Power Quality Improvement of PMSG Based DG Set Feeding Three-Phase Loads

ABSTRACT:

This paper presents power quality improvement of PMSG (Permanent Magnet Synchronous Generator) based DG (Diesel Generator) set feeding three-phase loads using STATCOM (Static Compensator). A 3-leg VSC (Voltage Source Converter) with a capacitor on the DC link is used as STATCOM. The reference source currents for the system are estimated using an Adaline based control algorithm. A PWM (Pulse Width Modulation) current controller is using for generation of gating pulses of IGBTs (Insulated Gate Bipolar Transistors) of three leg VSC of the STATCOM. The STATCOM is able to provide voltage control, harmonics elimination, power factor improvement, load balancing and load compensation. The performance of the system is experimentally tested on various types of loads under steady state and dynamic conditions. A 3-phase induction motor with variable frequency drive is used as a prototype of diesel engine with the speed regulation. Therefore, the DG set is run at constant speed so that the frequency of supply remains constant irrespective of loading condition.

KEYWORDS:

  1. STATCOM
  2. VSC
  3. IGBTs
  4. PMSG
  5. PWM
  6. DG Set
  7. Power Quality

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1 Configuration of PMSG based DG set feeding three phase loads.

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Dynamic performance at linear loads (a) vsab, isa,isb and isc ,(b) vsab, iLa,iLb and iLc (c) Vdc, isa,iLa and iCa

CONCLUSION:

The STATCOM has improved the power quality of the PMSG based DG set in terms voltage control, harmonics elimination and load balancing. Under linear loads, there has been negligible voltage variation (From 219.1 V to 220.9 V) and in case of nonlinear load, the voltage increases to 221 V. Thus, the STATCOM has been found capable to maintain the terminal voltage of DG set within ± 0.5% (220 ±1 V) under different linear and nonlinear loads.

Under nonlinear loads, the load current of DG set is a quasi square with a THD of 24.4 %. The STATCOM has been found capable to eliminate these harmonics and thus the THD of source currents has been limited to 3.9 % and the THD of terminal voltage has been observed of the order of 1.8%. Therefore, the THDs of source voltage and currents have been maintained well within limits of IEEE-519 standard under nonlinear load.

It has also been found that the STATCOM maintains balanced source currents when the load is highly unbalanced due to removal of load from phase ‘c’. The load balancing has  also been achieved by proposed system with reduced stress on the winding of the generator.

The proposed system is a constant speed DG set so there is no provision of frequency control in the control algorithm.

However, the speed control mechanism of prototype of the diesel engine is able to maintain the frequency of the supply almost at 50 Hz with small variation of ±0.2 %.

Therefore, the proposed PMSG based DG set along with STATCOM can be used for feeding linear and nonlinear balanced and unbalanced loads. The proposed PMSG based DG set has also inherent advantages of low maintenance, high efficiency and rugged construction over a conventional wound field synchronous generator based DG set.

 REFERENCES:

[1] Xibo Yuan; Fei Wang; Boroyevich, D.; Yongdong Li; Burgos, R., “DC-link Voltage Control of a Full Power Converter for Wind Generator Operating in Weak-Grid Systems,” IEEE Transactions on Power Electronics, vol.24, no.9, pp.2178-2192, Sept. 2009.

[2] Li Shuhui, T.A. Haskew, R. P. Swatloski and W. Gathings, “Optimal and Direct-Current Vector Control of Direct-Driven PMSG Wind Turbines,” IEEE Trans. Power Electronics, vol.27, no.5, pp.2325-2337, May 2012.

[3] M. Singh and A. Chandra, “Application of Adaptive Network-Based Fuzzy Inference System for Sensorless Control of PMSG-Based Wind Turbine With Nonlinear-Load-Compensation Capabilities,” IEEE Trans. Power Electronics, vol.26, no.1, pp.165-175, Jan. 2011.

[4] A. Rajaei, M. Mohamadian and A. Yazdian Varjani, “Vienna-Rectifier-Based Direct Torque Control of PMSG for Wind Energy Application,” IEEE Trans. Industrial Elect., vol.60, no.7, pp.2919-2929, July 2013.

[5] Mihai Comanescu, A. Keyhani and Dai Min, “Design and analysis of 42-V permanent-magnet generator for automotive applications,” IEEE Trans. Energy Conversion, vol.18, no.1, pp.107-112, Mar 2003.

Performance comparison of PI & ANN based STATCOM for 132 KV transmission line  

ABSTRACT:

 This paper presents simulation model of the 132KV transmission line with comparison of ANN based STATCOM and conventional PI based STATCOM. The STATCOM being the state-of-the-art VSC based dynamic shunt compensator in FACTS family is used now a days in transmission system for reactive power control, increase of power transfer capacity, voltage regulation etc. Such type of controller is applied at the middle of the transmission line to enhance the power transmission capacity of the line. The simulation result shows that the STATCOM is effective improve the power factor and voltage regulation for the 132kV line loading.

