Improving the Performance of Cascaded H-bridge based Interline Dynamic Voltage Restorer

IEEE Transactions on Power Delivery, 2015

 ABSTRACT:

 An interline dynamic voltage restorer (IDVR) is a new device for sag mitigation which is made of several dynamic voltage restorers (DVRs) with a common DC link, where each DVR is connected in series with a distribution feeder. During sag period, active power can be transferred from a feeder to another one and voltage sags with long durations can be mitigated. IDVR compensation capacity, however, depends greatly on the load power factor and a higher load power factor causes lower performance of IDVR. To overcome this limitation, a new idea is presented in this paper which allows to reduce the load power factor under sag condition, and therefore, the compensation capacity is increased. The proposed IDVR employs two cascaded H-bridge multilevel converters to inject AC voltage with lower THD and eliminates necessity to low-frequency isolation transformers in one side. The validity of the proposed configuration is verified by simulations in the PSCAD/EMTDC environment. Then, experimental results on a scaled-down IDVR are presented to confirm the theoretical and simulation results.

 

KEYWORDS:

  1. Back-to-back converter
  2. Cascaded H-bridge
  3. Interline dynamic voltage restorer

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Power circuit schematic of the IDVR with active power exchanging capability.

 

EXPECTED SIMULATION RESULTS:

Fig. 2. Investigating the IDVR performance when the proposed method is applied for a sag with depth of 0.4p.u.

Fig.3. Investigating the IDVR performance when the proposed method is applied for a sag with depth of 0.6p.u.

 

CONCLUSION:

In this paper, a new configuration has been proposed which not only improves the compensation capacity of the IDVR at high power factors, but also increases the performance of the compensator to mitigate deep sags at fairly moderate power factors. These advantages were achieved by decreasing the load power factor during sag condition. In this technique, the source voltages are sensed continuously and when the voltage sag is detected, the shunt reactances are switched into the circuit and decrease the load power factors to improve IDVR performance. Finally, the simulation and practical results on the CHB based IDVR confirmed the effectiveness of the proposed configuration and control scheme.

 

REFERENCES:

  • F. Comesana, D.F. Freijedo, J.D. Gandoy, O. Lopez, A.G. Yepes, J. Malvar, “Mitigation of voltage sags, imbalances and harmonics in sensitive industrial loads by means of a series power line conditioner” Electric Power systems Research 84 (2012) 20–30
  • [2] A. Felce, S. A. C. A. Inelectra, G. Matas, and Y. Da Silva, “Voltage Sag Analysis and Solution for an Industrial Plant with Embedded Induction Motors,” In Industry Applications Conference, 2004. 39th IAS Annual Meeting. Conference Record of the 2004 IEEE, vol. 4, pp. 2573-2578. IEEE, 2004.
  • [3] A. Sannino, M. G. Miller, and M. H. J. Bollen, “Overview of voltage sag mitigation”, IEEE Power Eng. Soc. Winter Meeting, vol. 4, pp.2872 -2878 2000
  • [4] E. Babaei, M. F. Kangarlu, and M. Sabahi, “Mitigation of voltage disturbances using dynamic voltage restorer based on direct converters,” IEEE Trans. Power Del., 25, no. 4, pp. 2676–2683, Oct. 2010
  • [5] H. K. Al-Hadidi , A. M. Gole and D. A. Jacobson “A novel configuration for a cascade inverter-based dynamic voltage restorer with reduced energy storage requirements“, IEEE Trans. Power Del., vol. 23, no. 2, pp.881 -888 2008 .

