Design and Evaluation of a Mini-Size SMES Magnet for Hybrid Energy Storage Application in a kW-Class Dynamic Voltage Restorer

ABSTRACT:

This paper presents the design and evaluation of a mini-size GdBCO magnet for hybrid energy storage (HES) application in a kW-class dynamic voltage restorer (DVR). The HES-based DVR concept integrates with one fast-response highpower superconducting magnetic energy storage (SMES) unit and one low-cost high-capacity battery energy storage (BES) unit. Structural design, fabrication process and finite-elementmodeling (FEM) simulation of a 3.25 mH/240 A SMES magnet wound by state-of-the-art GdBCO tapes in SuNAM are presented. To avoid the internal soldering junctions and enhance the critical current of the magnet simultaneously, an improved continuous disk winding (CDW) method is proposed by introducing different gaps between adjacent single-pancake coil layers inside the magnet. About 4.41% increment in critical current and about 3.42% increment in energy storage capacity are demonstrated compared to a conventional CDW method. By integrating a 40 V/100 Ah valve-regulated lead-acid (VRLA) battery, the SMES magnet is applied to form a laboratory HES device for designing the kW-class DVR. For protecting a 380 V/5 kW sensitive load from 50% voltage sag, the SMES unit in the HES based scheme is demonstrated to avoid an initial discharge time delay of about 2.5 ms and a rushing discharging current of about 149.15 A in the sole BES based scheme, and the BES unit  is more economically feasible than the sole SMES based scheme for extending the compensation time duration.

KEYWORDS:

1.      Superconducting magnetic energy storage (SMES)

2.       SMES magnet design, hybrid energy storage (HES)

3.      Battery energy storage (BES)

4.      Continuous disk winding (CDW)

5.      Dynamic voltage restorer (DVR)

6.       Voltage sag compensation

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig. 1. Circuit topology of the HES-based DVR.

EXPECTED SIMULATION RESULTS:

Fig. 2. Transient voltage curves: (a) Load voltage before compensation; (b) Compensation voltage from the DVR; (c) Load voltage after compensation.

Fig. 3. Transient voltage curves: (a) Load voltage before compensation; (b) Compensation voltage from the DVR; (c) Load voltage after compensation.

CONCLUSION:

The structural design, fabrication process and FEM simulation of a 3.25 mH/240 A SMES magnet wound by state-of-the-art GdBCO tapes have been presented in this paper. The FEM simulation results have proved the performance enhancements in both the critical current and energy storage capacity by using the improved CDW scheme. Such a mini-size SMES magnet having relatively high power and low energy storage capacity is further applied to combine with a 40 V/100 Ah VRLA battery for developing a laboratory HES device in a kW-class DVR. In a 5 Kw sensitive load applications case, voltage sag compensation characteristics of three different DVR schemes by using a sole SMES system, a sole BES system and a SMES-BES-based HES device have been discussed and compared. With the fast-response high-power SMES, the maximum output current from the BES system is reduced from about 149.15 A in the BES-based DVR to 62.5 A in the HES-based DVR, and the drawback from the initial discharge time delay caused by the inevitable energy conversion process is offset by integrating the SMES system. With the low-cost high-capacity BES, practical compensation time duration is extended from about 32 ms in the SMES-based DVR to a longer duration determined by the BES capacity. Therefore, the proposed HES concept integrated with fast-response high-power SMES unit and low-cost high-capacity BES unit can be well expected to apply in practical large-scale DVR developments and other similar SMES applications.

REFERENCES:

[1] Mohd. H. Ali, B. Wu, and R. A. Dougal, “An overview of SMES applications in power and energy systems,” IEEE Trans. Sustainable Energy, vol. 1, no. 1, pp. 38-47, 2010.

[2] X. Y. Chen et al., “Integrated SMES technology for modern power system and future smart grid,” IEEE Trans. Appl. Supercond., vol. 24, no. 5, Oct. 2014, Art. ID 3801605.

[3] IEEE Std 1159-2009, IEEE Recommended Practice for Monitoring Electric Power Quality, 2009.

