RRC Battery Energy Storage Systems (BESS)

Energy Management Systems (EMS) with Simon Chee

Q: What is an EMS and why is it important?

A: An EMS system monitors battery cell voltage, temperature, battery state-of-charge (SOC), and state-of-health (SOH). It also controls the battery charging profile SOC balance and isolates the battery from the source and loads when necessary or when conditions could cause the battery damage.

Q: What is the difference between EMS and SCADA?

A: EMS is a system that monitors and controls one or multiple Battery Management Systems (BMS). The EMS coordinates charge and discharge functions to maximize profit and minimize losses by participating in the energy market and/or coordinating with generator assets. The SCADA system is the hardware and software system that includes the plant controller and user interface. The SCADA system ties everything together including the solar plant controller, BMS controller, EMS system, and user interface. They go hand-in-hand. You can’t use one without the other.

Q: What are the major SCADA components of a storage system?

A: SCADA servers, historian server, SEL RTAC, network switches, fiber patch panel, and SCADA software

Q: What are the benefits of using one provider, like RRC, for developing both systems?

A: There are several benefits using one provider for both systems.

Cost: There’s less cost incurred because the system is already designed to function as one. There are no change orders or additional engineering to facilitate systems properly.

Time: There’s less of a burden on a project manager since there is less coordination on both sides of the project between the customer and the contractor. This will result in faster development and commissioning of the system.

Reliability: The burden of responsibility is on one contactor as opposed to two or more contractors. This will result in faster decision making and optimize turnaround time if issues arise.

This is a complex system. By adding more provider/sources, it adds complexity into the project. With one supplier, the system can be made more robust through the engineering and testing time.

Q: What’s an EMS turnkey solution?

A: A company like RRC offers turnkey solutions that manage all the BESS (Battery Energy Storage System), EMS, and SCADA – it’s a whole solution with the benefits described above.

Q: How does EMS relate to BESS?

A: On a battery storage project, you can have several BESS systems for the batteries. To connect those into a consistent stream of energy, we need EMS. RRC adheres to MESA standard design and specification to ensure the battery system is consistent with the grid code and maximized revenue.

Q: Are there any industry innovations that are particularly exciting?

A: The industry is always changing and evolving so it’s difficult to pinpoint one area of excitement. Something RRC is doing that’s unique is creating a holistic system that covers all functionality. For this industry, EMS and SCADA are both fairly new so there’s plenty of room to innovate. As a company, RRC seeks to customize our systems and solutions based on the individual project needs. There are standards being developed for EMS systems that make storage more marketable. This is mainly by improving grid reliability and flexibility. With these standards, the services that are applied to the grid can be performed in a physical location that is more localized to the point of use. This improves the power quality and reduces the load on larger equipment, such as transmission lines. With the changes that are constantly being made to energy storage including its flexibility and small footprint, energy storage is being applied to multiple areas and markets across the world. It is a rapid growing industry.

Q: What are the advantages of using an EMS system?

A: There’s a lot of functionality and customizability. An EMS takes the guess work out of energy storage. An EMS monitors the status of the electrical grid, current market conditions that the asset is participating in, and scheduling requirements. All the influencers of the storage asset are leveraged to return maximum profit and reliability. Having a battery storage system without a well-developed EMS system reduces the flexibility and potential profit of the storage system.

Q: What sets RRC apart in the EMS industry?

A: Our main strength is our connections with large companies and vendors who are at the forefront of the industry. As an organization, we have been able to stay ahead of the curve based on those relationships. If there are new modular designs or project specifications, we typically received an advanced look.

Q: What are the main factors when choosing an EMS provider?

A: The main factors in choosing an EMS are total cost of ownership, reliability, and potential for profit. RRC uses engineering tools and practices that improve reliability and reduce development and commissioning cost. Our experience in EMS development in various markets provide the owner with a more reliable and profitable system. A system with a proven performance.

Ethernet Cable Considerations with Jimmy Li and Kaushik Seshadri, PE

This week we are joined by both Jimmy Li, one of RRC’s SCADA leads, and Kaushik Seshadri, our lead energy storage engineer. We are discussing battery storage and a small project element with the potential for large impact on operation and costs.

Q: How is the design of an Ethernet network for a Battery Energy Storage System (BESS) different than the design of other networks?

