Electric Vehicles Charging simulation for an Urban

Electric Vehicles Charging simulation for an Urban Distribution Network's service sector Larisa Grackova

Irina Oleinikova

Gaidis Klavs

Institute of Physical Energetics Laboratory of Energy System Analysis and Optimisation Riga, Latvia [email protected]

Institute of Physical Energetics Smart Grid Research Centre Riga, Latvia [email protected]

Institute of Physical Energetics Laboratory of Energy System Analysis and Optimisation Riga, Latvia [email protected]

Abstract— The case study presents seasonal and daily energy consumption statistics of the tertiary sector’s facilities under the conditions of charging infrastructure development as an additional consumer. In addition, possible benefits of investing into the said development have been evaluated. As criteria for the charging stations infrastructure’s development, the total number of simultaneously charging electric vehicles, independent load of the buildings as well as their operational schedule have been considered. The investments’ advisability calculations indicate that charging stations’ installation could serve as an economic incentive for the afore-mentioned office buildings’ owners gaining profit. Index Terms - The Electrical Vehicle (EV), Electricity Market, Distribution Networks.

I.

INTRODUCTION

In competitive conditions, the electricity sector functions and develops more effectively, resulting in long-term profits for the consumers. This practice comes from the experience of several European countries where the liberalization of the energy market has taken place several years prior. As such, energy market liberalization is a time- and resourceconsuming process that requires constant governmental supervision and the ability to manage possible occurring problems, related to the changes in the law-bound proprietary interests and cross subsidization. In addition, other points of concern include improving several vital conditions, such as equipment modernization and addition of innovative technologies [1]. In Latvia, a full liberalization of the energy market for all groups of electricity consumers was implemented in 2015 [2]. The majority of energy-related issues of the 21st century are resolved by modern-day technologies. One of such innovations is the storage battery which allows electric vehicles to last for over a hundred kilometres on a single charge. With that, the overall number of EVs in Europe has increased over the period of five years, alongside the growth of the fossil fuel cars’ numbers. As for the EV owners, predominantly, these are the inhabitants from countries where

the government supports EV buyers by providing certain financial or other benefits, such as parking or communication within the city. Nowadays, there are a substantial number of different EV models available from Latvia’s car market. As of the 1st of January, 2016, 218 EVs were registered by the Road Traffic Safety Directorate (CSDD) [3]. In addition, a system of charging stations is being developed, supported by government programme. In 2014, the Ministry of Environmental Protection and Regional Development of the Republic of Latvia, using the financial means provided by the National Climate Change programme has announced a project competition for greenhouse gas emissions reduction in the transport sector, according to which it is planned to open at least 235 charge stations for electric vehicles by 2023 [4]. In the 2014, "Riga Smart City Sustainable Energy Action Plan for 2014 – 2020" has been developed and approved by the Riga City Council [5]. To an extent, the above mentioned issues are mentioned and discussed within the context of this project. Together with the aims proposed in the Action plan, addressing the issue of choosing locations for fast- and slowcharging stations has been given a high priority. Both, legal and private persons must be provided with protected public charging stations with appropriate equipment for regular EV charging. The issue in this case is that it is rather problematic – to organise slow-charging stations for EV owners who reside in multi-storey houses. The purpose of this study is to evaluate the existing seasonal and daily energy consumption of four objects of the tertiary sector, as well as to analyse the influence of EV charging on the overall electricity consumption and total cost of electricity on the basis of existing tariffs differentiated by time of day. Lastly, the economic motivation for the four objects participation in the electricity market will be examined.

I.

THE INFORMATION ABOUT OBJECTS

The objects of the study are four buildings: individual totals for each of 1 the Office Building (OB-1); 2 the Office Building (OB-2); 3 the Office Building (OB-3) and the Office Building 4 (OB-4) varies from 5500 m2 to 6200 m2. Their total occupied area is 0.054 km2 and their geographical location is on the territory of an urban residential district. All four objects have a common connection to the substation buses of 10kW and have three time zone tariffs payments for the electricity consumed (Figure 1).

OB-1

OB-2

electricity consumption of the Office Buildings (OBs average) can be observed. TABLE I.

ELECTRICITY CONSUMPTION

OB - 1

OB - 2

OB - 3

OB - 4

OBs aver.

