Distributed Cooperative Control and Stability Analysis of Multiple DC Electric Springs in a DC Microgrid

ABSTRACT:  

Recently, dc electric springs (dc-ESs) have been proposed to understand voltage regulation and power quality improvement in dc microgrids. This paper establishes a distributed unified control framework for multiple dc- ESs in a dc microgrid and presents the small-signal stability  separation of the system. The primary level implements a droop control to coordinate the operations of multiple dc-ESs. The secondary control is based on a unity algorithm to regulate the dc-bus voltage reference, incorporating  the state-of-charge (SOC) balance among dc-ESs.

ELECTRIC SPRINGS

With the design, the cooperative control can achieve average dc-bus voltage consensus and maintain SOC balance among different dc-ESs using only neighbor-to-neighbor  information. Furthermore, a small-signal model of a four dc-ESs system with the primary and secondary controllers is developed. The eigenvalue analysis is presented to show   the effect of the communication weight on system stability. Finally, the effectiveness of the proposed control scheme and the small-signal model is verified in an islanded dc microgrid under different scenarios through simulation and  experimental studies.

KEYWORDS:

  1. Consensus
  2. Dc microgrid
  3. Distributed control
  4. Electric springs (ES)
  5. Small-signal stability

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

 Fig.1.distributed network with multiple dc -ESs

 EXPECTED SIMULATION RESULTS:

 

Fig. 2.SEZ. Controller comparison. (a) Node bus voltage, (b) dc-ESs output

power, (c) SOC, and (d) state variables xi .

Fig. 3. Proposed controller with different aij . (a) and (d) Average  bus voltages with aij = 0.5 and aij = 10. (b) and (e) State variables with aij = 0.5 and aij = 10. (c) and (f) Bus voltages with aij = 0.5  and aij = 10.

Fig. 4. dc-ES4 failure at 5 s. (a) Node bus voltage, (b) output power,  and (c) SOC.

Fig. 5. Proposed controller with communication delay τ . (a) Node bus  average voltage, (b) SOC, and (c) state variables xi .

 

Fig. 6. Proposed controller with five dc-ESs. (a) Node bus voltage, (b) output power, and (c) SOC.

 CONCLUSION:

A hierarchical two-level voltage control scheme was proposed for dc-ESs in a microgrid using the consensus algorithm to estimate the average dc-bus voltage and promote SOC balance among different dc-ESs. The small-signal model of four dc-ESs system incorporating the controllers was developed for eigenvalues analysis to investigate the stability of the system. The consensus of the observed average voltages and the defined state variables has been proven.

MICROGRID

Results show that the control can improve the voltage control accuracy of dc-ESs and realize power sharing in proportion to the SOC. The resilience of the system against the link failure has been improved and the system can still maintain operations as long as the remaining communication graph has a spanning tree. Simulation and experimental results also verify that the correctness and effectiveness of the proposed model and controller strategy.

REFERENCES:

[1] X. Lu, K. Sun, J. M. Guerrero, J. C. Vasquez, and L. Huang, “State-ofcharge balance using adaptive droop control for distributed energy storage systems inDCmicrogrid applications,” IEEE Trans. Ind. Electron., vol. 61, no. 6, pp. 2804–2815, Jun. 2014.

[2] Q. Shafiee, T. Dragicevic, J. C. Vasquez, and J. M. Guerrero, “Hierarchical control for multiple DC-microgrids clusters,” IEEE Trans. Energy Convers., vol. 29, no. 4, pp. 922–933, Dec. 2014.

[3] W. Yao, M. Chen, J. Matas, J. M. Guerrero, and Z. M. Qian, “Design and analysis of the droop control method for parallel inverters considering the impact of the complex impedance on the power sharing,” IEEE Trans. Ind. Electron., vol. 58, no. 2, pp. 576–588, Feb. 2011.

[4] V. Nasirian, S. Moayedi, A. Davoudi and F. Lewis, “Distributed cooperative control of DC microgrids,” IEEE Trans. Power Electron., vol. 30, no. 4, pp. 6725–6741, Dec. 2014.

[5] J. M. Guerrero, J. C. Vasquez, J. Matas, L. G. de Vicu˜na, and M. Castilla, “Hierarchical control of droop-controlledAC andDCmicrogrids—A general  approach toward standardization,” IEEE Trans. Ind. Electron., vol. 58, no. 1, pp. 158–172, Jan. 2011.

A Simple Active and Reactive Power Control for Applications of Single-Phase Electric Springs

ABSTRACT

Aiming at effective power management in micro grids with high penetration of renewable energy sources (R E S s), the paper proposes a simple active and reactive power control for the so-called second-generation, single-phase electric springs (ES-2), that overcomes the shortcomings of the existing Electric  Springs control methods. By the proposed control, the unpredictable power generated from R E S s is divided into two parts, i.e. the one absorbed by the ES-2 that still varies and the other injected into the grid that turns to be controllable, by a simple and accurate signal manipulation that works both at steady-state and during RES transients.

