Photovoltaic Based Dynamic Voltage Restorer with Energy Conservation Capability using Fuzzy Logic Controller

ABSTRACT:

In this paper, a Photovoltaic based Dynamic Voltage Restorer (PV-DVR) is proposed to handle deep voltage sags, swells and outages on a low voltage single phase residential distribution system. It can recover sags up to 10%, swells up to 190% of its nominal value. Otherwise, it will operate as an Uninterruptable Power Supply (UPS) when the utility grid fails to supply. It is also designed to reduce the usage of utility power, which is generated from nuclear and thermal power stations. A series injection transformer is connected in series with the load when restoring voltage sag and swell and it is reconfigured into parallel connection using semiconductor switches when it is operating in UPS and power saver mode. The use of high step up dc-dc converter with high-voltage gain reduces the size and required power rating of the series injection transformer. It also improves the stability of the system. The Fuzzy Logic (FL)  controller with two inputs maintains the load voltage by detecting  the voltage variations through d-q transformation technique.  Simulation results have proved the ability of the proposed DVR  in mitigating the voltage sag, swell and outage in a low voltage single phase residential distribution system.

KEYWORDS:

1.      Dynamic Voltage Restorer

2.      Photovoltaic

3.      Voltage Sag

4.      Voltage Swell

5.      Outages

6.      High Step up dc-dc Converter

7.      Fuzzy Logic Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Structural block diagram of the proposed system.

EXPECTED SIMULATION RESULTS:

(a)     Supply Voltage

(b)     Injected Voltage

(c)     Load Voltage

(d)     Load Current

(e) Load voltage THD

Fig. 2. Supply voltage, Injected voltage, Load voltage, Load Current and

Fig. 3. Load Voltage with PI controller

(a)     PV array output voltage without low power boost converter

(b) PV array output voltage with low power boost converter

Fig. 4. PV array output voltage without and with boost converter

Fig. 5. Output voltage of the high step up DC-DC converter

CONCLUSION:

This paper proposed a new PV based DVR to reduce the energy consumption from the utility grid. The design of a Dynamic Voltage Restorer (DVR) which incorporates a PV array module with low and high power boost converters as a DC voltage source to mitigate voltage sags, swells and outages in low voltage single phase distribution systems using FL controller has been presented. The modeling and simulation of the proposed PV based DVR using MATLAB simulink has been presented. The FL controller utilizes the error signal from the comparator to trigger the switches of an inverter using a sinusoidal PWM scheme. The proposed DVR utilizes the energy drawn from the PV array and the utility source to charge the battries during normal operation. The stored energies in battery are converted to an adjustable single phase ac voltage for mitigation of voltage sag, swell and outage. The simulation result shows that the PV based DVR with FL controller gives better dynamic performance in mitigating the voltage variations. The proposed DVR is operated in:

Standby Mode: when the PV array voltage is zero and the inverter is not active in the circuit to keep the voltage to its nominal value.

Active Mode: when the DVR senses the sag, swell and outage. DVR reacts fast to inject the required single phase compensation voltages.

Bypass Mode: when DVR is disconnected and bypassed in case of maintenance and repair.

Power Saver mode: when the PV array with low step-up dc-dc converter output power is enough to handle the load.

Further work will include a comparison with laboratory experiments on a low voltage DVR in order to compare simulation and experimental results. The multiple functions of DVR require further investigation.

REFERENCES:

[1] H.Ezoji, A.Sheikholeslami, M.Tabasi, and M.M.Saeednia, “Simulation of dynamic voltage restorer using hysteresis voltage control,” European journal of scientific research, vol. 27, pp. 152-166, Feb 2009.

[2] F.A.L.Jowder, “Modeling and simulation of different system topologies for dynamic voltage restorer using simulink,” in proc. EPECS ’09, 2009, p. 1-6.

[3] R.Strzelecki, and G.Benysek, “Control strategies and comparison of the dynamic voltage restorer,” in proc. PQ ‘08, 2008, p. 79-82.

[4] P.Boonchiam, and N.Mithulananthan, “Understanding of dynamic voltage restorers through MATLAB simulation,” Thammasat Int. J. Sc. Tech., Vol. 11, No.3, pp. 1-6, Sep 2006.

[5] K.C.Bayinder, A.Teke, and M.Tumay, “A Robust control of dynamic voltage restorer using fuzzy logic,” in proc. ACEMP ’07, 2007, p.55

Performance Improvement of DVR by Control of Reduced-Rating with A Battery Energy Storage

ABSTRACT:

Voltage injection methods for DVRs (Dynamic Voltage Restorers) and operating modes are resolved in this paper. Using fuzzy logic control DVR with dc link& with BESS systems are operated. Power quality problems mainly harmonic distortion, voltage swell & sag are decreased with DVR using Synchronous Reference Theory (SRF theory) with the help of fuzzificaton waveforms are observed.

KEYWORDS:

1.      Dynamic Voltage Restorer

2.      Unit Vector

3.      Power quality

4.      Harmonic distortion

5.      Voltage Sag

6.      Voltage Swell

7.      Fuzzy logic controller

8.      Matlab/simulink software

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1.Block Diagram of DVR

 EXPECTED SIMULATION RESULTS:

Fig.2 Voltage waveforms at common coupling point (PCC) and load during harmonic distortion

Fig.3. the dc voltage injection from BESS connected DVR system at voltage swelling period

Fig.4. DVR waveforms during voltage sag at time of voltage in phase injection

Fig.5 Amplitude of load voltages and PCC voltages w.r.t time

Fig 6.DVR waveforms during harmonic distortion at the time of voltage in phase injection

CONCLUSION:

By applying different voltage injection schemes the role of DVR has been shown with a latest control technique. The presentation of DVR has been balanced with various schemes with a reduced-rating VSC. For getting the control of DVR, the reference load voltages have been determined with the help of unit vectors, for which the error of voltage insertion is reduced. By using SRF theory the reference DVR voltages have been determined. In the end, the result derived are that the in phase voltage insertion with PCC voltage reduces the DVR rating but at the same time at its DC bus the energy source is wasted.

