CONCEPT STUDY ON FAST CHARGING STATION DESIGN

Transcription

1 EDISON Deliverable D4.4.1, D4.4.2, D4.5.1, D4.5.2, ELECTRIC VEHICLES IN A DISTRIBUTED AND INTEGRATED MARKET USING SUSTAINABLE ENERGY AND OPEN NETWORKS CONCEPT STUDY ON FAST CHARGING STATION DESIGN Type: Report Identifier: D4.4.1, D4.4.2, D4.5.1, D4.5.2, Classification: Final Version: 1.2 Access Public Editors: Steffen Lind Kristensen, Siemens A/S Anders Foosnæs, Danish Energy Association Per Nørgård, DTU-Risø Oliver Gehrke, DTU- Risø Anton Schmitt, Siemens AG Date: 30/08/2011 Copyright EDISON Consortium All Rights Reserved Page 1 of 40

2 EDISON Deliverable D4.4.1, D4.4.2, D4.5.1, D4.5.2, 1 TABLE OF CONTENTS 1 Table of contents Executive summary Introduction Selected scenarios General observations Basic functionality Fast charging station concepts AC busbar concept DC busbar concept Fast charging station investment costs Two concepts AC bus or DC bus Cost of the grid connection Cost of the bus bar Cost of the primary AC / DC converter Cost of the secondary AC / DC converter Cost of the secondary DC / DC converter The cost of the charging spot Comparisons of investment costs Actors External communication From the grid operators perspective Full grid Access Limited grid Access EV charging spots as a new costumer category Future perspectives From the fast charging station owners perspective...25 Copyright EDISON Consortium All Rights Reserved Page 2 of 40

3 7.2.1 Full grid access Limited grid access Internal communication & control No local energy storage Full grid access or limited grid access With local energy storage Full grid access Limited grid access Communication standards COP 15 concept Electrical vehicle (EV) interfaces charging spot (CS) interfaces Interfacing between COMBOX and TM 1703 Mic Pilot Pin connectivity Communication between EV and UI implemented in COP 15 concept Conclusion...40 Copyright EDISON Consortium All Rights Reserved Page 3 of 40

4 2 EXECUTIVE SUMMARY EDISON The Edison Project is an international research project partly publicly funded by the Danish transmission system operator (TSO) Energinet.dk's research program FORSKEL. In the EDISON project Danish and international competences will be utilised to develop optimal system solutions for EV system integration, including network issues, market solutions, and optimal interaction between different energy technologies. Electric vehicles (EVs) provide a unique opportunity to reduce the CO 2 emissions from the transport sector. At the same time, EVs have the potential of playing a major role in an economic and reliable operation of an electricity system with a high penetration of renewable energy. EVs will be a very important balancing measure in enabling the Danish government s energy strategy, which implies 50% wind power penetration in the electric power system. Report The objective of this report is to evaluate the technologies needed for control and operation of fast charging stations. In particular the communication and control functions between the grid, the central charging stations and the vehicles, as well as the internal control and operation will be investigated. Outcome The result of the research during this project has shown that the recommended hardware solution is the AC busbar concept. If a battery bank is located together with the fast charging station, the flexibility in the control schedules are much higher. 3 INTRODUCTION In this report we have looked into the complexity of controlling and operating a fast charging station. Focus has been on the communication and control functions between the grid, the central charging stations and the vehicles (in particular the batteries). The report looks into various hardware concepts for fast charging stations in order to be able to make a cost analysis for fast charging stations. The cost of grid connection is also covered as we needed to look at these in order to design the control functions between the grid, the central charging stations, and the vehicles. Detailed information relating communication to external actors as well as internally in the fast charging station is a part of the report. Information of the ongoing standardisation activity concerning fast charging stations is also included. During the Edison project we have realised also test scenarios in order to test and verify our theories of how to design the fast charging station. The chapter COP 15 Concept describes how we designed the first intelligent AC charger to control charging of electrical vehicles. This implementation was presented at the COP 15 UN Climate Conference in Copenhagen Copyright EDISON Consortium All Rights Reserved Page 4 of 40

