shunt faults analysis of solar pv-based ac …

106 JREAS, Vol. 04, Issue 03, July 2019ISSN (Print) : 2456-6411, ISSN (Online) : 2456-6403

SHUNT FAULTS ANALYSIS OF SOLAR PV-BASED AC STANDALONE SYSTEM

1Assistant Professor, GHRCE, Electrical Engineering, Nagpur, India2Assistant Professor, YCCE, Nagpur, India

Abstract

Present generating stations are not competent to satisfy the present load demand. Hence, the availability of conventional fuels is limited, one should re-think for the new source of energy which will interminable in nature, harmless to our ecology and secure future demand. Due to modernization and industrialization, the electric power consumption increases drastically, but the energy source is not competent enough to satisfy the consumer energy demand and hence renewable energy like wind energy, fuel cell, solar energy, batteries or ultra-capacitor get attention in distributed power generation system. The Faults in the system with a continuously varying in nature affects the normal operation of the system. The cause and severity of such faults play a vital role while designing a protection scheme in the standalone system. In this paper, Electric model of an 11.58KW Solar PV-Based standalone system is developed in Matlab/Simulink and various shunt faults analysis are performed and analyze the response of the system before fault, during fault period and after fault conditions. A detailed short circuit (SC) analysis puts light on various short circuit conditions and provides useful analysis.

Keywords : Renewable energy sources(RES), Solar photovoltaic system(PV), Shunt faults, Distributed generation(DG).

1. Introduction

1 2Rinkesh Satpute , Pranay S. Shete

With Increasing population, basic requirement like clean air, clean water, and much more electricity are also increases. Environmental pollution is caused from the energy sources obtained from Fossil-Fuel. Technologies related to renewable energy plays a significant role from past few decades. Solar, wind, biomass, hydro, etc. are some example of such renewable energies. The benefits of all this type of renewable energy sources are that, they are inexhaustible, environment friendly, less maintenance cost. For the sustainable future, renewable energy sources crucial alternative option for the problem likes global warming, Pollution, potential energy crises, etc.

From the world's total energy generation in the past decade renewable energy sources generates approximately 15-20 percent. Generation of electrical energy from solar photovoltaic system is commonly preferred now a day as it is Abundantly available, pollution free and free of cost. Solar PV array generate DC electricity without harming environment and DC-AC converter is used to obtained AC electricity from the Regulated DC input. In India energy generation from solar photovoltaic system is affected in the monsoon season. The deregulation of the power system takes electricity as a commodity that opens opportunity for the standalone system. Solar photovoltaic system is also preferred to both grid connected and standalone system. The small scale generation and locally consumption that energy which is not connected to the main grid are commonly called as standalone system.

Generally, Solar PV-Based standalone system consists of some devices such as solar PV array, Battery (energy storage devices), DC-DC Converter, DC-AC converter/Inverter, Filter and Load. The average sunshine hour available in India is about 8 hours of the day throughout the year. While in operating conditions the system may be interrupted by some fault. Faults may be open circuit fault or short circuit fault. Minimum and maximum system fault current is available for abnormal conditions; generally short circuit analysis is performed. Fault current which is abundantly available is used to choose short circuit so that it can resist capacity of all electrical equipment. Least available fault current is used for choosing the pickup setting of the instantaneous overcurrent protection relay. Therefore, to protect equipment's deliberate function is executed.

The objective of this paper is to detect the variation in the voltage throughout different shunt faults in the system such as One phase to a Ground fault(L-G), Phase to Phase (L-L) Double Phase to Ground Fault (L-L-G), and Most severe all the three-phase short circuit fault (L-L-L).

2. Design Of Solar Photovoltaic System

The simplest model can be considered as a diode when exposed to light the electrons and holes are separated when the band gap energy is smaller than photon energy. Under the effect of the electric field of the p-n junction diode, the electrons and holes flow through an external


circuit. Finally, the light energy can be transformed into electrical energy.

Where T is an operating temperature of solar PV cell in op

K T is a reference operating temperature in Kelvin, R is Ref s

the PV-array series resistance, R is the PV-array parallel p

resistance, I and V are the Output current and voltage of the PV-array and I is the photocurrent and can be PH

obtained from the following equation:

1000)]298.([

GTkiSCIphI ´-+=

Where Is is reverse saturation current, q is the diode charge constant, E is the energy gap, K is a Boltzmann g

constant, Is and can be obtained from the equation:

úúû

ù

êêë

é -´´´ú

û

ùêë

é´=

Kn

TnTgEq

nT

TrsISI

.

