An emerging alternative solution to address energy shortage is the construction of a microgrid system. This paper develops a mixed-integer linear programming microgrid investment model considering multi-period and multi-objective investment setups. It further investigates the effects of uncertain demand by using a target-oriented robust optimization (TORO) approach. The model was validated and analyzed by subjecting it in different scenarios. As a result, it is seen that there are four factors that affect the decision of the model: cost, budget, carbon emissions, and useful life. Since the objective of the model is to maximize the net present value (NPV) of the system, the model would choose to prioritize the least cost among the different distribution energy resources (DER). The effects of load uncertainty was observed through the use of Monte Carlo simulation. As a result, the deterministic model shows a solution that might be too optimistic and might not be achievable in real life situations. Through the application of TORO, a profile of solutions is generated to serve as a guide to the investors in their decisions considering uncertain demand. The results show that pessimistic investors would have lower NPV targets since they would invest more in storage facilities, incurring more electricity stock out costs. On the contrary, an optimistic investor would tend to be aggressive in buying electricity generating equipment to meet most of the demand, however risking more storage stock out costs.
Capacity constraint of continuous generation technology l in month m (kW)
Capacity constraint of discrete generation technology i in month m (kW)
fc
Fraction of electricity charged into battery that is not lost in energy transfer
fe
Fraction of electricity discharged from battery that is not lost in energy transfer
fd
Fraction of electricity in battery that is lost in one time period
uc
Useful life of continuous generation technology l
ud
Useful life of discrete generation technology i
Fraction of maximum solar insolation incident upon location during month m
Efficiency of the solar panel previously purchased in month m
Efficiency of the wind turbine in converting wind energy to electricity during month m
Efficiency of the wind generators previously purchased in month m
Efficiency of the battery previously purchased in month m
Number of days the batteries can supply the community in case of emergency during month m
Efficiency of the generator previously purchased in month m
Nameplate power rating of discrete generation technology i (kW)
Maximum amount of allowable carbon emission generated by the system during month m
Total amount of budget per year y allotted for investment (Php) during month m
Number of days in a month
Tab.1
Item
Symbol
Description
Decision variables
Number of kW of continuous generation technology l installed in month m (kW)
Number of units of discrete generation technology i installed in month m (Units)
gm
Amount of electricity purchased from the grid during month m (kWh)
z
Binary variable on deciding whether the electricity from PV would go to the battery or to the consumer
System variables
Number of continuous generation technology l that break down in month m (kW)
Number of discrete generation technology i that break down in month m (kW)
Net amount of continuous generation technology l existing in month m (kW)
Net amount of discrete generation technology i existing in month m (kW)
Total number of carbon emitted in excess to the carbon target in month m
Generated electricity of discrete generation technology i installed in month m sold to customer (kWh)
Total electricity supply from wind power (kWh)
Electricity from wind power that is supplied to the customer during month m (kWh)
Electricity supply from photovoltaic power during month m (kWh)
Electricity supply from photovoltaic power that is supplied to the customer during month m (kWh)
Electricity supply from photovoltaic power that is send to the battery during month m (kWh)
Total electricity stored in batteries during month m (kW)
Total net electricity supply from batteries during month m (kW)
Total electricity supply during month m (kWh)
Amount of electricity sold to the grid (kWh)
Electricity from wind power that is sold to the grid during month m (kWh)
Electricity supply from photovoltaic power that is sold to the grid during month m (kWh)