A: Low installed cost and long design lifetime (typically 30 years) are primary design considerations for both. Ethernet cables are often buried without conduits. Issues relating to the direct burial, such as the influence of ground potential, can lead to reduced network operating speeds over time due to signal interference.

Q: What are some of the specific things you consider during the network design process?

A: Cable consideration is one of the main things we look at. There are trade-offs between using fiber-optic cables verses copper and there are trade-offs between using single-mode verses multi-mode fiber optic cables. Also, the network terminations supplied by the battery, inverter, and other vendors need to be known. If conduit is planned for some areas of the BESS, that can impact cable selection as well.

Q: What drives the choice to use a fiber cable versus a copper cable?

A: The first consideration is the run length of the cable. Ethernet over copper is limited to a maximum length of 300 feet. In practicality, it should be limited to much less due to factors that can reduce the bandwidth capability of the cable over time such as corrosion at the connection or grounding of the cable. Fiber-optic cables, specifically multi-mode fiber, is the first choice for cable runs as we start seeing limitations of copper after a certain length. Inefficiently planned routing with copper may require the use of repeater stations, which is sometimes found late in the commissioning process.

Q: What drives the choice between single core cables or multi-core cables?

A: Single mode cables are typically off-the-shelf, pre-terminated, and lowest cost. The downside is that they are not as well insulated from the environment. Multi-mode cables typically have 12 or more single cables wrapped together inside of an environmentally rugged outer layer and can be purchased with a robust EMF (Electromagnetic Field) shielding layer. The cable is more expensive and the terminations need to be added in the field. Distance and installed method determine which installation method will be the cheapest and most reliable.

Q: What other things should be considered when designing an ethernet network for a BESS system?

A: The BESS network should be dedicated and kept separate from any CCTV camera or VOIP networks. Also, if the site has a local wireless network, perhaps for things like environmental monitoring stations or use by maintenance workers, those should be considered when setting up these systems to account for security considerations.

BESS System Layout and Rack Considerations with Kaushik Seshadri, PE 

In this interview we explore how system layout and the use of containerized vs. centralized BESS systems impact the design and layout of the electrical sub-systems, overall installation, and operational costs.    

Q: Why is the layout of a BESS system something that is important to consider?

A: There is not one straightforward answer to that. It depends if the construction is new, a retrofit, or if there is collocation of wind, PV, and/or BESS. And it depends on the type of system- AC or DC coupled. It boils down to what balances the lowest installed cost with maintainability and constructability.

Q: What are the factors that you see owners and developers considering?

A: Cost is the main consideration. Sometimes cost per MW-hr delivered can be the main consideration, but sometimes project capital cost is given the higher priority. Other factors include use-cases, such as frequency control, load shifting, and PV smoothing play into the analysis. The client will typically perform an economic and use-case study to select technology, size, and best configuration.

Q: Is there an example that comes to mind where special considerations impacted the layout?

A: Sure. We were working on a new AC coupled site that was using hundreds of 40-foot BESS containers. One of the primary considerations was accessibility for installation and maintenance. There needed to be sufficient room for a forklift to install batteries into each container. That impacted the placement of other nearby equipment, cable routings, and how we minimized underground cable crossings.

Q: It sounds like, for that facility, there was enough real estate to spread out the containers. What if storage is going to be added to an existing facility with a limited piece of ground?

A: If the real estate is limited, then we may have to limit the size of energy storage or procure equipment that has a higher energy density. If the system is AC coupled, we have some flexibility as the BESS system can be located off site and tied into the grid. This flexibility is not available with DC coupled systems.

Q: What about locating the BESS in a single building? Is that a viable alternative?

A: Yes, we do see that from time to time on a few bid packages. The fire protection and HVAC design will be a bit more complex when it comes to a building design for BESS and we need the right expertise to design these systems. Depending on the size of the project, it could be a low-cost solution when compared to containers. There are also modular outdoor rated racks recently launched by CATL where the general design philosophy is like that for a building design but each rack has a self-contained cooling unit and fire suppression system instead of larger, centralized systems.

Q: What are some of the trends you are seeing?

A: Over the last year we’ve seen project sizes go from 50 MWH to 500 MWH and above. We are also seeing EPCs thinking about getting into the integration space. More and more RFPs on DC coupled projects as well.

Q: It sounds like BESS system layout is not a trivial thing. Any last thoughts?