[4] X. H. Jiang et al., “A 150 kVA/0.3 MJ SMES voltage sag compensation system,” IEEE Trans. Appl. Supercond., vol. 15, no. 2, pp. 1903-1906, Jun. 2005.

[5] S. Nagaya et al., “Field test results of the 5 MVA SMES system for bridging instantaneous voltage dips,” IEEE Trans. Appl. Supercond., vol. 16, no. 2, pp. 632-635, Jun. 2006.

An Interline Dynamic Voltage Restoring and Displacement Factor Controlling Device (IVDFC)

ABSTRACT:

An interline dynamic voltage restorer (IDVR) is invariably employed in distribution systems to mitigate voltage sag/swell problems. An IDVR merely consists of several dynamic voltage restorers (DVRs) sharing a common dc link connecting independent feeders to secure electric power to critical loads. While one of the DVRs compensates for the local voltage sag in its feeder, the other DVRs replenish the common dc-link voltage. For normal voltage levels, the DVRs should be bypassed. Instead of bypassing the DVRs in normal conditions, this paper proposes operating the DVRs, if needed, to improve the displacement factor (DF) of one of the involved feeders. DF improvement can be achieved via active and reactive power exchange (PQ sharing) between different feeders. To successfully apply this concept, several constraints are addressed throughout the paper. Simulation and experimental results elucidate and substantiate the proposed concept.

KEYWORDS:

1.      Displacement factor improvement

2.      Interline dynamic voltage restorer (IDVR)

3.      Interline dynamic voltage restoring and displacement factor controlling (IVDFC)

4.      PQ sharing mode

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Principle of IVDFC system operation during normal conditions (PQ sharing mode).

EXPECTED SIMULATION RESULTS:

Fig. 2. Per-phase PQ sharing mode simulation results: (a)–(c) for first case and (d)–(f) for the second case.

Fig. 3. Per-phase simulation results for voltage sag condition at: (a) feeder 1 and (b) feeder 2.

Fig. 4. Per-phase experimental and corresponding simulation results for DF improvement case: (a) and (b) receiving feeder; (c) and (d) sourcing feeder (time/div= 10 ms/div).

Fig. 5 Per-phase experimental results and corresponding simulation results for voltage sag case: (a) and (b) at feeder 1 and (c) and (d) at feeder 2 (time/div = 10 ms/div).

Fig. 6 Per-phase experimental results and corresponding simulation results for voltage swell case at: (a) and (b) feeder 1 and (c) and (d) at feeder 2 (time/div = 10 ms/div).

CONCLUSION

This paper proposes a new operational mode for the IDVR to improve the DF of different feeders under normal operation. In this mode, theDFof one of the feeders is improved via active and reactive power exchange (PQ sharing) between feeders through the common dc link.

The same system can also be used under abnormal conditions for voltage sag/swell mitigation. The main conclusions of this work can be summarized as follows:

1) Under PQ sharing mode, the injected voltage in any feeder does not affect its load voltage/current magnitude, however, it affects the DFs of both sourcing and receiving feeders. The DF of the sourcing feeder increases while the DF of the receiving feeder decreases.

2) When applying the proposed concept, some constraints should be satisfied to maintain the DF of both sourcing and receiving feeders within acceptable limits imposed by the utility companies. These operational constraints have been identified and considered.

3) The proposed mode is highly beneficial if the active power rating of the receiving feeder is higher than the sourcing feeder. In this case, the DF of the sourcing feeder will have a notable improvement with only a slight variation in DF of the receiving feeder.

The proposed concept has been supported with simulation and experimental results.

REFERENCES:

[1] S. A. Qureshi and N. Aslam, “Efficient power factor improvement technique and energy conservation of power system,” Int. Conf. Energy Manage. Power Del., vol. 2, pp. 749–752, Nov. 21–23, 1995.

[2] J. J. Grainger and S. H. Lee, “Optimum size and location of shunt capacitors for reduction of losses on distribution feeders,” IEEE Trans. Power App. Syst., vol. PAS-100, no. 3, pp. 1105–1118, Mar. 1981.