 

A Two Degrees of Freedom Resonant Control Scheme for Voltage Sag Compensation in Dynamic Voltage Restorers

 

 IEEE Transactions on Power Electronics, 2017

ABSTRACT:

This paper presents a two degrees of freedom (2DOF) control scheme for voltage compensation in a dynamic voltage restorer (DVR). It commences with the model of the DVR power circuit, which is the starting point for the control design procedure. The control scheme is based on a 2DOF structure implemented in a stationary reference frame (α−β), with two nested controllers used to obtain a pass-band behavior of the closed-loop transfer function, and is capable of achieving both a balanced and an unbalanced voltage sag compensation. The 2DOF control has certain advantages with regard to traditional control methods, such as the possibility of ensuring that all the poles of the closed-loop transfer function are chosen without the need for observers and reducing the number of variables to be measured. The use of the well-known double control- loop schemes which employ feedback current controllers to reduce the resonance of the plant is, therefore, unnecessary. A simple control methodology permits the dynamic behavior of the system to be controlled and completely defines the location of the poles. Furthermore, extensive simulations and experimental results obtained using a 5 kW DVR laboratory prototype show the good performance of the proposed control strategy.

 

KEYWORDS:

  1. Power Quality
  2. Dynamic Voltage Restorer (DVR)
  3. Control Design
  4. Resonant Controller
  5. Stationary Frame Controller
  6. Voltage Sag.

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig. 1. Power system with a DVR included.

 

EXPECTED SIMULATION RESULTS:

 

Figure 2. DVR simulation for a balanced voltage sag. (a) Line-to-neutral three-phase voltages at PCC, (b) line-to-neutral voltages generated by the DVR, (c) line-to-neutral load voltages, and (d) error signal in α − β (redblue).

Figure 3 DVR simulation for an unbalanced voltage sag. (a) Line-to-neutral three-phase voltages at PCC, (b) line-to-neutral voltages generated by the DVR, (c) line-to-neutral load voltages, and (d) error signal in α − β (redblue).

Figure 4. DVR simulation for a 30 % balanced voltage sag. (a) Line-to neutral three-phase voltages at PCC, (b) error signal in α − β (red-blue) for the 2DOF-Resonant scheme, (c) error signal in α − β (red-blue) for double loop scheme, and (d) error signal in α−β (red-blue) for the double-loop with Posicast scheme.

Figure 5. DVR simulation for a 30 % type-E unbalanced voltage sag. (a) Line-to-neutral three-phase voltages at PCC, (b) error signal in α − β (redblue) for the 2DOF-Resonant scheme, (c) error signal in α − β (red blue) for double-loop scheme, and (d) error signal in α − β (red-blue) for the double-loop with Posicast scheme.

 

 CONCLUSION:

This paper presents a control scheme based on two nested controllers for voltage sag compensation in a DVR. The nested regulators provide the control with two degrees of freedom, and the control scheme is implemented in the stationary reference frame. Furthermore, in order to accomplish the requirements for voltage sag compensation, it is necessary to track the component at the fundamental frequency. This is achieved using a resonant term in one of the controllers. The proposed control design methodology is able to define all the poles of the closed-loop system without observers and with a reduction in the number of variables that must be measured, thus making it possible to avoid the use of the traditional current loop employed in control schemes for the DVR. The structure with the nested regulators achieves perfect zero tracking error at the nominal frequency and blocks the DC offset, signifying that it has some advantages over other control methods, such as double-loop schemes with proportional-resonant regulators. Moreover, the design methodology is thoroughly explained when the delay in the calculations is taken into account.

In this case, the design procedure allows the dominant poles of the closed-loop system to be chosen. If the closed-loop poles are chosen carefully, this control structure can also be applied to other systems which require higher delays, e.g., power converter applications with a reduced switching frequency. The design methodology can additionally be extended to the discrete domain. Comprehensive simulated and experimental results corroborate the performance of the 2DOF-Resonant control scheme for balanced and unbalanced voltage sags. The proposed control scheme is able to compensate both types of voltage sags with a very fast transient response and an accurate tracking of the reference voltage, even when the different types of loads and frequency deviations of the grid voltages are considered. Extended comparisons with a PR controller using a double-loop scheme and a PR controller in a double loop with a Posicast regulator have been carried out, demonstrating that the performance of the 2DOF-Resonant controller is superior in all cases. Moreover, the study of the stability as regards parameter variations for the compared control schemes demonstrates the more robust behavior of the 2DOF-Resonant control scheme.

