Micro-grid powered by photovoltaic and micro turbine Ph. Degobert1, S. Kreuawan2 and X. Guillaud2 1
Laboratoire d\u2019Electrotechnique et d\u2019Electronique de Puissance de Lille (L2EP) Ecole Nationale Sup\u00e9rieure d\u2019Arts et M\u00e9tiers, Centre d\u2019Etudes et de Recherches, 8 Boulevard Louis XIV, 59046 Lille Cedex, France
Phone: (33)320.622 229 \u2013 Fax: (33)320.622 750 \u2013 E-mail:
[email protected] 2
Ecole Centrale de Lille,
Boulevard Paul Langevin, 59651 Villeneuve d\u2019ascq, France Phone: (33)320.335 387 \u2013 E-mail:
[email protected]
Abstract.
In this paper, we propose to study the possibility of using a photovoltaic system combined with a high speed micro-turbine. This hybrid system can work as stand-alone system or grid connected system as it will be a part of a microgrid. Initially, we propose simple dynamic models of photovoltaic and micro turbine systems. Then, we carry out a comparison between simulations and measurements of the two systems. At last, simulation results show the effectiveness of the suggested hybrid system.
converter. Figure 1 shows the studied hybrid system: a 17,3kWp photovoltaic system associated to a 28kW Capstone micro-turbine. This PV-system is installed in the north of France at the L2EP-ENSAM of Lille since December 2004. It can work as a stand-alone system or a grid connected system as it will be a part of a micro-grid [1],[2]. A 28kW MTG will be settled in April 2006.
Key words Micro-grid, hybrid system, photovoltaic, micro-turbine, distributed generation, simulation.
1. Introduction The production of photovoltaic system can vary slowly (day-night cycle and season change) and quickly because of weather conditions such as the passage of clouds. The power fluctuation might cause problems of power quality. Moreover a grid connected photovoltaic system is considered as a negative load by the grid because of its uncontrollable characteristic. To reduce these problems, we can integrate a storage system which allows the energy management [1]. The hybrid system is another interesting solution. It is using two or more renewable energy sources such as wind and/or solar and it becomes Figure 1. PV/MTG micro-grid control scheme. more wildly used [2 ]. The hybrid system with at least one controllable source such as diesel generator or micro turbine can solve this problem. This distributed generator 2. Photovoltaic system modelling is interesting because, it allows high efficiency with cogeneration system, low emission and fuel flexibility. A. Description of the PV system This paper presents a dynamic-simulation study of a photovoltaic system and a micro turbine operating within a multi-machine network [1]. Each generator can be connected via a DC bus. Then, a single static converter is connecting this DC bus to the grid. In this work, we choose to connect it to the AC bus because the expansion of system is not limited by the rated power of the static
The photovoltaic studied system, presented in figure 2, consists of 108 modules BP solar 3160 with power of 160Wp each. These modules are connected to a 3-phase grid via six inverters Fronius IG30 (one inverter connects 2 branches of 8 modules in parallel). In the first year of electric production, this 17,3kWp PV-system generated 13600kWh as shown in figure 3.
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Group of PV module
Inverter MPPT
3-phase MicroGrid
DC AC DC AC
DC AC DC
07: 00
AC
12: 00
21: 00
Figure 5. Photovoltaic power on May 7th, 2005.
DC AC
3. Capstone Micro-turbine modelling
DC AC
A. Description of the Micro-turbine generator
DC AC
Sensor
\
u
2
2
1
Irradiance
2
For this application, we have chosen a Capstone Micro
DSpace
Data acquisition system
Figure 2. PV control scheme. ENSAM - Lille
kWh/month 2500
Estimated energy Measured energy
2000
1500
The Turbo Generator includes a Gas Compressor (GC), a
1000
500
0 J
F
M
A
M
J
J
A
S
O
N
D
Figure 3. Photovoltaic energy produced in 2005.
B. PV modelling and simulation
In a previous work, we have compared two models of
The used High-speed Generator is a two-pole Permanent figure 4.