5 4 SELECTED SCENARIOS 4.1 GENERAL OBSERVATIONS A fast charging station is almost like a conventional gas station. However, it provides energy to electrical vehicles (EVs) instead of fuel to normal cars with combustion engine. The fast charging station will be designed with several charging spots so that a number of EVs can be charged at the same time. There are two possibilities for fast charging of EVs. One is the usage of a three phase AC current and conversion to DC inside the car. The other possibility is transferring DC current to the car with the suitable voltage level for the battery. In the first case, the transfer of the power is technically easy but for the conversion to DC a bulky inverter is needed inside the EV. The size of the inverter increases with the level of power. While using DC power for transfer, a DC inverter is not necessary inside the car. On the downside a complex interface between EV and charger has to be utilised for that solution. The fast chargers are of high power in order to transfer as much energy as possible for every charge. A limitation is however given by the battery itself. A charging with high currents, res. high power will reduce the life-time. Therefore, at the moment, the maximum power transfer is 50 kw. Due to the ongoing improvement of the batteries we might in the future see chargers up to 200 kw located in the fast charging station. With 50 kw it will take approx. 15 minutes to charge a battery so that the EV will be able to drive 100 km. In the future scenario, with the 200 kw charging, this may only need few minutes. All control schemes recommended are based on the idea that the fast charging station has to give as high a profit as possible. We have considered that there are two possible basic hardware architectures. It is also an option to add a local battery bank in both hardware layouts. As the main purpose of the fast charging station is to provide the vehicle user with energy as quickly as possible, V2G is not an option. V2G means that the EV will transfer power to the grid instead of receiving it. As a result the battery will be partially discharged instead of charged. Roaming service, market strategies etc. are not part of this report. 4.2 BASIC FUNCTIONALITY The fast charging station is in need of the following functionalities: 1. Communication towards external actors. This will be described in detail in chapter Internal control This will be described in detail in chapter Protection Each fast charging spot is equipped with an AC/DC or DC/DC converter. The charging spot must, depending on technology, be equipped with protection equipment. Primary protection devices have to be installed in the charger cabinet to ensure safety. Copyright EDISON Consortium All Rights Reserved Page 5 of 40

6 Following protection equipment should be installed depending on technology: - Overvoltage protection - Undervoltage protection - Overcurrent protection - Short circuit protection - Earth fault protection If any fault occurs the charging spot must switch off immediately in order to ensure full safety and should operate independently from the BMS (Battery Management System) located in the EV. Additionally the DC part within the fast charging station including the cable connection to the EV is disconnected from ground. Together with the DC part of the vehicle this forms an isolated terra net (IT net). The advantage of an IT net is that a bypass between one of the power lines and ground will not lead to a significant current flow. A short circuit will only occur if both power lines, DC + and DC -, show a ground fault. Therefore the IT net of the fast charging station is observed by an insulation monitor. 4. Metering We recommend that the subject metering is done in the same way as for AC charging. This should be done according to Danish legislation (Meters MUST be fixed installation). The standard used should be IEC 62056, electricity metering, data exchange for metering, reading and loading. On the user interface of the charging spot it must be possible to see the meter value, hereby enabling the vehicle user to log how much power is procured at any given time. 5. Forecast The fast charging station automation will have a forecast function, which should include market indications of when the prices are high and when the prices are low. Moreover the forecast function could include information relating to the grid connection, enabling the fast charging station to automatically control when to use the grid for loading power and when to use the local battery bank, if one is installed. 6. Payments/Roaming We have not evaluated how the payments/roaming should be performed. We assume that in the beginning all payments are done in cash or by credit card. Copyright EDISON Consortium All Rights Reserved Page 6 of 40

7 4.3 FAST CHARGING STATION CONCEPTS The fast charging station concept is based on the following design: If we look at a fast charging station with 20 chargers each of 50 kw, the total power consumption will be 1 MW. With this power consumption normally the transformer would be connected to the 10 kv grid. So the fast charging station will be connected to the grid via a 10/0.4 kv transformer. The transformer will be connected to a busbar. We will evaluate if the busbar should be of the AC or DC type. The functionality of the busbar is to distribute the electrical power within the fast charging station. It is a strip of copper or aluminium that conducts electricity between the transformer and the charging spots. The size of the busbar determines the maximum amount of current that can be safely carried. In our configuration the busbar can have a diameter of 400 mm² for the AC busbar and 800 mm² for the DC busbar. This is calculated using the above mentioned power and voltage levels and in accordance to the IEC standard used for busbar design. In the charging spots an AC/DC or a DC/DC converter is needed in order to transform the voltage to the correct DC voltage level needed to charge the EVs. Charging of the EV battery will be done with DC charging directly on the EVs battery pack. Copyright EDISON Consortium All Rights Reserved Page 7 of 40

8 4.3.1 AC BUSBAR CONCEPT The traditional substation layout is as follows: An AC busbar, on which the charging spots are connected, is connected to the grid using a 10/0,4 kv transformer. In the charging spots an AC/DC converter is needed in order to transform the voltage to DC. Then the EV battery is connected to the charging spot (CS), charging the EV with DC directly on the EVs battery pack. In case a battery bank is requested, an AC/DC converter is needed between the busbar and the battery bank in order to connect the battery to the busbar in the fast charging station. In order to disconnect the CS from the grid an AC circuit Breaker is needed for each charging spot. For each CS a filter is needed to ensure proper power quality. For more details see figure 1. Figure 1. Hardware layout AC busbar Copyright EDISON Consortium All Rights Reserved Page 8 of 40

