Tag Archives: Voltage source converter

A Novel Seven-Level Active Neutral Point Clamped Converter with Reduced Active Switching Devices and DC-link Voltage

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ABSTRACT:

This paper presents a novel seven-level inverter topology for medium-voltage high-power applications. It consists of eight active switches and two inner flying-capacitor units forming a similar structure as in a conventional Active Neutral Point Clamped (ANPC) inverter. This unique arrangement reduces the number of active and passive components. A simple modulation technique reduces cost and complexity in the control system design without compromising reactive power capability. In addition, compared to major conventional 7-level inverter topologies such as the Neutral Point Clamped (NPC), Flying Capacitor (FC), Cascaded H-bridge (CHB) and Active NPC (ANPC) topologies, the new topology reduces the dc-link voltage requirement by 50%. This recued dc-link voltage makes the new topology appealing for various industrial applications. Experimental results from a 2.2 kVA prototype are presented to support the theoretical analysis presented in this paper. The prototype demonstrates a conversion efficiency of around 97.2% ± 1% for a wide load range.

KEYWORDS:

  1. Multilevel Inverter
  2. 7-level inverter
  3. Active Neutral Point Clamped (ANPC) inverter
  4. Flying Capacitor
  5. Voltage Source Converter

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a novel eight-switch seven-level Active Neutral Point Clamped inverter is proposed. Modulation techniques are explored and operation under both active and reactive power factor conditions are systematically analyzed. A comparative analysis and a set of design guidelines are presented and followed by simulation and experimental verification. Compared to conventional seven-level inverter topologies, the ANPC inverter topology requires only eight power devices for a single-phase design and halves the dc-link voltage required to produce a given ac voltage output magnitude when compared to similar circuits. For applications such as for a grid-connected PV system, this may help eliminate additional power conversion stages (boost converters) and therefore increase the efficiency and reliability of the system. Further, this reduces the voltage stress on the dc-link capacitor, which reduces the cost and size of the system design. The inverter can operate at any power factor (leading or lagging) without requiring any changes to the modulation scheme. Compared with other seven-level configurations, the performance demonstrated by the new inverter is highly competitive, potentially making it an appropriate topology choice for a wide-range of power conversion applications, e.g. variable-speed drives, electric vehicles (V2G/G2V technologies), grid-connected renewable energy systems.

REFERENCES:

[1] M. Schweizer, T. Friedli, and J. W. Kolar, “Comparative Evaluation of Advanced Three-Phase Three-Level Inverter/Converter Topologies Against Two-Level Systems,” IEEE Trans. Ind. Electron., vol. 60, no. 12, pp. 5515-5527, Dec. 2012.

[2] H. Tian, Y. Li, Y. W. Li, “A Novel Seven-Level Hybrid-Clamped (HC) Topology for Medium Voltage Motor Drives,” IEEE Trans. Power Electron., vol. 33, no. 7, pp. 5543-5547, Jul. 2018.

[3] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, J. Rodriguez, M. A. Perez, and J. I. Leon, “Recent Advances and Industrial Applications of Multilevel Converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553-2580, Aug. 2010.

[4] J. Rodríguez, J. S. Lai, and F. Z. Peng, “Multilevel Inverters: A Survey of Topologies, Controls, and Applications,” IEEE Trans. Ind. Electron., vol. 49, no. 4, pp. 724-738, Aug. 2002.

[5] J. I. Leon, S. Vazquez, and L. G. Franquelo, “Multilevel Converters: Control and Modulation Techniques for their Operation and Industrial Applications,” Proc. of the IEEE, vol. 105, no. 11, pp. 2066-2081, Nov. 2017.

 

Power Management in PV-Battery-HydroBased Standalone Microgrid

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ABSTRACT:

This paper proposes a high-efficiency two stage three-level grid-connected photovoltaic inverter. that work deals with the frequency regulation, voltage regulation, power management and load levelling of solar photovoltaic (PV)-battery-hydro based microgrid (MG). In this MG, the battery capacity is reduced as compared to a system, where the battery is directly connected to the DC bus of the voltage source converter (VSC). A bidirectional DC–DC converter connects the battery to the DC bus and it controls the charging and discharging current of the battery. It also regulates the DC bus voltage of VSC, frequency and voltage of MG.

