Study of the impact on the protection plan of a pv production integrated to the mv grid

1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
63
STUDY OF THE IMPACT ON THE PROTECTION PLAN
OF A PV PRODUCTION INTEGRATED TO THE MV GRID
Mohamed DHARIF1
, Abdellah AIT OUHMAN1
, Lahbib BOUGHAMRANE2
, Ahmed IHLAL2
1
University CADI AYYAD, Marrakech, Morocco
2
University IBN ZOHR, Agadir, Morocco
ABSTRACT
In this paper, it was treated the dynamic stability of a photovoltaic production and its impact
on the level of protection, a number of simulations were performed to evaluate the system response
following the integration of a PV - production of 5 MW. The simulation results have explain
theunjustified operation of the protection system and the protection of the disconnection of the PV-
Production hence the need for treatment of individual cases of PV integration in order to adjust the
level of protection at the rate of penetration of PV distributed generation (DG) on MV grid.
Keywords: PV-Production, 3-Phases Injector, Simulation, Fault.
1. INTRODUCTION
After promulgation the law N°13-09 to renewable energies [1], relating to the clauses of
integration to the national electrical system the productions of energy from renewable sources, the
national electrical grid MV (Medium Voltage), know very soon a massive integration of productions
stemming of solar sources in the occurrence of them photovoltaic energy.
Gold, the MV grid conceived to insure the transit of energy of the uphill system to consumers
and to function on the basis of one direction of power flow, is not anticipated to welcome these DEP
(Decentralized Energy Production) to the large scale [2]. And consequently, circulation of power
flows are going to change and are going to be originally various problems disturbing the good
functioning of the electrical system.
Where, a behavior study is required so as to apprehend the reaction of the system MV in the
face of this integration, especially in terms of aspect controls the grid.
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2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
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2. DESIGN MODEL OF THE PRODUCTION PV
The production PV is designed by an injector of current with its regulation of power. The
system of control regulates the injected power, by the production PV, to the bus of connection
according to the irradiance.
The goal of this control is to impose injected reactive and active powers, by the production
PV to the bus of connection of the system MV, by defining external manner values of order Porder and
Qorder. In reality, the active power Porder is DGermined by the MPPT module of the production PV
and the reactive power Qorder its value is null [3].
The functioning of this model can be described as next (to see figure 1) ; from voltages and
currents measured to the point of connection of the injection, the reactive and active powers are
DGermined to need of regular control. These powers are controlled by simple Proportional-Integral
corrector type (Kp+Ki/p).
Figure 1: Principle of injector functioning of current P/Q
The currents references are then calculated in the referential of Park by the following formula:
‫ە‬
ۖ
‫۔‬
ۖ
‫ۓ‬‫ܫ‬ௗ =
2൫ܲ. ܸௗ + ܳ. ܸ௤൯
3൫ܸௗ
ଶ
+ ܸ௤
ଶ൯
‫ܫ‬௤ =
2൫ܲ. ܸ௤ − ܳ. ܸௗ൯
3൫ܸௗ
ଶ
+ ܸ௤
ଶ൯
(1)
Where;
• P and Q are active and reactive powers of reference of the production PV
• Vd and Vq are respectively the direct and squareness components of the voltage, measured to
the point of connection of the DEP.
• Id and Iq are respectively the direct and squareness components of the current produced by the
point of connection to the DEP
A loop to bolting of phase PLL (Phase Locked Loop) is used to synchronize the
transformation of Park on the pulsation of the voltage measured on the system. Thus, when the
system is in established regime, the direct component Vd in exit of the transformation of Park is an
image of the amplitude of the measured voltage, and the squareness component Vq is null.
These current are then converted in the three phases referential, the amplitude and phasor of
the currents injected on the system go thus regulated powers to their value of order.