 KEYWORDS:

  1. STATCOM
  2. PI
  3. ANN control strategy
  4. MatLab simulink

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig 1: Schematic Representation of the Control Circuit.

 EXPECTED SIMULATION RESULTS:

 

Fig 2 1-phase current and voltage waveform using STATCOM

Fig3 Phase Current and Voltage waveform when the STATCOM is ON

Fig 4Phase Current and Voltage waveform when Load is Varied in the system

Fig 5 Phase Current and Voltage waveform when suddenly a Load is remove from the system at 0.4sec

Fig 6 3-phase current and voltage waveform using STATCOM

Fig 7 Active and Reactive power flow in Transmission system using STATCOM

Fig8 1-phase current and voltage waveform for STATCOM using ANN

Fig 9 Phase Current and Voltage waveform when the STATCOM is ON

Fig 10 1 Phase Current and Voltage waveform when Load is Varied in the System

Fig11 3-phase voltage and current waveform for STATCOM using ANN

CONCLUSION:

The paper present that the STATCOM bring the power factor to the unity thereby enhancing the power transfer capability by supplying or absorbing controllable amount of reactive power. By using a STATCOM with ANN controller and the Response time is faster comparing to the PI Controller because of this voltage regulation maintained within a limit. More over ANN Controlled STATCOM will improve the stability of the system and improve the dynamic performance of the system.

REFERENCES:

[1] B.Sing ,R.saha, A.Chandra “Static Synchronous Compensator (STATCOM): a review” IET Power Electronic 2008

[2] N.G Hingroni and I Gyugyi. “Understanding FACTS: Concepts and Technology of flexible AC Transmission System”, IEEE Press, New York, 2000.

[3] D.J Hanson, M.L.Woodhouse, C.Horwill “STATCOM: a new era of Reactive Compensation” Power Engineering Journal June 2002

[4] Mustapha Benghanem — Azeddine Draou” A NEW MODELLING AND CONTROL ANALYSIS OF AN ADVANCED STATIC VAR COMPENSATOR USING A THREE–LEVEL (NPC) INVERTER TOPOLOGY” Journal of ELECTRICAL ENGINEERING, VOL. 57, NO. 5, 2006, 285–290

[5] Jagdish Kumar, Biswarup Das, and Pramod Agarwal “ Modeling of 11- Level Cascade Multilevel STATCOM” International Journal of Recent Trends in Engineering, Vol 2, No. 5, November 2009

Comparative Analysis of 6, 12 and 48 Pulse T-STATCOM

 ABSTRACT:

 This paper presents the performance and comparative analysis of Static Synchronous Compensator (STATCOM) based on 6, 12 and 48-pulse VSC configuration. STATCOM is implemented for regulation of the voltage at the Point of Common Coupling (PCC) bus which has time-variable loads. The dq decoupled current control strategy is used for implementation of STATCOM, where modulation index M and phase angle ø are varied for achieving voltage regulation at the PCC bus. The 6, 12 and 48-pulse configurations are compared and analyzed on the basis of Total Harmonic Distortion (THD) and time response parameters such as rise time, maximum overshoot and settling time. The simulation of various configurations of STATCOM is carried out using power system block-set in MATLAB/Simulink platform.

KEYWORDS:

  1. FACTS
  2. STATCOM
  3. Decoupled current control system
  4. Voltage Sourced Converter
  5. Total Harmonic Distortion

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig.1:Single line diagram of STATCOM.

 EXPECTED SIMULATION RESULTS:

 

 

Fig. 2: PCC bus voltage-VM for 6, 12 and 48 pulse STATCOM respectively.

Fig. 3: q-axis STATCOM current-ishq for PI controller of 6, 12 and 48 pulse STATCOM respectively.

Fig. 4: d-axis STATCOM current-ishd for PI controller of 6, 12 and 48 pulse STATCOM respectively.

a: Dc capacitor voltage-Vdc

b: Active power of loads-PL

c: Reactive power-Qstat

                                d: Active power-Pstat

Fig. 5: Vdc, PL, Qstat and Pstat for 48 pulse STATCOM respectively.

CONCLUSION:

In this paper, for voltage regulation and dynamic power flow control a 48-pulse ±100 MVA two-level GTO STATCOM has been modeled and simulated using decoupled current control strategy. By varying the modulation index (M) and phase angle (ɸ) between PCC bus voltage and STATCOM voltage, voltage regulation at the PCC bus is achieved. The THD and various time response parameters of 6, 12 and 48 pulse STATCOM are compared. The results show that THD of output voltage of 48 pulse STATCOM is less than 5%, which satisfies the IEEE 519 standard. Hence, there is no need of active filter. Also, 48 pulse STATCOM has better transient response as compared to 6, 12 pulse STATCOM.

REFERENCES:

[1] K. Padiyar, FACTS controllers in power transmission and distribution. New Age International, 2007.