It

is believed that such a control is suitable for the distributed power generation, especially at domestic homes.  In the paper, the proposed control is supported by a theoretical background. Its effectiveness is at first validated by simulations and then by experiments. To this purpose, a typical RES application is considered, and an experimental setup is arranged, built up around an Electric Springs -2 implementing the proposed control. Testing of the setup is carried out in three steps and proves not only the smooth operation of the Electric Springs-2 itself, but also its capability in running the application properly.

 

KEYWORDS

  1. Electric springs
  2. Smart load
  3. Microgrids
  4. active and reactive Power control
  5. Grid connected
  6. Distributed generation.

 

SOFTWARE:  MAT LAB/SIM U LINK

 

CIRCUIT DIAGRAM:

Fig. 1: Topology of Electric Springs -2 and associated circuitry

EXPECTED SIMULATION RESULTS

Fig. 2: Simulation wave forms under different variations of the input active power. (a) From 1.6 kW to 1.1 kW and then back to 1.6 kW @ VG=230 V. (b) From 8 kW to 2 kW and then back to 8 kW @ VG=200 V. (c) From 8 kW to 4 kW and then to 2 kW @ VG=200 V.

Fig. 3: Transient ES-2 responses to a change of the line voltage with Pinref=1.5kW. (a) From 240V to 210V. (b) From 210V to 240V.

Fig. 4: Simulation waveforms before and after grid distortion. (a) Results of PLL. (b) Results of active and reactive power of ES system.

CONCLUSION

The input active and reactive power control is proposed for the purpose of practical application of ES-2 in this paper. An overall review and analysis have been done on the existing control strategies such as δ control and RCD control, revealing that the essences of the controls on ES-2 are to control the input active power and reactive power. If being equipped together with the distributed generation from RESs, the ES-2 can manage the fluctuated power and make sure the controllable power to grid, which means that the ES-2 is able to deal with the active power captured by MPPT algorithm.

Simulations

have been done on the steady and transient analysis and also under the grid anomalies, validating the effectiveness of the proposed control. Three steps have been set in the experiments to verify the three typical situations and namely the active power generated by the GCC from RESs are, 1) more than; 2) less than; 3) the same as the load demand. Tested results have validated the proposed active and reactive power control.

 

REFERENCES

  • Cheng and Y. Zhu, “The state of the art of wind energy conversion systems and technologies: A review,” Energy Conversion and Management, vol. 88, pp. 332–347, Dec. 2014.
  • Sotoodeh and R. D. Miller, “Design and implementation of an 11-level inverter with FACTS capability for distributed energy systems,” IEEE J. Emerging Sel. Topics Power Electron., vol.2, no. 1, pp. 87–96, Mar. 2014.
  • Wang, and D. N. Truong, “Stability enhancement of a power system with a PMSG-based and a DFIG-based offshore wind farm using a SVC With an adaptive-network-based fuzzy inference system,” IEEE Trans. Ind. Electron., vol. 60, no. 7, pp. 2799–2807, Jul. 2013.
  • active and reactive power control projects

Mitigating Distribution Power Loss of DC Microgrids with DC Electric Springs

ABSTRACT:  

DC microgrids fed with substantial intermittent renewable energy sources (RES) face the immediate problem of power imbalance and the subsequent DC bus voltage fluctuation problem (that can easily breach power system standards). It has recently been demonstrated that DC electric springs (DCES), when connected with series non-critical loads, are capable of stabilizing the voltage of local nodes and improving the power quality of DC microgrids without large energy storage.

DC MICROGRID

In this paper, two centralized model predictive control (CMPC) schemes with (i) non-adaptive weighting factors and (ii) adaptive weighting factors are proposed to extend the existing functions of the DCES in the microgrid. The control schemes coordinate the DCES to mitigate the distribution power loss in the DC microgrids, while simultaneously providing their original function of DC bus voltage regulation. Using the DCES model that was previously validated with experiments, simulations based on MATLAB/SIMULINK platform are conducted to validate the control schemes. The results show that with the proposed CMPC schemes, the DCES are capable of eliminating the bus voltage offsets as well as reducing the distribution power loss of the DC microgrid.

KEYWORDS:

  1. DC microgrids
  2. DC electric springs (DCES)
  3. Centralized model predictive control (CMPC)
  4. Non-adaptive weighting factors
  5. Adaptive weighting factors
  6. Distribution power loss

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

 

Fig. 1. An m-bus DC microgrid with n RES units.

EXPECTED SIMULATION RESULTS:

 

 Fig. 2. Waveforms of the power supply by RES and the bus voltages of the DC microgrid without DCES.

Fig. 3. Waveforms of the bus voltages of the DC microgrid when the DCES is installed at the five buses.

