# Modeling, Analysis and Testing of Autonomous Operation of an Inverter-Based Microgrid

###### ABSTRACT:

The analysis of the small-signal stability of conventional power systems is well established, but for inverter based microgrids there is a need to establish how circuit and control features give rise to particular oscillatory modes and which of these have poor damping. This paper develops the modeling and analysis of autonomous operation of inverter-based microgrids.

Each sub-module is modeled in state-space form and all are combined together on a common reference frame. The model captures the detail of the control loops of the inverter but not the switching action. Some inverter modes are found at relatively high frequency and so a full dynamic model of the network (rather than an algebraic impedance model) is used. The complete model is linearized around an operating point and the resulting system matrix is used to derive the eigenvalues.

The eigenvalues (termed “modes”) indicate the frequency and damping of oscillatory components in the transient response. A sensitivity analysis is also presented which helps identifying the origin of each of the modes and identify possible feedback signals for design of controllers to improve the system stability.

With experience it is possible to simplify the model (reduce the order) if particular modes are not of interest as is the case with synchronous machine models. Experimental results from a microgrid of three 10-kW inverters are used to verify the results obtained from the model.

###### KEYWORDS:
1. Inverter
2. Inverter model
3. Microgrid
4. Power control
5. Small-signal stability

###### BLOCK DIAGRAM:

Fig. 1. Typical structure of inverter-based microgrid.

###### EXPECTED SIMULATION RESULTS:

Fig. 2. Active power (filtered) response of micro-sources with 3.8 kW of step

change in load power at bus 1.

Fig. 3. Reactive power exchange between the micro sources with 3.8 kW of

step change in load power at bus 1 (Initial values: Q1 =0, Q2 = 􀀀200, Q3 =

+200; Final values: Q1 = +600, Q2 = 􀀀300, Q3 = 􀀀200).

Fig. 4. Active power (filtered) response of micro-sources with 16.8 kW and

12 kVAR RL load step change at bus 1.

Fig. 5. Reactive power (filtered) response of micro-sources with 16.8 kW and

12 kVAR RL load step change at bus 1.

Fig. 6. Output voltage (d-axis) response with 27 kW of step change in load

power at bus 1.

Fig. 7. Inductor current (d-axis) response with 27 kW of step change in load

power at bus 1.

###### CONCLUSION:

In this paper, a small-signal state-space model of a microgrid is presented. The model includes inverter low frequency dynamics dynamics, high frequency dynamics, network dynamics, and load dynamics. All the sub-modules are individually modeled and are then combined on a common reference frame to obtain the complete model of the microgrid.

The model was analyzed in terms of the system eigenvalues and their sensitivity to different states. With the help of this analysis the relation between different modes and system parameters was established. It was observed that the dominant low-frequency modes are highly sensitive to the network configuration and the parameters of the power sharing controller of the micro sources. The high frequency modes are largely sensitive to the inverter inner loop controllers, network dynamics, and load dynamics.

Results obtained from the model were verified experimentally on a prototype microgrid. It was observed that the model successfully predicts the complete microgrid dynamics both in the low and high frequency range.

Small signal modeling has had a long history of use in conventional power systems. The inverter models (and the inclusion of network dynamics) illustrated in this paper allow microgrids to be designed to achieve the stability margin required of reliable power systems.

###### REFERENCES:

[1] R. H. Lasseter, “Microgrids,” in Proc. Power Eng. Soc.Winter Meeting, Jan. 2002, vol. 1, pp. 305–308.

[2] A. Arulapalam, M. Barnes, A. Engler, A. Goodwin, and N. Jenkins, “Control of power electronic interfaces in distributed generation microgrids,” Int. J. Electron., vol. 91, no. 9, pp. 503–523, Sep. 2004.

[3] R. Lassetter, “Integration of Distributed Energy Resources: The CERTS Microgrid Concept,” CERT Rep., Apr. 2002.