 

REFERENCES:

  • H. M. Quezada, J. R. Abbad, and T. G. S. Rom´an, “Assessment of energy distribution losses for increasing penetration of distributed generation,” IEEE Transactions on Power Systems, vol. 21, no. 2, pp. 533–540, May 2006.
  • K. Jukan, A. Jukan, and A. Toki´c, “Identification and assessment of key risks and power quality issues in liberalized electricity markets in europe,” International Journal of Engineering & Technology, vol. 11, no. 03, pp. 20–26, 2011.
  • EN-50160, European Standard EN-50160. Voltage Characteristics of Public Distribution Systems, CENELEC Std., November 1999.
  • 1547, IEEE Std. 1547-2003. Standard for Interconnecting Distributed Resources with Electric Power Systems, IEEE Std., June 2003.
  • P. Mahela and A. G. Shaik, “Topological aspects of power quality improvement techniques: A comprehensive overview,” Renewable and Sustainable Energy Reviews, vol. 58, pp. 1129–1142, May 2016.

Dynamic Voltage Conditioner, a New Concept for Smart Low-Voltage Distribution System

IEEE TRANSACTION ON POWER ELECTRONICS, 2017

 

ABSTRACT: Power Quality (PQ) improvement in distribution level is an increasing concern in modern electrical power systems. One of the main problems in LV networks is related to load voltage stabilization close to the nominal value. Usually this problem is solved by Smart Distribution Transformers, Hybrid Transformers and Solid-state Transformers, but also Dynamic Voltage Conditioner (DVC) can be an innovative and a cost effective solution. The paper introduces a new control method of a single-phase DVC system able to compensate these long duration voltage drifts. For these events, it is mandatory to avoid active power exchanges so, the controller is designed to work with non-active power only. Operation limits for quadrature voltage injection control is formulated and reference voltage update procedure is proposed to guarantee its continuous operating. DVC performance for main voltage and load variation is examined. Proposed solution is validated with simulation study and experimental laboratory tests. Some simulation and experimental results are illustrated to show the prototype device’s performance.

 

KEYWORDS:

  1. Power Quality
  2. Power conditioning
  3. Power electronics
  4. Dynamic Voltage Conditioner DVC
  5. Dynamic Voltage Restorer DVR
  6. LV Distribution System
  7. Smart Grid

 

SOFTWARE: MATLAB/SIMULINK

 

CIRCUIT DIAGRAM:

Fig. 1. DVC reference voltage generation block diagram.

 

 EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulation – DVC operation limit update procedure under voltage – limits due to : Case 2.b) – (a) grid and minimum grid voltage, (b) PCC and PCC reference voltage, (c) load power factor.

Fig. 3. Experimental – DVC response to load variation, adding and removing the load – (a),(d) PCC voltage, (b),(e) DVC injected voltage, (c),(f) load current.

 

CONCLUSION:

A new device concept, which goes beyond typical DVR functionalities, is presented. The proposed device is named DVC (Dynamic Voltage Conditioner), it is an active voltage conditioner able to cover both short- and fast-events, as a typical DVR, and long-events (in the grid voltage range from 0.9-1.1 p.u.). So it can perfectly satisfy modern power system DSO requirements. In particular the paper presents only the control strategy that can be adapted during steady state condition (long-events) for a single-phase DVC. Indeed, the steady state condition is not reported in literature and the single phase configuration seems to be the best economic solution for smart grid LV distribution system. The device controller, here introduced for first time, has been designed to operate with non-active power during steady state condition. So, to guarantee DVC continuous working, the paper describes a control method to generate DVC reference voltage considering its limits. Moreover, single-phase design can decrease device initial cost and it is also more compatible with LV distribution and mostly single-phase domestic loads.

Designed control method is verified by MATLAB based simulation and laboratory experimental test bed. Results show that, the device has good performance and it can improve PQ level of the installed distribution Smart Grid network effectively (mainly in the grid voltage range from 0.9-1.1 p.u.). This is essential for nowadays modern network because the proposed DVC can give flexibility to the system operator in order to move all problematic single-phase loads on a specific phase (where the DVC is installed).