)/1/1(0exp

3

Ns is the number of the cell connected in series, q is the electron charge constant, k is Boltzman's constant and T is the nominal temperature of the P-N Junction in Kelvin's, A is an ideality constant, V is an open circuit Voltage, I oc RS

is the photovoltaic current and can be expressed by:

1...

.

-úû

ùêë

é=

TKSNnOCVq

e

SCIrsI

And T is the temperature of the diode and can be calculated from T + 273 = T (4)opt

The ideality factor (A) it can be expressed by the equation:

N AKT=N AKT (5)S S

0Where: I is the PV-array generated current at 25 C and pv21000W/m (nominal conditions), K , K the current and i v

the voltage-temperature coefficient respectively, G is the irradiance on PV-array and G is the irradiance at nominal n

conditions and oT is the temperature difference between the actual and the nominal temperature in kelvin's can be expressed in:

(1)

(2)

(3)

shITSNknSRIVq

IphIPVI -úúû

ù

êêë

é-÷÷

ø

öççè

æ +-= 1

...

)..(exp.0

By applying Kirchhoff voltage law (KVL) to the equivalent circuit of the solar PV cell,

I= I - I - I (7)ph d RS

The I is depended upon both irradiance and temperature.ph

For modeling of solar PV cell some of the constant values -19are considered, that is, q is a 16*10 which is electron

charge constant, E is a band-gap energy of the cell, the g-23constant value for silicon cells is 1.1 eV, K is a 1.38*10 ,

value of Boltzmann Constant, reference temperature is 0considered of 25 C.

(6)

Table 1 P-V Panel Rating

Parameters

Rated Power (P )MPP

Voltages At Maximum Power (V )MPP

Current At Maximum Power (I )MPP

Open Circuit Voltage (V ) of PV-arrayOC

Short Circuit Current (I ) of PV-arraySC

Total Number Of Cell In Series (N ) of PV-arrayS

Total Number Of Cell In Parallel (N ) of PV-arrayP

Total Number of Panels in connected Series

Total Number of Panels in connected Parallel

Total Power Generation (KW)

Total Voltage (V DC)PV

Total Current ( I )PV

Shunt Resistance (Ohm)

Series Resistance (Ohm)

Rating

110.30 W

17.18V

6.42A

21.69V

6.93A

30

1

21

5

11.58

368

32.1

107.689o

0.31095o

A Battery stores the energy generated from a solar photovoltaic module, so it is assumed as constant value. DC-DC Boost converter step-up the output voltage from solar PV Module. The DC-DC boost converter contains two semiconductor devices (an IGBT and a Diode), Filter-capacitor(C), Boost-Inductor(L) and Restive Load R.

In the DC-DC Boost converter, the ON/OFF situation of the switch S controls the power flow. Duty Cycle D lies between the value 0 to1. Regulated Output voltage of boost converter is substantially large than the regulated DC input voltage of Boost Converter.

3. Design Of DC-DC Converter

Fig. 1: DC-DC Boost converter

Table 2 DC-DC Converter Rating

Parameters

Input Voltage (V )in

Input Full Load Current (I )in

Boost Inductor (L)

Filter Capacitor (C)

Resistive Load (R )L

Output Voltage (V )o

Output Full Load Current (I )L

Rating

368 V

46.86 A

5.949 mH

48.28 mF

20 o

590 V

29.58 A


A three phase converter is significantly used to convert a DC input into a three phase AC output. DC-AC converter is basically a hybridization of three single phase inverters place beyond the similar DC source. A multilevel converter is basically a power electronics device that has capacity to supply required alternating voltage level at the output side with the uses of multiple lover level DC voltage which is in the form of input. In this work AC voltage is generated by using Two-Level Inverter.

4. Design Of Inverter

A. Dc-ac Converter (inverter)

Table 3Inverter Rating

Parameters

Input Voltage (V) DC

KW Rating

Output Voltage (V) AC

KVA Rating (KVA)

Rating

590 V

1.92 KW

410

11.74 KVA

Fig. 2 : Circuit diagram of two level Inverter

Bipolar SPWM techniques are used for the generation of gate pulses to the inverter. The main advantage of Bipolar PWM over Unipolar PWM is a very low leakage current and low Electromagnetic Interference.

Fig. 3 : Gate Pulses for two level Inverter

In the simple series inductor filter circuit, the inductor will reduce both the effective values and peak value of the output voltage and output current. Similarly, on the other hand the simple shunt capacitor filter circuit, the capacitor will decrease the ripple voltage, but responsible to increase the diode current. This large current may cause the heating problem and decrease the efficiency of the filter and may damage the diode. Then if the combination of both the filter (C and L), a new L-C filter is designed in a manner which can have better efficiency, capable to block diode current and a factor which removes ripple. Series Inductor and Shunt capacitor filter can be merge and form a perfect practical (L-C) circuit.