Winter, MWh/month

95.8

56.2

82.8

60.9

395.6

Summer, MWh/month

75.1

39.1

58.6

44.3

217.1

Spring, MWh/month

81.0

43.1

67.1

48.4

239.7

Autumns, MWh/month

80.2

42.8

66.8

48.1

238.0

3.92

2.25

3.31

2.44

11.9

1.77

1.07

1.57

1.16

5.6

3.07

1.56

2.34

1.77

8.8

1.40

0.74

1.11

0.84

4.1

3.46

1.73

2.68

1.94

9.8

1.68

0.91

1.41

1.02

5.0

3.43

1.71

2.66

1.92

9.7

1.66

0.90

1.40

1.01

5.0

Seasonal

Winter, MWh

Summer, MWh

OB-4

OB-3

Figure 1. Scheme for urban distribution network

For the current research, monthly and hourly accounting data from 01.01.2013 on 31.12.2015 for the active energy of the four objects has been used. Reactive energy was not taken into account, as according to Republic of Latvia Cabinet Regulation No.50 of 21 January 2014 "Regulations Regarding the Trade and Use of Electricity" when using system services provided by the system operator, the customer has the duty to settle payments for the consumed reactive energy if the tg φ is greater than 0.4 (power coefficient cos φ < 0.92). In our case, tg φ = 0.27. Thus, the considered objects’ account for reactive energy is not illustrated. To evaluate the existing seasonal and daily energy consumption of the four objects, the average load during seasons, months, and days was calculated for each object. Calculation results of the months and average daily electricity consumption indicate (see Table 1) that the maximum power consumption occurs during the winter season, whereas the minimum consumption occurs during the summer season. In addition, it was estimated that working days accounts for 75% of electricity consumption of the overall monthly consumption. The average daily electricity consumption profile shows that all four objects have identical consumption profiles which can be attributed to the same work schedule, namely – from 9.00 to 18.00 and the similarities in weekend and holidays. Due to the fact that consumers have very similar profiles of daily load curve and have the same energy consumption tariff plans, it was decided that the research could be carried out using the general average daily data of the said objects. As a result, a summary of the seasons (months) and average daily

THE SEASONS, WORKING DAYS, WEEKEND AND HOLIDAYS

Spring, MWh

Autumns, MWh

working day weekend and holidays working day weekend and holidays working day weekend and holidays working day weekend and holidays

Creating infrastructures of charging stations and integrating them as additional consumers into the local network of the said office buildings, subjects to the receipt of payment for the electric charges, can be viewed as the economic motivation for the four considered objects. Thus, to achieve the set goal, it is necessary to estimate the power consumption of the EVs needed for a full charge, the necessary amount of time, as well as – the overall number of electric vehicles which could be integrated into the objects’ local network, depending on the season. II.

THE NUMBER OF VEHICLES AND PUBLIC CHARGING STATIONS

A. The technical data of vehicles In order to determine the electricity consumption of electric cars (EVs) from the network and the amount of hours (time) required for a full charge, it is necessary to know the average power consumption at different times of the year, as from experience it is known that weather conditions do indeed affect the mileage of EVs. To calculate the average power consumption of a single electric vehicle, practical data was used, taken from the following models, available in Latvia: FIAT Fiorino Elettrico, Volkswagen e-up, Nissan eNV200 Electric Van. The gathered data allowed concluding that the mileage, claimed by the manufacturers, of a fully charged EV might be lower than initially specified. The changes in mileage might occur due to seasonal changes (consequently – road quality

changes), the work of the interior electric heater, the influence of low temperatures on the battery, as well as due to the work of air conditioning, charging of other devices in the car, and of course – due to the individual manner of driving. As a result, a single full charge run’s mileage might become reduced by 30%. In view of the above, the calculations showed that to cover a distance of 100 km on an average a single charge the electric vehicle consumes: 24 kWh during winter, 17 kWh during summer, and 21 kWh during spring and autumn. The number of hours required for charging a storage battery using slow charging varies from 7 to 9 hours and the fast-charging requires from 30 to 55 minutes. B. Charging points for electric vehicles For the discussed objects, the following public charging stations were considered: the slow charging Mode 2/Type 2, 13A, 230V AC (1-phase), max 3.0 kW (6-12 hours)1, two output connection, the fast charging - Mode 4, multi-standard DC outputs (Mode-4), with optional AC (Mode-3), 3-phases, DC (50 kWh), AC (43 kWh), three output connections, with charging time of 30 minutes2. According to 2015 estimates, 333-400 passenger cars from 10:00 to 17:00 and from 147 to 269 from 18:00 to 09:00 on weekdays, from 150 to 240 on weekend and holidays with 00:00 to 23:00 were in the parking lots (parking zones) near the office buildings as it is illustrated in Figure 2. An increase in the number of vehicles on weekends during the period from 10:00 to 16:00 is explained by the fact that some offices are opened on Saturdays. It is known that there about 200 of the parked cars belong to the employees of offices, and about 125 cars are property of residents of the multi-family houses, while the rest belongs to non-residents (OB visitors). 450 400 350 300 250 200 150 100 0

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

50

working day

weekend and holidays

Figure 2. The number of cars in the parking lot during weekdays, weekends and holidays, by the hour

From that we can conclude that the electric cars, remaining at the parking lot 7-10 hours can be charged via both fast and slow charging. Based on the average daily energy consumption (all seasons), it was estimated that 70 EVs can be successfully integrated into the local area network facilities. In addition, as 1 2

www.abb.com http://electricmobility.efacec.com/ev-public-charger/

shown by the analysis of the flow of cars in the parking lot, the owners of EVs would be able to use both – slow and fast charging options. III.