[2] K. K. Sen and M. L. Sen, Introduction to FACTS controllers: theory, modeling, and applications. John Wiley & Sons, 2009, vol. 54.

[3] A. Edris, “Facts technology development: an update,” IEEE Power engineering review, vol. 20, no. 3, pp. 4–9, 2000.

[4] El-Moursi and A.M. Sharaf, “Novel controllers for the 48-pulse vscstatcom and ssscfor voltage regulation and reactive power compensation,” IEEE Transactions on Powersystems, vol. 20, no. 4, pp. 1985–1997, 2005.

[5] N. G. Hingorani and L. Gyugyi, Understanding FACTS: concepts and technology of flexible AC transmission systems. Wiley-IEEE press, 2000.

Modeling of 18-Pulse STATCOM for Power System Applications

ABSTRACT:

 A multi-pulse GTO based voltage source converter (VSC) topology together with a fundamental frequency switching mode of gate control is a mature technology being widely used in static synchronous compensators (STATCOMs). The present practice in utility/industry is to employ a high number of pulses in the STATCOM, preferably a 48-pulse along with matching components of magnetics for dynamic reactive power compensation, voltage regulation, etc. in electrical networks. With an increase in the pulse order, need of power electronic devices and inter-facing magnetic apparatus increases multi-fold to achieve a desired operating performance. In this paper, a competitive topology with a fewer number of devices and reduced magnetics is evolved to develop an 18-pulse, 2-level + 100MVAR STATCOM in which a GTO-VSC device is operated at fundamental frequency switching gate control. The inter-facing magnetics topology is conceptualized in two stages and with this harmonics distortion in the network is minimized to permissible IEEE-519 standard limits. This compensator is modeled, designed and simulated by a Sim Power Systems tool box in MATLAB platform and is tested for voltage regulation and power factor correction in power systems. The operating characteristics corresponding to steady state and dynamic operating conditions show an acceptable performance.

KEYWORDS:

  1. Fast Fourier transformation
  2. Gate-turn off thyristor
  3. Magnetic
  4. STATCOM
  5. Total harmonic distortion
  6. Voltage source converter

SOFTWARE: MATLAB/SIMULINK

MATLAB MODEL:

Fig. 1 MATLAB model of ±100MVAR 18-pulse STATCOM

EXPECTED SIMULATION RESULTS:

Fig. 2 Three phase instantaneous voltage(va , vb, vc) and current (ia, ib, ic) with 75MW 0.85pf lagging load when V* sets at 1.0pu, 1.03pu and 0.97pu

Fig. 3 Operating characteristics in voltage regulation mode for 70MW, 0.85pf(lag) load

Fig. 4 Voltage(va) spectrum in capacitive mode

Fig. 5. Voltage spectrum (va) in inductive mode.

Fig. 6. Current (ia) spectrum in capacitive mode.

Fig. 7. Current spectrum (ia) in inductive mode.

Fig. 8 Operating characteristics for unity power factor (upf) Correction in var control mode for 75MW, 0.85pf(lag) load

Fig. 9. Voltage harmonics(va) spectrum for upf correction.

Fig. 10 Current harmonics(ia) spectrum for upf correction

Fig. 11 Operating characteristics following 10% load injection at the instant of 0.24s in voltage regulation mode on 70MW, 0.85pf(lag) load

Fig. 12 Voltage harmonics (va) spectrum after load variation

Fig. 13. Current harmonics (ia) spectrum after load variation.

Fig. 14 Operating characteristics in var control mode for incremental Load variation of 10% at the instant of 0.24s on an initial load of 70MW, 0.85pf(lag)

Fig. 15 Voltage harmonics (va) spectrum after the load injection

Fig. 16. Current harmonics (ia) spectrum after the load injection.

CONCLUSION:

A new 18-pulse, 2-level GTO-VSC based STATCOM with a rating of + 100MVAR, 132kV was modeled by employing three fundamental 6-pulse VSCs operated at fundamental frequency gate switching in MATLAB platform using a Sim Power Systems tool box. The inter-facing magnetics have evolved in two stage sinter- phase transformers (stage-I) and phase shifter (stage-II), and with this topology together with standard PI-controllers, harmonics distortion in the network has been greatly minimized to permissible IEEE-519 standard operating limits [9]. The compensator was employed for voltage regulation, power factor correction and also tested for dynamic load variation in the network. It was observed from the various operating performance characteristics which emerged from the simulation results that the model satisfies the network requirements both during steady state and dynamic operating conditions. The controller has provided necessary damping to settle rapidly steady states for smooth operation of the system within a couple of cycles. The proposed GTO-VSC based 18-pulse STATCOM seems to provide an optimized model of competitive performance in multi-pulse topology.

REFERENCES:

[1] Colin D. Schauder, “Advanced Static VAR Compensator Control System,” U.S. Patent 5 329 221, Jul. 12, 1994.

[2] Derek A. Paice, “Optimized 18-Pulse Type AC/DC, or DC/AC Converter System,” U.S. Patent 5 124 904, Jun. 23, 1992.