3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
65
Gold, so as to keep the realistic and dynamic aspect of this model tells simplified, the DEP and
the converter insuring the interface with the system are going to be designed by a limitation and a
delay.
2.1. Hypothesis of study [2] & [3]
A. Simplification of dynamics
We consider that the dynamics of the converter is very rapid as compared to the dynamics of
the element of production. The dynamic deduction for the converter is in the order the tenth of
second. As for the dynamics of the unit of production PV is in the order some seconds.
In these conditions, the dynamics (constant of time) of the converter is retained for the regulation of
the reactive power and that the unit of production for the regulation of the active power.
B. Consideration of limitations
The limit for the component Id is chosen according to the maximal current in exit of the
converter and the active power limit of the production PV, gold limits it the component Iq is chosen
consequently, manner to does not exceed the limit of the reactive power datum by a report Q/P=0,4.
The next table recapitulates dynamics and limitations considered for our model of the production
PV:
Table 1: characteristics of regulation loops P/Q
Loop of regulation Parameter Value retained
Active Power
τ 0,5
Ki 2
Kp 1
Reactive Power
τ 0,1
Ki 10
Kp 1
C. Validation of the model of simulation of DG-PV
The next graph represents the different dynamics of the control P/Q for two values of order,
of the reactive power P=2.5MW and 5MW to t=3s. The value of order of the reactive power is
maintained at Q=0MVAR.
Figure 2: Active and Reactive power
0 1 2 3 4 5 6
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
x 10
6
Time (s)
Power(W/VAR)
Production active and reactive
Active Power
Reactive Power

4. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
66
Figure 3: Current PV Production
3. SYSTEM OF STUDY
To undertake studies of simulation, a system aerial typical MV has been modeled (figure 4),
this system is constituted a transformer HTB/MV and three MV lines.
Figure 4: Grid MV of study
Parameters of this system are illustrated on the following table:
Table 2: characteristics of MVgrid
Component Parameter Value retained
HV Source
Psc 277MVA
Nominal voltage 63kV
Nominal frequency 50Hz
R/X 0,05
Transformer data
Power 20MVA
Primary voltage 63kV
Secondary voltage 22kV
Usc 16%
Wiring YNyn
Neutral resistance 42,5 m
Line N°1 data
Length 36km
Section 148mm²
Rd 0,2236 m/km
Ro 0,368 m/km
Xd 0,35 m/km
Xo 1,588 m/km
Cd 11,13nF/km
Co 5nF/km
0 1 2 3 4 5 6
0
20
40
60
80
100
120
140
160
Current production PV
Time (s)
Current(A)

5. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
67
The value of neutral resistance is 42,5 m so as to limit the current to the earth to 300A.
Loads are simply modeled by a RL circuit in parallel; the next table recapitulates the different load
by line;
Table 3: Values of loads
Line
Active load (P
en kW)
Reactive
load (Q en
kVAR)
Line N°1 5103 2016
Line N°2 4217 1668
Line N°3 5808 2295
The settings of the relays installed of the arrival MV and the line N°1 are DGermined as follows:
Table 4: Setting of protection Bus MV and line N°1
Protection Fonction Setting
Bus MV
Max I- Phase 610A
Max I -Homopolaire 17A
Line N°1
Max I-Phase 240A
Max I-Homopolaire 14A
Concerning the production PV, its protection of DG Disconnection is that typical H3 according to [4]
& [5]:
Table 5: thresholds of setting protection PV Production
Protection Relay Setting Action
Phase to Earth Faults Max V0 10%Vn 0.650 s
Phase to Phase Faults Min U 85%Um 0.650 s
Separate grid working
Min U 85%Um 0.650 s
Max U 115%Um instantaneous
Min freq 49.5Hz instantaneous
Max frq 50.5Hz instantaneous
Strong off-peak voltage Min U 25%Um instantaneous
4. SCENARIOS OF STUDY
The line N°1 having sheltered the PV production of 5MW is considered to equip a normal
ASR (Automatism of Service Resumption) of where the line faults are supposed cancelled in rapid
cycle temporized to 150ms.
Three types of fault will be analyzed:
• Three-Phase symmetrical and frank fault;
• Two-phase Frank fault;
• Phase-earth fault, with resistances of earth are 30ohm and 450ohm.
These faults will be simulated on four points:
• In end of line N°1
• To the MV bus
• To the adjacent line N°2
• To the HTB bus