Even if the paper analyzed a single-phase system, all the theoretical analysis on device limits can be extended for three phase system and it will be addressed in future works. It should be noted that, this solution since it injects the compensation voltage in quadrature to line current, creates phase shifting on installed phase voltage so, it can impose voltage unbalance issues to the supplied three-phase loads. Therefore this device can be used effectively in LV distribution network with single phase loads only.

 

REFERENCES:

  • “IEEE recommended practice for monitoring electric power quality,” IEEE Std 1159-2009 (Revision of IEEE Std 1159-1995), pp. c1–81, June 2009.
  • Sankaran, Power quality. CRC press, 2001.
  • “IEEE application guide for IEEE std 1547(TM), IEEE standard for interconnecting distributed resources with electric power systems,” IEEE Std 1547.2-2008, pp. 1–217, April 2009.
  • Standard, “50160,” Voltage characteristics of public distribution systems, 2010.
  • Farhangi, “The path of the smart grid,” IEEE Power and Energy Magazine, vol. 8, no. 1, pp. 18–28, January 2010.

Design and Performance Analysis of Three-Phase Solar PV Integrated UPQC

IEEE Transactions on Industry Applications, 2017 IEEE

ABSTRACT: This paper deals with the design and performance analysis of a three-phase single stage solar photovoltaic integrated unified power quality conditioner (PV-UPQC). The PV-UPQC consists of a shunt and series connected voltage compensators connected back to back with common DC-link.The shunt compensator performs the dual function of extracting power from PV array apart from compensating for load current harmonics. An improved synchronous reference frame control based on moving average filter is used for extraction of load active current component for improved performance of the PVUPQC. The series compensator compensates for the grid side power quality problems such as grid voltage sags/swells. The compensator injects voltage in-phase/out of phase with point of common coupling (PCC) voltage during sag and swell conditions respectively. The proposed system combines both the benefits of clean energy generation along with improving power quality. The steady state and dynamic performance of the system are evaluated by simulating in Matlab-Simulink under a nonlinear load. The system performance is then verified using a scaled down laboratory prototype under a number of disturbances such as load unbalancing, PCC voltage sags/swells and irradiation variation.

KEYWORDS:

  1. Power Quality
  2. Shunt compensator
  3. Series compensator
  4. UPQC
  5. Solar PV
  6. MPPT

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. System Configuration PV-UPQC

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Performance of PV-UPQC under Voltage Sag and Swell Conditions

Fig. 3. Performance PV-UPQC during Load Unbalance Condition

Fig. 4. Performance PV-UPQC at Varying Irradiation Condition

Fig. 5. Load Current Harmonic Spectrum and THD

Fig. 6. Grid Current Harmonic Spectrum and THD

CONCLUSION:

The design and dynamic performance of three-phase PVUPQC have been analyzed under conditions of variable irradiation and grid voltage sags/swells. The performance of the system has been validated through experimentation on scaled down laboratory prototype. It is observed that PVUPQC mitigates the harmonics caused by nonlinear load and maintains the THD of grid current under limits of IEEE-519 standard. The system is found to be stable under variation of irradiation, voltage sags/swell and load unbalance. The performance of d-q control particularly in load unbalanced condition has been improved through the use of moving average filter. It can be seen that PV-UPQC is a good solution for modern distribution system by integrating distributed generation with power quality improvement.

REFERENCES:

[1] B. Mountain and P. Szuster, “Solar, solar everywhere: Opportunities and challenges for australia’s rooftop pv systems,” IEEE Power and Energy Magazine, vol. 13, no. 4, pp. 53–60, July 2015.

[2] A. R. Malekpour, A. Pahwa, A. Malekpour, and B. Natarajan, “Hierarchical architecture for integration of rooftop pv in smart distribution systems,” IEEE Transactions on Smart Grid, vol. PP, no. 99, pp. 1–1, 2017.

[3] Y. Yang, P. Enjeti, F. Blaabjerg, and H. Wang, “Wide-scale adoption of photovoltaic energy: Grid code modifications are explored in the distribution grid,” IEEE Ind. Appl. Mag., vol. 21, no. 5, pp. 21–31, Sept 2015.