[3] Kenneth Lipman, “Harmonic Reduction for Multi-Bridge Converters,” U.S. Patent 4 975 822, Dec. 4, 1990.

[4] K.K. Sen, “Statcom – Static Synchronous Compensator: Theory, Modeling, And Applications,” IEEE PES WM, 1999,Vol. 2, pp. 1177 –1183.

[5] Guk C. Cho, Gu H. Jung, Nam S. Choi, et al. “Analysis and controller design of static VAR compensator using three-level GTO inverter,” IEEE Transactions Power Electronics, Vol.11, No.1, Jan 1996, pp. 57 –65.

Cascaded Control of Multilevel Converter based STATCOM for Power System Compensation of Load Variation

ABSTRACT:

The static synchronous compensator (STATCOM) is used in power system network for improving the voltage of a particular bus and compensate the reactive power.It can be connected to particular bus as compensating device to improve the voltage profile and reactive power compensation. In this paper, a multi function controller is proposed and discussed. The control concept is based on a linearization of the d-q components with cascaded controller methods. The fundamental parameters are controlled with using of proportional and integral controller. In closed loop method seven level cascaded multilevel converter (CMC) is proposed to ensure the stable operation for damping of power system oscillations and load variation.

KEYWORDS:

  1. FACTS
  2. PWM
  3. CMC
  4. STATCOM

 SOFTWARE: MATLAB/SIMULINK

TEST SYSTEM:

 Figure 1.STATCOM network connection.

 EXPECTED SIMULATION RESULTS:

Figure 2. Load terminal dq0 Currents with Load variation

Figure 3. Source terminal dq0 Currents with Load variation.

Figure 4. Iqref output for load rejection.

Figure 5. Source Voltage for load rejection with AGC.

Figure 6. THD of output Voltage of Cascaded Multilevel converter.

Figure 7. THD of output Current of Cascaded Multilevel Converter

Figure 8.Source Active and Reactive power.

Figure 9. Power factor in Load and Source Bus

Figure 10.Three phase Supply Voltage of multilevel converter.

 CONCLUSION:

The cascaded controller is designed for seven level CMC based STATCOM. This control scheme regulates the capacitor voltage of the STATCOM and maintain rated supply voltage for any load variation with in the rated value. It has been shown that the CMC is able to reduce the THD values of output voltage and current effectively. The CMC based STATCOM ensures that compensate the reactive power and reduce the harmonics in output of STATCOM.

 REFERENCES:

[1] N. Hingorani and L. Gyugyi, 2000, “Understanding FACTS: Concepts and Technology Flexible AC Transmission Systems”, New York: IEEE Press.

[2] P. Lehn and M. Iravani, Oct.1998, “Experimental evaluation of STATCOM closed loop dynamics”, IEEE Trans. Power Delivery, vol.13, pp.1378-1384.

[3] Mahesh K.Mishra and Arindam Ghosh, Jan 2003, ”Operation of a D-STATCOM in Voltage Control Mode”, IEEE Trans. Power Delivery, vol.18, pp.258-264.

[4] Arindam Ghosh, Avinash Joshi, Jan 2000, ”A New Approach to Load Balancing and Power Factor Correction in Power Distribution System”, IEEE Trans. Power Delivery, vol.15, No.1, pp. 417-422.

[5] Arindam Ghosh, Gerard Ledwich, Oct 2003,”Load Compensating DSTATCOM in Weak AC Systems”, IEEE Trans. Power Delivery, vol.18, No.4, pp.1302-1309.

 

A Five Level Cascaded H-Bridge Multilevel STATCOM

ABSTRACT:

This paper describes a three-phase cascade Static Synchronous Compensator (STATCOM) without transformer. Lt presents a control algorithm that meets the demand of load reactive power and also voltage balancing of isolated dc capacitors for H-bridges. The control algorithm used for inverter in this paper is based on a phase shifted carrier (PSC) modulation strategy that has no restriction on the cascaded number. The performance of the STATCOM for different changes of loads was simulated.

 KEYWORDS:

  1. STATCOM
  2. PSCPWM
  3. Cascaded Multilevel Inverter

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig1.cascaded multilevel STATCOM.

EXPECTED SIMULATION RESULTS:

 

Fig. 2 Source voltage, source current and inverter current far inductive load(sourece current gain-5 and Inverter current gain-8).

Fig. 3 Load & Inverter Reactive componenets of current for Inductive load.

F ig. 4 Response of DC link voltage for inductive load.

Fig. 5 Source voltage and inverter current for the change of inductive load to half of the load at I sec(lnverter current gain-8)

Fig. 6 Load & Inverter Reactive componenets of current for the change of Inductive load to half of the load at I sec.

Fig. 7 Source voltage and inverter current for the change of inductive load to standby at 1 sec (Inverter current gain-8).

Fig. 8 Load & Inverter Reactive componenets of current for the change of Inductive load to standby at 1 sec

F ig. 9 Inverter Output Voltage

Fig. 10 Harmonie spectrum ofInverter line voltage.