[4] M. S. Illindala, P. Piagi, H. Zhang, G. Venkataramanan, and R. H. Lasseter, “Hardware Development of a Laboratory-Scale Microgrid Phase 2: Operation and Control of a Two-Inverter Microgrid,” Nat. Renewable Energy Rep., Mar. 2004.

[5] Y. Li, D. M. Vilathgamuwa, and P. C. Loh, “Design, analysis and realtime testing of a controller for multibus microgrid system,” IEEE Trans. Power Electron., vol. 19, no. 5, pp. 1195–1204, Sep. 2004.

# Simulation and Analysis of Stand-alone Photovoltaic System with Boost Converter using MATLAB/Simulink

#### ABSTRACT:

Use of renewable energy and in particular solar energy has brought significant attention over the past decades.  Many research works are carried out to analyze and validate the performance of P V modules. Implementation of experimental set up for P V based power system with DC-DC converter to validate the performance of the system is not always possible due to practical constraints. Software based simulation model helps to analyze the performance of P V and a common circuit based model which could be used for validating any commercial P V module will be more helpful.

##### Simulation

of mathematical model for Photo voltaic (P V) module and DC-DC boost converter is presented in this paper. The model presented in this paper can be used as a generalized P V module to analyze the performance of any commercially available P V modules. I-V characteristics and P-V characteristics of P V module under different temperature and irradiation level can be obtained using the model. The design of DC-DC boost converter is also discussed in detail. Simulation of DC-DC converter is performed and the constant DC supply fed converter and P V fed converter generates the results.

#### BLOCK DIAGRAM:

Fig. 1 Sim u link Model of proposed system

#### EXPECTED SIMULATION RESULTS:

Fig.2 P WM Pulse generation

Fig. 3(a) Input Voltage of DC-DC Boost Converter

Fig. 4(b) Output Voltage of Boost Converter constant DC input supply

Fig. 5 (c) Output current of Boost Converter constant DC input supply

Fig. 6 (a) Input voltage of P V fed converter

Fig. 7 (b) Output voltage and current waveform of P V fed converter

Fig. 8. Change in irradiation level of P V Module

Fig. 9. Output Voltage and Current wave forms of Boost Converter at

#### CONCLUSION:

A circuit based system model of P V modules helps to analyze the performance of commercial P V modules. The commonly used blocks in the form of masked subsystem block develops a general model of P V module. I-V and P-V characteristics outputs are generated for MS X 60 P V module under different irradiation and different temperature levels and the matlab/simulink simulates the module under various conditions as presented in the data sheet. The results obtained from the simulation shows excellent matching with the characteristics graphs provided in the data sheet of the selected models.

##### Thus,

the model can be used to analyze the performance of any commercial P V module. Matlab/Simulink simulates the DC-DC boost converter and the converter generates  the results with constant DC input supply and by interconnecting the P V module with it. The results shows close match between the output of converter with constant DC input and the P V fed converter. The P V fed DC-DC boost converter generates the output voltage and current for change of irradiation levels at constant temperature is also presented.

#### REFERENCES:

[1] J. A. Go w, C.D.Manning, “ Development of photo voltaic array model for the use in power electronic simulation studies,” I E E Proceedings Electric power applications, Vol. 146, No.2, March,1999.

[2] J e e-H o o n Jung, and S. Ahmed, “Model Construction of Single Crystalline Photo voltaic Panels for Real-time Simulation,” IEEE Energy Conversion Congress & Expo, September 12-16, 2010, Atlanta, USA.

[3] T. F. E l shatter, M. T. E l ha g r y, E. M. Ab o u-E l z a  h a b, and A. A. T. Elk o u s y, “Fuzzy modeling of photo voltaic panel equivalent circuit,” in Proc. Conf. Record 28th IEEE Photo voltaic Spec. Conf., pp. 1656– 1659, 2000.

[4] M. Ba l z a n i and A. Re at ti, “Neural network based model of a P V array for the optimum performance of P V system,” in Proc. P h.D. Res. Micro electron. Electron., vol. 2, pp. 123–126, 2005.