The proposed system manages the power flow of different sources like hydro and solar PV array. However, the load levelling is managed through the battery. Battery with VSC absorbs the sudden load changes, resulting in rapid regulation of DC link voltage, frequency and voltage of MG. Therefore, the system voltage and frequency regulation allows the active power balance along with the auxiliary services such as reactive power support, source current harmonics mitigation and voltage harmonics reduction at the point of common interconnection. Experimental results under various steady state and dynamic conditions, exhibit the excellent performance of the proposed system and validate the design and control of proposed MG.

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1 Microgrid Topology and MPPT Control (a) Proposed PV-battery-hydro MG,

EXPECTED SIMULATION RESULTS:

Fig. 2 Dynamic performance of PV-battery-hydro based MG following by solar irradiance change (a) vsab, isc, iLc and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isa, iLa and ivsca, (d) Vdc, Ipv, Vb and Ib

Fig.3 Dynamic performance of hydro-battery-PV based MG under load perturbation (a) vsab, isc, Ipv and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isc, Ipv and ivscc, (d) Vdc, Ipv, and Vb

 CONCLUSION: 

In the proposed MG, an integration of hydro with the battery, compensates the intermittent nature of PV array. The proposed system uses the hydro, solar PV and battery energy to feed the voltage (Vdc), solar array current (Ipv), battery voltage (Vb) and battery current (Ib). When the load is increased, the load demand exceeds the hydro generated power, since SEIG operates in constant power mode condition.

This system has the capability to adjust the dynamical power sharing among the different RES depending on the availability of renewable energy and load demand. A bidirectional converter controller has been successful to maintain DC-link voltage and the battery charging and discharging currents. Experimental results have validated the design and control of the proposed system and the feasibility of it for rural area electrification.

REFERENCES:

[1] Ellabban, O., Abu-Rub, H., Blaabjerg, F.: ‘Renewable energy resources: current status, future prospects and technology’, Renew. Sustain. Energy Rev.,2014, 39, pp. 748–764

[2] Bull, S.R.: ‘Renewable energy today and tomorrow’, Proc. IEEE, 2001, 89, (8), pp. 1216–1226

[3] Malik, S.M., Ai, X., Sun, Y., et al.: ‘Voltage and frequency control strategies of hybrid AC/DC microgrid: a review’, IET Renew. Power Gener., 2017, 11, (2), pp. 303–313

[4] Kusakana, K.: ‘Optimal scheduled power flow for distributed photovoltaic/ wind/diesel generators with battery storage system’, IET Renew. Power Gener., 2015, 9, (8), pp. 916–924

[5] Askarzadeh, A.: ‘Solution for sizing a PV/diesel HPGS for isolated sites’, IET Renew. Power Gener., 2017, 11, (1), pp. 143–151

Power management in PV-battery-hydro based standalone microgrid

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ABSTRACT:

This work deals with the frequency regulation, voltage regulation, power management and load levelling of solar photovoltaic (PV)-battery-hydro based microgrid (MG). In this MG, the battery capacity is reduced as compared to a system, where the battery is directly connected to the DC bus of the voltage source converter (VSC). A bidirectional DC–DC converter connects the battery to the DC bus and it controls the charging and discharging current of the battery. It also regulates the DC bus voltage of VSC, frequency and voltage of MG. The proposed system manages the power flow of different sources like hydro and solar PV array. However, the load levelling is managed through the battery. The battery with VSC absorbs the sudden load changes, resulting in rapid regulation of DC link voltage, frequency and voltage of MG. Therefore, the system voltage and frequency regulation allows the active power balance along with the auxiliary services such as reactive power support, source current harmonics mitigation and voltage harmonics reduction at the point of common interconnection. The experimental results under various steady state and dynamic conditions, exhibit the excellent performance of the proposed system and validate the design and control of proposed MG.