9 4.3.2 DC BUSBAR CONCEPT An alternative substation layout could be as follows: Instead of an AC we suggest a DC busbar solution. Here we have a large AC/DC converter and one DC busbar on which the charging spots are connected. For each charging spot a DC/DC converter is needed in order to connect more than one vehicle at the same time. The reason for this is that the voltage level of the EV battery varies depending of the state of charge of the battery. The more charged the battery is, the higher is the voltage level. However, the voltage level on the busbar side of the DC/DC converter is always the same for all charging spots. While the voltage level in the charging spot is higher than the voltage level in the EV, the EV battery will be charged. If it was the other way around the battery would be discharged. The EV battery is connected to the charging spot, charging the EV with DC directly on the EVs battery pack. In case a battery bank is requested a DC/DC converter is also needed. The DC/DC converter will be located between the busbar and the battery bank in order to connect the battery to the busbar in the fast charging station. The battery bank can be loaded when the energy price is low and discharged when the energy price is high. In chapter 7 and 8 we look into more details in the advantages of a battery bank. In order to disconnect the CSs from the grid an AC circuit breaker is needed. This could be located between the transformer and the AC/DC charger. Also, in order to ensure proper power quality, one filter located at the transformer is needed, to ensure proper power factor correction and to eliminate unwanted harmonics to be transmitted to the grid. For more details see the figure below. Copyright EDISON Consortium All Rights Reserved Page 9 of 40

10 Figure 2. Hardware layout DC busbar Copyright EDISON Consortium All Rights Reserved Page 10 of 40

11 5 FAST CHARGING STATION INVESTMENT COSTS 5.1 TWO CONCEPTS AC BUS OR DC BUS The investment costs for two different fast charging station concepts are compared: The concept with a common AC bus the AC bus concept and the concept with a common DC bus the DC bus concept (Figure 3). As many of the components are the same for both concepts, the cost comparisons are only made for those components that differ. The total costs indicated are thus not for the entire station, but only for those components taken into account. The comparisons between the two concepts are made with different bus voltage (U bus ), charging power capacity (P c ) and number of charging spots (N) (Table 1). Figure 3: Illustration of the components taken into account in the investment cost comparison between the AC bus concept and the DC bus concept. The investment costs for the following components have been estimated and taken into account in the comparison: - Grid connection, including transformer (common for both concepts) - Primary AC / DC converter (only for the DC bus concept) - Secondary AC / DC converters (only for the AC bus concept) - Secondary DC / DC converters (only for the DC bus concept) - The charging spots (common for both concepts) Copyright EDISON Consortium All Rights Reserved Page 11 of 40

12 The AC bus concept The DC bus concept Grid voltage U grid 10 kvac 10 kvac Bus voltage U bus 0.7 / 2 kvac 0.5 / 2 kv Charging power P c 100 / 200 / 300 kw 100 / 200 / 300 kw Number of charging spots N 3 / 5 / 10 3 / 5 / 10 EV battery voltage U bat 350 Vdc 350 Vdc Table 1: The values of the parameters used in the comparisons of the investment costs for the two concepts. The grid voltage (U grid ) is assumed to be 10 kv, and the voltage of all the EV batteries (U bat ) are assumed to be 350 V. For simplification, the capacity of the grid connection (P grid ) is assumed to be: where P c is the charging power capacity and N is the number of charging spots. Copyright EDISON Consortium All Rights Reserved Page 12 of 40

13 5.2 COST OF THE GRID CONNECTION The investment cost of the grid connection covers the 10 kv breakers, the line filters, the 10 kv transformer and the overload protection. The total grid connection cost is estimated at 1000 DKK/Ampere, corresponding to 33 DKK/kW or kv - Figure 4 (Source: Dansk Energi). 5 Cost ( /kw) Grid 10 kv (MW) Figure 4: Relative investment cost of the grid connection (@ 10 kv grid voltage). (Source: Dansk Energi) 5.3 COST OF THE BUS BAR The investment costs for the 3 phase AC and the DC bus bars have been estimated by Siemens for bus different current levels based on a copper price of 12 /kg, a bus bar with number of outlets one higher than the number of charging spots - Table 2. The Power capacity of the AC bus bar is given at cosϕ=0,8. Pac is the charging power capacity for the AC bus, and Pdc for the DC bus. Copyright EDISON Consortium All Rights Reserved Page 13 of 40

14 Bus AC bus DC bus Cost Cost Pac Pac Pdc Pdc 400 V 500 V AC bus DC bus 2p 10p 2p 10p A MW MW /outlet /outlet kw kw kw kw 400 0,22 0, ,44 0, ,11 1, ,66 1, ,77 2, ,88 3, ,10 4, Table 2: The cost of bus bars per outlet for different bus current levels and 400 Vac or 500 Vdc line-line voltage, and with indication or the corresponding bus power and charging power for 2 or 10 charging spots. (Source: Siemens) The cost per outlet increases only slightly with the power capacity. 50 Bus bar cost Cost per outlet ( /kw) Charging power (kw) AC bus 2p AC bus 10p DC bus 2p DC bus 10p Figure 5: Investment cost per outlet of the common bus relative to the charging power (@ 400 Vac or 500 Vdc bus bar voltage). (Source: Siemens) The relative cost of the bus bar decrease with the charging power capacity and with the number of charging spots. Copyright EDISON Consortium All Rights Reserved Page 14 of 40