CASE STUDY

To achieve this goal the following two stages were implemented: 1.

The energy consumption load on the OBs when using charging stations was estimated.

2.

The analysis of the electricity cost on the basis of existing tariffs, differentiated by the times of day was conducted.

It has been decided to base the estimation of energy consumption in the network of the office buildings (when using fast and slow charging stations) on the time intervals of maximum and minimum parking lots’ load. The time interval for the slow charge has been addressed and considered during the “Planning of Electric Vehicle Charging in the Urban Network" study. The calculation showed that the urban power networks can provide with electricity a substantial number of EVs if the slow charging happens during the period from 23:00 to 07:00 on weekdays and from 00:00 to 23:00 on weekends and holidays, when there are low electricity demands [6]. In the present study, the estimated number of slow charging EVs is 70 which suggests the need to install 35 the slow charging points (with two output connection). The time period from 9:00 to 18:00 has been accepted for fast charging of EVs during weekdays and weekends, as the number of parked cars is significantly higher during this particular time interval. On the basis of statistical data from the past five years, the daily mileage of an EV car is estimated to be between 35 and 200 km. Hence, with slow charging being a mandatory condition, fast charging could be considered as essential for office workers. Based on the above stated, a single fast charging would suffice to meet the needs of EV owners in this parking lot. In this case, calculations show that from 9:00 to 18:00 the overall load will not be constant; resulting is from 1 to 3 EVs per hour. IV.

RESULTS AND DISCUSSION

The results of the performed calculations for the average months and daily (by seasons): • • • •

Winter: PW.month = 406.7 MWh in the month, PW.work.d. = 14.4 MWh in the working day, PW.week.holidays = 10.8 MWh in the weekend and holidays; Summer: PS.month = 322.8 MWh in the month, PS.work.d. = 10.8 MWh in the working day PS.week.holidays = 8.9 MWh in the weekend and holidays; Spring: PSp.month = 343.4 MWh in the month, PSp.work.d. = 12.1 MWh in the working day PSp.week.holidays = 10.2 MWh in the weekend and holidays; Autumn: PAut.month = 341.4 MWh in the month, PAut.work.d. = 12.1 MWh in the working day PAut.week.holidays = 10.2 MWh in the weekend and holidays.

Comparing the results of energy consumption, the energy consumption increases by 37.6% during winter months , by 48.7% during summer months, by 43.3% during spring months, by 43.4% during autumns months, with the use of charging stations, that illustrated in Figure 3. 1.6 1.4 1.2 P =1

1

Average monthly electricity consumption

0.8 0.6 0.4 0.2 0 Winter

Summer

Spring

Autumns

Figure 3. Comparison of the energy consumption

Using of slow and fast charging could increase energy consumption for more than 20% during the weekdays, and more than twice in the weekend and holidays. V.

ANALYSIS OF ELECTRICITY COST AND POSSIBLE ECONOMICAL PROFITS

The mentioned objects are subjects to the same energy cost, based on tariffs which are differentiated by the times of day. According to the local energy traders, for legal entities the payment is based on 3 time zone tariffs [7]. To elaborate, during weekdays: maximum tariffs (0.05262 EUR/kWh) are from 8:00 to 10:00 and from 17:00 to 20:00, day tariffs (0.04049 EUR/kWh) are from 7:00 to 8:00, from 10:00 to 17:00 and from 20:00 to 23:00, and from 23:00 to 7:00 the night and weekend tariffs (0.02433 EUR/kWh) are applied3.

tariff, with 45% paid as day tariffs and 37% as night and weekend tariffs respectively. With slow and charge stations installed and posing as additional energy consumers of the local network, the night and weekend tariffs payments increases from 37 to 54%. Figure 4 compares the results of the time zone tariffs for OBs with and without the said charging stations. With the integration of a new consumer into the local network, the cost of monthly consumption increases. During winter months, the consumption grew by 37.6%, and the value increased by 28.4%; during summer months, the consumption increased by 48.7%, the value – by 36.7%; for spring months – increased by 43.3% and the rate – by 32.2%; and lastly, in autumn, it increased by 43.4%, with the cost growing by 32.4%. By adding electric vehicle charging to the calculation, it shows that the buildings owners’ annual load demand for electricity increases by 29.8%: from 990.4 MWh to 1,410 MWh, simultaneously increasing electric equipment’s efficiency. In turn, the overall cost for the consumed energy increases by 24%. This results in a chance to study charging station parks not only as additional consumers, but also as an object of profit. Objects that are able to combine the socioeconomic and commercial benefits are viewed as the greatest value for the community [8]. In this study, the starting point for the analysis is the commercial advantages. The costbenefit assessment of the feasibility of investment into charging stations parks infrastructure for electric vehicle owners of office buildings was carried out taking into account the following two criteria: investments made for a period of ten years at 6.5% interest rate and, secondly, assuming that for ten years the electricity tariff remains unchanged or will not exceed the current cost level. As a result, the calculations have shown that the provision of services for clients’ park charging stations at the price of the daily rate ensures a profit for the office buildings’ owners in the amount of 5553.9 EUR or 11.7% of total consumption.