B. L-C FILTER

Table 4L-C Filter Parameter

Parameters

Filter Inductor

Filter Capacitor

Rating

3.5 mH

90 mF

The simple Static load is considered for the analysis of the system. In a power system static loads are fixed, continuous loads that don't alter significantly over short time intervals.

C. Static Load

Table 5 Connected Load (Static Load)

Parameters

Voltage

Current

KW Rating

Load Resistance

Load Inductor

Power Factor

Rating

410 V

2.38 A

1.92 KW

100 o

30 Mh

0.9862

5. Shunt Faults In Power System

Fig. 4 : Standalone system with Faults conditions

Fig. 5 : Faults in Power System


As shown in Fig5. There are two types of fault in system one is short circuit fault also called as shunt faults and another is open circuit fault also called as series faults.

Shunt faults also categories into two symmetrical faults and unsymmetrical fault. Three phase short circuit fault (L-L-L) and Three phase to ground short circuit fault(L-L-L-G) are the symmetrical faults whereas single Phase to ground (L-G), Two Phases to ground (L-L-G) and Phase to Phase fault (L-L) are the unsymmetrical faults.

“STUDY OF SOLVENT-SOLVENT

2 3S.R.Dudhat , S.S.Chine and M.V.Kulkarni

Asst. Prof., Department of Engineering Sciences, SRES, College of Engineering,Savitribai Phule Pune University, Pune.

Abstract

The basic parameters like velocity (U), density(ρ) and viscosity (η) can be measured by ultrasonic Interferometer. From these parameters various thermodynamical and acoustical parameters such as adiabatic compressibilit Ultrasonic velocities, densities and viscosities in the wide range of

0 0 0concentrations at 35 C, 40 C and 45 C temperatures for Acetone + Propanol – 2

Table 1Ultrasonic Velocity and related parameters for Acetone+ Propanol-2 + Toluene

Fig. : PEV with V2G capability

water absorption (%) = x 100W - Ww d

Wd

Table 6Chances of occurrence of faults in system

Type of Fault Chances of occurrence in system

Phase to Ground (L-G)

Phase to Phase fault (L-L)

Two Phases to Ground fault (L-L-G)

Three phases short circuit fault (L-L-L)

Three phase to ground short circuit fault (L-L-L-G)

1-3%

70%

15%

10%

2-3%

A. Single Phase to Ground Fault (L-G Fault):

Power system is commonly vulnerable to frequent phase to ground fault. Their probability of occurrence is 70% in power system.

B. Phase to Phase Fault (L-L)

When two conductors of the system are short circuited then such type of fault called as Phase-Phase fault. Their chance of occurrence is only just 15 % in the power system.

C. Double Phase to Ground Fault (L-L-G)

When two phases of the system are short circuited with ground then such type of fault called as Double Phase-Ground fault. It is called Line-to-line-to-ground fault (L-L-G). Their chance of appearance is hardly 10 %.

D. Three phase short circuit fault (L-L-L)

When all the three phases of power system are short circuited because of breakdwn of insulation between all three phases then it is called as Line-Line-Line (L-L-L) fault. Their chances of occurrence is infrequently 2 % to 3% in the power system.

E. Three phase to ground short circuit fault (L-L-L-G)

This is the most severe type of the fault and very rarely arises in the power system. When all the three phases are short circuited with ground because of the breakdown of insulation. Its presence is only 2% to 3% in the power system.

6. Simulation Results

Fig 6 shows the output of the solar photovoltaic array while

Fig.7 shows the boost voltage of the DC-DC converter.

Fig. 6 : The output voltage of PV Array VPV

Fig. 7 : The output voltage of the DC-DC converter

Fig. 8 : Output voltage and current of the inverter with L-C filter for Balance conditions

Let us consider that one phase B is short-circuited with the ground for the time period of 0.02 to 0.08 seconds Fig 9 shows the effect of short circuit fault on system voltage and current. While fig 10 shows the effect of L-G fault on Power delivered to the load or system power.

A. L-G FAULT :

Fig. 9 : System voltage and current





Abstract






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Fig. 10 : Active Power and Reactive Power of the system

Fig. 11 : Load side voltage and current

Fig. 12 : Load side Power

Fig. 13 : Voltage and current through fault point

Let us consider that two phases Y and B are short circuited for the time period of 0.02 to 0.1 seconds Fig. 14 shows the effect of short circuit fault on system voltage and current.

Fig.11 shows the load side voltage and current, and Fig. 12 shows the power, obtain at load point while Fig.13 shows the nature of fault voltage and nature of fault current for the duration of 0.02-0.08 sec.