15 5.4 COST OF THE PRIMARY AC / DC CONVERTER A primary AC / DC converter is only used in the DC bus concept, and only a single unit is needed (Figure 3). The capacity of the primary AC / DC converter is assumed to be the same as the grid connection capacity. No specific cost data are available. Cost is extrapolated from the cost of the secondary AC/DC converter (Source: Siemens). 5.5 COST OF THE SECONDARY AC / DC CONVERTER Secondary AC / DC converters are used only in the AC bus concept and in a quantity corresponding to the number of charging spots N (Figure 3). The secondary AC / DC converter covers the AC and DC filters. The cost per unit at different power levels and AC voltages has been estimated by Siemens - Table 3 and Figure 6. No data available for 100 Vac. Power 400V 690V 1000V 400V 690V kw k k k /kw /kw ,2 32,5 Table 3: The estimated cost per uni-directional AC-DC converter at different power levels and AC voltages. (Source: Siemens) Copyright EDISON Consortium All Rights Reserved Page 15 of 40

16 Uni-directional AC / DC converter 60 Cost ( /kw) V 690V Power (kw) Figure 6: Investment cost of a uni-directional AC / DC converter. No cost date available for 100 Vac. (Source: Siemens) The relative cost decrease with increasing AC voltage level and with increasing charging power level. 5.6 COST OF THE SECONDARY DC / DC CONVERTER Secondary uni-directional DC / DC converters are used only in the DC bus concept and in a quantity corresponding to the number of charging spots N (Table 1). No specific cost data are available. The best guess is to use the same cost figures as for the uni-directional AC / DC converter at corresponding power capacity - Table 3 and Figure 6 (Source: Siemens). 5.7 THE COST OF THE CHARGING SPOT The charging spots are designed for battery voltages in the range Vdc, corresponding to the currents indicated in Figure 7 for different charging power levels. Copyright EDISON Consortium All Rights Reserved Page 16 of 40

17 The cost for the charging spot 400 V / 500 A / 200 kw) is estimated at DKK or 2700 per charging spot DKK for equipment and DKK for installation work (Source: Siemens) Charging current Current (A) Power (kw) 300V 500V Figure 7: The charging currents for different battery voltages and charging power levels. 5.8 COMPARISONS OF INVESTMENT COSTS As the cost of the grid connection and the costs of the charging spots are independent of the concepts, the comparisons are made for the investment cost for the converters and the bus bars only (Table 4 and Figure 8). With the cost figures as indicated above, the AC-bus solution will always be slightly cheaper than the DC-bus solution. For the AC concept the cost per charging spot does not depend on the number of charging spots. In general, the relative cost (per kw) reduces with the charging power level. Copyright EDISON Consortium All Rights Reserved Page 17 of 40

18 Power 2p 10p AC - 2p AC - 10p DC - 2p DC - 10p AC - 2p AC - 10p DC - 2p DC - 10p kw kw kw k k k k /kw /kw /kw /kw Table 4: The estimated total cost of the AC to DC conversion for the two concepts for different charging power levels and different number of charging spots. 250 Total AC -DC conversion costs Cost per post ( /kw) Charging power (kw) DC -2p DC -10p AC -2p AC -10p Figure 8: Total costs of the converters and the bus bar for the AC-bus and the DC-bus concepts for different charging power capacities and different number of charging spots (2 and 10), based on the cost figures as indicated above. Copyright EDISON Consortium All Rights Reserved Page 18 of 40

19 6 ACTORS Since several chargers are connected to the same busbar in the fast charging station, there will be a need for central control, hereafter called fast charging station control. The functionality of this fast charging station control is as follows: Trade electricity with the electricity retailer Retrieve information from the distribution system operator (DSO) regarding grid constraints Inform the vehicle user of the energy prices by using a user interface (UI) Control the charging spots and the use of the battery bank if one is installed. The fast charging station control is also responsible for the control schedules explained in details in Chapter 7 and Chapter 8. Although the ISO/IEC is only approved as a Committee Draft (CD) we use the actors defined in this standard, also for the fast charging station. As described above we have the following Actors: Electric Vehicle (EV) Electric vehicle Vehicle user Person or legal entity using the vehicle and providing information about driving needs (e.g. range and availability) and therefore consequently influences charging patterns Electricity retailer Body to conclude the energy supply contract with the customer Distribution System Operator (DSO) Operator responsible for the voltage stability in the distribution grid (medium and low voltage power grid) Charging Spot (CS) The physical unit to that the EV is connected in order to transfer energy to the vehicle. Copyright EDISON Consortium All Rights Reserved Page 19 of 40

20 All the above actors are already specified in the commenting draft of the ISO/IEC standard.the Committee Draft (CD) of the ISO/IEC defines DC charging of EVs in Mode 4. However, at present the standard only covers the communication between one DC charging spot and one EV, therefore we have additionally defined the following actors: User Interface (UI) The user interface will inform the vehicle user of the current energy price. This could be by using smart phone APPs, navigator systems or a billboard which is already known today from conventional gas stations. We have not evaluated which system is the best to use. Fast charging station controller (FCSC). The fast charging station controller has the following tasks: Trade electricity with the electricity retailer, retrieve information from the DSO regarding grid constraints, inform the vehicle user of the energy prices by using a user interface (UI) and finally control the charging spots and the use of the battery bank if one is installed. Copyright EDISON Consortium All Rights Reserved Page 20 of 40