Fig. 4. Waveforms of the bus voltages of the DC microgrid with three DCES installed at bus 1, bus 4 and bus 5.

Fig. 5. The comparisons of the power loss on the distribution lines between α=1 and α=0.9 when three DCES are installed.

Fig. 6. Waveforms of the bus voltages of the DC microgrid with four DCES installed at bus 1, bus 2, bus 4 and bus 5.

Fig. 7. Comparisons of the power loss on the distribution lines for different values of α when four DCES are installed.

CONCLUSION:

 DC electric springs (DCES) is an emerging technology that can be used to stabilize and improve the power quality of DC microgrids. In this paper, a centralized model predictive control (CMPC) with both non-adaptive weighting factors and adaptive weighting factors is proposed for multiple DCES to further mitigate the power loss on the distribution lines of a DC microgrid.

CMPC

Using a DCES model previously verified with experiments, simulation studies have been conducted for a DC microgrid setup. Simulation results on a 48 V five-bus DC microgrid show that the energy is saved about 49.4% in the 5 seconds when three DCES are controlled by the CMPC with non-adaptive weighting factors and is saved about 58.5% in the 5 seconds when four DCES are controlled by the CMPC with non-adaptive weighting factors. It is also demonstrated that the power loss on the distribution lines of the DC microgrid can be further reduced by the CMPC with adaptive weighting factors, as compared to the CMPC with non-adaptive weighting factors.

REFERENCES:

[1] B. C. Beaudreau, World Trade: A Network Approach, iUniverse, 2004.

[2] G. Neidhofer, “Early three-phase power,” IEEE Power and Energy Magazine, vol. 5, no. 5, pp.88−100, Sep. 2007.

[3] R. H. Lasseter and P. Paigi, “Microgrid: a conceptual solution,” in Proc. IEEE Power Electron. Spec. Conf., 2004, pp. 4285−4290.

[4] S. Anand, B. Fernandes, and J. Guerrero, “Distributed control to ensure proportional load sharing and improve voltage regulation in low-voltage dc microgrids,” IEEE Tran. Pow. Elect., vol. 28, no. 4, Aug. 2012.

[5] T. Gragicevic, X. Lu, J. C. Vasquez, and J. M. Guerrero, “DC microgrids−part I: a review of control strategies and stabilization techniques,” IEEE Trans. Pow. Elect., vol. 31, no. 7, Jul. 2016.

An Improved Beatless Control Method of AC Drives for Railway Traction Converters

ABSTRACT:  

The traction converter consists of a single phase AC DC rectifier and a three phase DC AC invert er. Due to special structural characteristics of single phase rectifier, a fluctuating voltage component with the frequency twice of the grid’s, exists in DC link voltage. Fed by fluctuating DC link voltage, a beat phenomenon occurs in traction motor, and harmonic components appear in both stat or current and electromagnetic torque, especially when motor operates near the ripple frequency. In this paper, the mechanism and influence of fluctuating voltage are analyzed in detail. Based on modeling analysis of motor and switching function of invert er, a frequency compensation factor is derived in vector control of induction motor. Then an improved frequency compensation control method is proposed to suppress beat phenomenon without LC resonant circuit. Finally the simulation verifies the modified scheme.

KEYWORDS:

  1. Fluctuating DC voltage
  2. Beat phenomenon
  3. Vector control
  4. Beat less control

 SOFTWARE: MAT LAB/SIM U LINK

 BLOCK DIAGRAM:

 Fig. 1. F O C with frequency compensation for Induction Motor

 EXPECTED SIMULATION RESULTS:

 Fig. 2. Waves of stat or current and electromagnetic torque of traction Motor

Fig. 3. FF T of stat or current and electromagnetic torque before adding frequency compensation method

Fig. 4. FF T of stat or current and electromagnetic torque after adding traditional frequency compensation method

Fig. 5. FF T of stat or current and electromagnetic torque after adding improved frequency compensation method

 CONCLUSION:

 In high power traction converters, without LC filter circuit paralleled in DC link, a fluctuating voltage twice of the grid frequency contains in DC link voltage. This paper aims at adopting software control method to suppress beat phenomenon in traction motor caused by DC ripple voltage. According to theoretical analysis, output power of motor, DC link capacitor and power factor influenced the DC ripple voltage. Then, the aspect of switching function and motor model analyzed the influences of fluctuating voltage in detail. Based on above analysis, combining with rotor field oriented control of traction motor, the frequency of switching function is modified to suppress beat phenomenon. An improved frequency compensation control method is proposed. Simulation model is built to verify the proposed scheme. Finally, the drag experiment on a dynamo meter test platform verified the proposed control method.

REFERENCES:

[1] J. K l i ma, M. Ch  o mat, L. Sch re i e r, “Analytical Closed-form Investigation of P WM Invert er Induction Motor Drive Performance under DC Bus Voltage Pulsation,” I ET Electric Power Application, Vol. 2, No. 6, pp. 341–352, Nov, 2008.