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both electronic converters are identical [6]. It can be
In [13], a linearized model of the micro-turbine was
Heat Grid
Natural gas
Heat Recuperator HR
Fuel valve
Air flow
PMSM
High-speed Generator
GC
CC
Temperature measurement
T
Combustion Gas Chamber Compressor
After analysing these different modelling, we concluded Fuel Control System (FCS)
Turbine DC Bus measurement
C
LC Filter
VDC PMSM side CONVERTER
AC Electric
Table I presents the identified rise time value of output
Grid
Grid side CONVERTER Digital Power Controller (DPC) SCADA Interface
Figure 6. Gas micro-turbine generator. A micro-turbine requires about 15-20 seconds for a 50%
TABLE I. \u2013 MTG rise time value of output power \u2206
-28000
P
/
50
P
5000
10000
50
50
50
15000
50
20000
50
-15000
52
52
52
39
26
18
-10000
44
44
28
12
15
16
-5000
36
28
22
12
12
10
0
37
25
24
15
13
9
5000
38
22
26
18
14
8
10000
38
38
40
42
23
12
15000
38
38
38
30
21
16
28000
49
49
49
49
49
49
25000
28000
Figure 7. Capstone C330 Micro turbine Step Change Response.
To remove such limitations in the dynamics of the power measured output power
B. MTG modelling and simulation
Simulated output power
Figure 8. comparison between measured and simulated results of C330 Micro turbine step power change response.
The dynamic modelling and simulation of the Micro4. Hybrid Photovoltaic/Microturbine system turbine have been discussed in details in many literatures [3]-[17]. We propose a short review of most of them. In A. Description of the PV/MTG 1983, a combustion gas turbine model was developed to The association of a photovoltaic system and a micro turbine allows the energy management:
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B. Simulation of the PV/MTG
References
The Matlab-Simulink model of PV/MTG micro-grid is
[1] Abu-Sharkh S. et al. “Can microgrids make a major [2] R. Lasseter, A. Akhil, C. Marnay, J. Stephens, J. Dagle, R.
[3] R. Lasseter, "Dynamic models for micro-turbines and fuel
Desired Ppwer
Micro Grid
MTG
Temperature
[4] R. Lasseter, K. Tomsovic and P. Piagi, “Scenarios for
Irradiance
measure t
PV Inverter
Figure 9. Matlab model of the PV/MTG micro-grid.
Figure 10 shows the various powers with an applied reference electric power of 28kW. The simulated results
[5] S. F. Gillette, “CHP Case Studies – Saving Money and Increasing Security”, Capstone Turbine Corporation. [6] http://www.capstoneturbine.com [7] R.J. Yinger, “Behavior of Capstone and Honeywell Micro [8] O.Fethi, L.-A. Dessaint, K. Al-Haddad, “Modeling and
[9] W. I. Rowen, "Simplified mathematical representation of heavy duty gas turbine" ASME Trans. 1983, Vol.105, N°1. [10] L. N. Hannett, A. Khan, "Combustion turbine dynamic [11] Working Group on Prim Mover and Energy Supply
13: 00
16: 00
19: 00
[12] L. N. Hannett, G. Jee, B. Fardanesh, "A governor turbine [13] A. Al-Hinai, A. Feliachi, “Dynamic model of a microof the Thirty-Fourth South-eastern Symposium on 18-19 March 2002, pp. 209–213; [14] H. J. Nern, H. Kreshman, F. Fischer, HA. Nour Eldin, 13: 00
16: 00
19: 00
[15] H. Nikkhajoei, M. R. Iravani, "Modelling and analysis of a [16] A. Al-Hinai, K. Schoder, A. Feliachi "Control of grid-
13: 00
16: 00
19: 00
Figure 10. Power of PV/MTG micro-grid.
5. Conclusion
[17] G. Joos, B. T. Ooi, D. McGillis, F. D. Galiana, R.
[18] H.S. Rauschenbach, “Solar Cell Array Design Handbook”, Van Nostrand-Reinhold, NY, 1980.