[4] M. J. E. Alam, K. M. Muttaqi, and D. Sutanto, “An approach for online assessment of rooftop solar pv impacts on low-voltage distribution networks,” IEEE Transactions on Sustainable Energy, vol. 5, no. 2, pp.663–672, April 2014.

[5] J. Jayachandran and R. M. Sachithanandam, “Neural network-based control algorithm for DSTATCOM under nonideal source voltage and varying load conditions,” Canadian Journal of Electrical and Computer Engineering, vol. 38, no. 4, pp. 307–317, Fall 2015.

Design and Performance Analysis of Three-Phase Solar PV Integrated UPQC

2016 IEEE

ABSTRACT: In this paper, the design and performance of a threephase solar PV (photovoltaic) integrated UPQC (PV-UPQC) are presented. The proposed system combines both the benefits of distributed generation and active power filtering. The shunt compensator of the PV-UPQC compensates for the load current harmonics and reactive power. The shunt compensator is also extracting maximum power from solar PV array by operating it at its maximum power point (MPP). The series compensator compensates for the grid side power quality problems such as grid voltage sags/swells by injecting appropriate voltage in phase with the grid voltage. The dynamic performance of the proposed system is simulated in Matlab-Simulink under a nonlinear load consisting of a bridge rectifier with voltage-fed load.

KEYWORDS:

  1. Power Quality
  2. DSTATCOM
  3. DVR
  4. UPQC
  5. Solar PV
  6. MPPT

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1. System Configuration PV-UPQC

EXPECTED SIMULATION RESULTS:

 Fig. 2. Performance PV-UPQC at steady state condition

Fig. 3. PCC Voltage Harmonic Spectrum and THD

Fig. 4. Load Voltage Harmonic Spectrum and THD

Fig. 5. Load Current Harmonic Spectrum and THD

Fig. 6. Grid Current Harmonic Spectrum and THD

Fig. 7. Performance PV-UPQC at varying irradiation condition

Fig. 8. Performance of PV-UPQC under voltage sag and swell conditions

CONCLUSION:

The dynamic performance of three-phase PV-UPQC has been analyzed under conditions of variable irradiation and grid voltage sags/swells. It is observed that PV-UPQC mitigates the harmonics caused by nonlinear and maintains the THD of grid voltage, load voltage and grid current under limits of IEEE-519 standard. The system is found to be stable under variation of irradiation from 1000𝑊/𝑚2 to 600𝑊/𝑚2. It can be seen that PV-UPQC is a good solution for modern distribution system by integrating distributed generation with power quality improvement.

REFERENCES:

[1] Y. Yang, P. Enjeti, F. Blaabjerg, and H. Wang, “Wide-scale adoption of photovoltaic energy: Grid code modifications are explored in the distribution grid,” IEEE Ind. Appl. Mag., vol. 21, no. 5, pp. 21–31, Sept 2015.

[2] B. Singh, A. Chandra and K. A. Haddad, Power Quality: Problems and Mitigation Techniques. London: Wiley, 2015.

[3] M. Bollen and I. Guo, Signal Processing of Power Quality Disturbances. Hoboken: Johm Wiley, 2006.

[4] P. Jayaprakash, B. Singh, D. Kothari, A. Chandra, and K. Al-Haddad, “Control of reduced-rating dynamic voltage restorer with a battery energy storage system,” IEEE Trans. Ind. Appl., vol. 50, no. 2, pp. 1295– 1303, March 2014.

[5] M. Badoni, A. Singh, and B. Singh, “Variable forgetting factor recursive least square control algorithm for DSTATCOM,” IEEE Trans. Power Del., vol. 30, no. 5, pp. 2353–2361, Oct 2015.

Application of Neural Networks in Power Quality

2015 International Conference on Soft Computing Techniques and Implementations- (ICSCTI)

 ABSTRACT: Use of power electronic converters with nonlinear loads produces harmonic currents and reactive power. A shunt active power filter provides an elegant solution to reactive power compensation as well as harmonic mitigation leading to improvement in power quality. However, the shunt active power filter with PI type of controller is suitable only for a given load. If the load is varying, the proportional and integral gains are required to be fine tuned for each load setting. The present study deals with neural network based controller for shunt active power filter. The performance of neural network controller evaluated and compared with PI controller.