A: Yes, things are changing fast in the world of storage. It is a good idea to work with a team that has seen lots of different situations. RRC has a solid team of engineers with years of project experience in the renewables industry.

BESS Storage Configurations with Kaushik Seshadri, PE 

In this topic, we touch on the application of smaller, fully contained BESS packages verses the use of racked batteries. 

Q:  What different types of BESS storage configurations are you seeing on projects these days? 

A:  Containers seem to be the most proficient currently, especially for greenfield BESS or Solar+BESS projects.  We are also seeing smaller, packaged units (outdoor rated modular racks or cubes) being used on projects.  Indoor rack systems can be a better fit where space is limited or there is an existing building that can be utilized.  It all depends on the specifics of the application. 

Q: What factors dictate what kind of storage configuration is used? 

A: Cost per MW-hr delivered is usually the main consideration, but sometimes project capital costs are given the higher priority.  It also depends on factors like how the power will be used, frequency control, load leveling, and factors like co-location with PV (DC-coupled).  The investor will typically perform an economic and use-case study to select the best configuration. If there are existing structures that can house the BESS units, that can play into selection as well. 

Q: What are some of the trends you are seeing? 

A: Towards modular design is certainly the direction.  First–off, modular systems are completely assembled and tested before bringing on-site. Although they may be a little more expensive to purchase, overall, they will cost the project less and allow for a shorter overall project schedule as it becomes plug and play versus installation on site.  

Q: Are modular systems here to stay or are there new approaches coming? 

A: Modular design is certainly the current focus as it can save a lot on labor costs if the racks come pre-populated with battery packs. Modular enclosures for outdoor are approaches that are likely to continue.   What is coming into the market is more specialization to the enclosures and being able to combine HVAC, fire suppression, and battery racks in a smaller footprint and also provide ease of connections between these modules.  In general, modules give you scalability and the ability to fit storage more easily into existing real-estate.   

Q: Other thoughts on energy storage overall? 

A:  We are at an inflection point where we are going to see multiple GWh scale projects coming online in the next few years. This is going to give the Power Balancing Authorities and ISOs a lot of flexibility to meet the demand with appropriate supply, help deploy more nano and microgrids, and transform the electricity market. It is not beyond imagination now that the current BESS systems can transition into a longer-duration (seasonal) storage systems providing even greater flexibilities.   

The Future of BESS EMS with Kaushik Seshadri, PE

To close out our conversations around BESS, we asked the team to comment on their new Energy Management Software (EMS), what it is, what it does, and what is unique about EMS for BESS.

Q:  At a high-level could you tell us what Energy Management Software is, what it does?

A:  Sure, EMS are generally thought about as something used in buildings to monitor and meter HVAC, lighting, and other equipment.  It monitors, regulates, and reports energy usage, and is meant to keep energy costs under control.

Q:  Is this what an EMS does in a BESS system?

A:  The focus of an EMS system for BESS is to monitor and control the charging and discharging of the batteries, at a system level in various use case, which is a different focus than traditional EMS systems.  An EMS system for BESS has different control modes and operational states that can be used for different charging and consumption scenarios. Such as load shifting, frequency regulation, spinning reserve.

Q:  If they are different, why is it called an EMS system?

A:  It is an EMS system in the general sense because energy management is still the key function.

Q:  What is unique about EMS for a BESS system, what is its primary purpose?

A:  A BESS system is typically intended to meet different operational requirements, and those can change either predicably or not.  The BESS might primarily be operating in Active Power Smoothing, then be called on to supplement Peak Power, Load Following, Dynamic Reactive Current, or other modes.  The BESS EMS system is used to smoothly transition between different operating modes then manage the BESS efficiently while in any given mode.

Q:  How is the system that RRC provides different than what the battery system providers include?

A:  The RRC EMS is a SCADA solution, so it is a supervisory control layer that sits above the individual battery management system software and interfaces with the plant-wide SCADA, and communications with the ISO.  The system was designed to meet the Modular Energy Storage Architecture (MESA) standards which is an open standard for interoperability of grid-scale energy storage systems.

Q: What are the trends you see for SCADA systems like this?

A:  As more and more solar systems are being installed, along with storage, the complexity of managing the grid is growing.  Add to that the different types of battery systems that will be attached to the grid in the upcoming years, and you have the need for interoperability and operational flexibility, which is what the MESA standard and the RRC system are all about.