Controlador embarcado para configuração remota de carga RLC passiva com interface MQTT

Abstract

The Santa Maria Federal University Intelligent Networks Institute (INRI-UFSM) is accredited by CGCRE/INMETRO to execute conformity tests on grid-connected photovoltaic inverters up to 75kW rated power. The INMETRO’s Conformity Evaluation Regulament consists of 17 tests based on ABNT NBR 16149:2013, ABNT NBR 16150:2013 and ABNT IEC 62116:2012 normatives. Of the 17 tests, the non-intentional islanding detection. According to ABNT NBR IEC 62116:2012 normative it consitsts of 33 sub-tests, which the objective is the verification of the inverter’s capacity to detect and identify islanding in the most challen- ging conditions. For such tests a resistive-inductive-capacitive (RLC) load with high quality factor is used in parallel with the inverter. The load’s parameters are adjusted for every sub-test, taking into account that adjustments are required due to the inverter’s operation. In cases that the RLC load cannot be adjusted under load, the resulting test time is too long and also very demanding in the staff. This work presents the design and implementation of a 75kW tri-phase RLC load capable of automatic and remote parameter adjustment, while under load. The proposed solution is based on groups of discrete load levels, controlled via solid state relays (SSR) for each RLC element, for each phase. The control of these groups is done via the MQTT protocol over TCP/IP. The entire project was installed, tested and validated, yielding adequate performance.