Fig. 11 Load & Inverter reactive component for the change of Inductive to

capacitive load at 1.5 Sec.

Fig. 12 Response of oe link voltage for change in mode of operation from

inductive to capacitive load at 1.5 Sec.

Fig. 13 Inverter reactive component for the change of Inductive to capacitive load at 2 Sec

Fig. 14 Response of OC link voltage for change in mode of operation from inductive to capacitive at 2 Sec

CONCLUSION:

The cascaded H-bridge multilevel topology is used as one of the more suitable topologies for reactive-power compensation applications. This paper presents a new control strategy for cascaded H-bridge multilevel converter based STATCOM. By this control strategy, the dc-link voltage of the inverter is controlled at their respective values when the ST A TCOM mode is converted from inductive to capacitive. The dc link voltages of the inverter are kept balanced in all the circumstances, and the reactive power that is produced by the STATCOM is equally distributed among all the H-bridges.

REFERENCES:

[1] N. N. V. Surendra Babu, and B.G. Fernandes, ” Cascaded Two Level Inverter- Based Multilevel ST ATCOM for High-Power Applications,” IEEEE Trans. Power Delivery., vol. 29, no. 3, pp. 993-1001, lune. 2014.

[2] N.G. Hingorani and L. Gyagyi, “Understanding F ACTS”, Delhi, India: IEEE, 2001, Standard publishers distributors.

[3] B. Singh, R. Saha, A. Chandra, and K. AI- Haddad, ” Static synchronous compensators (ST A TCOM): A review, ” lET Power Electron., vol. 2, no. 4, pp. 297-324, 2009.

[4] Hirofumi Akagi, Shigenori Inoue and Tsurugi Yoshii, “Control and Performance of a Transformerless Cascade PWM ST A TCOM With Star Contiguration,” IEEE Trans. Ind. Appl., vol. 43, no. 4, pp. 1041-1049, July/ August 2007.

[5] H. Akagi, H. Fujita, S.Yonetaniand Y. Kondo, “A 6.6-kV transformerless ST ATCOM based on a tivelevel diode-clamped PWM converter: System design and experimentation of a 200-V 1 O-kV A laboratory model,” IEEE Trans. Ind. Appl., vol. 44, no. 2, pp. 672-680, Mar./Apr. 2008.

Enhancement of Power Quality in Distribution System using D-Statcom

ABSTRACT:

STATCOM (static synchronous compensator) as a shunt-link flexible AC transmission system(FACTS) controller has shown extensive feasibility in terms of cost-effectiveness in a wide range of problem solving abilities from transmission to distribution levels. Advances in power electronic technologies such as Voltage Source Converter (VSC) improves the reliability and functionality of power electronic based controllers hence resulting in increased applications of STATCOM. In this paper, design and implementation of a Distribution type, Voltage Source Converter (VSC) based static synchronous compensator (DSTATCOM) has been carried out. It presents the enhancement of power quality problems, such as voltage sag and swell using Distribution Static Compensator (D-STATCOM) in distribution system. The model is based on Sinusoidal Pulse Width Modulation (SPWM) technique. The control of the Voltage Source Converter (VSC) is done with the help of SPWM. The main focus of this paper is to compensate voltage sag and swell in a distribution system. To solve this problem custom power devices are used such as Fixed Compensators (FC, FR), Synchronous Condenser, SVC, SSSC, STATCOM etc. Among these devices Distribution STATCOM (DSTATCOM) is the most efficient and effective modern custom power device used in power distribution networks. DSTATCOM injects a current into the system to mitigate the voltage sag and swell. The work had been carried out in MATLAB environment using Simulink and SIM power system tool boxes. The proposed D-STATCOM model is very effective to enhance the power quality of an isolated distribution system feeding power to crucial equipment in remote areas. The simulations were performed and results were found to be satisfactory using MATLAB/SIMULINK.

KEYWORDS:

  1. Statcom
  2. Facts Controllers
  3. D-Statcom
  4. Voltage Source Converter
  5. Total Harmonic Distortions

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Schematic diagram of D-STATCOM

 EXPECTED SIMULATION RESULTS:

 

 Fig.2 Three Phase to Ground -Voltage at Load Point is 0.6600 p.u

Fig.3 Double Line to Ground- Voltage at Load Point is 0.7070 p.u

Fig.4 Line to Line- Voltage at Load Point is 0.7585

Fig.5 Single Line to Ground- Voltage at Load Point is 0.8257

Fig.6 The waveforms shows THD (41.31%) results of fixed load and variable inductive load.