%

VI.

100 18.1

14.3

16.9

12.7

17.8

13.7

17.7

13.7

80 37.0

60

45.6

32.5 43.2

34.8 45.1

Maximum tariffs

34.7 45.4

Day tariffs

40 20

48.7 36.3

54.7 39.9

51.6 37.1

51.6 36.9

0

Night and weekend and holidays tariffs

OBs OBs with OBs OBs with OBs OBs with OBs OBs with without of the without of the without of the without of the of the Ch.St. of the Ch.St. of the Ch.St. of the Ch.St. Ch.St. Ch.St. Ch.St. Ch.St. winter

summer

spring

autumns

Figure 4. Comparison of the time zone tariffs OBs without and with of the charging stations

According to the monthly accounting protocols of energy consumption, approximately 18% are paid at the maximum 3

All shown prices exclude the mandatory components of procurement for the final customers. http://www.eptirgotajs.lv/

CONCLUSIONS

The conducted analysis of seasonal and daily energy consumption of several service sector objects with installed charging stations, as well as an estimation of possible tariffs differentiated by times of day has indicated that increasing the load during the period of the cheapest tariff would allow the optimization of the cost of electrical energy and could result in getting profits. •

70 EVs is a sufficient number of cars that could be added to the local network under consideration.

•

The use if EVs increases energy consumption, simultaneously optimizing the electricity cost for a month.

•

OB owners could profit by creating an infrastructure for EVs charging and proposing appropriate tariffs.

•

With flexible pricing policy, building owners can offer mutually beneficial rates to attract customers.

•

The number of simultaneously charged EVs, network load and its operation schedule, as well as possible technical limitations should be considered as criteria for selecting a location for charging station infrastructure development.

The office buildings’ equipment responsible for energy distribution is not loaded for more than 50% during the periods of maximum consumption. Thus, not only it is possible to create an infrastructure of charging stations that would be integrated into the local network, but also possible to be beneficial for the buildings’ owners. For that, several factors should be considered, however: estimation of charging stations equipment’s cost, its proper installation into the local network, and an accurate study of possible economical profits from such an investment into the energy trading business. ACKNOWLEDGMENT This paper has been supported by the Latvia National Research Programme 2014-2017 "LATENERGI". REFERENCES [1]

OECD. (2005, Dec.). Lessons from Liberalised Electricity Markets. Energy Market Experience. IEA Publ. France Code 612005321p1. ISBN 92 64 10959 5, p. 224. [Online]. Available: http://www.iea.org/

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[8]

publications/freepublications/publication/ lessons-from-liberalisedelectricity-markets.html Available. Legislation of the republic of Latvia. Laws of the Republic of Latvia, Electricity Market. Web site: http://likumi.lv/doc.php? id=108834 Available Road Traffic Safety Directorate of the Republic of Latvia (CSDD). Web site: http://www.csdd.lv/eng/information_and_services/ Ministry of Environmental Protection and Regional Development of the Republic of Latvia. Open tender of Climate Change Financial Instrument. [Online]. Available: http://www.varam.gov.lv/lat/darbibas_ veidi /KPFI/projekti/?doc=17817] Riga Smart City sustainable Energy Action Plan for 2014-2020. Decision 1358. 2014. 131 p. [Online]. Available: http://www.rea.riga.lv/files/RIGA_SMART_CITY_SEAP_20142020_EN.pdf L.Grackova, I.Oleinikova, G.Klavs. The Planning of Electric Vehicle Charging in the Urban Network. Proceedings of the 8th International Scientific Symposium on Electrical Power Engineering ELEKTROENERGETIKA 2015 September 16–18, 2015, Stara Lesna, Slovak Republic.188-191.pp. ISBN 978-80-553-2187-5. Code 114480. CDROM. Indexed in Thomson-Reuters, SCOPUS, Web of Knowledge. Available. Sadales tiklis AS. Electricity traders for legal entities. Web site: http://sadalestikls.lv/eng/elektroenergijas_tirgus/electricity_market_for _legal_/traders/ Henry M. Levin, Patrick J. McEwan. Cost-Effectiveness Analysis: Methods and Applications (1-Off) Sage Publications, Inc (2000), Edition: 2nd, Paperback, 328 pages.