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6. VALIDATION OF THE RESULTS

6.3 Profitability calculation

The appropriateness of the established schedule can be estimated by calculation of its profitability. First of all, it is necessary to calculate the cost of the battery work per cycle.

According to [33], the LiFePO4 battery will reach 80% SOH after approximately 3000 FEC with 100% DOD. In [46] it was pointed out that the round trip efficiency of LiFePO4 battery is 98%. In addition, the authors noted the variable battery price is 752 €/kWh.

60

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Therefore, the total amount of cycles over the lifetime is:

2 βˆ™ πœ‚π‘…π‘‡ βˆ™ 𝐢 π·π‘œπ·(100%) βˆ™ π‘π‘Žπ‘£,𝑐𝑦𝑐𝑙𝑒𝑠 = π‘‡π‘œπ‘‘π‘Žπ‘™ π‘ π‘‘π‘œπ‘Ÿπ‘’π‘‘ π‘’π‘›π‘’π‘Ÿπ‘”π‘¦ (2) The investment cost of the BESS is calculated by the next formula:

πΆπ‘œπ‘ π‘‘π‘π‘Žπ‘‘π‘‘π‘’π‘Ÿπ‘¦βˆ™ πΆπ‘π‘Žπ‘‘π‘‘π‘’π‘Ÿπ‘¦= πΆπ‘Žπ‘π‘’π‘₯ π‘π‘Žπ‘‘π‘‘π‘’π‘Ÿπ‘¦ € (3)

The price of the battery work per 1 kWh is

πΆπ‘œπ‘ π‘‘1π‘˜π‘Šβ„Ž= πΆπ‘Žπ‘π‘’π‘₯ π‘π‘Žπ‘‘π‘‘π‘’π‘Ÿπ‘¦ €

π‘‡π‘œπ‘‘π‘Žπ‘™ π‘ π‘‘π‘œπ‘Ÿπ‘’π‘‘ πΈπ‘›π‘’π‘Ÿπ‘”π‘¦= 0.13 𝑐€

π‘˜π‘Šβ„Ž, (4)

where

Ι³RT round trip efficiency

CDOD(100%) capacity with a DOD = 100%,

Nav.cycles the average number of cycles

Costbattery cost of the battery

Cbattery battery capacity

Since the amount of charging or discharging energy was assumed as permanent for Elspot and Elbas market, it is necessary to calculate the cost of one discharge or charge event:

19.8 π‘˜π‘Šβ„Ž βˆ™0,13€

π‘˜π‘Šβ„Ž = 2.57€

For FCR-N market, the battery cost is calculated by other way. Firstly, the changing of battery’s SOC needs to be defined:

π‘†π‘‚πΆπ‘‘βˆ’ 𝑆𝑂𝐢𝑑+𝑛 = βˆ†π‘†π‘‚πΆ (5)

Secondly, changing of capacity regarding every change of SOC is calculated:

|βˆ†π‘†π‘‚πΆ βˆ™ πΆπ‘π‘Žπ‘‘π‘‘π‘’π‘Ÿπ‘¦|

100 = βˆ†πΆ (6)

Then, sum of the capacity change for one hour is considered:

βˆ‘ βˆ†πΆ = βˆ†πΆ1 β„Žπ‘œπ‘’π‘Ÿ (7)

Finally, the operation cost of one hour of work on FCR-N market is defined as:

βˆ†πΆ1 β„Žπ‘œπ‘’π‘Ÿβˆ™ πΆπ‘œπ‘ π‘‘1π‘˜π‘Šβ„Ž = πΆπ‘œπ‘ π‘‘1β„Ž (8)

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Consequently, the revenue from all the markets was calculated and presented at Table 3.

Table 3. Calculation of the revenue flow during the battery operation, 6.12.2018

Time Type of the market Allocated capacity, kW; kWh Market price, €/MWh; €/MW Battery cost, € Market revenue, € Revenue, €

5:00

47

As it can be seen from the table, the revenue for one day of battery work amounts -30.27€.

Further, the same calculation was conducted for another two days (Table 4).

Table 4. Calculation of the revenue

Date Revenue, €

7.12.2018 -38

8.12.2018 -30.71

Eventually, according to the results of the tests all three days brought a negative profit. It is worth to note that the chosen hours of work on Elspot and FCR-N market in majority were the most profitable. During three days, 8:00 and 9:00 on Elspot market were the most profitable during the morning or even during the all day. In the future, the chosen hours are needed to be selected every day with accounting of various details.

It is worth to note that during the calculation, the cost of the contracts concluded with TSO and Nord Pool were not considered. Furthermore, the tests with a real battery were conducted in November and December of 2018. The profitability of the battery will drastically increase at the period from April till September. The growth of power output of the PV panels will lead to reduction of Elbas market as energy source for charging the battery.

