5, THD= 4.46% Harmonic order 92

93 Capacitor voltage (V) t(sec) 93

94 Harmonic extraction method: Synchronous Detection method (S-D Method)

95 Reference current generation using Synchronous Detection (SD) Theory Harmonics currents have been extracted and used as reference current signal using synchronous detection method. Equal current distribution method of synchronous detection algorithm: Assumptions (i) Voltage is not distorted; (ii) loss in the neutral line is negligible (iii) The peak values of source currents are balanced after compensation: I am =I bm =I cm Vam Iam VamI am Real power to be supplied from source in phase a Pa Peak values of active current in each phase after compensation are I am =2P a /V am, I bm =2P b /V bm, I cm =2P c /V cm

96 Reference current generation using Synchronous Detection Theory (Cont.) I am =2P a /V am, I bm =2P b /V bm, I cm =2P c /V cm I am =I bm =I cm 2P a /V am = 2P b /V bm = 2P c /V cm P b = (V bm /V am ).P a P c = (V cm /V am ).P a Vam Iam VamIam P Pa av = P a +P b +P c Vbm Vcm Vam Vbm Vcm Pav Pa (1 ) Pa ( ) V V V Vt Pa ( ) V P a V V am am t P av am am am Vt Vam Vbm Vcm P P b P LPF Pav c V V bm t V V cm t P av P av

97 Reference current generation using Synchronous Detection Theory (Cont.) The reference active source currents (at any instant) are calculated using the average power, P av as i sa (t)=p av *V a (t)/((v am / 2)*(V t / 2) = (2P av /V am.v t ).V a (t) i sb (t)=p av *V b (t)/((v bm / 2)*(V t / 2) = (2P av /V bm.v t ).V b (t) i sc (t)=p av *V c (t)/((v cm / 2)*(V t / 2) = (2P av /V cm.v t ).V c (t) The reference compensating current is obtained as i ca (t) = i a (t) - i sa (t) i cb (t) = i b (t) - i sb (t) i cc (t) = i c (t) - i sc (t) i ( t), i ( t) and i ( t) are load currents in phase a, phase b and phase c respectively a b c P av = P a +P b +P c V V V V t am bm cm

98 Block diagram for implementing synchronous detection algorithm i sa (t)= (2P av /V am.v t ).V a (t) i sb (t)= (2P av /V bm.v t ).V b (t) i sc (t)= (2P av /V cm.v t ).V c (t)

99 SIMULINK MODELS Synchronous Detection Method

100 Simulink model for reference current generation using SDM 1 ilabc signal rms -K- 2 signal rms Vma -K- 2 vabc signal rms Vmb -K- Vmc Vtot va i*can va iacc ican vb Fo= 80 Hz N= 1 Vam*Vt vb ibcc i*cbn 1 Out1 Goto 3 vc p Pav LPF Vbm *Vt vc i*ccn iccc Vcm*Vt

101 SUBSYSTEM- APF WITH CONTROL Vdc Goto 1 ilabc ilabc Out1 + - Voltage Measurement v 2 Vabc Vabc Unit Vector Template Generator PID Uabc vabc Contol block DC link Capcitot 680 Constant Inverter g + A B - C pulses 3 A B C Smoothening Reactor A B C i - i - i - 1 ia 2 ib 3 ic 1 z 1 z Scope Iaref Goto 1 Ibref Goto 2 Iabc Icref Goto 3 1 ap _an _bp _bn _cp_cn Pulses Iabc* Hysteresis pulse generator

102 SIMULATION RESULTS Harmonic extraction method: Synchronous detection theory

103 Load current 6 load current (A) t(sec)

104 Injected harmonic current (A) t(sec)

105 Harmonic compensation considering a non-linear load of 3-phase diode bridge with resistive load Source voltage and current source voltage and current voltage current 200 (V), (A) t(sec)

106 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation (THD=3.98%) Fundamental (50Hz) = 30.83, THD= 3.98% Harmonic order

107 Load current 8 load current (A) t(sec)

108 Injected harmonic current (A) t(sec)

109 Harmonic compensation considering a non-linear load of 3-phase diode bridge with R-L load Source voltage and current source voltage and current voltage current (V), (A) t(sec)

110 Mag (% of Fundamental) Total harmonic distortion of the source current after compensation with R-L load(thd=3.81%) Fundamental (50Hz) = 35.72, THD= 3.81% Harmonic order

111 Sudden change in load at time t=0.15sec Load current (A) t(sec)

112 Injected harmonic current (A) t(sec)

113 Dynamic response under sudden change in load Sudden change in load at time t=0.15sec Source voltage and current (V), (A) t(sec) 113

114 Comparison study METHOD USED %THD Diode bridge with R load %THD Diode bridge with RL load %THD Diode bridge with RC load Before compensation 29.4% 28.13% 29.75% SD 3.98% 3.81% 4.81% D-Q 4.90% 4.83% 5.48% P-Q 6.69% 5.41% 6.9%

115 Conclusion P-Q theory,d-q and S-D methods have been used to generate reference signals to compensate reactive and harmonic currents using shunt active power filter Hysteresis control method for harmonic current compensation has been proposed. It is shown by simulation that the proposed scheme is successfully able to track the harmonic current required to be injected. Comparison study of P-Q, D-Q and S-D methods are presented. The system has good dynamic response. 115

116 References [1] Nanda Kumar, M., Krishna Vasudevan, A novel hysteresis switching strategy for harmonic compensation, Int. J.Energy Technology and Policy, Special issue on FACTS controllers in Power systems 2006, vol.4,pp [2] Akagi H, Trends in active power conditioners Proceedings on IEEE IECON, Nov 1992, pp [3] Joao L.afonso, H.J.Ribeiro da Silva and Julio.S.Martins Active Filters for Power Quality Improvement 2001 IEEE Porto PowerTech.ISBN Porto [4] Raju, N.R., Venkata, S.S., Kagalwala, R.A. (1995) An active power quality conditioner for reactive power and harmonic compensation, Proceedings of PESC 95, Vol.1, pp [5] Rastogi, M., Mohan, N., Edris, A.A. (1995) Filtering of Harmonic Currents and Damping of Resonance in Power Systems with a Hybrid Active Filter, Proceedings on IEEE APEC 95, Vol.1, pp

117 [6] C.E. Lin, C.L.Chen and C.L.Huang, Calculating approach and implementation for Active filters in unbalanced three phase system using synchronous detection method, IEEE IECON 92, San Diego,Nov 19-21,1992, pp [7] Smedley, K.M., Qiao, C., Jin, T. (2004) One cycle control of 3- phase active filter with vector control, IEEE Transaction on Industrial Electronics, April2004, Vol.51, pp [8] Smedley, K.M., Zhou, L. (2000) Unified constant frequency integration control of active power filter, IEEE Applied Power Electronic Conference, APEC-2000, Vol.1, pp [9] Hurng-Liahng Jou, Member, IEEE, Jinn-Chang Wu, Yao-Jen Chang, and Ya-Tsung Feng A Novel Active Power Filter for Harmonic Suppression IEEE Transatctions on power delivery, Vol. 20, NO. 2, April 2005 [10] Brod, D.M., Novotny, D.W., Current Control of VSI-PWM Inverters. IEEE Transactions on Industry Applications, IA-21,

118 Thank you

Control of Grid Interactive Inverter Systems

Control of Grid Interactive Inverter Systems Dr. M.Nanda Kumar Professor Dept. of Electrical Engg. Govt. Engineering College, Thrissur What is a Grid interactive inverter? DC Source Inverter AC Grid TCR