The emergence of the Megawatt scaled Solar Power Plant (SPP) has led to grid codes that require SPPs to remain connected and provide reactive current support during a fault. This paper introduces a Supervisory Controller for a 9 Megawatt SPP which provides Fault Ride-Through (FRT) capability in accordance with the German Transmission Code . The FRT criteria includes: 1.) Meet the rules set by the FRT characteristic curve, 2.) Contribute a minimum 2% reactive current for every 1% change in the voltage at the Point of Common Coupling (PCC) within 20 ms of fault detection and 3.) After the fault is cleared, restore active power at a gradient of at least 20% the rated power per second. A Supervisory Controller is designed to meet the FRT criteria and simulated on the off-line simulation tool PSCAD/EMTDC. The Supervisory Controller on the off-line simulation is validated through a Control-Hardware-in-the-Loop (CHIL) simulation using the real time simulation tool RTDS to test the supervisory controller modelled on the National Instruments FPGA CompactRIO hardware controller . In conclusion, a Supervisory Controller is developed that successfully meets the FRT criteria for all types of symmetrical and asymmetrical faults. The paper aims to provide insight on how existing control concepts for wind systems can be utilized in a SPP control system in order to enable FRT capability.
K.C. Samarasekera, R. Iravani, In Proc. Cigre Canada 2018, Calgary, Alberta, October 2018, Paper 015
KEYWORDS: Solar, fault-ride-through, low voltage logic, two-level voltage source converter, control-hardware-in-the-loop, photovoltaic, supervisory control