B. L-L Fault:

Fig. 14 : Effect of L-L fault on system voltage and Current

Fig. 15 : Effect of L-L fault on Power delivered to the load

In above Fig.15 shows the nature of active and Reactive power delivered to the load whereas Fig.16 shows the load side voltage and load side current and Fig.17 shows the power obtained at load for the double line fault. Similarly, the Fig.18 shows the nature of fault voltage and fault current at fault point. For the Fault period the magnitude of current increases drastically. Where the Sag creates in voltage for the fault period. After the fault duration system restores in its normal conditions.

Fig .16 : Lode side Voltage and Current for L-L Fault





Abstract






Wd

Fig. 17 : Load side Active power and Reactive Power

Fig. 18 : Fault Voltage and Fault Current for L-L Fault

C. Three phases Short Circuit Fault:

Consider that all three phases are short-circuited for the period of 0.02-0.1 sec which is a very severe fault in power system.

Fig. 19 : System voltage and current for three-phase fault

Fig. 20 : Active and Reactive Power of the system for three phases fault

Fig. 21 : Load side Voltage and Current for Three phase fault

Fig. 22 : Power Obtain at Load side

Fig. 23 : Fault Voltage and Fault Current at Fault Point

All three phases short circuit fault is symmetrical fault where the magnitude of current increases equally of all the three phases. Fig. 19 shows the nature of system voltage and current, Fig.20 shows the nature of Active power and Reactive Power of system, Fig.21 shows the voltage and current obtained at load side, Fig 22 shows the Power obtained at the load side and last Fig. 23 shows the nature of the fault current and fault voltage at the fault point. It is observing that the magnitude of current increases drastically whereas the magnitude of voltage becomes zero for the fault period.





Abstract






Wd

A Solar PV-Based AC standalone system model has been designed and simulated using MATAB environment. This system has been considered in several type of operating conditions with major faults in it; with the assistance of this analysis, significant graphs has been plotted and observed the response of the system under various faulty conditions. From the above analysis of AC standalone system, the fault or any unintentional condition arrived in the system will affect the stability of the system. Here, for analysis purpose, all type of shunt faults is considering for short circuit analysis. The fault period is considering as 0.02 to 0.1 sec for clear observation of effect on a system parameter. The system again restores to its original position when the fault was cleared. The System can be favorable for understanding the standalone system's working independently for active grid support.

7. CONCLUSION

[1] M.A., Islam, A. Merabet, R., Beguenane, H., Ibrahim "Modeling solar photovoltaic cell and simulated performance analysis of a 250W PV module", IEEE Electrical Power & Energy Conference (EPEC), pp. 1-6, 2013

[2] Sumei Liu, Tianshu Bi, S.M., Ancheng Xue and Qixun Yang, "Fault Analysis of Different Kinds of Distributed Generators," IEEE Con., - 978-1-4577-1002, 2011.

[3] Jan T. Bialasiewicz, "Renewable Energy Systems With Photovoltaic Power Generators: Operation and Modeling," IEEE Trans. on Ind. Electron., Vol. 55, no. 7, July 2008.

References

[4] Piyush Kadukar, P. S. Shete. S. P. Gawande, "Transient Analysis of Distributed Generation AC Microgrid using ETAP", International conference on current trends towards converging technology, DOI: 978-5386-3702-9/18

[5] P. S. Shete, N. S. Maurya,Dr. R.M. Moharil, A. A. Dutta, "Analysis of Micro grid Under Different Loading Conditions," International Conference on Industrial Instrumentation and Control (ICIC)College of Engineering Pune, India, pp. 1120-1 124, May 28-30,2015.

[6] G. Pepermans, J. Driesen, D. Haeseldonckx, W. D' Haeseleer and R. Belmans, "Distributed generation: Definition, benefits and issues," Energy Policy, vol. 33,no. 6, pp. 787 798,2005.

[7] Shailesh M. Deshmukh, Bharti Dewani, S. P. Gawande, "Analysis of Balance and Unbalance Sag on Distribution System," ITSI Transaction on Electrical and Electronics Engineering (ITSI-TEEE) ISSN: 2320-8945, Vol.1,Issue6, 2013

[8] Nivedita R. Rode, S. R. Gaigowal, A. A. Dutta, Prashant A. Meshram, "Multilevel Inverter based PV-STATCOM," IEEE Conference onRecent Trend in E lec t ron ics , In fo rmat ion & communication Technology, May, 2018.

[9] Abhay Dalal, P.S.Patil, "A New approach towards symmetrical fault analysis using harmonic impedance," International conference on Emerging trends and research in Engineering and Technology. IBSS college of Engineering Amravati, 30-31 March 2013

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