Grid Interconnection and Power Quality Assessment of Distributed Resources Farid Katiraei Ph.D. Candidate Department of Electrical and Computer Engineering University of Toronto Wind Power Generation Symposium Feb. 20, 2004 Outline • DR connection process • Utility impact assessment • Interconnection requirements • Power quality issues • Case studies: A Hybrid system Decentralized Power System Standards and Regulations • “IEEE Std. 1547, for interconnecting Distributed Resources with Electric Power System”, IEEE Standards, July 2003 • CSA Standard CAN3-C235, C325, C107.1 • “MicroPower Connect Interconnection Guideline”, July 2003 • Ontario Electrical Safety Code (OESC) • Ontario Energy Board Act, 1998 ( sec. 27.1) • Electric Safety Authority (ESA) DR Connection Process • Step 1: Basic planning - Data collection and Plan development, - Environmental assessment • Step 2: Feasibility study - Utility impact assessment, - Electrical inspection requirements (ESA) • Step 3: Implementation - Detailed design and review, - Basic interfacing equipments, - ESA plan approval • Step 4: Commissioning & Authorization of the connection • Step 5: Operation & Maintenance Utility Impact Assessment • Power quality assessment • Interconnection requirements – line/equipment upgrades – Grounding – Power flow • System protection modification – Fault currents, re-coordination • Synchronization Power Quality Issues – Voltage regulation (Load dependent) – Voltage fluctuation (not greater than 5%) – Flicker (No objectionable flicker) – Voltage Unbalance – Harmonic injection (TDD,THD < 5%) – DC injection (< 0.5% of In) – Reactive power requirements (Preferred pf. : 0.9 lag 0.95 lead) – Surge withstand performance ( up to 220% of the rated voltage) Study system • Impact assessments of a Hybrid system: DG1: 2 MVA gas-fired diesel generator DG2: 2.5 MVA electronically-interfaced DG3: 1.5 MW wind turbine (Rotor diameter 76m, Wind speed: 5-25 m/s, Hub height: 64m) Load demand: Sensitive load, Industrial/Residential load • Case I: Wind turbine start up » Scenario 1: Grid interconnected system » Scenario 2: Stand-alone system • Case II: Short circuit analysis » Line-Ground fault on the Utility side, Fault clearing Wind turbine start up • Direct connected generators: – Speeding up with the wind, connection at 85% of synchronous speed – Soft starter, limit start up current – Second winding (two speed turbines) • Electronically interfaced: – Synchronization • Wind farm: – Sequential start up I-1: Grid Connected System • Bus voltages - Startup @ t=2.0 s I-1: Grid Connected System • Power variation - Startup @ t=2.0 s I-2: Stand-alone System • Bus voltages - Startup @ t=2.0 s I-2: Stand- alone System • Power variation - Startup @ t=2.0 s Case II: Fault Analysis • Voltage fluctuation - Fault @ t=0.5 s - Clear @ t=0.58 s Case II: Fault Analysis • Freq. variation -Fault @ t=0.5 s -Clear @ t=0.58 s -Reconnect @ t=1.08s Conclusion • Comprehensive study of the system – Steady-state analysis – Dynamic Analysis • Appling uniform interconnection Standards Thank You Question(s) ?