ATEPS. General System Description.

Transcription

1 ATEPS General System Description

2 Contents Scope ESS Technology Design Battery Packs Converters Battery Management System Energy Management System Components Typical Applications Planning ATEPS received, as 1st company in the world, the DNV GL Statement of Conformity for GRIDSTOR Contact +31(0) info@ateps.com Panovenweg 34, 5708 HR Helmond, The Netherlands 2

3 Scope Applications can vary and the contents of this brochure only gives general information on the hardware and integral controllers of the Energy Storage Systems of ATEPS. Trading the energy on power exchanges and the algoritms used for that are not part of the scope of supply of ATEPS. However, assistance is provided in case a new energy trading company wants to interface to the stoarge system. Every system has small deviations on the design that can occure depending on your application, intended use and the specific requierments from the 3 rd party that controls the system, on the owner s behalf, in case stored energy is being traded on power-exchanges. Power stored for later local conspumtion and delivering power back to the public grid are just two of the business models where storage systems find their applications. Peak shaving and thereby reducing contracual cost is another one. Please talk to ATEPS for more applications and the resulting design of the ESS. Systems from ATEPS are modular and can be changed easily changed depending on your application due to their modular design. Since the control on the power exchange is done by a 3rd party, there is the freedom to change this service provider if your business case changes. Disclaimer: The user/owner of the ESS is responsible for the contract between him and the 3 rd party responsible for the energy trading. This party optimises your power use and is responsible for the best possible business case. This service is not part of the scope of supply of the ATEPS system although we do provide the necessary support during the implementation. 3

4 ESS Technology There is a world of difference between Energy Storage Systems Energy Storage is HOT In many publications, on internet and more traditional media, a lot is spoken about different forms of energy storage. Smart- Grid, Home Storage, ESS and Community Storage are used in mixed forms and within different a context. More often than not, these terms tell little about the technology used but focus on the location and type of control of these systems. Smart-Grid is commonly used for systems whereby the electricity company is able to remotely control the systems to adjust the load on parts of the network. This can include both the amount of power available as well as for frequency stabilisation. Home-Storage is a form of local storage for home-generated solar energy for private homes and small offices. Neighbourhood Storage is often used for systems that control multiple houses, offices and small production locations from a centralised system. In some cases small villages can be supported from a community system. In many cases these terms are influenced by regional or national regulations and the electricity market in general. Due to this calculations made for specific areas might not be correct for other areas or countries. Uncontrolled vs controlled Most forms of green energy are hard to control. Solar energy is, obviously, only available during the day while wind energy is dependant on areas with high and low barometric pressure. Non of these can be influenced by technology or otherwise. Despite the fact that this energy is often available at a times this is not fully used, the installed base is increasing rapidly and in some areas even in an uncontrolled way. This can generate issues for the electricity companies that are legally bound to be able to deliver all energy needed in their market. The inability to control solar- and wind energy makes it impossible for the electricity companies to switch generators of or reduce their capacity. Controlling green energy The unpredictability of many green energy sources reduces the efficiency while adding more and more of these sources decreases the stability of the grid. Adding more of these sources will not reduce the number of traditional electricity generators while they must be able to supply energy also during the night or times of low wind speeds. Storage of energy in battery systems transforms uncontrollable energy into controllable 4

5 ESS Technology energy. If enough storage systems are installed, the available energy will be large enough to actually shut-down traditional generator plants while still being able to deliver the required energy to the market. The ATEPS ESS The systems developed and built by ATEPS can be used in a variety of applications: Trading of energy on exchanges and unbalance markets Adjustment of the frequency on the public electricity grid Reduction of peak loads on the public electricity grid Storage of energy for later use such as fast charging of electric vehicles. Off-grid use whereby large capacities are needed for use in hotels, islands and other remote areas. Combinations of the above. Due to these specifics the ESS applications made by ATEPS are somewhat different from other systems used for back-up etc. In most cases the converters are more powerful to maximize the potential on the energy exchanges and they are bi-directional so the batteries can be used to charge from the grid as well. This also influences the selected batteries, these should be able to withstand the higher charge end discharge current associated with this type of use, without degradation of the cells used. The battery control system must be able to react much faster then in conventional systems since the current and times in the energy trading- and imbalance applications are high and short. In order to calculate a correct State of Charge - SoC of the batteries, these measurements must be done much faster compared to systems that are discharging with a constant current over a longer period of time. How does this work? For the control of these ESS applications on energy exchanges, a number of companies offers specialised services. These companies often manage (large) solar and wind farms for the owner, buy and sell energy on behalf of industrial and other users. The option to now also use the stored energy in one or more ESS-es increases the commercial potential of the algorithms used by these service providers since they can now control the time at which this energy is released. The ATEPS ESS can communicate with the control systems used by these service providers through a simple and open protocol. Depending on the set-points for buying or selling, energy can be sold at the optimum price, batteries charged when prices are very low or even negative or used by the owner of the ESS. In order to further optimise the system, one should not only look at the energy exchanges but also take into consideration any taxes on energy use, transportation cost of energy and peak charges paid by the user of the system. 5

