Report

A Grid Compatible Methodology for Reactive Power Compensation in Renewable Based Distribution System Tareq Aziz, U. P. Mhaskar, Tapan K. Saha, N. Mithulananthan School of Information Technology and Electrical Engineering, The University of Queensland, Australia Grid Requirements Motivations Results (Continued) Voltage recovery requirement : Time Domain simulation Reactive Power Generation Capability High penetration of small Distributed Generation (DG) units Grid standard Power-factor control mode Slow post-fault voltage recovery Sensitivity index dV/dIR based methodology is proposed to ensure faster recovery Voltage at Bus 6 with DG2 Steady State Voltage, Continuous Operation range DG bus voltage should remain within the range of ±10% of nominal voltage. Interconnection System Response to Abnormal Voltage Voltage Range (p.u.) V < 0.5 0.5 ≤ V < 0.88 1.1 < V < 1.2 V ≥ 1.2 Clearing time (sec) 0.16 2.00 1.00 0.16 Test Systems 16 Bus Commercial Feeder Proposed Methodology Voltage at Bus 3 with DG1 IEEE Std 1547-2003 does not allow DG units to actively regulate voltage at PCC. Voltage recovery time for 16 Bus System 43 Bus Industrial Feeder DG node Without Capacitors With Capacitors 3 (DG1) 6 (DG2) N/A N/A 1.15 Sec 1.59 Sec Voltage at Bus 4 with DG1 With STATCOM at bus 3 1.26 Sec 1.97 Sec With STATCOM at bus 7 0.26 Sec 1.26 Sec Voltage at Bus 50 with DG2 Take DG integrated Distribution System Optimal Capacitor Placement to minimize grid loss with load variation Time domain simulation Dynamic Voltage restoring compatibility to meet grid requirement New Index Yes Complete Simulation Tool used : DigSILENT PowerFactory Release 14.0 No Calculate dV/dIR and its direction for optimal capacitor nodes Replace capacitor with STATCOM on the bus with most negative dV/dIR Time domain simulation Dynamic Voltage restoring compatibility to meet grid requirement Yes Complete Voltage recovery time for 43 Bus System Index dV/dIR Check next location for STATCOM No Results V Per unit change in node voltage (V) with reactive current (IR) injection/ absorption XT V0 VSC VDC Without Capacitors With Capacitors 4 (DG1) 50 (DG2) 3.12 Sec 0.71 Sec 2.35 Sec 0.54 Sec With STATCOM at bus 21 2.49 Sec 0.42 Sec With STATCOM at bus 39 1.61 Sec 0.37 Sec Conclusions Steady State requirement: Optimal Capacitor Solution for 16 Bus System Optimal Node Capacitor Size (MVAr) Sensitivity index dV/dIR (Vp.u/Ip.u.) 7 3 1.8×2 1.2 -0.1428 (Inductive) 0.11 (Capacitive) IR DG node Steady State requirement: Optimal Capacitor Solution for 43 Bus System Optimal Node Capacitor Size (MVAr) Sensitivity index dV/dIR (Vp.u/Ip.u.) 39 21 1.1 0.6 -0.25 (Inductive) 0.33 (Capacitive) School of Information Technology and Electrical Engineering, The University of Queensland A step by step method has been proposed for static and dynamic reactive power planning of DG integrated distribution system. Proposed index-based approach ensures fast voltage recovery and hence improves uptime of DG units. Minimizes number of expensive STATCOM in a system with multiple DG units.