Control Strategies for Power Electronic Interfaces in Unbalanced Diesel Hybrid Mini-Grids with Renewable Sources and Storage

摘要: Traditionally, remote communities worldwide consist of autonomous power systems (mini-grids) supplied almost exclusively by diesel-engine generator sets (gensets) at relatively high costs. Integration renewable energy sources (RESs), such as, photovoltaic (PV) and wind, can substantially reduce the cost electricity generation emissions in these communities. However, highly variable load profile typical mini-grids fluctuating characteristics RESs, cause frequent operation diesel genset low loading condition, efficiency points subject to carbon build up, which significantly affect maintenance costs even life time genset. Another important issue that is frequently overlooked small (< 100 kVA) mini-grids, usually present a number loads thus reducing averaging effect, unbalance. Diesel gensets supplying unbalanced experience overheating synchronous vibration shaft. For efficient operation, should be operated near its full capacity also balanced mode. In order address above mentioned issues, fast reliable multi-mode battery storage system (BESS) employing voltage source inverter (VSI), proposed this thesis. In support mode, as basic feature, it provide minimum for supplement under peak conditions. addition, balancing reactive compensation mini-grid system. Therefore, operates condition within ideal range. cases when demand from low, due supply RESs and/or consumption, shut-down BESS forms grid, regulating frequency grid forming mode. Besides, logic defining operating mode achieving smooth transitions between modes are presented thesis. The conventional approach control three-phase VSI with uses vector (dq) symmetrical components calculator results slow dynamic responses. common (P) vs. (f) droop characteristic what further complicates design controller VSI. new adaptive per-phase dq-control scheme three-wire four-wire based on concept fictive axis emulation presented. It enables current/voltage each phase separately achieve better performance hybrid The effectiveness techniques demonstrated means simulation experimental results.