21 7 EXTERNAL COMMUNICATION 7.1 FROM THE GRID OPERATORS PERSPECTIVE The DSOs have the following income components to cover costs and a reasonable return on investments within the revenue cap defined by the authorities: grid connection fee (paid once by the costumer at the time of grid connection or an increase in the maximum capacity of the installation) Subscription fee (invoiced continuously, covers for example metering costs and costumer service) grid tariff (invoiced continuously, covers e.g. grid operation costs and grid maintenance cost) Section 7.1 will mainly focus on the grid connection fee FULL GRID ACCESS At the moment a grid connection for a fast charging station would be treated just as a grid connection for any other consumer. The general rule for grid connections is that the costumer should pay the costs that it is imposing on the grid. The price of a grid connection depends on which voltage level the costumer is connected to (PCC point of common connection). The industry separates between A, B and C costumers: A0 A1 A2 B1 B2 C Figure 9. Definition of A, B and C costumers Copyright EDISON Consortium All Rights Reserved Page 21 of 40

22 In an industry guide by the Danish Energy Association the following example is given showing the variation of costs of the grid connection for different costumer categories: A-level 10 kv (expansion) B1 -level 10 kv B2 -level 0,4 kv C- level P.C.C. Specific Average cost 594 kr/a 746 kr/a 746 kr/a 202 kr/a Total 594 kr/a 746 kr/a 948 kr/a. Adm. cost. 149 kr/a 187 kr/a 237 kr/a Unit price 743 kr/a 933 kr/a Avg.. unit price 954 kr/a kr/a Figure 10. Price examples of different costumer categories 1 1 These prices are revised annually. The exchange rate is approximately 7,5 DKK/Euro. Copyright EDISON Consortium All Rights Reserved Page 22 of 40

23 The Danish Energy Association reports an industry standard for the grid connection fee for C costumers ex spot every year to the Danish energy Regulatory Authority. The figures for 2009 and 2010 can be seen in the table below: Category Reported for 2009 Reported for 2010 Single family house / summer house DKK DKK Small/row house DKK DKK Apartment DKK 8350 DKK Youth-/ senior homes DKK 4400 DKK Single phase connection DKK 1450 DKK Standard tariff for industry DKK/A * 950 DKK/A * * Industry pays a connection fee equal to single family houses for the first 25 A (at 400 V) and the specified tariff for additional amps of maximum capacity. Each DSO can however report own prices to the Danish energy Regulatory Authority if they want to deviate from the standard figures reported by the Danish energy Association. It is recommended that DKK/A is used in the calculations regarding bus bar design and energy storage in this report LIMITED GRID ACCESS As a step towards integrating more consumption into in the regulating market, the DSOs can now offer an alternative grid connection to electrical boilers located in combined heat and power plants. This new type of grid connection is called limited grid access and means that the costumers, who e.g. connect a boiler, avoid the normal connection fee if the connection and operation does not inflict uncovered cost on the local distribution company. All costs related to the connection and control of the boiler is covered by the plant. These costs among others include: online measurements, reprogramming of SCADA system (supervisory control and data acquisition), communication lines between DSO control centre and remote terminal unit (RTU) at the boiler site. To get this advantage the costumer needs to allow automatic and manual disconnection of the boiler by signal from the DSO, and in some cases an automatic cap signal that limits the allowable power usage on the boiler, based on online measurements in identified bottlenecks in the network. Furthermore, if the available capacity in the grid decreases for any reason, the capacity available to the boiler will be reduced accordingly. The financial risk is solely placed on the costumer. However, it is difficult to implement this scenario in the calculations regarding bus bar design and energy storage since the grid connection cost will depend on the actual case, and since there will be a financial risk for the investor (if access capacity is no longer available due to load increase or rebuild of the network). Copyright EDISON Consortium All Rights Reserved Page 23 of 40

24 7.1.3 EV CHARGING SPOTS AS A NEW COSTUMER CATEGORY The 25 th of May 2011 the Danish DSOs proposed a change of the grid connection rules for charging spots. In order to implement these changes they need to be approved by the Danish energy Regulatory Authority. The proposal contains two important changes (the latter being very relevant for fast charging station s): 1. Costumers that have a separate grid connection for their EV on their cadastre, will have the possibility of utilising their existing capacity of delivery (for the house installation), thus avoiding an extra grid connection fee for the new installation. 2. The DSOs will work towards defining charging spots in public space as its own costumer category with its own calculation method for the connection fee. This calculation method will consider the expected low utilisation for the coming years and that the coincidence factor for several charging spots will be low. This will mean that charge spots will pay a lower grid connection fee (DKK/A) than they do in the current system. This initiative is suggested to be valid for a limited number of years as a test period. If this proposal is accepted, and the grid connection cost for charging spots are reduced, the incentive for installing a battery bank to cope with a connection capacity that is lower than the peak demand of the charger is reduced FUTURE PERSPECTIVES Looking further into the future, the DSOs might develop new tariff systems that will increase the incentives for installing a battery bank in combination with the fast charging station. Suggested developments for such tariff systems and development of the electricity market are described in two reports from WP2.3. Copyright EDISON Consortium All Rights Reserved Page 24 of 40