Fig..7 The wave forms shows THD (21.28%) results of fixed load and variable capacitive load

Fig.8 Three Phase to Ground-Voltage at Load Point is 0.9367 p.u

Fig.9 Double Line to Ground- Voltage at Load Point is0.9800 p.u

Fig.10 Line to Line- Voltage at Load Point is 1.068

Fig.11 Single Line to Ground – Voltage at Load Point is 0.9837

Fig.12 The waveform for pure inductive,capacitive loads with statcom

Fig.13 The waveform for without filter THD results 41.31%

Fig.14 The above waveform for with filter THD results 1.11%

 CONCLUSION:

The simulation results show that the voltage sags can be mitigate by inserting D-STATCOM to the distribution system. By adding LCL Passive filter to D-STATCOM, the THD reduced. The power factors also increase close to unity. Thus, it can be concluded that by adding DSTATCOM with LCL filter the power quality is improved.

REFERENCES:

[1] A.E. Hammad, Comparing the Voltage source capability of Present and future Var Compensation Techniques in Transmission System, IEEE Trans, on Power Delivery. Volume 1. No.1 Jan 1995.

[2] G.Yalienkaya, M.H.J Bollen, P.A. Crossley, “Characterization of Voltage Sags in Industrial Distribution System”, IEEE transactions on industry applications, volume 34, No. 4, July/August, PP.682-688, 1999

[3] Haque, M.H., “Compensation of Distribution Systems Voltage sags by DVR and D STATCOM”, Power Tech Proceedings, 2001 IEEE Porto, Volume 1, PP.10-13, September 2001.

[4] Anaya-Lara O, Acha E., “Modeling and Analysis Of Custom Power Systems by PSCAD/EMTDC”, IEEE Transactions on Power Delivery, Volume 17, Issue: 2002, Pages: 266 272.

[5] Bollen, M.H.J.,”Voltage sags in Three Phase Systems”, Power Engineering Review, IEEE, Volume 21, Issue: 9, September 2001, PP: 11-

 

Enhancement of Power Quality in Distribution System using D-Statcom

 

ABSTRACT:

STATCOM (static synchronous compensator) as a shunt-link flexible AC transmission system(FACTS) controller has shown extensive feasibility in terms of cost-effectiveness in a wide range of problem solving abilities from transmission to distribution levels. Advances in power electronic technologies such as Voltage Source Converter (VSC) improves the reliability and functionality of power electronic based controllers hence resulting in increased applications of STATCOM. In this paper, design and implementation of a Distribution type, Voltage Source Converter (VSC) based static synchronous compensator (DSTATCOM) has been carried out. It presents the enhancement of power quality problems, such as voltage sag and swell using Distribution Static Compensator (D-STATCOM) in distribution system. The model is based on Sinusoidal Pulse Width Modulation (SPWM) technique. The control of the Voltage Source Converter (VSC) is done with the help of SPWM.

The main focus of this paper is to compensate voltage sag and swell in a distribution system. To solve this problem custom power devices are used such as Fixed Compensators (FC, FR), Synchronous Condenser, SVC, SSSC, STATCOM etc. Among these devices Distribution STATCOM (DSTATCOM) is the most efficient and effective modern custom power device used in power distribution networks. DSTATCOM injects a current into the system to mitigate the voltage sag and swell. The work had been carried out in MATLAB environment using Simulink and SIM power system tool boxes. The proposed D-STATCOM model is very effective to enhance the power quality of an isolated distribution system feeding power to crucial equipment in remote areas. The simulations were performed and results were found to be satisfactory using MATLAB/SIMULINK.

KEYWORDS:

  1. Statcom
  2. Facts Controllers
  3. D-Statcom
  4. Voltage Source Converter
  5. Total Harmonic Distortions

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 Schematic diagram of D-STATCOM

 EXPECTED SIMULATION RESULTS:

 

Fig.2 Three Phase to Ground -Voltage at Load Point is 0.6600 p.u

Fig.3 Double Line to Ground- Voltage at Load Point is 0.7070 p.u

Fig.4 Line to Line- Voltage at Load Point is 0.7585

Fig.5 Single Line to Ground- Voltage at Load Point is 0.8257

Fig.6 The waveforms shows THD (41.31%) results of fixed load and variable inductive load.

 

Fig.7 The wave forms shows THD (21.28%) results of fixed load and variable capacitive load

Fig.8 Three Phase to Ground-Voltage at Load Point is 0.9367 p.u

Fig.9 Double Line to Ground- Voltage at Load Point is0.9800 p.u

Fig.10 Line to Line- Voltage at Load Point is 1.068

Fig.11 Single Line to Ground – Voltage at Load Point is 0.9837

Fig.12 The waveform for pure inductive,capacitive loads with statcom

Fig.13 The waveform for without filter THD results 41.31%

Fig.14 The above waveform for with filter THD results 1.11%

 

CONCLUSION:

The simulation results show that the voltage sags can be mitigate by inserting D-STATCOM to the distribution system. By adding LCL Passive filter to D-STATCOM, the THD reduced. The power factors also increase close to unity. Thus, it can be concluded that by adding DSTATCOM with LCL filter the power quality is improved.