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:
Fig. 1 Microgrid Topology and MPPT Control

(a) Proposed PV-battery-hydro MG

 EXPECTED SIMULATION RESULTS

 

 Fig. 2 Dynamic performance of PV-battery-hydro based MG following by solar irradiance change

(a) vsab, isc, iLc and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isa, iLa and ivsca, (d) Vdc, Ipv, Vb and Ib

 

Fig. 3 Dynamic performance of hydro-battery-PV based MG under load perturbation

(a) vsab, isc, Ipv and ivscc, (b) Vdc, Ipv, Vb and Ib, (c) vsab, isc, Ipv and ivscc, (d) Vdc, Ipv, and Vb

CONCLUSION:

In the proposed MG, an integration of hydro with the battery, compensates the intermittent nature of PV array. The proposed system uses the hydro, solar PV and battery energy to feed the voltage (Vdc), solar array current (Ipv), battery voltage (Vb) and battery current (Ib). When the load is increased, the load demand exceeds the hydro generated power, since SEIG operates in constant power mode condition. This system has the capability to adjust the dynamical power sharing among the different RES depending on the availability of renewable energy and load  demand. A bidirectional converter controller has been successful to maintain DC-link voltage and the battery charging and discharging currents. Experimental results have validated the design and  control of the proposed system and the feasibility of it for rural area electrification.

REFERENCES:

[1] Ellabban, O., Abu-Rub, H., Blaabjerg, F.: ‘Renewable energy resources: current status, future prospects and technology’, Renew. Sustain. Energy Rev.,2014, 39, pp. 748–764

[2] Bull, S.R.: ‘Renewable energy today and tomorrow’, Proc. IEEE, 2001, 89  (8), pp. 1216–1226

[3] Malik, S.M., Ai, X., Sun, Y., et al.: ‘Voltage and frequency control strategies of hybrid AC/DC microgrid: a review’, IET Renew. Power Gener., 2017, 11, (2), pp. 303–313

[4] Kusakana, K.: ‘Optimal scheduled power flow for distributed photovoltaic/ wind/diesel generators with battery storage system’, IET Renew. Power  Gener., 2015, 9, (8), pp. 916–924

[5] Askarzadeh, A.: ‘Solution for sizing a PV/diesel HPGS for isolated sites’, IET Renew. Power Gener., 2017, 11, (1), pp. 143–151

 

 

 

Modeling of 18-Pulse STATCOM for Power System Applications

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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.

Static synchronous compensator (STATCOM) Projects

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A static synchronous compensator (STATCOM), also known as a static synchronous condenser (STATCON), is a regulating device used on alternating current electricity transmission networks. It is based on a power electronics voltage-source converter and can act as either a source or sink of reactive AC power to an electricity network. If connected to a source of power it can also provide active AC power. It is a member of the FACTS family of devices. It is inherently modular and electable.

A STATCOM is a voltage source converter (VSC)-based device, with the voltage source behind a reactor. The voltage source is created from a DC capacitor and therefore a STATCOM has very little active power capability. However, its active power capability can be increased if a suitable energy storage device is connected across the DC capacitor. The reactive power at the terminals of the STATCOM depends on the amplitude of the voltage source. For example, if the terminal voltage of the VSC is higher than the AC voltage at the point of connection, the STATCOM generates reactive current; conversely, when the amplitude of the voltage source is lower than the AC voltage, it absorbs reactive power.The response time of a STATCOM is shorter than that of a static VAR compensator (SVC), mainly due to the fast switching times provided by the IGBTs of the voltage source converter. The STATCOM also provides better reactive power support at low AC voltages than an SVC, since the reactive power from a STATCOM decreases linearly with the AC voltage (as the current can be maintained at the rated value even down to low AC voltage).

Enhancement of Power Quality in Distribution System using D-Statcom

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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

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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-

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

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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.

 

 

A Two-Level, 48-Pulse Voltage Source Converter for HVDC Systems

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ABSTRACT

This paper deals with an analysis, modeling and control of a two level 48-pulse voltage source converter for High Voltage DC (HVDC) system. A set of two-level 6-pulse voltage source converters (VSCs) is used to form a 48-pulse converter operated at fundamental frequency switching (FFS). The performance of the VSC system is improved in terms of reduced harmonics level at FFS and THD (Total Harmonic Distribution) of voltage and current is achieved within the IEEE 519 standard. The performance of the VSC is studied in terms of required reactive power compensation, improved power factor and reduced harmonics distortion. Simulation results are presented for the designed two level multipulse converter to demonstrate its capability. The control algorithm is disused in detail for operating the converter at fundamental frequency switching.