6 Design The systems are designed using many standard components based on the high energy density of the 19 battery modules. Using standard racks enables a fast and foolproof configuration of larger systems whereby placing multiple racks in parallel increases the capacity as required by the specific application. Each rack has a nominal voltage of 700Vdc and has its own Battery Management Unit (BMU) for the control of the rack and communication to the Energy Management System. 19 modules Racks BMS 6

7 Reefer Containers Standard reefer that can be maintained all over the world The ATEPS ESS is constructed in standard 20 or 40 feet refrigerated (reefer) containers or combinations thereof. These reefers are standard isolated containers that have their cooling integrated into the backside. Due to this, the ESS is fully closed so no outside air have to enter the container. The batteries, converters and control electronics are thereby shielded from dust, moisture and hence corrosion. Attached to the stainless steel inside, above the cabinets holding the batteries, are isolated solid copper bus-bars with individual fuses for each cabinet. Using double isolated cables the bus-bar is connected to the converters that are installed at the opposite side facing the batteries. This compact construction makes it possible to install large capacities on a relatively small footprint while larger systems can be configured by combining multiple container that can be stacked or placed side-to-side. The refrigerating system, that also controls the humidity, is set in such a way that the energy consumption is limited as much as possible and only functions if the temperature gets outside the set window of 15 C to 30 C. 7

8 Battery Packs A good design saves cost Battery packs The assembly of multiple cells into battery packs requires careful planning whereby electrical, thermal and mechanical parameters play a role. Some of these requirements are in contradiction to each other, for example strong mechanical design could ask for a fully enclosed box while the thermal requirements ask for a much more open design. A well designed pack uses individually fused cells that are connected to a current collector plate. The maximum current flowing through these fuses, is such that the packs work well within their designated range but any short circuit in a cell will disconnect this cell. Depending on the final design, the complete pack is covered by flame retardant, isolating plates that are bolted together to form a mechanically strong cell-block. Since lithium cells require electronics to measure their voltage and protect them against over- and under voltage and over- and under temperature, these sensors are inserted into the pack and voltage sense wires are connected. These wires are as short as possible and supported so vibration will not result into open circuits. Batteries designed for use in industrial environments need special attention. The high impedance of the temperature- and voltage measurements make them very sensitive for EM noise and either a special filter or other measures need to be taken to prevent erroneous readings of this important data. All the above is then inserted into an enclosure that meets the mechanical requirements including positive and negative terminals and the communication interface to the battery management system. The power cables connecting multiple cells in series and/ or parallel and the communication cables requires careful planning. The communication cable connects the batteries to a Battery Management Unit (BMS) which controls the complete set of batteries as a whole. In larger systems this can be 10 to 20 battery modules which all need to communicate to this BMS. Communication speed and integrity are important factors that need to be taken into consideration. Serviceability of (larger) systems is an important factor as well. Building a battery system in a workshop and testing the functionality is one thing. On-site maintenance, often under difficult conditions, is a totally different thing. The software of the Battery Controller (BC), the battery management system (BMS) and the Energy Management System (EMS) that combines many BMSes, is crucial. 8

9 Well-designed software and hardware is of utmost importance for effective servicing of complex systems. Multiplexed hard-wired inputs and outputs are often found on simpler systems. They need careful reading and interpretation of the data before a fault can be found. Therefore systems with individual outputs for errors, warnings and faults are preferred. Depending on the system design, these I/O ports can easily interface with other equipment, enabling motors and other equipment to be switched of directly, without the need for complex and sometimes slower software interpretation in external equipment. All of these signals en data is available in the ATEPS Energy Management System and since the software is created locally, changes to meet customer s requirements can be implemented quickly. 19 battery modules High-Capacity Battery Racks 19 battery modules in standard racks Traditional lead acid system 9