[3] S. M. Kannan, P. Renuga, and A. R. Grace, “Application of fuzzy logic and particle swarm optimization for reactive power compensation of radial distribution systems,” J. Electr. Syst., 6-3, vol. 6, no. 3, pp. 407–425, 2010.

[4] L. Ramesh, S. P. Chowdhury, S. Chowdhury, A. A. Natarajan, and C. T. Gaunt, “Minimization of power loss in distribution networks by different techniques,” Int. J. Electr. Power Energy Syst. Eng., vol. 3, no. 9, pp. 521–527, 2009.

[5] T. P.Wagner, A. Y. Chikhani, and R. Hackam, “Feeder reconfiguration for loss reduction: An application of distribution automation,” IEEE Trans. Power Del., vol. 6, no. 4, pp. 1922–1933, Oct. 1991.

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

Single-Phase Active Power Filtering Method Using Diode-Rectifier-Fed Motor Drive

ABSTRACT:

 This paper presents a single-phase high power factor motor drive system with active power filter function. Since most of electrical equipment connected to the grid must comply with regulations regarding grid current harmonics, motor drive systems are generally equipped with Power Factor Corrector (PFC) which is comprised of power switches and reactive components, e.g., inductor and capacitor. The reactive components are bulky and increase the system cost especially in low-cost applications such as electrical home appliances. In this paper, a new motor drive algorithm which is capable of both driving a permanent magnet motor and filtering the harmonic currents produced by other non-linear loads belong to the system is proposed. Since the input current of the drive system is directly controlled by manipulating not the motor current reference but the output voltage reference of the inverter, it is possible to achieve exact and immediate control of the grid current. The effectiveness of the proposed algorithms is validated by experiments with a permanent magnet motor drive system.

KEYWORDS:

1.      Active damping

2.      Constant power load

3.       Dc-link capacitor

4.       Dc-link voltage stabilization

5.      Electrolytic capacitor

6.       Power factor corrector

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

                   

Figure 1. Block diagram of the input current control and the active power filter function.

 EXPECTED SIMULATION RESULTS:

Figure 2. (a) Motor currents (a-phase current in the stationary frame and d-q axes currents in the syncronous reference frame) with the proposed input current control, and (b) grid current, dc-link voltage, speed error and estimated torque.

Figure 3. Experimental results : input current of non-linear load and motor drive, grid current, dc-link voltage of both diode-rectifier (a) with the input current control algorithm, (b) with both the input current control and the active harmonic filtering algorithms, (c) three-phase motor currents (ia, ib, ic), grid voltage and current.

Figure 4. (a) PFC operation at light motor load (15% motor load) , and (b) during load change from 15% to 100% motor load.

CONCLUSION:

In motor drive systems supplied by a single-phase grid, the problems of input harmonic currents have been mitigated by a PFC, which makes the system bulk and expensive. In this paper, a power factor correction method for motor drive systems without PFC has been proposed. In the proposed system, the dc-link capacitor is reduced for continuous conduction of diode rectifier front end. And, the input current is controlled by directly manipulating the inverter output voltage according to the motor currents and the input current reference. Since the input current can be shaped into any waveforms using the proposed input current control method, it is also possible to eliminate the harmonics in the grid current that other electric loads generate by injecting the opposite harmonics. It was validated by experiments that the input current can be controlled using the proposed algorithm and the harmonic currents from other non-linear loads can be actively suppressed.

REFERENCES:

[1] Electromagnetic Compatibility (EMC), Part 3-2: Limits-Limits for Harmonic Current Emissions (Equipment Input Current≤ 16 A Per Phase), International Standard IEC 61000-3-2, 2005, 2013.

[2] H. Endo, T. Yamashita and T. Sugiura, "A high-power-factor buck converter", in Proc. IEEE Power Electron. Spec. Conf. (PESC), pp.1071 -1076 Jun. /Jul., 1992.