REFERENCES:

[1] Math H.J. Bollen, Understanding Power Quality Problems- Voltage Sags and Interruptions, IEEE Press, New York, 2000.

[2] A. Ghosh and G. Ledwich, Power Quality Enhancement using Custom Power devices, Kluwer Academic Publishers, London, 2002

[3] Eddy C. Aeloíza, Prasad N. Enjeti, Luis A. Morán, Oscar C. Montero- Hernandez, and Sangsun Kim, “Analysis and Design of a New Voltage Sag Compensator for Critical Loads in Electrical Power Distribution Systems”, IEEE Trans. on Ind. Appl., vol. 39, no. 4, pp 1143-1150, Jul/Aug 2003.

[4] J. W. Liu, S.S. Choi and S. Chen, “Design of step dynamic voltage regulator for power quality enhancement”, IEEE Trans. on Power Delivery, vol. 18, no.4, pp. 1403 – 1409, Oct. 2003.

[5] Arindam Ghosh, Amit Kumar Jindal and Avinash Joshi, “Design of a capacitor supported dynamic voltage restorer for unbalanced and distorted loads” IEEE Trans. on Power Delivery, vol.19, no. 1, pp. 405-413, Jan 2004.

Performance Analysis of DVR, DSTATCOM and UPQC For Improving The Power Quality With Various Control Strategies

ABSTRACT:

Here, we have studied the voltage quality improvement methods by using Dynamic Voltage Restorer (DVR), Distribution Static Synchronous Compensator (D-STATCOM) and Unified Power Quality Conditioner (UPQC) using two different controller Strategies. The controllers used are Proportional Integral Controller (PIC) and Fuzzy Logic Controller (FLC). A PI Controller calculates an error value as the difference between a measured variable and desired set point. The fuzzy logic controller has real time inputs measured at every sample time, named error and error rate and one output named actuating signal for each phase. The input signals are fuzzified and represented in fuzzy set notations as functions. The defined 'If ... Then .. .' rules produce output actuating signals and these signals are defuzzified to analog control signals for comparing with a carrier signal to control PWM inverter.

KEYWORDS:

1.      Dynamic Voltage Restorer (DVR)

2.      Distribution Static Synchronous Compensator (D-STATCOM)

3.      Unified Power Quality Conditioner (UPQC)

4.      Power Quality

5.      PI Controller

6.      Fuzzy Controller and MATLAB

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig 1. The equivalent circuit diagram of DVR

Fig 2. The equivalent circuit diagram of DST A TCOM

Fig 3.The circuit diagram of UPQC

EXPECTED SIMULATION RESULTS:

Fig 4. Input voltage and input current waveform without compensation

Fig 5. Load voltage and load current waveform without compensation

Fig 6. load voltage and load current waveform after compensation(DVR)

Fig 7. Output load voltage without compensation

Fig 8. Output load voltage with compensation using FLC

Fig 9.load voltage and load current waveform after compensation (D-STATCOM)

Fig 10. Load voltage and load current waveform after compensation (D-STATCOM)

Fig 11. Load voltage and load current waveform for UPQC with PI Controller.

Fig 12 Load voltage and load current waveform with compensation

CONCLUSION:

In this paper, we have studied the series, shunt and series shunt compensators. Performance analysis has been done by comparing the power quality using each compensator. The performance of DVR has been analyzed with PI controller the load voltage during fault is almost equal to the desired load voltage. Load current magnitude is almost equal but still there are some imbalances between the phases for a small duration of time. DVR have been found to regulate voltage under Fuzzy Logic controller. It is clear that DVR reduces harmonics from load voltage very effectively and makes it smooth. Hence, it is concluded that DVR has a huge scope in improving power quality in distribution systems. DSTATCOM is proved to compensate voltage levels under faulty conditions. Using PI controller, harmonics have been reduced considerably. But current got unbalanced for the entire duration of time. By using the Fuzzy Logic Controller instead of the PI Controller gives better transient response. The DC Link voltage is suddenly increased above the reference value. And it is brought back to its reference value. A good voltage control is also achieved by implementing Fuzzy logic control. Also the steady state is reached faster. The control strategies of UPQC were described and compared with respect to its performance through simulation. The power quality issues are almost reduced. The closed loop control schemes of current control, for the proposed UPQC have been investigated. Total harmonic distortion was analyzed and it describes that the UPQC with fuzzy controller provides more efficiency than the other strategies.

 REFERENCES:

[1] Smriti De)'. Comparison of DVR and D-STATCOM for Voltage (",)uality Improvement, [JET AE (ISSN 2250- 2459), Vol 4, Issue 10, October 2014, PP 187-193.

[2] Ganeshkumar.A, Ananthan.N, Performance Comparison Of UPQC For Improving The Power Quality With Various Controllers Strategy ,IJETCSE, Vol 13 Issue 2, March2015,PP 12-17.

[3] Shipra Pandey, Dr. S.Chatterji, Ritula Thakur. Fuzzy Controlled DSTATCOM for Voltage Sag Compensation and DC-Link Voltage Improvement. [JEECS , ,Vol 3, Issue I, April 2014.

[4] C. Sankaran "Power Quality", CRC Press 2002.

[5] N.G. Hingorani and L Gyugyi, Understanding FACTS - Concepts and Technology OF Flexible AC Transmission Systems, IEEE Press, New York, 2000.