Power converters and communication links are important elements of electrical networks (microgrids, smart grids) and the Internet of Things (IoT). Power electronic converters underpin low-level operation (e.g. power transmission and stability) and communication underpins high-level system operation (e.g. dispatch, balancing and metering).

Conventional techniques for communication on these networks, such as Fieldbus or CAN bus, require extra hardware (transceivers, cables) beyond the power cable itself and so incur additional installation costs. Wireless communication protocols, such as Zigbee and LoRa, also require extra hardware (transceivers, antenna) and are vulnerable to interference and congestion. Power line communication (PLC) uses the electrical power cable as the channel for data transmission; however, conventional PLC requires additional transmitter and receiver circuitry to achieve modulation and demodulation, which increases the complexity and cost of the overall system.

Oxford PLC solution

Researchers at Oxford have developed a widely-applicable, zero-incremental-cost method of exchanging information between power converters that are connected in a grid.

The approach exploits the built-in capabilities of power converters to modulate their output (and so transmit a signal) and their built-in voltage and current sensors that can be used to receive a signal. The communication algorithm exploits specific properties shared by many power converter types to insert communication signals ‘on top of’ the main power transmission function in a way that requires no additional hardware (i.e. it is a ‘pure software solution’).

This feature is advantageous for cost reasons, but it also reduces the complexity of the converter hardware, reducing the number of hardware dependencies and possible failure modes in critical applications.