# Modeling, Implementation and Performance Analysis of a Grid-Connected Photovoltaic/Wind Hybrid Power System

ABSTRACT:

This paper investigates dynamic modeling, design and control strategy of a grid-connected photovoltaic (PV)/wind hybrid power system. The hybrid power system consists of PV station and wind farm that are integrated through main AC-bus to enhance the system performance. The Maximum Power Point Tracking (MPPT) technique is applied to both PV station and wind farm to extract the maximum power from hybrid power system during variation of the environmental conditions. The modeling and simulation of hybrid power system have been implemented using Matlab/Simulink software. The effectiveness of the MPPT technique and control strategy for the hybrid power system is evaluated during different environmental conditions such as the variations of solar irradiance and wind speed. The simulation results prove the effectiveness of the MPPT technique in extraction the maximum power from hybrid power system during variation of the environmental conditions. Moreover, the hybrid power system operates at unity power factor since the injected current to the electrical grid is in phase with the grid voltage. In addition, the control strategy successfully maintains the grid voltage constant irrespective of the variations of environmental conditions and the injected power from the hybrid power system.

KEYWORDS:

1. PV
2. Wind
3. Hybrid system
4. Wind turbine
5. DFIG
6. MPPT control

BLOCK DIAGRAM:

Fig. 1. The system configuration of PV/wind hybrid power system.

EXPECTED SIMULATION RESULTS:

(b) PV array voltage.

(c) PV array current.

(d) A derivative of power with respect to voltage (dPpv/dVpv).

Fig. 2. Performance of PV array during the variation of solar irradiance.

(b) d-q axis components of injected current from PV station.

(c) Injected active and reactive power from PV station.

(d) Grid voltage and injected current from PV station.

(e) The power factor of the inverter.

(f) Injected current from PV station.

Fig. 3. Performance of PV station during variation of the solar irradiance.

(a) Wind speed profile.

(b) The mechanical torque of wind turbine.

(c) The DC-bus voltage of DFIG.

(d) Injected active and reactive power from the wind farm.

(e) The power factor of the wind farm.

(f) Injected current from the wind farm.

Fig. 4. Performance of wind farm during variation of the wind speed.

(a) Power flow between PV station, wind farm, and hybrid power system.

(b) Injected active and reactive power from the hybrid system.

(c) PCC-bus voltage.

Fig. 5. Performance of hybrid power system at PCC-bus.

CONCLUSION:

In this paper, a detailed dynamic modeling, design and control strategy of a grid-connected PV/wind hybrid power system has been successfully investigated. The hybrid power system consists of PV station of 1MW rating and a wind farm of 9 MW rating that are integrated through main AC-bus to inject the generated power and enhance the system performance. The incremental conductance MPPT technique is applied for the PV station to extract the maximum power during variation of the solar irradiance. On the other hand, modified MPPT technique based on mechanical power measurement is implemented to capture the maximum power from wind farm during variation of the wind speed. The effectiveness of the MPPT techniques and control strategy for the hybrid power system is evaluated during different environmental conditions such as the variations of solar irradiance and wind speed. The simulation results have proven the validity of the MPPT techniques in extraction the maximum power from hybrid power system during variation of the environmental conditions. Moreover, the hybrid power system successfully operates at unity power factor since the injected reactive power from hybrid power system is equal to zero. Furthermore, the control strategy successfully maintains the grid voltage constant regardless of the variations of environmental conditions and the injected power from the hybrid power system.

REFERENCES:

[1] H. Laabidi and A. Mami, “Grid connected Wind-Photovoltaic hybrid system,” in 2015 5th International Youth Conference on Energy (IYCE), pp. 1-8,2015.

[2] A. B. Oskouei, M. R. Banaei, and M. Sabahi, “Hybrid PV/wind system with quinary asymmetric inverter without increasing DC-link number,” Ain Shams Engineering Journal, vol. 7, pp. 579-592, 2016.