48 7. CONCLUSION

The Master’s thesis presents the decision-making simulation tool imitating artificial work of the BESS on the electricity markets. The battery implements several tasks: supply of energy to Elspot and Elbas markets and work for the market of ancillary services – maintenance of frequency stability. For the battery charging, SPPs installed on the university base were used as a main energy source. If the power production of the PV panels is low, Elbas market was applied for the battery charging. The battery operational schedule was settled on the base of historical data. Coincidence of peak hours for the last year was calculated for Elspot market and FCR-N market. Then, these hours were settled for the operating schedule. Left hours were established for work on Elbas market. The simulation tool was developed by use of Python.

Operation of BESS implies many parameters that cannot be predicted or calculated in advance. For this reasons, parameters such as battery degradation were neglected. The amount of provided or absorbed power was established as permanent.

Eventually, the simulation tool demonstrated its efficiency and proved the ability of BESS to work during the day. The energy was supplied to the priority markets at the morning and at the evening. In addition, the energy was also provided to the hourly market. During the day the battery was successfully charged either from the SPPs or from Elbas market.

After the tests of artificial battery, validation of obtained results was done with a real LiFePO4 battery. The line of the tests approved determined operational schedule. Also, it is shown that the estimated value of SOC change for 1 hour approximately matched the real one. The slight deviation could be explained by a number of terms such as battery degradation rate, number of cycles, temperature and others. Therefore, in further studies battery’s SOH is needed to be taken into account. In addition, the yield of the project for the owner was calculated. The calculation did not consider cost of the contracts concluded with Nord Pool and TSO. Eventually, according to the results, work of the battery in the framework of the chosen strategy is not profitable. It is worth to note that the tests were conducted in November and December. During the summer period the profitability will increase due to replacement of charging from Elbas market by use of SPPs.

There are a lot of open questions regarding the use of BESS as energy source. Besides it, BESS installed in the residential sector can also be used for the grid needs. At the current

49

moment, the cost of the BESS is one of the main issues that inhibits their high penetration to the market due to absent of profitability. It is worth to note that the cost reduction and sufficient support from the government will positively effect on their distribution. Their application for both – the owner and the grid – will impact towards sustainable work of the electrical grid, increasing of owner’s profit, penetration of renewable energy sources and development of distribution generation.

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56 Appendix A. The reserves products [38]

Market place Contract type Minimum

bid size Market gate closure Frequency of use Price level 2018

FCR-N Hourly market 0,1 MW Yearly market previous autumn,

hourly market day before at 18:30 Several times a day 14 €/MW,h (yearly market)

FCR-D Yearly and

hourly markets 1 MW Yearly market previous autumn, hourly market day before at 18:30

Several times per day - per year

2,8 €/MW,h (yearly market)

aFRR Hourly market 5 MW Day before at 17:00 Several times a day

Hourly market price + balancing energy

price Balancing power

market (mFRR) Hourly market 5 MW 45 min before each hour According to the bids,

several times/day - per year Market price Balancing

capacity market (mFRR)

Weekly

auctions 5 MW Week before

on Tuesday at 12:00

According to the bids,

several times/day - per year ~3 €/MW,h

57

58 Appendix C. Proposed scenario of act

Time Market 1 SOC1, % Action 1 Market 2 SOC2, % Action 2

00:00 65 Standby mode 65 Standby mode

01:00 65 Standby mode 65 Standby mode

02:00 65 Standby mode 65 Standby mode

03:00 65 Standby mode 65 Standby mode

04:00 65 Standby mode 65 Standby mode

05:00 FCR-N 65 Discharge FCR-N 65 Charge

06:00 FCR-N 50 Discharge FCR-N 80 Charge

07:00 35 Standby mode 95 Standby mode

08:00 Elspot 35 Discharge Elspot 95 Discharge

09:00 Elspot 20 Discharge Elspot 80 Discharge

10:00 PV/Elbas 5 Charge 65 Standby mode

11:00 PV/Elbas 20 Charge Elbas 65 Discharge

12:00 PV/Elbas 35 Charge 50 Standby mode

13:00 PV/Elbas 50 Charge Elbas 50 Discharge

14:00 65 Standby mode 35 Standby mode

15:00 Elbas 65 Discharge Elbas 35 Discharge

16:00 50 Discharge 20 Standby mode

17:00 Elbas 50 Standby mode Elbas 20 Discharge

18:00 Elspot 35 Discharge Elspot

Penalty 5 Standby mode

19:00 Elspot 20 Discharge Elspot

Penalty 5 Charge from

Elbas

20:00 Elbas 5 Charge Elbas 20 Charge

21:00 Elbas 20 Charge Elbas 35 Charge

22:00 Elbas 35 Charge Elbas 50 Charge

23:00 Elbas 50 Charge Elbas 65 Charge