In part 1 of this blog we started looking at why power companies want to switch to a smart grid. We looked at what end-point equipment is needed (where the power is used) to facilitate the implementation of the smart grid. That's the smart meter. Then we started looking at System-on-Chip requirements for a smart meter.
The main feature of the primary digital core is to run a meter application and a metrology algorithm.
The secondary digital core is a signal processing engine and the PLC protocol stack. It runs the real-time functions to guarantee the real-time control of the data coming from the metrology sub-system. It has to be as accurate as possible. Typically, accuracy should be within a fraction of a percent.
Each core has a dedicated memory. The access time to each memory, for read or write purpose, has to be as low as possible to guarantee a real-time system working.
The metrology subsystem is composed of a net of silicon-based integrated sensors. These sensors have to be really accurate and reliable, because they are driven by a dedicated process unit that communicates directly with the digital core. A failure in one or more of these sensors would cause a malfunction of the main digital core and of the overall system. Moreover there is an analog front-end block that interfaces the analog waveforms with the process unit of the metrology subsystem to protect the sensors and to condition the signals that are the inputs/outputs of the sensors.
To guarantee the communication of the data stored into the memories of the two cores of the SoC, a PLC line driver, including a power line amplifier, is integrated in the SoC. The power line is coupled to the line driver. In turn, it is interfaced to the real-time system core by mean of a digital front-end and an analog front-end system. The communication of the data has to be secured by mean of a cryptographic engine. This guarantees that a failure in the security of the data transmission would not affect the overall system end-to-end security.
A recently released SoC features a programmable PLC signal-processing engine for multi-protocol management and an ARM 32-bit Cortex-M4F subsystem with programmable RAM and flash memory. The analog and digital metering front-end is realized in a three-channel front-end interface having high-accuracy. Moreover, it has a security engine that supports important PLC protocols such as METERS AND MORE, G3-PLC, and IEEE 1901.2. These protocols allow remote reconfiguration. This will support new protocols to be developed at some future date. In turn, this should guarantee a secure and effective end-to-end communication. Moreover, the metrology sub-system supports the PRIME standard for measurement.
Going into deeper details, the metering subsystem exceeds Class 0.2 meter requirements, combining three high-accuracy 24-bit ADCs, integrated filters, and a configurable hardwired DSP for energy calculations. The integrated PLC engine supports output signals up to 28 V peak-to-peak and has extended bandwidth of up to 500 kHz, while the dedicated security engine supports cryptography and multiple security modes for privacy and anti-hacking protection, enhancing the SoC's security.
Have you worked with an SoC similar to the one presented here which integrates a metrology sub-system and the digital cores for the PLC? How important is end-to-end security in a system like this? Did you ever use the METERS AND MORE and G3 PLC protocols for smart grid systems? What do you think of the PRIME standard of measurement?