[2] H. W. van d e r Bro e ck and H. C. S k u d e l n y, “Analytical analysis of the harmonic effects of a P WM AC drive,” in IEEE Transactions on Power Electronics, vol. 3, no. 2, pp. 216-223, Apr 1988.

[3] K Na k at a, T N a k a m a chi , K Na k am u r a, “A beat less control of invert er-induction motor system driven by a rippled DC power source,” Electrical Engineering in Japan, Vol.109, No.5, pp.122-131,1989.

[4] Z Sal am, C.J. Goodman, “Compensation of fluctuating DC link voltage for traction invert er driver,” Power Electronics and Variable Speed Drives, 1996. Sixth International Conference on (Conf. Pub l. No. 429), pp. 390-395, 1996.

[5] S. K o u r o, P. Le z an a, M. An g u lo and J. Rodriguez, “Multi carrier P WM With DC-Link Ripple Feed forward Compensation for Multilevel Invert er s,” IEEE Transactions on Power Electronics, vol. 23, no. 1, pp. 52- 59, Jan. 2008.

Integrated Photovoltaic and Dynamic Voltage Restorer System Configuration

ABSTRACT:  

This paper presents a new system structure for integrating a grid-connected photo voltaic (P V) system together with a self-supported dynamic voltage restorer (DVR). The proposed system termed as a “six-port converter,” consists of nine semiconductor switches in total. The proposed configuration retains all the essential features of normal P V and DVR systems while reducing the overall switch count from twelve to nine. In addition, the dual functionality feature significantly enhances the system robustness against severe symmetrical/asymmetrical grid faults and voltage dips. A detailed study on all the possible operational modes of six-port converter is presented. An appropriate control algorithm is developed and the validity of the proposed configuration is verified through extensive simulation as well as experimental studies under different operating conditions.

KEYWORDS:

  1. Bidirectional power flow
  2. Distributed power generation
  3. Photovoltaic (PV) systems
  4. Power quality
  5. Voltage control

 SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

 

 Fig. 1. Proposed integrated PV and DVR system configuration.

 EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation results: operation of proposed system during health grid mode (PV-VSI: active and DVR-VSI: inactive). (a) Vpcc; (b) PQload; (c) PQgrid; (d) PQpv-VSI; and (e) PQdvr-VSI.

Fig. 3. Simulation results: operation of proposed system during fault mode (PV-VSI: inactive and DVR-VSI: active). (a) Vpcc; (b) Vdvr; (c) Vload; (d) PQload; (e) PQgrid; (f) PQpv-VSI; and (g) PQdvr-VSI.

Fig. 4. Simulation results: operation of proposed system during balance three phase sag mode (PV-VSI: active and DVR-VSI: active). (a) Vpcc; (b) Vdvr-VSI; (c) Vload; (d) PQgrid; (e) PQpv-VSI; and (f) PQdvr-VSI.

Fig. 5. Simulation results: operation of proposed system during unbalanced sag mode (PV-VSI: active and DVR-VSI: active). (a) Vpcc; (b) Vdvr-vsi; (c) Vload; (d) PQgrid; (e) PQpv-VSI; and (f) PQdvr-VSI.

Fig. 6. Simulation results: operation of proposed system during inactive PV plantmode (PV-VSI: active and DVR-VSI: active). (a) Vpcc; (b) Vload; (c) Vdc; (d) PQload; (e) PQdvr-VSI; and (f) PQpv-VSI.

 CONCLUSION:

 In this paper, a new system configuration for integrating a conventional grid-connected P V system and self supported DVR is proposed. The proposed configuration not only exhibits all the functionalities of existing P V and DVR system, but also enhances the DVR operating range. It allows DVR to utilize active power of P V plant and thus improves the system robustness against sever grid faults. The proposed configuration can operate in different modes based on the grid condition and P V power generation. The discussed modes are healthy grid mode, fault mode, sag mode, and P V inactive mode. The comprehensive simulation study and experimental validation demonstrate the effectiveness of the proposed configuration and its practical feasibility to perform under different operating conditions. The proposed configuration could be very useful for modern load centers where on-site P V generation and strict voltage regulation are required.

REFERENCES:

[1] R. A. Walling, R. Saint, R. C. Dugan, J. Burke, and L. A. Kojovic, “Summary of distributed resources impact on power delivery systems,” IEEE Trans. Power Del., vol. 23, no. 3, pp. 1636–1644, Jul. 2008.

[2] C. Meza, J. J. Negroni, D. Biel, and F. Guinjoan, “Energy-balance modeling and discrete control for single-phase grid-connected PV central inverters,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2734–2743, Jul.2008.