[3] R. Benadli and A. Sellami, “Sliding mode control of a photovoltaic-wind hybrid system,” in 2014 International Conference on Electrical Sciences and Technologies in Maghreb (CISTEM), pp. 1-8, 2014.

[4] A. Parida and D. Chatterjee, “Cogeneration topology for wind energy conversion system using doubly-fed induction generator,” IET Power Electronics, vol. 9, pp. 1406-1415, 2016.

[5] B. Singh, S. K. Aggarwal, and T. C. Kandpal, “Performance of wind energy conversion system using a doubly fed induction generator for maximum power point tracking,” in Industry Applications Society Annual Meeting (IAS), 2010 IEEE, 2010, pp. 1-7.

# Top Electrical Projects Ideas for Engineering Students

Approximately each & every technology in modern living relies on electrical engineering in some or the other way. Electrical engineers labor with energy (together with light, electricity, sound, and electro-magnetic fields) and intellect (data, modeling, algorithms, simulation and control). Even though many of these occurrences are undetectable, they broaden the potential of surviving in modern world. With innovative projects and ideas dispensing almost every other day, it becomes necessary for electronics & electric students to position a practicable and within your means electrical projects for their submission which can be carried out by them simply.

Design of External Inductor for Improving Performance of Voltage Controlled DSTATCOM

An Enhanced Single Phase Step-Up Five-Level  Inverter

A Hybrid-STATCOM with Wide Compensation Range and Low DC-Link Voltage

A Capacitor Voltage-Balancing Method for Nested Neutral Point Clamped (NNPC) Inverter

T-type direct AC/AC converter structure

Modular Multilevel Converter Circulating Current Reduction Using Model Predictive Control

Parallel inductor multilevel current source  inverter with energy – recovery scheme for inductor currents balancing

Open-Circuit Fault-Tolerant Control for Outer Switches of Three-Level Rectifiers in Wind Turbine Systems

Enhancing DFIG wind turbine during three phase fault using parallel interleaved converters and dynamic resistor

Development and Comparison of an Improved Incremental Conductance Algorithm for Tracking the MPP of a Solar PV Panel

Impact of Switching Harmonics on Capacitor Cells Balancing in Phase-Shifted PWM Based Cascaded H-Bridge STATCOM

Effect of circulating current on input line current of 12-pulse rectifier with active inter-phase reactor

Modular Multilevel Converter-Based Bipolar High-Voltage Pulse Generator With Sensorless Capacitor Voltage Balancing Technique

Power-Electronics-Based Energy Management System With Storage

Modulation and Control of Transformerless UPFC

A Hybrid Simulation Model for VSC HVDC

Switching Control of Buck Converter Based on Energy Conservation Principle

A Three-Phase Multilevel HybridSwitched-Capacitor PWM PFC Rectifier for High-Voltage-Gain Applications

A dc-Side Sensorless Cascaded H-Bridge Multilevel Converter Based PhotovoltaicSystem

Phase angle calculation dynamics of type-4wind turbines in rms simulations during severe voltage dips

A Multi-Level Converter with a Floating Bridge for Open-Ended Winding Motor Drive Applications

Model Predictive Control of Quasi-Z-Source Four-Leg Inverter

Using Multiple Reference Frame Theory for Considering Harmonics in Average-Value Modeling of Diode Rectifiers

Cascaded Dual Model Predictive Control of an Active Front-End Rectifier

Simple Time Averaging Current Quality Evaluation of a Single-Phase Multilevel PWM Inverter