25 7.2 FROM THE FAST CHARGING STATION OWNERS PERSPECTIVE Taking a look at the external communication from the fast charging station owner s perspective, we have realised that the only external actors, to which the fast charging station gateway needs to communicate, are as follows (see also chapter 6): Electricity retailer DSO CS UI Vehicle User Also, the fast charging station will be connected to the grid either with full grid access or with limited grid access. We expect that all new installation will be with full grid access. However, future power demands and changes in the infrastructure might lead to a situation where the fast charging station is connected with limited grid access FULL GRID ACCESS In case the fast charging station is connected with full grid access, the communications towards the external actors are as follows: 1. The fast charging station owner trades with the electricity retailer, hereby making a price agreement. 2. The fast charging station owner now announces the price. 3. The EV will need fuel and hence connect to the charging spot. 4. Financial settlement is performed. 5. In case of an increase or decrease in prices a new price is traded with the electricity retailer. 6. The fast charging station owner now announces the new price. 7. The EV will need fuel and hence connect to the charging spot. 8. Financial settlement is performed Copyright EDISON Consortium All Rights Reserved Page 25 of 40

26 Figure 11. Control Schedule for External Communication, Full grid Access. This is also known as a price demand solution. It will however be difficult to force extra business due to these price adjustments unless they are of significant difference LIMITED GRID ACCESS In case the fast charging station is connected with limited grid access, the communications towards the external actors are as follows: 1. The fast charging station owner trades with the electricity retailer, hereby making a price agreement. 2. The fast charging station owner now announces the price. 3. The EV will need fuel and hence connect to the charging spot. Copyright EDISON Consortium All Rights Reserved Page 26 of 40

27 4. Financial settlement is performed. 5. If the DSO informs of a grid constraint, the fast charging station owner now announce the new price. This price will be higher as the fast charging station is in a situation where it is unable to make as much profit as before. The reduced amount of power available for selling will be compensated by the higher price. 6. The EV will need fuel and hence connect to the charging spot. 7. Financial settlement is performed Figure 12. Control Schedule for External Communication, limited grid access. This is also known as a bottleneck in the grid. A bottleneck in the grid means that the upper grid is unable to provide the demanded power. This might happen in case of cable failure or overloaded power lines. Copyright EDISON Consortium All Rights Reserved Page 27 of 40

28 8 INTERNAL COMMUNICATION & CONTROL The following chapters will look at the internal control needed to enable the fast charging station to operate optimal regarding profit. The aim of the fast charging station control is to procure the energy at lowest rate and to sell at highest rate. Also, in case of a bottleneck which affects the ability to provide maximum power to the charging spots, the fast charging station control must assist in providing the best charging pattern possible. The following chapters will look at the different charging scenarios and define the best charging pattern possible in respect of gaining the highest profit for the fast charging station owner. 8.1 NO LOCAL ENERGY STORAGE FULL GRID ACCESS OR LIMITED GRID ACCESS When the fast charging station has no local energy storage installed, there are no differences in the control schedule whether or not the grid connections are full or limited. But if several EVs are connected to the charging spot in the fast charging station, hereby using the maximum power of the fast charging station, the control schedule may be influenced. If the DSO informs of a grid constraint (this is also known as a bottleneck in the grid.), the internal control should operate as follows: 1. The fast charging station control must make a priority control of the charging spots. 2. Action 1: Close/shutdown all charging spot which are not in use. 3. If this does not solve the problem, following action must be taken. 4. Action 2: Start to serve the EVs after priority. Copyright EDISON Consortium All Rights Reserved Page 28 of 40

29 Figure 13. Control Schedule for Internal Communication, No local energy storage. There are several ways to do priority controlled action. We have discussed the possibilities and have the following suggestions: 1. The first EV to connect to the CS will be the first EVs to be served. 2. The % of power available will be equally divided between the connected EVs, hereby increasing the charging time slightly for all EVs and not increasing the charging time significantly for a few EV owners. 3. Gold Card contract means that the fast charging station owner has provided you with better agreements towards charging your EV. Those drivers will be charged with priority. 8.2 WITH LOCAL ENERGY STORAGE FULL GRID ACCESS If the fast charging station is equipped with local energy storage and full grid access, we will not experience a problem providing the needed energy. However, hence the fast charging station is equipped with a local energy storage, we are able to operate using price demand signals. The internal control should operate as follows: 1. The fast charging station owner trades with the electricity retailer, hereby making a price agreement. 2. If the price is lower than normal, the fast charging station owner will store this energy in the battery bank. Copyright EDISON Consortium All Rights Reserved Page 29 of 40

30 3. The EV will need fuel and hence connect to the charging spot. 4. If the price is low the fast charging station will provide power from the grid. 5. If the price is high the fast charging station will provide power from the battery bank, as long as the capacity is sufficient. 6. When the battery power is lower than the power needed to charge all the EVs connected to the fast charging station, it will charge from the grid. Fast Charging Station Controller Electricity Retailer DSO CS Battery Bank EV Trading of energy/ Price agreement made The price is lower than normal, energy to be stored in battery bank The car needs fuel and connects to the charging spot The car needs fuel and connects to the charging spot If price is lower than normal: Provide power from grid If price is higher than normal: Provide power from battery bank If power in battery bank < power needed switch to power from grid Figure 14. Control Schedule for Internal Communication, with local energy storage, Full grid Access. By operating as the above it will be possible to implement a price Demand solution in the fast charging station. Copyright EDISON Consortium All Rights Reserved Page 30 of 40