[3] T. Shimizu, O. Hashimoto, and G. Kimura, “A novel high-performance utility-interactive photovoltaic inverter system,” IEEE Trans. Power Electron., vol. 18, no. 2, pp. 704–711, Mar. 2003.

[4] S. B. Kjaer, J. K. Pedersen, and F. Blaabjerg, “A review of single-phase grid-connected inverters for photovoltaic modules,” IEEE Trans. Ind.Appl., vol. 41, no. 5, pp. 1292–1306, Sep./Oct. 2005.

[5] T. Esram, J. W. Kimball, P. T. Krein, P. L. Chapman, and P. Midya, m“Dynamic maximum power point tracking of photovoltaic arrays using ripple correlation control,” IEEE Trans. Power Electron., vol. 21, no. 5, pp. 1282–1291, Sep. 2006.

Investigation on cascade multilevel inverter with symmetric, asymmetric, hybrid and multi-cell configurations

ABSTRACT:  

In recent past, numerous multilevel architectures came into existence but in this background, cascaded multilevel invert er (CM LI) is the promising structure. This type of multilevel invert er s synthesizes a medium voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltage and current wave forms, however, when the number of levels increases switching components and the count of dc sources are also increased.

This issue became a key motivation for the present paper which is devoted to investigate different types of CM LI using less number of switching components and dc sources thus finally proposed a new version of Multi-cell based CM LI. In order to verify the proposed topology, MAT LAB – simulations and hardware verification are carried out and results are presented.

KEYWORDS:
  1. Cascade multilevel invert er
  2. Multi-cell
  3. Switching components
  4. High quality output voltages

 SOFTWARE: MAT LAB/SIM U LINK

 INVESTIGATION ON CASCADE MULTILEVEL INVERT ER:

Figure 1 (a) CH B multilevel invert er, (b) key waveform for seven-level invert er, (c) CH B multilevel invert er by employing single-phase transformers, (d) simulation verification of seven-level CH B multilevel invert er, (e) F  FT spectrum.

 

Figure 2 (a) Asymmetrical thirteen-level CH B invert er, (b) simulation verification of thirteen-level CH B multilevel invert er, (c) FF T spectrum.

 

Figure 3 (a) Asymmetrical CH B multilevel invert er, (b) output voltages of each H-bridge module, (c) twenty-seven level output voltage waveform, (d) F FT spectrum.

 

Figure 4 (a) Asymmetrical CH B multilevel invert er using sub-cells, (b) output voltage of sub-cells, (c) thirty-one level output voltage waveform, (d) FF T spectrum.

 

Figure 5 (a) Hybrid CH B multilevel invert er, (b) output voltage of each H-bridge and load voltage (nine-level) waveform, (c) FF T spectrum.

Figure 6 (a) Hybrid multilevel invert er using traditional invert er, (b) output voltage waveform, (c) FF T Spectrum.

 

Figure 7 The proposed multi-cell CM LI.

.Figure 8 (a) The proposed 25-level asymmetric multi-cell CM LI, (b) key wave forms.

Figure 9 (a) Output voltage of first H-bridge, (b) output voltage of second H-bridge, (c) resultant output voltage with 25-levels, (d) FF T spectrum.

 CONCLUSION:

 In this paper CM LI with sub-cells is proposed with less number of switches. To highlight the merits of proposed invert er, an in-depth investigation is carried out on symmetric, asymmetric and hybrid multilevel invert er s based on CH B top o log i es. Symmetric configuration has capacity to produce only limited number of levels in output voltage, On the counter side, symmetrical configuration can be operated in asymmetrical mode with different DC sources. However, asymmetrical configurations can produce higher number of output levels and thereby qualitative output wave forms could be generated.

Later,

hybrid CH B invert er s are also introduced, which utilizes single DC source for entire structure. Thus complexity and voltage balancing issues can be reduced. Finally proposed invert er is introduced with less number of switching components and able to produce qualitative output wave forms. To verify the proposed invert er adequate simulation is done with help of MAT LAB/sim u link. Later on, hardware variations are carried out in laboratory. Verification are quite impressive with greater number of levels in the output voltage and lower harmonic content in FF T spectrum s. Spectrum s indicate that, low order harmonics are drastically reduced. Thus power quality is significantly enhanced. Thus proposed invert er shows some promising attributes when compared with traditional CH B based architectures.