 REFERENCES:

[1] A.E. Hammad, Comparing the Voltage source capability of Present and future Var Compensation Techniques in Transmission System, IEEE Trans, on Power Delivery. Volume 1. No.1 Jan 1995.

[2] G.Yalienkaya, M.H.J Bollen, P.A. Crossley, “Characterization of Voltage Sags in Industrial Distribution System”, IEEE transactions on industry applications, volume 34, No. 4, July/August, PP.682-688, 1999

[3] Haque, M.H., “Compensation of Distribution Systems Voltage sags by DVR and D STATCOM”, Power Tech Proceedings, 2001 IEEE Porto, Volume 1, PP.10-13, September 2001.

[4] Anaya-Lara O, Acha E., “Modeling and Analysis Of Custom Power Systems by PSCAD/EMTDC”, IEEE Transactions on Power Delivery, Volume 17, Issue: 2002, Pages: 266 272.

[5] Bollen, M.H.J.,”Voltage sags in Three Phase Systems”, Power Engineering Review, IEEE, Volume 21, Issue: 9, September 2001, PP: 11-

Doubly Fed Induction Generator for Wind Energy Conversion Systems with Integrated Active Filter Capabilities

ABSTRACT

This paper deals with the operation of doubly fed induction generator (DFIG) with an integrated active filter capabilities using grid-side converter (GSC). The main contribution of this work lies in the control of GSC for supplying harmonics in addition to its slip power transfer. The rotor-side converter (RSC) is used for attaining maximum power extraction and to supply required reactive power to DFIG. This wind energy conversion system (WECS) works as a static compensator (STATCOM) for supplying harmonics even when the wind turbine is in shutdown condition. Control algorithms of both GSC and RSC are presented in detail. The proposed DFIG-based WECS is simulated using MATLAB/Simulink. A prototype of the proposed DFIGbased WECS is developed using a digital signal processor (DSP). Simulated results are validated with test results of the developed DFIG for different practical conditions, such as variable wind speed and unbalanced/single phase loads.

 KEYWORDS

  1. Doubly fed induction generator (DFIG)
  2. Integrated active filter
  3. Nonlinear load
  4. Power quality
  5. Wind energy conversion system (WECS).

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

image001

Fig. 1. Proposed system configuration.

image002

Fig. 2. Control algorithm of the proposed WECS.

EXPECTED SIMULATION RESULTS

Simulated performance of the proposed DFIG-based WECS at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).

Fig. 3. Simulated performance of the proposed DFIG-based WECS at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).

Simulated waveform and harmonic spectra of (a) grid current (iga), (b) load current (ila), (c) stator current (isa), and (d) grid voltage for phase “a” (vga) at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).

Fig. 4. Simulated waveform and harmonic spectra of (a) grid current (iga), (b) load current (ila), (c) stator current (isa), and (d) grid voltage for phase “a” (vga) at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).

Simulated performance of the proposed DFIG-basedWECS working as a STATCOM at zero wind speed

Fig. 5. Simulated performance of the proposed DFIG-basedWECS working as a STATCOM at zero wind speed.

image006

Fig. 6. Simulated waveforms and harmonic spectra of (a) load current (ila) and (b) grid current (iga) working as a STATCOM at wind turbine shut down condition.

image007

Fig. 7. Simulated performance of proposed DFIG for fall in wind speed.

Dynamic performance of DFIG-based WECS for the sudden removal and application of local loads.

Fig. 8. Dynamic performance of DFIG-based WECS for the sudden removal and application of local loads.

CONCLUSION

The GSC control algorithm of the proposed DFIG has been modified for supplying the harmonics and reactive power of the local loads. In this proposed DFIG, the reactive power for the induction machine has been supplied from the RSC and the load reactive power has been supplied from the GSC. The decoupled control of both active and reactive powers has been achieved by RSC control. The proposed DFIG has also been verified at wind turbine stalling condition for compensating harmonics and reactive power of local loads. This proposed DFIG-based WECS with an integrated active filter has been simulated using MATLAB/Simulink environment, and the simulated results are verified with test results of the developed prototype of this WECS. Steady-state performance of the proposed DFIG has been demonstrated for a wind speed. Dynamic performance of this proposed GSC control algorithm has also been verified for the variation in the wind speeds and for local nonlinear load.

 REFERENCES

  1. M. Tagare, Electric Power Generation the Changing Dimensions. Piscataway, NJ, USA: IEEE Press, 2011.
  2. M. Joselin Herbert, S. Iniyan, and D. Amutha, “A review of technical issues on the development of wind farms,” Renew. Sustain. Energy Rev., vol. 32, pp. 619–641, 2014.
  3. Munteanu, A. I. Bratcu, N.-A. Cutululis, and E. Ceang, Optimal Control of Wind Energy Systems Towards a Global Approach. Berlin, Germany: Springer-Verlag, 2008.
  4. A. B. Mohd Zin, H. A. Mahmoud Pesaran, A. B. Khairuddin, L. Jahanshaloo, and O. Shariati, “An overview on doubly fed induction generators controls and contributions to wind based electricity generation,” Renew. Sustain. Energy Rev., vol. 27, pp. 692–708, Nov. 2013.
  5. S. Murthy, B. Singh, P. K. Goel, and S. K. Tiwari, “A comparative study of fixed speed and variable speed wind energy conversion systems feeding the grid,” in Proc. IEEE Conf. Power Electron. Drive Syst. (PEDS’07), Nov. 27–30, 2007, pp. 736–743.