31 8.2.2 LIMITED GRID ACCESS All though all indications show that a fast charging station always will be installed in an area where there is full grid access, there might be a future scenario in which this is not the case. It could occur that the fast charging station was initially built in an area of full grid access. Due to changes in the infrastructure, the fast charging station is now equipped with local energy storage and limited grid access. If the fast charging station is equipped with local energy storage and limited grid access, we should experience a mix of issues related to the operation. Here we will experience both, the need for operating by using the price demand signals, but also we experience the problem relating to bottlenecks. In order to be able to operate both using price demand and operating when there are bottlenecks, the following operation must be performed: 1. The fast charging station owner trades with the electricity retailer, hereby making price agreements. 2. If the price is lower than normal, the fast charging station owner will store this energy in the battery bank. 3. The EV will need fuel and hence connect to the charging spot. 4. If the price is low the fast charging station will provide power from the grid. 5. If the price is high the fast charging station will provide power from the battery bank, as long as the capacity is sufficient. 6. When battery power is lower than the power needed to charge all the EVs connected to the fast charging station, it will charge from grid. This is the operation using price demand signals., Under normal conditions (without bottleneck) this is the best way of operation: 7. Several EVs are connected to the charging spot in the fast charging station. Hereby using the maximum power of the fast charging station. 8. The DSO informs of a grid constraint. 9. The fast charging station control must make a priority control of the charging spots. 10. Action 1: Close/shutdown all charging spot which are not in use. 11. If this does not solve the problem, following action must be taken. 12. Action 2: Start to serve the EVs after priority. There are several ways to do priority controlled Action, we have discussed the possibilities and have following suggestions: 4. The first EV to connect to the CS will be the first EV to be served. Copyright EDISON Consortium All Rights Reserved Page 31 of 40

32 5. The % of power available will be equally divided between the connected EVs. Hereby increasing the charging time slightly for all EVs and not increasing the charging time significantly for a few EV owners. 6. Gold Card contract means that the fast charging station owner has provided you with better agreements towards charging your EV. Those drivers will be charged with priority. Fast Charging Station Controller Electricity retailer DSO CS Battery Bank EV Trading of energy/ Price agreement made The price is lower than normal, energy to be stored in battery bank The car needs fuel and connects to the charging spot The car needs fuel and connects to the charging spot If price is lower than normal: Provide power from grid If price is higher than normal: Provide power from battery bank If power in battery bank < power needed switch to power from grid The car needs fuel and connects to the charging spot The power needed is the maximun power for the fast charging station Information of grid constraint Action 1: Close/shotdown all Cs which are not in use Action 2: Start serving Evs after priority Figure 15. Control Schedule for Internal Communication, with local energy storage, limited grid access. This is the solution to a bottleneck in the grid. Copyright EDISON Consortium All Rights Reserved Page 32 of 40

33 9 COMMUNICATION STANDARDS In the Edison consortium we have endorsed the use of international norms and communication standards, such as the IEC standards. This is to ensure well documented and easy implemented communication interfaces. At the moment lots of activities are ongoing relating to the communication standards, in particular the IEC and the IEC Throughout the Edison project we have had a lot of discussions, both internally in our work package WP4 but also with other Edison partners in the other work packages, where we concluded the usefulness of both protocols. The IEC standard covers communication to De-centralised Energy Resources (DER). During the whole Edison project we discussed intensively that an Electrical Vehicle (EV) was to be regarded as a DER. Based on this and the current standardisation activities relating to the IEC we have evaluated that the IEC standard can be used in the fast charging station scenario for the communication between the fast charging station controller and the external actors. Furthermore, for adaptation of this standard several Logical Nodes (LN) had to be added. A Logical Node describes the functionality of the object which needs to be used. However in the current version of the standard there are no suitable LNs which reflects the EV e.g. State Of Charge (SOC). In regard to the communication between EV and the charging spot, we have evaluated that the best option for communication protocol is the IEC 61851/IEC JWG We base the conclusion on the above mentioned discussion and our success in making the test setup which was presented at the COP 15 conference. In chapter 10 you can read more details about our COP 15 implementation. In electrical engineering and power system automation, the International Electrotechnical Commission standards define systems used for telecontrol (supervisory control and data acquisition). Such systems are used for controlling electric power transmission grids and other geographically widespread control systems. By use of standardized protocols, equipment from many different suppliers can be made to interoperate. IEC standard could be used as the communication standard between fast charging station and external actors as an alternative. IEC is a communication standard for the design of operating, controlling and protection of electrical substation automation. Looking at the hardware design of the fast charging station it is similar to the electrical substations. Hence this standard is suitable for the communication internally between fast charging station controller and hardware components described in chapter 4. Below we have made an overview of recommended standards for communication: From fast charging station to external actors IEC with extra logical nodes reflecting EVs; IEC Copyright EDISON Consortium All Rights Reserved Page 33 of 40