Tab.2
Fig.2
Fig.3
Scenario
o
k
j_dg
g
u
33080945
0
0
0
2515599000
32
20890100
0
0
2956656520
7050
1211217
60000
0
1,040,181
g = 1
7050
1107699
52470
6024
935364
Tab.3
Fig.4
Fig.5
Fig.6
Fig.7
Fig.8
Fig.9
Fig.10
Fig.11
Fig.12
1
Ravindra K, Iyer P. Decentralized demand–supply matching using community microgrids and consumer demand response: a scenario analysis. Energy, 2014, 76: 32–41 https://doi.org/10.1016/j.energy.2014.02.043
2
Woite G. Capital investment costs of nuclear power plants. International Atomic Energy Agency Bulletin, 1978, 20(1):11–23
3
Huang J, Jiang C, Xu R. A review on distributed energy resources and microgrid. Renewable & Sustainable Energy Reviews, 2008, 12(9): 2472–2483 https://doi.org/10.1016/j.rser.2007.06.004
4
Lasseter R, Microgrid P P. A conceptual solution. In: Proceedings of 35th Annual IEEE Power Electronics Specialists Conference, Aachen, 2004
5
5.Wang R, Wang P, Xiao G, Gong S. Power demand and supply management in microgrids with uncertainties of renewable energies. Electrical Power and Energy Systems, 2014, 63: 260–269 https://doi.org/10.1016/j.ijepes.2014.05.067
6
Mittal A, Agrawal M. Microgrid technological activities across the globe: a review. International Journal of Research and Reviews in Applied Science, 2011, 7: 147–152
7
Stadler M, Groissböck M, Cardoso G, Marnay C. Optimizing distributed energy resources and building retrofits with the strategic DER- CA model. Applied Energy, 2014, 132: 557–567 https://doi.org/10.1016/j.apenergy.2014.07.041
Soroudi A, Ehsan M. A possibilistic–probabilistic tool for evaluating the impact of stochastic renewable and controllable power generation on energy losses in distribution networks — a case study. Renewable & Sustainable Energy Reviews, 2011, 15(1): 794–800 https://doi.org/10.1016/j.rser.2010.09.035
10
Mohammadi S, Soleymani S, Mozafari B. Scenario-based stochastic operation management of microgrid including wind, photovoltaic, micro-turbine, fuel cell and energy storage devices. International Journal of Electrical Power & Energy Systems, 2014, 54: 525–535 https://doi.org/10.1016/j.ijepes.2013.08.004
11
Jabr R. Robust transmission network work expansion planning with uncertain renewable generation and loads. IEEE Transactions on Power Systems, 2013, 28(4): 4558–4567 https://doi.org/10.1109/TPWRS.2013.2267058
12
Yu H, Chung Y, Wong P, Zhang J H. A chance constrained transmission network expansion planning method with consideration of load and wind uncertainties. IEEE Transactions on Power Systems, 2009, 24(3): 1568–1576 https://doi.org/10.1109/TPWRS.2009.2021202
13
Ben-Tal A, Goryashko A, Guslitzer E, Nemirovski A. Adjustable robust solutions of uncertain linear programs. Mathematical Programming, 2004, 99(2): 351–376 https://doi.org/10.1007/s10107-003-0454-y
14
Bertsimas D, Iancu D, Parrilo P. Optimality of affine policies in multi-stage robust optimization. Mathematics of Operations Research, 2010, 35(2): 363–394 https://doi.org/10.1287/moor.1100.0444
15
Ng T S, Sy C. An affine adjustable robust model for generation and transmission network planning. Electrical Power and Energy Systems, 2014, 60: 141–152 https://doi.org/10.1016/j.ijepes.2014.02.026
16
Sy C, Aviso K, Ubando A, Tan R R. Target-oriented robust optimization of polygeneration systems under uncertainty. Energy, 2016, 116(2): 1334–1347 https://doi.org/10.1016/j.energy.2016.06.057
17
Soshinskaya M, Crijns-Graus W, Guerrero J, et al.. Microgrids: experiences, barriers and success factors. Renewable & Sustainable Energy Reviews, 2014, 40: 659–672 https://doi.org/10.1016/j.rser.2014.07.198
18
Ihamaki J. Integration of microgrids into electricity distribution networks. Dissertation for the Master’s Degree. Lappeenranta, Finland: Lappeenranta University of Technology, 2012
19
Dietrich M. Net-metering reference guide: How to avail solar roof tops and other renewables below 100 kW in the Philippines. Makati: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, 2013
20
Dale M. A comparative analysis of energy costs of photovoltaic, solar thermal, and wind electricity generation technologies. Applied Sciences, 2013, 3(2): 325–337 https://doi.org/10.3390/app3020325
21
Guda H, Aliyu U. Cost comparison between photovoltaic and diesel generator water pumping systems. IACSIT International Journal of Engineering and Technology, 2015, 5(5): 304–309