Piloting Wireless Communication-based Condition Monitoring in an HVDC Station

Besides environmental sensors measuring temperatures, humidity, air pressure also measurements like vibration, air quality, or gases could be sensed. Few earlier works have explored different communication protocols, mainly based on Low Power Wide Area Network but also higher frequencies, and it has been found that inside converter halls multiple gateways can successfully receive wireless sensor data despite the electro-magnetic fields caused by the converters. In VSC-HVDC stations, however, no demonstration of WSN has been published for a station in operation. This paper summarizes system architecture, cybersecurity posture and site installation of a Bluetooth Low Energy (BLE)-based WSN pilot for an operational VSCHVDC station in Germany. The system architecture includes a sensor to gateway to cloud infrastructure to support the direct utilization of the recorded measurements. Advanced

Cybersecurity mechanisms such as using symmetric cryptosystems with several keys have been implemented to harden the system. The main focus of the pilot was to de-risk the communication performance in most of the areas of the site. The pilot contains an indoor WSN system which covers 22 sensors in the valve hall, the reactor hall and the DC hall as well as an outdoor WSN system which collects data from 17 sensors in the AC yard. The pilot has been commissioned during a planned maintenance window and has been operational for 3 months so far. Collected communication performance data has been analyzed. The communication performance unveils that the received signal strength indicator (RSSI) indicates very good values for valve hall and outdoor environment. For the reactor hall and DC hall, the physical barrier between the gateway (placed in the valve hall) and the sensor is too stringent and results in decreased performance. The wireless sensors use BLE technology and for almost all sensors the packet success rate (PSR) is above 60% which results in good data capture from the systems.

It was confirmed that wireless communication based on BLE can reliably cope with EMF exposure inside such HVDC stations. The de-risking of communication performance has already been achieved after a few months of operation. The pilot will be decommissioned after one year of operation. The results so far have been very promising for WSN systems for monitoring in HVDC stations.