6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
68
A comparison with the functioning of system without PV production has been made so as to
divulge the impact of the integration of the generator PV on the behavior of system protection. View
that 80% of the faults are fugitive defects [6]&[7]; the faults is supposed cancelled in rapid cycle
The different stemming curves of the simulation are represented to the next section.
4.1. Results of simulation the fault in end of line N°1
A. 3-Phase symmetrical fault
The next table recapitulates the behavior of the different protections:
Table 6: Recapitulation of simulation results
Point of grid Relay Measure Action
Grid with PV-P
Bus MV Max I 590A Not activated
Line N°1 Max I 470A Activated
Connection PV
Production
Min U 9732V Activated
Max U 19.103
V Not Activated
Min freq 49,8Hz Not Activated
Max Frq 50,15Hz Not Activated
Grid without PV-P
Bus MV Max I 638A Activated
Line N°1 Max I 506A Activated
For a three-phase fault, we observe the normal opening of the line N°1 breaker, the PV
production is not disconnect seen the temporization of the relay Max Vo.
Nevertheless, we observe the blindness of the protection Max I bus MV in case of system with PV
production
B. PH A-B
The next table recapitulates the behavior of the different protections:
Table 7: Recapitulation of simulation results
Point of grid Relay Measure Action
Grid with PV-P
Bus MV Max I 574A Not activated
Line N°1 Max I 427A Activated
Connection PV
Production
Min U 9700V Activated
Max U 19.103
V Not activated
Min freq 49,9Hz Not activated
Max Frq 50,0Hz Not activated
Grid without PV-P
Bus MV Max I 657A Activated
Line N°1 Max I 478A Activated
For a two-phase fault, we observe the normal opening of the line N°1 breaker, the PV
production is not disconnect seen the temporization of the relay Max Vo.
Nevertheless, we observe the blindness of the protection Max I bus MV in case of system
with PV production

7. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
69
C. Fault PH 1-Ground (30 m)
The next table recapitulates the behavior of the different protections:
Table 8: Recapitulation of simulation results
Point of grid Relay Measure Action
Grid with PV-P
Bus MV
Max I 255A Not activated
Max Ihom 25A Activated
Line N°1
Max I 59A Not activated
Max Ihom 8,5A Not activated
Connection
PV
Production
Max VO 9320V Activated
Min U 18,9.104
V Not activated
Min freq 49,8Hz Not activated
Max freq 50,0Hz Not activated
Grid without PV-P
Bus MV
Max I 374A Not activated
Max Ihom 24A Activated
Line N°1
Max I 150A Not activated
Max Ihom 8A Not activated
For a phase-earth fault, with an earth resistance is 30Ohm , we observe the normal opening of
the Bus MV breaker, the PV production is not disconnect seen the temporization of the relay Max
Vo.
D. Fault PH 1-Ground (450 m)
The next table recapitulates the behavior of the different protections:
Table 9: Recapitulation of simulation results
Point of grid Relay Measure Action
Grid with PV-P
Bus MV
Max I 245A Not activated
Max Ihom 12,5A Not activated
Line N°1
Max I 57A Not activated
Max Ihom 4,19A Not activated
Connection
PV
Production
Max VO 4580V Activated
Min U 19,9.104
V Not activated
Min freq 49,91Hz Not activated
Max freq 49,99Hz Not activated
Grid without PV-P
Bus MV
Max I 363A Not activated
Max Ihom 11,8A Not activated
Line N°1
Max I 139A Not activated
Max Ihom 3,9A Not activated
In this type of fault with a great resistance of earth, alone the PV production is disconnected
to the system.
In reality a research of the earth resistance undertakes to the level the source MV, this relay is
temporized to 15s.

8. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
70
4.2. Results of simulation the fault in adjacent line N°2
In this part it will be processed the behavior of the production PV beside to the faults situated
on the adjacent line. Alone numerical simulation results will be presented, considered faults are
short-circuit 3 phases and phase-earth to variable distances.
A. 3-Phase symmetrical fault
Table 10: Recapitulation of simulation results
Point of grid Relay Measure Action
To 1km of bus MV
Connection
PV
Production
Min U 900V Activated
Min freq 49,95Hz Not activated
Max freq 51,17Hz Activated
To 5km of bus MV
Connection
PV
Production
Min U 4350V Activated
Min freq 49,87Hz Not activated
Max freq 50,14Hz Not activated
To 10km of bus MV
Connection
PV
Production
Min U 7090V Activated
Min freq 49,80Hz Not activated
Max freq 50,20Hz Not activated
For 1Km of distances the PV production will be disconnected instantaneously by the relay
Max freq, in the other cases it disconnection is make to the level of the line N°2.
B. Fault PH 1-Ground (30 m)
Table 11: Recapitulation of simulation results
Point of grid Relay Measure Action
To 1km of bus MV
Connection PV
Production
Max VO 1,45.104
V Activated
Min U 1,90.104
V Not activated
Min freq 49,89Hz Not activated
Max freq 50,01Hz Not activated
To 5km of bus MV
Connection PV
Production
Max VO 1,43.104
V Activated
Min U 1,90.104
V Not activated
Min freq 49,89Hz Not activated
Max freq 50,01Hz Not activated
To 10km of bus MV
Connection PV
Production
Max VO 1,41.104
V Activated
Min U 1,90.104
V Not activated
Min freq 49,89Hz Not activated
Max freq 50,01Hz Not activated
For resistant faults, alone the line N°2 will be disconnected.

9. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print),
ISSN 0976 – 6553(Online) Volume 6, Issue 1, January (2015), pp. 63-71© IAEME
71
4.3. Results of simulation the fault in grid HTB
In this time the 3 phases fault is supposed localized on the system HTB, the system HTB is
considered equipped an automatism of service resumption.
Table 12: Recapitulation of simulation results
Point of grid Relay Measure Action
To 1km of bus MV
Connection
PV
Production
Min U 2800V Activated
Min freq 49,95Hz Not activated
Max freq 51,81Hz Activated
In case of three phase fault to the level of the bus HTB, the production will be disconnected
by Min voltage
5. CONCLUSION
In this article it has been object to study the stability of the PV-production and its impact on
the protection plan of the MV grid.
Results of simulation have revealed:
• Blindness of the protection Max I bus MV in case of failure protection Max I line N°1, for
the 3 - Phase and 2 – Phase faults;
• Unjustified Disconnection of the PV production by Min VO, in case of research of the
resistance earth ;
• Unjustified Disconnection of the PV production by Min U and Max Freq, in case fault on the
adjacent line ;
• Unjustified Disconnection of the PV production by Min U and Max freq, in case of HV fault.
In this paper, it was demonstrated the need for simulation of the electrical network in case of
integration of PV products, to provide for the review of the thresholds of protection settings,
and therefore protect the network against faults that may occur.
6. REFERENCES
1. Law N°13-09 to renewable energies
2. Thi Minh Chau LE, Coupling Photovoltaic Inverters and Network aspects / control and disturbance
rejection, PH.D. THESIS UNIVERSITY OF GRENOBLE, 2012
3. G.RAMI, "Auto-adaptive voltage control for decentralized energy productions connecting to the
electrical distribution grid", PhD thesis of ENSIEG, November 2006
4. ERDF-PRO-RES_09E Study Impact Protection Plan connecting distributed generation in MV,
Version 3, 01/03/2008
5. ERDF-NOI-RES_13E, Protection of production systems connected to the public distribution
system, Version 3, 01/07/2011
6. B.de Metz, Calculation of short circuit, Technical Manual N°158,Schneider Electric, Octobre, 2000
7. ABDELHAY.A.SALLAM, O.P.MALIK « Electric Distribution Systems », IEEE Press Editorial
Board, 2011
8. Nimmy George, “Grid Connected Pv System Using 9-Level Flying Capacitor Multilevel Inverter”
International Journal of Electrical Engineering & Technology (IJEET), Volume 5, Issue 12, 2014,
pp. 57 - 64, ISSN Print : 0976-6545, ISSN Online: 0976-6553.