# A Combination of Shunt Hybrid Power Filter and Thyristor-Controlled Reactor for Power Quality

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 61, NO. 5, MAY 2014

ABSTRACT: This paper proposes a combined system of a thyristor-controlled reactor (TCR) and a shunt hybrid power filter (SHPF) for harmonic and reactive power compensation. The SHPF is the combination of a small-rating active power filter (APF) and a fifth-harmonic-tuned LC passive filter. The tuned passive filter and the TCR form a shunt passive filter (SPF) to compensate reactive power. The small-rating APF is used to improve the filtering characteristics of SPF and to suppress the possibility of resonance between the SPF and line inductances. A proportional–integral controller was used, and a triggering alpha was extracted using a lookup table to control the TCR. A nonlinear control of APF was developed for current tracking and voltage regulation. The latter is based on a decoupled control strategy, which considers that the controlled system may be divided into an inner fast loop and an outer slow one. Thus, an exact linearization control was applied to the inner loop, and a nonlinear feedback control law was used for the outer voltage loop. Integral compensators were added in both current and voltage loops in order to eliminate the steady-state errors due to system parameter uncertainty. The simulation and experimental results are found to be quite satisfactory to mitigate harmonic distortions and reactive power compensation.

KEYWORDS:

1. Harmonic suppression
2. Hybrid power filter
3. Modeling
4. Nonlinear control
5. Reactive power compensation
6. Shunt hybrid power filter and thyristor-controlled reactor (SHPF-TCRcompensator)
7. Thyristor-controlled reactor (TCR)

BLOCK DIAGRAM:

Fig. 1. Basic circuit of the proposed SHPF-TCR compensator.

EXPECTED SIMULATION RESULTS:

Fig. 2. Steady-state response of the SHPF-TCR compensator with harmonic generated load.

Fig. 3. Harmonic spectrum of source current in phase 1. (a) Before compensation. (b) After compensation

Fig. 4. Dynamic response of SHPF-TCR compensator under varying distorted harmonic type of load conditions.

Fig. 5. Dynamic response of SHPF-TCR compensator under the harmonic and reactive power type of loads.

Fig. 6. Harmonic spectrum of source current in phase 1. (a) Before compensation. (b) After compensation.

Fig. 7. Steady-state response of the SHPF-TCR compensator with harmonic produced load.

CONCLUSION:

In this paper, a SHPF-TCR compensator of a TCR and a SHPF has been proposed to achieve harmonic elimination and reactive power compensation. A proposed nonlinear control scheme of a SHPF-TCR compensator has been established, simulated, and implemented by using the DS1104 digital realtime controller board of dSPACE. The shunt active filter and SPF have a complementary function to improve the performance of filtering and to reduce the power rating requirements of an active filter. It has been found that the SHPF-TCR compensator can effectively eliminate current harmonic and reactive power compensation during steady and transient operating conditions for a variety of loads. It has been shown that the system has a fast dynamic response, has good performance in both steady-state and transient operations, and is able to reduce the THD of supply currents well below the limit of 5% of the IEEE-519 standard.

REFERENCES:

[1] A. Hamadi, S. Rahmani, and K. Al-Haddad, “A hybrid passive filter configuration for VAR control and harmonic compensation,” IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2419–2434, Jul. 2010.

[2] P. Flores, J. Dixon, M. Ortuzar, R. Carmi, P. Barriuso, and L. Moran, “Static Var compensator and active power filter with power injection capability, using 27-level inverters and photovoltaic cells,” IEEE Trans. Ind. Electron., vol. 56, no. 1, pp. 130–138, Jan. 2009.

[3] H. Hu, W. Shi, Y. Lu, and Y. Xing, “Design considerations for DSPcontrolled 400 Hz shunt active power filter in an aircraft power system,” IEEE Trans. Ind. Electron., vol. 59, no. 9, pp. 3624–3634, Sep. 2012.

[4] X. Du, L. Zhou, H. Lu, and H.-M. Tai, “DC link active power filter for three-phase diode rectifier,” IEEE Trans. Ind. Electron., vol. 59, no. 3, pp. 1430–1442, Mar. 2012.

[5] M. Angulo, D. A. Ruiz-Caballero, J. Lago, M. L. Heldwein, and S. A. Mussa, “Active power filter control strategy with implicit closedloop current control and resonant controller,” IEEE Trans. Ind. Electron., vol. 60, no. 7, pp. 2721–2730, Jul. 2013.