10 Industrial and made in Europe Converters Converters come in many different shapes and forms and are used to converter a DC current into a AC current or vice versa.. The simplest form is probably the charger of your mobile phone that converters the 240Vac to 5Vdc. In solar applications the converters are much bigger and powerful, normally in the range of 5kW to 20kW and these converter the DC of the solar panels into 240Vac voltage for use by your appliances and to feed this back into the grid. For the ATEPS on-grid applications and some off-grid systems special converters are required. These converters can convert DC into AC and AC into DC voltages and can hence both discharge and charge the batteries, an important feature of the ESS functionality to respond to the volatile energy prices. These converters are also much more powerful than standard converters as used for solar applications. Power in the range of 100kW up to 1MW and more, enable the feed-in of large amounts of energy during short periods of time. After an evaluation of a number of suppliers, ATEPS has selected European made converters due to their excellent efficiency, world wide support network and small size. VACON from Finland is recognised for its experience in heavy industrial applications on board of ships, cranes and other applications. These units are developed for continues use and have the correct qualifications for use in nearly all countries around the world. The converters are delivered as bare units that are installed by ATEPS in cabinets together with the earth fault detection and other electronics. The converters have their own individual LCL filters that prevent electrical noise to influence the converters and will also filter out any noise to enter the grid. These more than 200kg heavy filters are installed in suitable cabinets too for extra shielding and safety. Multiple converters can be connected in parallel in order to adjust the available power to the specific application. By selecting converters with different power, losses are minimized due to sequential control based on the power commands. The interface between the converters and the EMS of the ESS is based on the MODbus protocol as used in many industrial applications. Therefore, the system can withstand electrical noise from switching motors and other heavy equipment onand off, both inside the ESS and from the outside. 10

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12 Battery Management System Experience meets design A Battery Controller is placed in each battery module and measures voltage, temperature and current at cell level. The Battery Controller communicates with the Battery Management System (BMS) via an advanced data communication protocol which is isolated by means of electrooptical components. The BMS collects and checks the data of one or more (up to 127) battery controllers. Besides that, it checks for system integrity, can log data and will issues warnings and alarms via both hard-wired I/O and different software options. The software of both the Battery Controller and the BMS can be updated and changed depending on the application and cell technology used, thereby creating a very flexible system. For larger systems or systems that need local interfaces to 3rd party devices such as converters or other more processor intensive uses, a separate Energy Management Systems (EMS) is used. This EMS can interface up to 127 BMS-es. Hence, the EMS can control a system of 127 x 127 = battery modules. However, practical reasons such as cable length, will see more master controllers in large systems and combining more master controllers in a single system is just as easy as connecting multiple Battery Management Systems. With the software running the on the EMS, the system as a whole becomes compatible to existing and emerging protocols used in the energy sector such as Modbus/ RTI and Modbus/TCP, DNP3, MESA (Modular Energy Storage Applications) and others. The tool-kit of the EMS can be used to easily configure other protocols while the hard-wired I/O for warnings and alarms can be used in parallel for additional information supply or to interface to products that do not have intelligent communication features. In addition, the EMS may be equipped with software that gives the user the possibility to set a number of parameters to start and stop 3rd party devices. This creates a useful system for both on- and off-grid applications whereby the energy level in the batteries can be a trigger to start and stop (pump) motors, generators and other equipment. 12

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14 The ATEPS ESS A flexible and reliable design Using the earlier described components, the system is configured in accordance with the standards as described in the UL regulations for high voltage systems and the Dutch NEN1010 for AC installations. Each system is equipped with an external, highly sensitive earth fault detection system for additional safety. The cooling is connected via an external unit that measures and controls the temperature and humidity of the container. Each time the cooling switches on and off is being logged so run-times of the system can be logged as well. After the construction a defined number of tests will be performed and by using these test protocols the system will be released for transport to the customer s site. Once on location, a number of tests are being repeated in combination with the locally installed grid-transformers etc. The functionality of the battery controllers, BMS, master controllers and all other components are hence fully ensured. Only after passing all these tests, the system is handed over to the end-user. All test results are logged and stored as reference so future service can use this as a basis for testing and maintenance at a later date. Service and maintenance The system needs very little maintenance due to the fully enclosed system that has no connection to the outside world via ventilators or other air-ducts. Dirt, grease, moisture and other unwanted particles can not enter the container so the location where the system is placed in not very critical. However, a service contract is still recommended for periodic testing of the batteries and other components whereby also the specific safety features are tested and, if required, certified. During the service, the cooling system is checked and if needed, serviced as well. Control system In many cases, especially if used for energy trading, the ESS is controlled by and external system operated by the energy trader. The interface specifications needed for this will be supplied by ATEPS and for new implementations, ATEPS will support the developer in creating the correct control system as well. However, the correctness of the control algorithms, the implementation of the control rules and therefore the R.o.I. of the ESS is very dependant on this. ATEPS will, again, support both the service provider and the end-user in implementing the application(s) but can not be held responsible for the ultimate results of this (software) system. 14