References

] B ab a e  E, Ali l u S, La a l i S. A new general topology for cascaded
multilevel invert er s with reduced number of components based on
developed H-bridge. IEEE Trans Ind Electron 2014;61(8):3932–9.
[2] Malinowski Mar i us z, Go p a k u mar K, Rodriguez Jose, P e´re z
Marcelo A. A survey on cascaded multilevel invert er s. IEEE
Trans Ind Electron 2010;57(7):2197–205.
[3] Wu J C, Wu K D, Jo u H L, Xi a o ST. Diode-clamped multi-level
power converter with a zero-sequence current loop for three-phase
three-wire hybrid power filter. Elsevier J Elect r Power S y  s t Res
2011;81(2):263–70.
[4] K ho u c ha Far id, Lag o  n M o u n a So um i a, K he l o i Ab d e l a z i z,
Ben b o u z d Mohamed E l Ha ch e mi. A comparison of symmetrical
and asymmetrical three-phase H-bridge multilevel invert-er for
DTC induction motor drives. IEEE Trans Energy Converse
2011;26(1):64–72.
[5] E bra him i J, Ba b a e i E, G h a r e h p e ti an GB. A new topology of
cascaded multilevel converters with reduced number of components for high-voltage applications. IEEE Trans Power Electron
2011;26(11):3119–30

Analysis and Implementation of a Novel Bidirectional DC–DC Converter

ABSTRACT:  

A novel bidirectional dc–dc converter is presented in this paper and its circuit configuration of the proposed converter is very simple. The proposed converter employs a coupled induct-or with same winding turns in the primary and secondary sides. In step-up mode, the primary and secondary winding s of the coupled induct-or are operated in parallel charge and series discharge to achieve high step-up voltage gain. In step-down mode, the primary and secondary winding s of the coupled induct-or are operated in series charge and parallel discharge to achieve high step-down voltage gain.

Proposed converter

Thus, the proposed converter has higher step-up and step-down voltage gains than the conventional bidirectional dc–dc boost/buck converter. Under same electric specifications for the proposed converter and the conventional bidirectional boost/buck converter, the average value of the switch current in the proposed converter is less than the conventional bidirectional boost/buck converter. The operating principle and steady-state analysis are discussed in detail. Finally, a 14/42-V prototype circuit is implemented to verify the performance for the automobile dual-battery system.

KEYWORDS:
  1. Bidirectional dc–dc converter
  2. Coupled induct-or
 SOFTWARE: MAT LAB/SIMULATION
 CIRCUIT DIAGRAM:

 

Fig. 1. Proposed bidirectional dc–dc converter.

 EXPECTED SIMULATION RESULTS:

 

 Fig. 2. Some experimental wave-forms of the proposed converter in step-up mode. (a) iL1, iL2, and iL, (b) iS1, iS2, and iS3. (c) vDS1, vDS2, and vDS3.

 

 Fig. 3. Dynamic response of the proposed converter in step-up mode for the output power variation between 20 and 200 W.

Fig. 4. Some experimental wave-forms of the proposed converter in step down mode. (a) iLL, iL1, and iL2, (b) iS3, iS1, and iS2. (c) vDS3, vDS1, and vDS2.

Fig. 5. Dynamic response of the proposed converter in step-down mode for the output power variation between 20 and 200 W.

CONCLUSION:

 This paper researches a novel bidirectional dc–dc converter. The circuit configuration of the proposed converter is very simple. The proposed converter has higher step-up and step-down voltage gains and lower average value of the switch current than the conventional bidirectional boost/buck converter. From the experimental results, it is see that the experimental wave-forms agree with the operating principle and steady-state analysis. At full-load condition, the measured efficiency is 92.7% in step-up mode and is 93.7% in step-down mode. Also, the measured efficiency is around 92.7%–96.2% in step-up mode and is around 93.7%–96.7% in step-down mode, which are higher than the conventional bidirectional boost/buck converter.

REFERENCES:

[1] M. B. Cam a r a, H. G u a lo us, F. Gust in, A. Berth on, and B. D a k yo, “DC/DC converter design for super capacitor and battery power management in hybrid vehicle applications—Polynomial control strategy,” IEEE Trans. Ind. Electron., vol. 57, no. 2, pp. 587–597, Feb. 2010.

[2] T. B h at t a char ya, V. S. G i r i, K. Mathew, and L. U man and, “Multi phase bidirectional fly back converter topology for hybrid electric vehicles,” IEEE Trans. Ind. Electron., vol. 56, no. 1, pp. 78–84, Jan. 2009.

[3] Z. Am j ad i and S. S. Williamson, “A novel control technique for a switched-capacitor-converter-based hybrid electric vehicle energy storage system,” IEEE Trans. Ind. Electron., vol. 57, no. 3, pp. 926–934, Mar. 2010.

[4] F. Z. Pen g, F. Zhang, and Z. Q i an, “A magnetic-less dc–dc converter for dual-voltage automotive systems,” IEEE Trans. Ind. App l., vol. 39, no. 2, pp. 511–518, Mar./Apr. 2003.

[5] A. Na sir i, Z. N i e, S. B. Be k i a r o v, and A. E mad i, “An on-line UPS system with power factor correction and electric isolation using BI F RED converter,” IEEE Trans. Ind. Electron., vol. 55, no. 2, pp. 722–730, Feb. 2008.