# Application of Unified Power Flow Controller in Interconnected Power Systems—Modeling, Interface, Control Strategy, and Case Study

ABSTRACT:

In this paper, a new power frequency model for unified power flow controller (UPFC) is suggested with its dc link capacitor dynamics included. Four principal control strategies for UPFC series element main control and their impacts on system stability are discussed. The main control of UPFC series element can be realized as a combination of the four control functions. The supplementary control of UPFC is added for damping power oscillation. The integrated UPFC model has then been incorporated into the conventional transient and small signal stability programs with a novel UPFC-network interface. Computer tests on a 4-generator interconnected power system show that the suggested UPFC power frequency model and the UPFC- network interface method work very well. The results also show that the suggested UPFC control strategy can realize power flow control fairly well and improve system dynamic performance significantly.

CIRCUIT DIAGRAM:

Fig. 1. Transmission line with UPFC installed

CONTROL SYSTEM

Fig. 2. The main control and phasor diagram.

EXPECTED SIMULATION RESULTS:

Fig. 3. Plots of case 1a.

Fig. 4.Plots of case 1b.

Fig. 5. Plots of case 1c.

Fig. 6. Effects of supplementary control.

Fig. 7. Results of the suggested control scheme.

CONCLUSION:

The suggested UPFC power frequency model and the  developed UPFC-network interface method work very well in the study of power system dynamics with satisfied convergence and accuracy. Four principal main control strategies are discussed and the computer tests results support the discussion conclusion very well. The constant power flow control is good for steady state control and the constant series compensation control is useful for first swing stability. The supplementary control is very efficient in damping intcrarea power oscillation. The suggested UPFC control can realize the desired control strategy flexibly and improve system dynamic performance significantly.

REFERENCES:

[1] L. Gyugyi, “Unified Power-Flow Control Concept for Flexible AC Transmission Systems,” IEE Proceedings-C, vol. 139, no. 4, pp. 323–331, July 1992.

[2] I. Papic, P. Zunko, and D. Povh, “Basic Control of Unified Power Flow Controller,” IEEE Trans. on Power Systems, vol. 12, no. 4, pp. 1734–1739, Nov. 1997.

[3] R. Mihalic, P. Zunko, and D. Povh, “Improvement of Transient Stability Using Unified Power Flow Controller,” IEEE Trans. on Power Delivery, vol. 11, no. 1, pp. 485–491, Jan. 1996.

[4] K. S. Smith, L. Ran, and J. Penman, “Dynamic Modeling of a Unifed Power Flow Controller,” IEE Proc.-Gener. Transm. Distrib., vol. 144, 1, pp. 7–12, Jan. 1997.

[5] M. Noroozian, L. Angquist, and M. Ghandhari, et al., “Improving Power System Dynamics by Series-connected FACTS devices,” IEEE Trans. on Power Delivery, vol. 12, no. 4, pp. 1635–1641, Oct. 1997.

# A Combination of Shunt Hybrid Power Filter and Thyristor-Controlled Reactor for Power Quality

ABSTRACT:

This paper proposes a combined system of a thyristor-controlled reactor (TCR) and a shunt hybrid power filter (SHPF) for harmonic and reactive power compensation. The SHPF is the combination of a small-rating active power filter (APF) and a fifth-harmonic-tuned LC passive filter. The tuned passive filter and the TCR form a shunt passive filter (SPF) to compensate reactive power. The small-rating APF is used to improve the filtering characteristics of SPF and to suppress the possibility of resonance between the SPF and line inductances. A proportional–integral controller was used, and a triggering alpha was extracted using a lookup table to control the TCR. A nonlinear control of APF was developed for current tracking and voltage regulation. The latter is based on a decoupled control strategy, which considers that the controlled system may be divided into an inner fast loop and an outer slow one. Thus, an exact linearization control was applied to the inner loop, and a nonlinear feedback control law was used for the outer voltage loop. Integral compensators were added in both current and voltage loops in order to eliminate the steady-state errors due to system parameter uncertainty. The simulation and experimental results are found to be quite satisfactory to mitigate harmonic distortions and reactive power compensation.