15 EASY HUMAN-MACHINE INTERFACE From a simple LCD screen to more comprehensive display and data representation, all is possible with the advanced battery control systems from ATEPS. OPEN SYSTEM: EASY CONNECTION Multiple hardware and software standards and protocols are available for interfacing to local and remote systems. REMOTE LOGGING AND ACCESS Well protected internet access allows for remote data logging, monitoring and control of the battery management system. SERVICE IS EASY TOO No battery ID-numbers to program, no special tools or software needed, easy to install, service and upgrade. 15

16 Main Battery Controller features: Feature Voltage measurement Current measurement Temperature measurement Auto ID-Numbering Cell-Chemistry Heartbeat Automatic shutdown Firmware update Balancing Description The cell voltage is measured with an accuracy of <0,0005V using sophisticated techniques to prevent the effects that EM noise may have on these measurements. EM noise can influence systems and therefore result in false readings and thus erroneous shutdowns. The current in each battery module is measured. By comparing the current from each module, any leakage and hence unsafe situation is monitored by the system. Since temperature also influences the calculation of the State of Charge, a total of 13 temperature sensors are used in each battery module for the accurate establishment of the cell temperature. As soon as a system is powered on, the BMS will automatically issue ID numbers to each of the connected Battery Controllers. No operator action is required making the system configuration and service is much easier and the failure rate due to wrong or double ID numbers is reduced to zero. The Battery Controller can be programmed for different cell technologies so future upgrades in chemistry and/or voltage levels can be accommodated. System integrity comes from a heartbeat that indicates correct communication and is visible on the front of each battery module. Power consumption of the Battery Controller is kept to an absolute minimum to prevent battery drainage during storage. A sleep mode will be initiated automatically when the battery is not polled by the BMS during >10 minutes. New Battery Controller firmware can be installed automatically via the BMU. Obviously this is protected and can only be done using the correct user name and password entered into the BMU. The Battery Controller will automatically even-out any differences in the State of Charge between cells in a battery module. This balancing helps in obtaining maximum accuracy in SoC calculations and increases functional battery life tremendously. Main Battery Management Unit features: Features Collection of battery/ BMU data From the above, the following alarms and warnings are derived. Description Voltage of any cell Voltage of all cells Temperature of the batteries (13 locations per battery module) Temperature of any BC (PCB in the battery module) Balancing of batteries State of Charge of batteries State of health of battery sensors Total system (rack) voltage Under-voltage warning and alarms Over-voltage warning and alarms Over-temperature warning and alarms Over-temperature alarm of any BMU Too large difference in SoC between batteries warning Too large difference in impedance between batteries warning Too low State of Charge of batteries alarm Alarm communication integrity: Module lost comm. heart-beat Health of battery sensors alarm 16

17 Main Energy Management System features: Feature Description Data logging Absolute maximum discharge current Average discharge current Absolute maximum charge current Average charge current Absolute highest battery temperature Absolute lowest battery temperature Number of cycles. Pre-charge Charge controller output Initiate inter-battery balancing All this data is stored in a 3-months log file on a memory card and can be accessed via an internet or other data communication port. On order to prevent too high inrush currents during charge and discharge (capacitive loads), resistors can be connected in series to limit these pre-charge currents. The EMS sends the control signals for these to the BMU. Hardwired and software outputs are available to control the charge current of converters. The EMS initiates balancing between the battery racks to equalize any differences in SoC. Optional data display System voltage Current (charge & discharge) State of Charge (SoC) Average and highest battery temperature Optional extended data display Configuration External Communication, Man-Machine Interface (MMI) All of the above Graphic option to see charge/discharge/soc curves Zoom function into each battery showing: SoC Cell voltage Temperature of Battery Controller Average cell temperature With user friendly PC software, a qualified user is able to program the battery configuration: number of batteries in series and strings in parallel, system voltage, etc. Warning and alarm limits, pre-charge/discharge times and currents, as well as a number of other parameters can be configured as well. Since many applications are used in areas where no operator is available there are a number of options to communicate with the battery systems: Web interface showing the important parameters including the option to enable some, less critical, parameters. This web interface is available both within a customer s LAN as well as WAN for the supplier or advanced end-user. Warning- and alarm via TXT-messages to a mobile phone (optional) For systems in close proximity to the responsible persons, an LCD screen showing key information is available. (Optional) Hardware protocols: ModbusRTU RS 485 IP/Internet USB CANbus: Due to the different versions of the CANbus protocol, one can insert these as an optional piggy-back boards on the EMS. 17