Dynamic Modeling, Design, and Simulation of a Combined PEM Fuel Cell and Ultracapacitor System for Stand-Alone Residential Applications

ABSTRACT:  

The available power generated from a fuel cell (F C) power plant may not be sufficient to meet sustained load demands, especially during peak demand or transient events encountered in stationary power plant applications. An ultracapacitor (U C) bank can supply a large burst of power, but it cannot store a significant amount of energy. The combined use of F C and U C has the potential for better energy efficiency, reducing the cost of F C technology, and improved fuel usage. In this paper, we present an F C that operates in parallel with a U C bank. A new dynamic model and design methodology for an F C- and U C based energy source for stand-alone residential applications has been developed. Simulation results are presented using MAT LAB, Simulation, and Sim Power Systems environments based on the mathematical and dynamic electrical models developed for the proposed system.

KEYWORDS:
  1. Combined system
  2. Dynamic modeling
  3. Fuel cell (F C)
  4. Proton exchange membrane fuel cell (PE M F C)
  5. Ultracapacitor (U C)
 SOFTWARE: MAT LAB/SIM U LINK
BLOCK DIAGRAM:

     Fig. 1. Combination of F C system and U C bank.

                Fig. 2. PCU and load connection diagram.

EXPECTED SIMULATION RESULTS:

 

Fig. 3. Real power of residential load.

Fig. 4. Variation of FC system output voltage according to load demand.

 Fig. 5. Variation of UC bank terminal voltage according to load demand.

 

Fig. 6. Variation of UC bank charging and discharging current according to load switching.

Fig. 7. Variation of ac output power.

 

 Fig. 8. Variation of ac load voltage.

 

Fig. 9. Variation of modulation index corresponding to load demand.

 

Fig. 10. Variation of ac voltage phase angle.

Fig. 11. Variation of FC system dc output power.

Fig. 12. Variation of hydrogen flow rate.

CONCLUSION:

 A UC-based storage system is designed for a PEMFC operated grid independent home to supply the extra power required during peak demand periods. The parallel combination of the FC system and UC bank exhibits good performance for the stand-alone residential applications during the steady-state, load-switching, and peak power demand. Without the UC bank, the FC system must supply this extra power, thereby increasing the size and cost of the FC system.

Results

The results corresponding to high peak load demand during short time periods are not shown in order to simulate more realistic load profile. The load profile was created by measuring data at 15-s sampling interval. However, the proposed model can be used for different load profiles consisting of different transients and short-time interruption. Also, it can be extended for use in many areas such as portable devices, heavy vehicles, and aerospace applications. The lifetime of an FC system can be increased if combined FC system and UC bank is used instead of a stand-alone FC system or a hybrid FC and standby battery system.

REFERENCES:

[1] L. Gao, Z. Jiang, and R. A. Dougal, “An actively controlled fuel cell/battery hybrid to meet pulsed power demands,” J. Power Sources, vol. 130, no. 1–2, pp. 202–207, May 2004.

[2] T. S. Key, H. E. Sitzlar, and T. D. Geist, “Fast response, load-matching hybrid fuel cell,” Final Tech. Prog. Rep., EPRI PEAC Corp., Knoxville,TN NREL/SR-560-32743, Jun. 2003.

[3] S. Buller, E. Karden, D. Kok, and R. W. De Doncker, “Modeling the dynamic behavior of supercapacitors using impedance spectroscopy,” IEEE Trans. Ind. Appl., vol. 38, no. 6, pp. 1622–1626, Nov. 2002.

[4] J. L. Duran-Gomez, P. N. Enjeti, and A. Von Jouanne, “An approach to achieve ride-through of an adjustable-speed drive with flyback converter modules powered by super capacitors,” IEEE Trans. Ind. Appl., vol. 38, no. 2, pp. 514–522, Mar.–Apr. 2002.

[5] A. Burke, “Ultracapacitors: Why, how, and where is the technology,” J. Power Sources, vol. 91, no. 1, pp. 37–50, Nov. 2000.

Analysis of Active and Reactive Power Control of a Stand-Alone PEM Fuel Cell Power Plant

ABSTRACT:

This paper presents analytical details of how active and reactive power output of a stand-alone proton-exchange-membrane (PE M) fuel cell power plant (F C PP) is controlled. This analysis is based on an integrated dynamic model of the entire power plant including the reformer. The validity of the analysis is verified when the model is used to predict the response of the power plant to: 1) computer-simulated step changes in the load active and reactive power demand and 2) actual active and reactive load profile of a single family residence. The response curves indicate the load-following characteristics of the model and the predicted changes in the analytical parameters predicated by the analysis.

 

KEYWORDS:

  1. Active power control
  2. Fuel cell
  3. Fuel cell model,
  4. PEM fuel cell
  5. Proton exchange membrane (PEM)
  6. Reactive power.

 

BLOCK DIAGRAM:

Fig. 1. FCPP, inverter and load connection diagram.