 KEYWORDS

Two-Level Voltage Source Converter

HVDC Systems

Multipulse

Fundamental Frequency Switching

Harmonics.

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

1

Fig. 1 A 48-Pulse voltage source converter based HVDC system configuration

 EXPECTED SIMULATION RESULTS:

2

Fig. 2 Steady state performance of proposed 48-pulse voltage source converter

3 4

Fig. 3 Dynamic performance of proposed 48-pulse voltage source converter

 5 6

 Fig. 4 Waveforms and harmonic spectra of 48-pulse converter (a) supply voltage (b) supply current (c) converter voltage

 CONCLUSION

A 48-pulse two-level voltage source converter has been designed, modeled and controlled for back-to-back HVDC system. The transformer connections with appropriate phase shift have been used to realize a 48-pulse converter along with a control scheme using a set of two level six pulse converters. The operation of the designed converter configuration has been simulated and tested in steady sate and transient conditions which have demonstrated the quite satisfactory converter operation. The characteristic harmonics of the system has also improved by the proposed converter configuration.

 REFERENCES

[1] J. Arrillaga, Y. H. Liu and N. R. Waston, “Flexible Power Transmission, The HVDC Options,” John Wiley & Sons, Ltd, Chichester, UK, 2007.

[2] Gunnar Asplund Kjell Eriksson and kjell Svensson, “DC Transmission based on Voltage Source Converter,” in Proc. of CIGRE SC14 Colloquium in South Africa 1997, pp.1-8.

[3] Y. H. Liu R. H. Zhang, J. Arrillaga and N. R. Watson, “An Overview of Self-Commutating Converters and their Application in Transmission and Distribution,” in Conf. IEEE/PES Trans. and Distr.Conf. & Exhibition, Asia and Pacific Dalian, China 2005.

[4] B. R. Anderson, L. Xu, P. Horton and P. Cartwright, “Topology for VSC Transmission,” IEE Power Engineering Journal, vol.16, no.3, pp142- 150, June 2002.

[5] G. D. Breuer and R. L. Hauth, “HVDC’s Increasing Poppularity”, IEEE Potentials, pp.18-21, May 1988.

A Two-Level 24-Pulse Voltage Source Converter with Fundamental Frequency Switching for HVDC System

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 ABSTRACT

This paper manages the execution investigation of a two-level, 24-beat Voltage Source Converters (VSCs) for High Voltage DC (HVDC) framework for power quality enhancement. A two dimension VSC is utilized to understand a 24-beat converter with least exchanging misfortune by working it at fundamental recurrence exchanging (FFS). The execution of this converter is contemplated on different issues, for example, consistent state activity, dynamic conduct, responsive power pay, control factor amendment, and sounds mutilation. Reproduction results are exhibited for a two dimension 24-beat converter to show its ability.

 BLOCK DIAGRAM:

 1

 Fig. 1 A 24-Pulse voltage source converter based HVDC system Configuration

EXPECTED SIMULATION RESULTS

 2

Fig. 2 Synthesis of Stepped AC voltage waveform of 24-pulse VSC.

 

3

Fig. 3 Steady state performance of proposed 24-pulse voltage source Converter

4

Fig. 4 Dynamic performance of proposed 24-pulse voltage source converter

 

5

Fig. 5 Waveforms and harmonic spectra of 24-pulse covnerter i) supply voltage ii) supply current (iii) converter voltage

CONCLUSION

A two dimension, 24-beat voltage source converter has been structured and its execution has been approved for HVDC framework to enhance the power quality with major recurrence exchanging. Four indistinguishable transformers have been utilized for stage move and to understand a 24-beat converter alongside control conspire utilizing a two dimension voltage source converter topology. The enduring state and dynamic execution of the planned converter setup has been exhibited the very attractive task and found appropriate for HVDC framework. The trademark sounds of the converter framework has likewise enhanced by the proposed converter design with least exchanging misfortunes without utilizing additional sifting necessities contrasted with the ordinary 12-beat thyristor converter.