18 Data available via the open interface of the Energy Management Systems Battery system System Level Cabinet level Battery level Cell level Voltage Temperature Charge current Discharge current State of Charge Balancing Heartbeat Hardware I/O Warnings: (Voltage, current, temperature, SoC, SoH,) Alarms: (Voltage, current, temperature, SoC, SoH, heartbeat) SoC (5-20mA) SoH (5-20mA) Okay/Not Okay signal Converter(s) Notes Select converter Used when more than 1 converter is installed Discharge Allow discharge or not Discharge power Set discharge power in kw Charge Allow charge or not Time Set discharge duration (HH:MM:SS) Charge power Charge power in kw Time Set charge duration (HH:MM:SS) Shutdown Shutdown converter(s) (idle) Temperature Temperature feedback Others Notes (for containerized systems) Burglar alarm Via master controller and external flashlight Smoke/Fire detection Via master controller and external flashlight Cooler functionality Okay/Not okay signal Temperature Container temperature and humidity 220Vac available System power Available Not available ATEPS reserves the right to update, change, modify or otherwise alter the specifications of the Battery Controller, Battery Management Systems, Master Controller or any other component in their system(s). 18

19 Energy Management System 19

20 Components Fuse boxes and bus-bar Battery Cabinet Energy Management Systems Backplane 20

21 Typical Applications Different markets and tariffs result in different applications, however, due to the modular design of the ATEPS systems, most of these can be handled by the same storage system. Dedicated software modules in the Energy Management System can make the ATEPS ESS compatible to on- and off-grid systems and other, more specialized applications. Please contact ATEPS to discuss your application or in case of any questions. Primary Reserve: Assisting frequency stabilisation is a typical application where battery storage systems have a good fit. Since these can charge and discharge they can load and support the grid depending on the actual grid frequency. The ATEPS Energy Management System can measure the frequency locally and communicate the actual status to the grid company and other parties. The integrated SoC and Frequency compensation enable fast response and close following of the 50Hz deviations. PV- and wind energy storage: Cost reduction by storing self-generated energy for use during the night or other periods green energy is not available. Reduction of contracted energy and peak shaving are also often combined with this. This can often be combined with trading energy at power exchanges, imbalance trading, peak-shaving and primary reserve (50Hz) support as well. Neighbourhood Batteries: Home Storage is not always the most optimal solution and in combination with smart metering, PV and other energy can be stored in a centrally installed battery more easily and safer. Due to the single interface to the DSO and the higher capacity and power available, grid support functionality is easier to implement without having to maintain communication to privately installed systems. This also increases the safety for the DSO and thereby the grid, since all communication is done within his trusted environment. Due to the large variety of rules, regulations and business cases, ATEPS does not supply the actual trading interface(s). Local parties, that have insight in the specifics of the regulations and tariffs, can connect to the ATEPS systems. ATEPS will support these companies in the design of the optimal communication protocols and safety standards but will not be responsible for the effectiveness of the control actual algorithm. 21

22 Planning Most ESS applications are tailor-made and will need a close cooperation and communication with the end user concerning location and application. Since, in many cases, local changes will be necessary too, a site visit can be part of this process. After the initial kick-off, frequent communication, in combination with project planning will be undertaken to update all parties involved. Depending on the final application, size and other factors, the customer will also be responsible for a number of dedicated tasks that will be monitored by the ATEPS project manager. On- and off-line tools are used to plan projects and inform our customers. Disclaimer: The user/owner of the ESS is responsible for the contract between him and the 3 rd party responsible for the energy trading. This party optimises your power use and is responsible for the best possible business case. This service is not part of the scope of supply of the ATEPS system although we do provide the necessary support during the implementation. 22

23 Notes: 23

24 GSD: ATEPS Nederland BV Professionals in Energy Phone: +31(0) info@ateps.com Panovenweg 34, 5708 HR Helmond, The Netherlands