Digital Simulation of the Generalized Unified Power Flow Controller System with 60-Pulse GTO-Based Voltage Source Converter

 

ABSTRACT:

The Generalized Unified Power Flow Controller (GUPFC) is a Voltage Source Converter (VSC) based Flexible AC Transmission System (FACTS) controller for shunt and series compensation among the multiline transmission systems of a substation. The paper proposes a full model comprising of 60-pulse Gate Turn-Off thyristor VSC that is constructed becomes the GUPFC in digital simulation system and investigates the dynamic operation of control scheme for shunt and two series VSC for active and reactive power compensation and voltage stabilization of the electric grid network. The complete digital simulation of the shunt VSC operating as a Static Synchronous Compensator (STATCOM) controlling voltage at bus and two series VSC operating as a Static Synchronous Series Capacitor (SSSC) controlling injected voltage, while keeping injected voltage in quadrature with current within the power system is performed in the MATLAB/Simulink environment using the Power System Block set (PSB). The GUPFC, control system scheme and the electric grid network are modeled by specific electric blocks from the power system block set. The controllers for the shunt VSC and two series VSCs are presented in this paper based on the decoupled current control strategy. The performance of GUPFC scheme connected to the 500-kV grid is evaluated. The proposed GUPFC controller scheme is fully validated by digital simulation.

KEYWORDS:

60-Pulse GTO Thyristor Model VSC, UPFC, GUPFC,Active and Reactive Compensation, Voltage Stability

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

UPFC with 60-Pulse GTO-Based Voltage Source Converter

Figure 1. Three-bus system with the GUPFC at bus B5 and B2

EXPECTED SIMULATION RESULTS:

2

 Figure 2. Sixty-pulse VSC output voltage

3

Figure 3. Simulated results of the GUPFC .shunt converter operation for DC voltage with Qref = 0.3pu; 0.5 pu

4

Figure 4. Simulated results of the GUPFC series converter operation Pref=8.7pu; 10pu, Qref=-0.6pu; 0.7pu

5

Figure 5. Simulated results of the GUPFC series converter operation Pref=7.7pu; 9.0pu, Qref=-0.5pu; 0.9pu

6

Figure 6. Digital simulation results for the decoupled current controller schemes for the shunt VSC in a weak power system

 CONCLUSION:

The paper presents and proposes a novel full 60-pulse GTO voltage source converter that it constructed becomes GUPFC FACTS devices. It comprises the full 60-pulse VSC-cascade models connected to the grid network through the coupling transformer. These full descriptive digital models are validated for voltage stabilization, active and reactive compensation and dynamically power flow control using three decoupled current control strategies. The control strategies implement decoupled current control switching technique to ensure accountability, minimum oscillatory behavior, minimum inherent phase locked loop time delay as well as system instability reduced impact due to a weak interconnected ac system and ensures full dynamic regulation of the bus voltage (VB), the series voltage injected and the dc link voltage Vdc. The 60-pulse VSC generates less harmonic distortion and reduces power quality problems in comparison to other converters such as (6,12,24 and 36) pulse. In the synchronous reference frame, a complete model of a GUPFC has been presented and control circuits for the shunt and two series converters have been described. The simulated results presented confirm that the performance of the proposed GUPFC is satisfactory for active and reactive power flow control and independent shunt reactive compensation.

 REFERENCES:

[1] K. K. Sen, “SSSC-static synchronous series compensator. Theory, modeling and application”, IEEE Transactions on Power Delivery, Vol. 13, No. 1, pp. 241-246, January 1998.

[2] B. Fardanesh, B. Shperling, E. Uzunovic, and S. Zelingher, “Multi-Converter FACTS Devices: The Generalized Unified Power Flow Controller (GUPFC),” in IEEE 2000 PES Summer Meeting, Seattle, USA, July 2000.

[3] N. G. Hingorani and L. Gyugyi, “Understanding FACTS, Concepts and Technology of Flexible AC Transmission Systems. Pscataway, NJ: IEEE Press. 2000.

[4] X. P. Zang, “Advanced Modeling of the Multicontrol Func-tional Static Synchronous Series Compensator (SSSC) in Newton Power Flow” , IEEE Transactions on Power Systems, Vol. 20, No. 4, pp. 1410-1416, November 2005,

[5] A. H. Norouzi and A. M. Sharaf, Two Control Schemes to Enhance the Dynamic Performance of the Statcom and Sssc”, IEEE Transactions on Power Delivery, Vol. 20, No. 1, pp. 435-442, January 2005.