KEYWORDS:

1. Harmonic suppression,
2. Hybrid power filter
3. Modeling
4. Nonlinear control
5. Reactive power compensation
6. Shunt hybrid power filter and thyristor-controlled reactor (SHPF-TCRcompensator)
7. Thyristor-controlled reactor (TCR)

BLOCK DIAGRAM:

Fig. 1. Basic circuit of the proposed SHPF-TCR compensator.

EXPECTED SIMULATION RESULTS:

Fig. 2. Steady-state response of the SHPF-TCR compensator with harmonic generated load.

Fig. 3. Harmonic spectrum of source current in phase 1. (a) Before compensation.

(b) After compensation.

Fig. 4. Dynamic response of SHPF-TCR compensator under varying distorted

Fig. 5. Dynamic response of SHPF-TCR compensator under the harmonic and reactive power type of loads.

Fig. 6. Harmonic spectrum of source current in phase 1. (a) Before compensation. (b) After compensation.

Fig. 7. Steady-state response of the SHPF-TCR compensator with harmonic produced load.

CONCLUSION:

In this paper, a SHPF-TCR compensator of a TCR and a SHPF has been proposed to achieve harmonic elimination and reactive power compensation. A proposed nonlinear control scheme of a SHPF-TCR compensator has been established, simulated, and implemented by using the DS1104 digital realtime controller board of dSPACE. The shunt active filter and SPF have a complementary function to improve the performance of filtering and to reduce the power rating requirements of an active filter. It has been found that the SHPF-TCR compensator can effectively eliminate current harmonic and reactive power compensation during steady and transient operating conditions for a variety of loads. It has been shown that the system has a fast dynamic response, has good performance in both steady-state and transient operations, and is able to reduce the THD of supply currents well below the limit of 5% of the IEEE-519 standard.

REFERENCES:

[1] A. Hamadi, S. Rahmani, and K. Al-Haddad, “A hybrid passive filter configuration for VAR control and harmonic compensation,” IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2419–2434, Jul. 2010.

[2] P. Flores, J. Dixon, M. Ortuzar, R. Carmi, P. Barriuso, and L. Moran, “Static Var compensator and active power filter with power injection capability, using 27-level inverters and photovoltaic cells,” IEEE Trans. Ind. Electron., vol. 56, no. 1, pp. 130–138, Jan. 2009.

[3] H. Hu, W. Shi, Y. Lu, and Y. Xing, “Design considerations for DSPcontrolled 400 Hz shunt active power filter in an aircraft power system,” IEEE Trans. Ind. Electron., vol. 59, no. 9, pp. 3624–3634, Sep. 2012.

[4] X. Du, L. Zhou, H. Lu, and H.-M. Tai, “DC link active power filter for three-phase diode rectifier,” IEEE Trans. Ind. Electron., vol. 59, no. 3, pp. 1430–1442, Mar. 2012.

[5] M. Angulo, D. A. Ruiz-Caballero, J. Lago, M. L. Heldwein, and S. A. Mussa, “Active power filter control strategy with implicit closedloop current control and resonant controller,” IEEE Trans. Ind. Electron., vol. 60, no. 7, pp. 2721–2730, Jul. 2013.

# Analysis and Design of High-Frequency Isolated Dual-Bridge Series Resonant DC/DC Converter

ABSTRACT:

Bidirectional dual-bridge dc/dc converter with high frequency isolation is gaining more attentions in renewable energy system due to small size and high-power density. In this paper, a dual-bridge series resonant dc/dc converter is analyzed with two simple modified ac equivalent circuit analysis methods for both voltage source load and resistive load. In both methods, only fundamental components of voltages and currents are considered. All the switches may work in either zero-voltage-switching or zero-current-switching for a wide variation of voltage gain, which is important in renewable energy generation. It is also shown in the second method that the load side circuit could be represented with an equivalent impedance. The polarity of cosine value of this equivalent impedance angle reveals the power flow direction. The analysis is verified with computer simulation results. Experimental data based on a 200 W prototype circuit is included for validation purpose.