 KEYWORDS:

  1. Active Power Filter
  2. Neural Networks
  3. Back Propagation Algorithm
  4. Soft Computing.

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Schematic Diagram of Shunt Active Power Filter

Fig1. Schematic Diagram of Shunt Active Power Filter

  

EXPECTED SIMULATION RESULTS:

 

Fig 2. (a) Waveform of Load Current, Compensating Current, Source Current and Source Voltage for 1kVA with 􀄮=60º and (b) Waveform of Source Voltage and in the phase Source Current of Fig. (a)

 

CONCLUSION:

The active power filter controller with neural network based controller has been seen to eminently minimize harmonics in the source current when the load demands non sinusoidal current, irrespective of whether the load is fixed or varying. Simultaneously, the power factor at source also becomes the unity, if the load demands reactive power. Thus, neural network based controller is far superior to PI type of controller which requires fine tuning of Kp and Ki every time the load changes. In the present work, the performance of a range of values of the load is considered to robustly test the controller. It has been demonstrated that neural network based controller, therefore, significantly improves the performance of a shunt active power filter.

 

REFERENCES:

  • Laszlo Gyugyi, “Reactive Power Generation and Control by Thyristor Circuits”, IEEE Transactions on Industry Applications, vol. IA-15, no. 5, September/October 1979.
  • Akagi, Y. Kanazawa, and A. Nabae, “Instantaneous reactive power compensators comprising switching devices without energy storage components,” IEEE Transaction Industrial Applications, vol. IA-20, pp. 625-630, May/June 1984.
  • Z. Peng, H. Akagi, and A. Nabae, “A study of active power filters using quad series voltage source pwm converters for harmonic compensation,” IEEE Transactions on Power Electronics, vol. 5, no. 1, pp. 9–15, January 1990.
  • Conor A. Quinn, Ned Mohan, “Active Filtering of Harmonic Currents in Three-phase, Four-Wire Systems with Three-phase and Single-phase Non-Linear Loads”, IEEE-1992.
  • A. Morgan, J. W. Dixon, and R. R. Wallace, “A three-phase active power filter operating with fixed switching frequency for reactive power and current harmonic compensation,” IEEE Transactions on Industrial Electronics, vol. 42, no. 4, pp. 402–408, August 1995.

PSO – PI Based DC Link Voltage Control Technique for Shunt Hybrid Active Power Filter

2016 IEEE

ABSTRACT: In power systems, the intensive use of nonlinear loads causes several power quality problems such as current harmonic pollution. In order to reduce the current harmonic pollution, the shunt hybrid active filter (SHAPF) is the best solutions effectively. In shunt hybrid active filter systems SHAPFs, the design of dc link controller is a significant and challenging task due to its impact on the performance and stability of the overall system. The main contribution of this paper is that the particle swarm optimization (PSO) algorithm is applied gains for PI controller which can result in the improved response in terms of response time and overshoot. In proposed control method, the performance results of harmonic compensation are satisfactory. Theoretical analyses and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for proposed system in order to demonstrate that the harmonic compensation performance meets the IEEE-519 standard.

KEYWORDS

  1. DC link controller
  2. Harmonics
  3. Particle swarm optimization
  4. Power quality
  5. PSCAD
  6. Shunt hybrid active power filter

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Figure 1. SHAPF Power System

 EXPECTED SIMULATION RESULTS

 