 

EXPECTED SIMULATION RESULTS:

Fig. 2 Load step changes.

Fig. 3. FCPP output current.

Fig. 4. AC output voltage.

Fig. 5. Active output power.

Fig. 6. Reactive output power.

Fig.7 Output voltage phase angle.

Fig. 8. Hydrogen flow rate.

Fig. 9. AC output power.

Fig. 10. Active power of residential load.

Fig. 11. Reactive power of residential load.

Fig. 12 FCPP active power output.

Fig. 13. FCPP reactive power output.

                                                                                                                                                             CONCLUSION:

This paper introduces an integrated dynamic model for a fuel cell power plant. The proposed dynamic model includes a fuel cell model, a gas reformer model, and a power conditioning unit block. The model introduces a scenario to control active and reactive power output from the fuel cell power plant. The analysis is based on traditional methods used for the control of active and reactive power output of a synchronous generator. To test the proposed model, its active and reactive power outputs are compared with variations in load demand of a single family residence. The results obtained show a fast response of the fuel cell power plant to load changes and the effectiveness of the proposed control technique for active and reactive power output.

 

REFERENCES:

[1] M. A. Laughton, “Fuel cells,” Power Eng. J., vol. 16, no. 1, pp. 37–47, Feb. 2002.

[2] S. Um et al., “Computational fluid dynamics modeling of proton exchange membrane fuel cell,” J. Power Electrochem. Soc., vol. 147, no. 12, pp. 4485–4493, 2000.

[3] D. Singh et al., “A two-dimension analysis of mass transport in proton exchange membrane fuel cells,” Int. J. Eng. Sci., vol. 37, pp. 431–452, 1999.

[4] J. C. Amphlett et al., “A model predicting transient response of proton exchange membrane fuel cells,” J. Power Sources, vol. 61, pp. 183–188, 1996.

[5] J. Padulles et al., “An integrated SOFC plant dynamic model for power systems simulation,” J. Power Sources, vol. 86, pp. 495–500, 2000.

Control of Induction Motor Drive using Space Vector PWM

ABSTRACT:  

In this paper speed of acceptance engine is controlled, supply from three stage connect transform er because the variety in information Voltage or recurrence in turn both changes the speed of an taking in engine. Variable voltage and recurrence for Adjustable Speed Drives (AS D) is constantly acquires from a three-stage Voltage Source Invert er (V SI) also P WM strategies controls the Voltage and recurrence of transform er, so which is an imperative viewpoint in the use of AS D s.

P WM Techniques

A number of P WM techniques are there to obtain variable voltage and frequency supply such as P WM, SP WM, S VP WM and among the various modulation strategies, SVPWM is one of the most efficient techniques as it has better performance and output voltage is similar to sinusoidal. SVPWM the modulation index in linear region will also be high when compared to other.

 BLOCK DIAGRAM:

 Figure 1: AS D Block Diagram

 EXPECTED SIMULATION RESULTS:

 Figure 2: SP WM Pulses

Figure 3: Invert er o/p line voltages

Figure 4: Motor Speed and Electromagnetic torque.

Figure 5: SVPWM output gate pulses

                  Figure 6:Open Loop Drive Speed response with TL=0

Figure 7: Open Loop Drive Speed response with different TL

Figure 8: Sinusoidal PWM based open loop drive Load Current T H D

 CONCLUSION:

MAT LAB/Sim u link is used to carryout the simulation of “Control of Induction Motor Drive Using Space Vector P WM” for open loop as well as closed control by which the appropriate output results are obtained. The variation of speed of Induction Motor is observed by varying the load torque in open loop control and the table gives the results. Also observed that for the change in input speed commands the motor speed is settled down to its final value within 0.1 sec in closed loop model.

REFERENCES:

[1] Ab d e l fat ah K o l l i, Student Member, IEEE, Olivier Be t ho u x, Member, IEEE, A l e x a n d re D e Be r n a  r d in i s, Member, IEEE, Eric Lab our e, and G e r a rd Co q u e r y “Space-Vector P WM Control Synthesis for an H-Bridge Drive in Electric Vehicles” IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 62, NO. 6, JULY 2013. pp. 2241-2252.

[2]Mr. Sand e e p N Pan ch a l, Mr. Vi s h a l S She t h, Mr. A k s hay A P and ya “Simulation Analysis of S V P WM Invert er Fed Induction Motor Drives” International Journal of Emerging Trends in Electrical and Electronics (IJET E  E) Vol. 2, Issue. 4, April-2013. pp. 18-22 .

[3]H a o ran S hi, Wei X  u, Chen  g h u a F u and Y a o Yang. “Research on Three phase Voltage Type P  WM Rectifier System Based on S V P WM Control” Research Journal of Applied Sciences, Engineering and Technology 5(12): 3364-3371, 2013. pp. 3364-3371.