Investigation of the communication protocol for the power plant controller

Abstract

This research investigates the communication of photovoltaic (PV) inverters to Power Plant Controllers (PPC). Currently, the only communication option is to use the Modbus protocol, as all inverter manufacturers provide Modbus-compatible communication modules to the PV inverters. With the worldwide adoption of the International Electrotechnical Committee (IEC) 61850 standard, the MMS protocol is compared to the Modbus protocol. This investigation involves a simulation of PV systems compiled on a real-time digital simulator (RTDS) NovaCor machine. This simulation can interact with external Intelligent Electronic Devices (IEDs) through a communication card called GTNETx2. The PPC is configured using the SEL 3555 RTAC as the device and interacts with the simulation. The first iteration of the investigation is compiled using Modbus, and the second iteration modifies the communication integration with the IEC 61850 MMS protocol. Data is captured and transmitted between the RTDS NovaCor GTNETx2 card (simulation) and the SEL 3555 RTAC (PPC). This data provides insights analysed using packet analyzer software called Wireshark and IED Explorer. Interpreting the data is based on comparing the two protocols and identifying the efficiencies and functionalities of each protocol. The IEC 61850 MMS protocol displays advanced functionality such as timestamping, quality data bits, reporting, and complex adoption towards the power systems use case. However, larger packet files and more complicated configuration causes distinct disadvantages. The investigation extends to the implementation of data monitoring to develop the interpretations used for comparison.