Figure 2 Comparison of PI, PID and PSO based PI controller for DC link

Control

Figure 3 Three phase Source Voltages, Load – M-SHAPF – Source

Currents, SHAPF DC link Voltage

Figure 4 Source -Load-M-SHAPF active power, Source -Load-M-SHAPF

reactive power

 CONCLUSION

The intensive use of nonlinear loads causes several power quality problems such as current harmonic pollution. In order to reduce the current harmonic pollution, the shunt hybrid active filter (SHAPF) is the best solution effectively. In shunt hybrid active filter systems (SHAPF)s, the design of dc link controller is a significant and challenging task due to its impact on the performance and stability of the overall system. On account of the limitations between existing literatures, the purpose of this paper is that PSO algorithm has been proposed to adapt the dc link controller gains of the SHAPF. In this paper, the particle swarm optimization (PSO) algorithm is applied gains for PI controller which can result in the improved response in terms of response time and overshoot. In proposed control method, the performance results of harmonic compensation are satisfactory. Theoretical analyses and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for proposed system in order to demonstrate that the harmonic

REFERENCES

[1] B. Soudan and M. Saad, “An evolutionary dynamic population size PSO implementation,” in Information and Communication Technologies: From Theory to Applications, 2008. ICTTA 2008. 3rd International Conference on, 2008, pp. 1–5.

[2] J. Kennedy, “Particle swarm optimization” IEEE International Conference on Neural Network , pp. 1942 – 1948 , 1995. doi: 10.1109/ICNN.1995.488968.

[3] Chien-Hung Liu and Yuan-Yih Hsu, “Design of a Self-Tuning PI Controller for a STATCOM Using Particle Swarm Optimization,” IEEE Transactions on Industrial Electronics, vol. 57, no. 2, pp. 702– 715, Feb. 2010.

[4] J. Turunen, M. Salo and H. Tuusa, “Comparison of three series hybrid active power filter topologies”, 11th International Conference on. Harmonics and Quality of Power, pp. 324–329, Sept. 2004. doi: 10.1109/ICHQP.2004.1409375.

[5] M. A. Mulla, C. Rajagopalan, A. Chowdhury,”Compensation of three-phase diode rectifier with capacitive filter working under unbalanced supply conditions using series hybrid active power filter”, IET Power Electronics, vol.7, (6), pp. 1566–1577, 2014, doi: 10.1049/iet-pel.2013.0605.

Ensuring Power Quality and Stability in Industrial and Medium Voltage Public Grids

2018, IEEE

 ABSTRACT: Until recently, most of the power system equipment in industrial grids has been operating with deviations from the nominal voltage and frequency supplied by the utility. However, power electronics based equipment is vulnerable to such deviations and might get damaged in case of possible grid faults. This paper addresses this issue by proposing a stabilizing device that can be connected between the public grid and the industrial grid which provides not only power quality and security of supply during fault for the industrial grid but also ensuring the power quality for the public grid.

KEYWORDS:

  1. Public grid
  2. Industrial grid
  3. Power quality
  4. Security of supply
  5. Grid stability

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig. 1. Device representation

 EXPECTED SIMULATION RESULTS:

 

 Fig. 2. Harmonic current injection and compensation

 

Fig. 3. Individual harmonic distortion voltage for different Sk’’

Fig. 4. THDu for different Sk’’

Fig. 5. Voltage behavior during load switching with and without Netz-Patron unit

Fig. 6. Voltage behavior during motor starting with and without Netz-Patron unit

Fig. 7. Voltage behavior during three phase fault with and without Netz-Patron unit

 CONCLUSION:

The paper presents the different functionalities of the Netz-Patron unit that is designed to provide different support functionalities like harmonic compensation and voltage support in case of disturbed grid operation. In order to analyze the effectiveness of the Netz-Patron unit, a simulation model has been developed within the DIgSILENT PowerFactory software environment. The different scenarios and their simulation results are shown in this paper and the behavior of different functionalities has been analyzed. A brief summary of the main findings is given in the following. A 900 kVA active filter has been considered to provide harmonic compensation from the AC/DC converter for Sk ’’ greater than 50 MVA.

In this paper, the study has been carried out by considering a class 2 type of load with injected harmonics of 10 minutes average value (long term). The harmonic values considered for the study are not measured values, but typical values observed in practice. Real laboratory tests are planned to be performed to check the harmonics injected by th

load before designing the Netz-Patron unit to provide harmonic compensation. The effectiveness of the voltage support function provided by the Netz-Patron unit in case of any disturbance registered at the PCC has also been analyzed in this paper.

