Communication is often an afterthought when designing or deploying new distributed energy resource (DER) projects. In practice, though, these communication issues can make or break integration projects when deployed to the energy grid. See how model-based system engineering (MBSE) and HIL-compatible devices can be used to safely validate communication and control issues before real hardware is used to deploy a system and greatly simplify the integration and commissioning of new renewables, microgrids, and virtual power plants (VPPs). Communication will make or break the new grid.
Why is communication potentially the biggest roadblock to a large-scale, smart, decentralized, digitalized grid? Can you imagine wanting to text a friend from your Apple iPhone and not being able to do so because she was using a Samsung Galaxy? Or, can you imagine requiring driver software to be installed each time you wanted to use your USB memory stick on a different computer? Life would be hell on earth and our digital world would grind to a standstill, right? Of course, these scenarios are figments of (nightmarish) imagination.
Or do they not? Unfortunately, the landscape of communication standardization of distributed energy devices (DERs) is essentially nonexistent for the vast majority of DERs that rely on MODBUS. Since its launch in 1979, MODBUS has established itself as a de-facto standard communication protocol for all types of industrial equipment and continues to live on in millions of MODBUS devices that make our industrial civilization possible and our grid operational. Even though most DERs support the same communication protocol – MODBUS – they cannot really “talk” to each other, in the same way, that an IR remote from Sony and an IR remote from Panasonic cannot control the other company’s device despite using the same IR LED and chip.
Mostly, it is about MODBUS…
While MODBUS is a well-established standard for communication across many DER devices, it only standardizes the way messages are organized and transmitted, not the messages themselves. Considering this, trying to integrate devices based on MODBUS support alone is comparable to assuming a group of people can communicate successfully by agreeing to use words, but still allowing everyone to speak in their own language. In practice, this means that the MODBUS message for monitoring the active power output of, say, an SMA solar inverter will be completely different from the MODBUS message used for the very same purpose in a Kostal inverter. Worse still, the same MODBUS message may have completely different effects on inverters made by different manufacturers. For example, one manufacturer’s inverter may use a message to limit the inverter’s output to a predetermined level, but another manufacturer’s inverter will turn the inverter off with the same message. Even the same manufacturer may at times decide to alter the “meaning” of MODBUS messages between DER generations. …however, the solutions for MODBUS issues may result in additional issues. Modbus SunSpec, OPC UA, IEC 61850, and OCPP are examples of modern communication protocols that solve the MODBUS message interoperability issue by introducing a brand-new communication protocol interoperability issue. A device that “speaks” one of these protocols—for example, an OPC UA-based battery storage system—cannot “talk” to another device that “speaks” another protocol—for example, an OCPP-based electric vehicle charger. Just as multiple languages require either translation or multilingualism to facilitate useful communication, multiple DER control protocols require the same: error-free translation among protocols or full support for multiple protocols in a single device. Both of these are vanishingly rare or fundamentally nonexistent among even the most current and top-of-the-range DERs and the supervisory control systems that they communicate with.