34 From EV to charging spot IEC and ISO/IEC JWG Internal in the station (operation, control & protection) IEC (Station Bus) Copyright EDISON Consortium All Rights Reserved Page 34 of 40

35 10 COP 15 CONCEPT At the COP 15, UN Climate Conference in Copenhagen, we showed the first AC charger which could intelligently control charging of electrical cars. We implemented the concept in close cooperation between Eurisco working in WP 5 and Siemens working in WP4. The task for WP5 is to look into the communication between the charging spot and the electric vehicle. The objective was to present a working demonstration model of a central charging station including EV, the user of the vehicle and the grid operator. The system consisted of the following actors, grid operator (DSO), user interface (UI), charging spot (CS), and electrical vehicle (EV). SICAM 230 SERVER Grid Operator (DSO) SICAM 230 WEB SERVER TM 1703 Mic LAN Eurisco Backend Server WLAN Hardwire ComBox ComBox Smart Phone Electrical Vehicle (EV) Charging Spot (CS) Figure 16. The COP 15 Concept User Interface (UI) Copyright EDISON Consortium All Rights Reserved Page 35 of 40

36 We developed the communication between CS and EV based on the protocol IEC The communication between the DSO and the CS was based on IEC At the time of COP15 no electric vehicle was equipped for intelligent charginga ComBox was build into the test car. We will explain the functionality of the ComBox in the EV in more details later in this chapter. In the charging spot 2 hardware modules were installed, a second ComBox and the TM 1703 Mic. The functionality of the TM 1703 Mic was to ensure that the plug placed in the CS, is not energized if no EV is connected to it. The reason for this was that the CS would be located in the public area and by law no plugs must be under power in the public area. We will explain the functionality of the ComBox in the CS in more details later in this chapter. The UI was consisting of 2 hardware components, the Eurisco backend server and the smart phone. This enabled the EV user/owner to observe and operate the charging process of the EV. To simulate the grid operation of the DSO, we installed a standard SCADA application of the SICAM 230 family. On this application it was possible to remotely see the state of charge of the EV. It was also possible to operate the Tm 1703 remotely, e.g. to start and stop charging of the EV if needed ELECTRICAL VEHICLE (EV) INTERFACES In the EV the following interfaces were supported by the ComBox. Pilot Signal, PE ground RS232 interface to the BMS to figure out battery charging state; Communication controller will read battery charging state 10.2 CHARGING SPOT (CS) INTERFACES In the CS the following interfaces were supported. Pilot Signal, PE ground ComBox controller logic TM 1703 Mic controller Meter (PAC 3200) with Ethernet interface connection for accessing meter data by ComBox. Connection to backend server Ethernet (internet connection) between ComBox and backend server. SICAM 230 server IEC communication between TM1703 Mic and SICAM 230. Copyright EDISON Consortium All Rights Reserved Page 36 of 40

37 10.3 INTERFACING BETWEEN COMBOX AND TM 1703 MIC The target of the COP 15 implementation was to minimise the impact between the ComBox on the TM 1703 Mic. Especially we want to assure: That the operation of the ComBox does not conflict with the TM 1703 Mic, i.e. that a switch or relay is not commanded to be on by one controller and off by the other. Therefore two input signals and two output signals were added to the TM 1703 Mic as an interface to the ComBox. Electrically, these signals were potential-free relay contacts, which were closed when activated. The following is the TM 1703 Mic view of these signals: Input START_CHARGING. This is a trigger signal to indicate that the user has authenticated and that power on the plug should be provided. The signal is a pulse command with the duration of 1sec and is triggered on the falling edge. The behaviour of the TM 1703 Mic should be as if a user has authenticated using the chip card and has then pressed the start button Input STOP_CHARGING. This is a trigger signal to indicate that the charging should end. The signal is a pulse command with the duration of 1sec and is triggered on the falling edge. As a result, the TM 1703 Mic should de-energize the power plug. If both signals (START_CHARGING and STOP_CHARGING) are activated the ComBox indicates that an EV with no communication controller is connected to the charging spot. This status will be permanently indicated during the whole charging time and the signals are not pulsed as in the cases described above. In the case both signals are activated, the charging spot has to perform the normal authentication procedure via chip card before the power plug can be activated. Output CHARGING_STATUS. This signal provides information to the ComBox whether a charging is in progress. If activated, the ComBox will not send a START_CHARGING request. If activated, the ComBox will send a STOP_CHARGING request in case it has initiated the charging before. Output CHARGING_ERROR. This signal provides information to the ComBox that an error occurred. In the case the signal is on and the EV arrives at the charging spot, it will not connect to the charging spot. The charging spot displays this situation to the user by a red LED placed on the charging spot. In case the signal is activated during charging the ComBox will force the EV to disable charging. This procedure insures that, if the charging spot reactivates the Miniature Circuit Breaker (MCB), no current will flow immediately. Copyright EDISON Consortium All Rights Reserved Page 37 of 40