Future work is planned to focus on a multimaster      concept which implies the analysis of the parallel operation of several Netz-Patron units connected at the PCC of different industrial grids or same industrial grid in the medium voltage network.

REFERENCES:

[1] EPRI PEAC Corporation, “C. E. Commission:, Power Quality Solutions for Industrial Customers,” August 2000.

[2] R.C.Dugan, M.F.McGranaghan, S.Santoso and H.W.Beaty, Electrical Power Systems Quality, second edition, McGraw- Hill, 2004.

[3] W. Reid, “Power Quality Issues – Standards and Guidelines,” in IEEE Transactions of Industry Applications Vol.32,No.3, 1996.

[4] DIN EN 61000-2-4: Electromagnetic compatibility (EMC) Part 2-4: Environment – Compatibility levels in industrial plants for low-frequency conducted disturbances, VDEVerlag GmbH, 2002-06.

[5] DIN EN 61000-4-11: Electromagnetic compatibility (EMC) Part 4-11: Environment – Testing and measurement techniques – Voltage dips, short interruptions and voltage variations immunity tests for equipment with input current less than 16 A per phase, February 2005.

Variable speed drive with PFC front-end for three-phase induction motor

 

ABSTRACT:

 A variable frequency drive for an induction motor is proposed. The drive uses a power factor (PF) correction bridgeless single-ended primary inductor converter-controlled rectifier operating in discontinuous inductor current mode as a front-end in order to improve the input power quality and a variation of the constant volts per hertz controller, with feedback to regulate the velocity of the motor shaft. The frequency slip is measured and compensated, since the input stage. Experiments with and without load are carried out and presented. Input power quality measurements are also presented. The proposed system is effective to regulate the velocity and achieving a close to unity PF.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1 Proposed AC–DC–AC converter

 EXPECTED SIMULATION RESULTS:

 

 

Fig. 2 Results from experiments I and II

Fig. 3 Input voltage and current waveforms and input current harmonics

a Input voltage and current waveforms, Channel 1 for current and Channel 2 for voltage. Current is measured by V–I converter with 1 V:1.6 A conversion ratio

b First 39 non-fundamental current harmonics

 CONCLUSION:

The proposal of an SEPIC converter as the front-end of single-phase to three-phase AC–DC–AC converter for an induction motor for improving the input power quality is presented. It is also shown a variation of the CVH controller to regulate the angular velocity of the motor shaft using the aforementioned topology. The controller compensates the frequency slip, due to mechanical load, since the rectifying stage. The experimental results show that the topology is effective for regulating the velocity and that the topology can achieve a close to unity PF and low THD. The computed spectrum can be used to design passive input filters and further improve the THD and the PF of the circuit.

REFERENCES:

1 Moghani, J.S., and Heidari, M.: ‘High efficient low cost induction motor drive for residential applications’. Int. Symp. Power Electronics, Electrical Drives, Automation and Motion, 2006 SPEEDAM 2006, Taormina, Italy, May 2006, pp. 1399–1402

2 Singh, S., and Singh, B.: ‘A voltage-controlled PFC Cuk converter-based PMBLDCM drive for air-conditioners’, Trans. Ind. Appl., 2012, 48, (2), pp. 832–838

3 Bist, V., and Singh, B.: ‘An adjustable-speed PFC bridgeless buck–boost converter-fed BLDC motor drive’, Trans. Ind. Electron., 2014, 61, (6), pp. 2665–2677

4 Abe, K., Haga, H., Ohishi, K., and Yokokura, Y.: ‘Fine current harmonics reduction method for electrolytic capacitor-less and inductor-less inverter based on motor torque control and fast voltage feedforward control for IPMSM’, Trans. Ind. Electron., 2017, 64, (2), pp. 1071–1080

5 APA Sabzali, A.J., Ismail, E.H., Al-Saffar, M.A., and Fardoun, A.A.: ‘New bridgeless DCM SEPIC and Cuk PFC rectifiers with low conduction losses’, Trans. Ind. Appl., 2011, 47, (2), pp. 873–881

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

IEEE Transactions on Industry Applications, 2015

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.