KEYWORDS:

1. Analysis and simulation
2. Dc-to-dc converters
3. Modeling
4. Renewable energy systems
5. Resonant converters

BLOCK DIAGRAM:

Fig. 1. Hybrid renewable energy generation system with battery back-up function.

EXPECTED SIMULATION RESULTS:

Fig. 2. Output power versus phase-shift angle φ. (a) F = 1.1, M = 0.95,

and different Q. (b) F = 1.1, Q = 1, and different converter gain M.

Fig. 3. Operation in charging mode (Vi = 110 V, Vo = 100 V), simulated waveforms of vAB and vCD , resonant current iS , resonant capacitor voltage vCs , output current before filter capacitor io for output power (a) Po = 200W, (b) Po = 100 W, and (c) Po = 20 W.

Fig. 4. Operation in regeneration mode (Vi = 110V, Vo = 100 V). Simulated waveforms of vAB and vCD , resonant current iS , resonant capacitor voltage vCs , output current before filter capacitor io for output power Po = −200 W.

Fig. 5. Full-load test results (Vi = 110 V, Vo = 100 V). (a) From top to bottom vAB (100V/div), vCD (100V/div), is (2A/div). (b) vC (100V/div). (c) Primary switch current (1A/div). (d) Secondary switch current (1A/div).

Fig. 6. (a) Half-load test results (Vi = 110 V, Vo = 100 V): from top to bottom: vAB (100 V/div), vCD (100 V/div), is (2 A/div), primary switch current (1 A/div), secondary switch current (1 A/div). (b) 10% load condition test results (Vi = 110 V, Vo = 100 V): from top to bottom: waveforms of (a) repeated.

Fig. 7. Output current of secondary converter under different load levels (Vi = 110 V, Vo = 100 V). (a) 200 W (2A/div). (b) 100 W (2A/div). (c) 20 W (1A/div).

CONCLUSION:

In this paper, a HF isolated dual-bridge series resonant dc/dc converter has been proposed, which is suitable for renewable energy generation applications. Two modified ac equivalent circuit analysis methods were presented to analyze the DBSRC. First method used was voltage-source type of load, whereas, second method uses a controlled rectifier with resistive load. It was shown that an equivalent impedance could be used to represent the secondary part circuit in the case of resistive load to include the bidirectional feature. Detailed analysis has been presented for both the methods. Same results were obtained from both the methods. ZVS turn-ON for primary-side switches and ZCS turn-OFF for secondary-side switches could be achieved for all load and input/output voltage conditions. Design procedure has been illustrated by a 200Wdesign example. Through the SPICE simulation and experimental results, the theoretical results have been verified.

In the DAB converter, performance of the converter is heavily dependent on the leakage inductance of the transformer (used for power transfer and should be as small as possible) [15], [19], whereas, in the DBSRC, leakage inductance is used as part of resonant tank. If the DAB converter is used for application with wide input/output voltage variation, ZVS of primary-side converter may be hard to achieve [19]. DBSRC has low possibility of transformer saturation due to the series capacitor (that can be split as mentioned earlier). The disadvantage of DBSRC is the size of resonant tank (additional capacitor), which brings extra size and cost. Further work is required to compare the DAB converter with the DBSRC for such applications. In the future, more study will be done based on the DBSRC. Efforts will focus on modifications to realize ZVS on the secondary side to reduce the switching losses further. With all two quadrant switches replaced with four-quadrant switches [23], the converter could be controlled as an ac/ac electronic transformer, which can be used in doubly fed induction generator (DFIG) based wind generation system. For high-power applications, multicells of the converter may be used to meet high power density requirements.

REFERENCES:

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