[3] L. Yen-Wu and R. J. King, "High performance ripple feedback for the buck unity-power-factor rectifier", IEEE Trans. Power Electron., vol. 10, no. 2, pp.158 -163, 1995

[4] B. Chen , Y. Xie , F. Huang and J. Chen, "A novel single-phase buck PFC converter based on one-cycle control", in Proc. IEEE Power Electron. Motion Control Conf. (IPEMC), vol. 2, pp.1 -5 Aug., 2006.

[5] W. W. Weaver and P. T. Krein, "Analysis and applications of a current-sourced buck converter", in Proc. IEEE Appl. Power Electron. Conf. (APEC), pp.1664 -1670 Feb. /Mar., 2007.

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) v_sab, i_sa,i_sb and i_sc ,(b) v_sab, i_La,i_Lb and i_Lc (c) V_dc, i_sa,i_La and i_Ca

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.

Power Factor Correction in Bridgeless-Luo Converter Fed BLDC Motor Drive

ABSTRACT:

This paper presents a power factor correction (PFC) based bridgeless-Luo (BL-Luo) converter fed brushless DC (BLDC) motor drive. A single voltage sensor is used for the speed control of BLDC motor and PFC at AC mains. The voltage follower control is used for a BL-Luo converter operating in discontinuous inductor current mode (DICM). The speed of the BLDC motor is controlled by an approach of variable DC link voltage, which allows a low frequency switching of voltage source inverter (VSI) for electronic commutation of BLDC motor; thus offers reduced switching losses. The proposed BLDC motor drive is designed to operate over a wide range of speed control with an improved power quality at AC mains. The power quality indices thus obtained are under the recommended limits of IEC 61000-3-2. The performance of the proposed drive is validated with test results obtained on a developed prototype of the drive.

KEYWORDS:

1.      Bridgeless Luo Converter

2.       Brushless DC motor

3.      Power Factor Correction

4.      Power Quality

5.      Voltage Source Inverter

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Fig. 1. Proposed PFC BL-Luo Converter fed BLDC motor drive.

EXPECTED SIMULATION RESULTS:

Fig. 2. Test results of proposed BLDC motor drive (a) At rated load  torque on BLDC motor with Vdc=50V and Vs=220V, (b) At rated load torque on BLDC motor with Vdc=200V and Vs=220V

Fig. 3. Test results of proposed BLDC motor drive showing (a) iLi1, iLo1, VC1 with Vs, (b) PFC converter’s switch voltage and current at rated load torque on BLDC motor (c) Enlarged waveforms of PFC converter’s switch voltage and current.

Fig. 4. Test results of proposed BLDC motor drive showing dynamic performance (a) during starting at 50V, (b) during change in DC link voltage from 100V to 150V, (c) during change in supply voltage from

250 to 180V.

CONCLUSION:

A PFC based BL-Luo converter fed BLDC motor drive has been proposed for wide range of speeds and supply voltages. A single voltage sensor based speed control of BLDC motor using a concept of variable DC link voltage has been used. The PFC BL-Luo converter has been designed to operate in DICM and to act as an inherent power factor preregulator. An electronic commutation of the BLDC motor has been used which utilizes a low frequency operation of VSI for reduced switching losses. The proposed BLDC motor drive has been designed and its performance is simulated in MATLAB/Simulink environment for achieving an improved power quality over wide range of speed control. Finally, the performance of proposed drive has been verified experimentally on a developed hardware prototype. A satisfactory performance of proposed drive has been achieved and is a recommended solution for low power applications.

REFERENCES:

[1] C. L. Xia, Permanent Magnet Brushless DC Motor Drives and Controls, Wiley Press, Beijing, 2012.

[2] T. Kenjo and S. Nagamori, Permanent Magnet Brushless DC Motors, Clarendon Press, Oxford, 1985.

[3] R. Krishnan, Electric Motor Drives: Modeling, Analysis and Control, Pearson Education, India, 2001.

[4] T. J Sokira and W. Jaffe, Brushless DC Motors: Electronic Commutation and Control, Tab Books, USA, 1989.

[5] H. A. Toliyat and S. Campbell, DSP-based Electromechanical Motion Control, CRC Press, New York, 2004.