Micro-grid Case Study in China

Transcription

1 IEA PVPS WORKSHOP at PVSEC-22 Micro-grid Case Study in China Wang Yibo Institute of Electrical Engineering, CAS Nov. 6 th, 2012

2 2 Contents 1.Background and Significance 2. Case 1: Hydro/PV/Diesel/Battery Hybrid Micro-grid (10s MW) 3.Case 2: Wind/PV/Diesel/Battery Hybrid Island (100s kw) 4. Conclusion

3 1.Background and Significance(1) Emergency Demands Large-scale application of distributed PV is ahead; To supply electricity in remote area. Solar Generation Goals of 12 th Five-Year Plan Total Capacity of Solar Generation is 21GW, including: Central PV station 10GW, Distributed PV 10GW, CSP 1GW; 30 demonstrations of micro-grid: 10 isolated, 20 grid-on;

4 1.Background and Significance(2) (2) Typical Cases Two Pilot Demonstrations of Isolated Micro Grid Hydro/PV/Diesel/Battery PV/Wind/Diesel/Battery The first hydro/pv/diesel/battery (A remote area demo) Finished by the end of 2011 in Yushu, Qinghai province Total 14MW of generators(exclude 10MW diesels for backup) 15.2MWh of Lead-acid battery An island demo Finished in 2011 on Dongfushan island, Zhejiang province Total 560kW of generators 960kWh of Lead-acid battery

5 2.Hydro/PV/Diesel/Battery Hybrid Micro-grid grid(1) Description Jiegu County PV station Geographic location of 2MWp PV station Grid accessing schematic of 2MWp PV station Location: Jiegu county, where is in Yushu of Qinghai Province. Electricity Demand: 2MW PV+12 MW hydro power(existed), isolated grid 2MW PV supplies night peak load for 4 hours Main Issues: Reliability of small hydro: no water, no power, often in dry season Stability of high-penetration of PV: fluctuations, intermittence,

6 2.Hydro/PV/Diesel/Battery Hybrid Micro-grid grid(2) Schematic Small hydro Grid-connected PV load 20 of 100kW PV-B Branches 100kWp H-axis PV panel 150kW PV/B Charger(DC/DC) 760kWh Lead-acid battery 150kVA dispatchable inverter EMS ispatchable PV with battery Technical risk: Stability among paralleled inverters Stability between inverter and hydro genset

7 Hydro/PV hybrid system in Yushu, Qinghai Location: Yushu, Qinghai Grid: 12MW hydro, ( )13MW load, and 35kV isolated-grid PV station 1 st stage: 2MWp PV+15.2MWh Battery (Finished in Dec., 2011) 2 nd stage: 8MWp PV with Battery (planning in 2013)

8 2.Hydro/PV/Diesel/Battery Hybrid Micro-grid grid(3) Inverter 96.69% efficiency in stand-alone mode 95.98% efficiency in grid-connected mode 10kVA,150kVA and 250kVA VS-inverter by IEE Voltage-source inverter(droop control) Function: charge or discharge battery, grid-forming Status: 10kVA~250kVA 3-phases VS-inverters Indicator: η max =96.69%, switching time=20ms Key Issues: Parallel connection in stand-alone mode Smooth switching between stand-alone and grid-on

9 2.Hydro/PV/Diesel/Battery Hybrid Micro-grid grid(4) Charger 5kW and150kw DC/DC charger(pv-battery) by IEE PV/Battery Charger(DC/DC) Function: charge battery by PV Status: 5kW and 150kW chargers Indicator: η max =98% Key Issues: MPPT control of PV array Smart charging strategy

10 1 2.Hydro/PV/Diesel/Battery Hybrid Micro-grid grid(5) Inverter Stability With unbalance load Smooth Shift between two modes Sudden increase of load Stable operation and well load-sharing between inverters under different load condition; And keep stable in transient process of modeshifting, start-up and load-varing

11 2.Hydro/PV/Diesel/Battery Hybrid Micro-grid grid(6) System Stability Frequency(Hz) X: Y: Time(s) Simulation model of hydro/pv/bat micro grid Little influence of irradiance fluctuation on grid frequency and voltage; Significantly improve the ability of resisting load disturb. Frequency(Hz) Time(s) 1

12 1 3. Wind/PV/Diesel/Battery Hybrid Island (1) Description Location Dongfushan island 50km to east-north of Zhoushan island, Zhejiang Province Area 3.27 km 2 emands Tens of residences (peak load is about 100kW) Windy area where has experienced typhoon Shortage of electricity as well as drinking water

13 1 3. Wind/PV/Diesel/Battery Hybrid Island (2) Schematic Battery PV array DC/DC DC/DC VS PCS DC/AC Diesel Gen Dongfu Village WT AC/DC/AC Desalination 100kWp PV panels 210(7*30)kW wind turbines 250kW diesel gen set 50 ton/day desalination

14 1 3. Wind/PV/Diesel/Battery Hybrid Island (3) Control room 980kWh leadacid battery 50ton/d desalination 7 30kW WT 100kW PV station EMS

15 1 3. Wind/PV/Diesel/Battery Hybrid Island (4) Gen-cost Compare Comparison of generation cost of Yongxin Island (similar as Dongfushan Island) Diesel gen-cost:rmb /kWh (with fuel price in 2011) Expectation of inflation of fuel:rmb 7000/t in 2010,RMB 8500 元 /t in 2011 WT gen-cost:rmb 0.307/kWh, RMB 元 /kwh(with battery) Assumption: MW-class WT, without abandoned wind,10hours battery with replacement PV gen-cost: RMB 元 /kwh, RMB 元 /kwh(with battery) Assumption: without abandoned PV power, 2hours battery with replacement

16 1 4. Conclusion China has started comprehensive demonstration on micro grid with high-penetration PV: Chinese government has an ambition to widely use distributed PV in 12 th FYP, and both isolated MG and grid-on MG are pushed into pilot demonstration. In remote area powered by small hydro or on a island with residence, a MG with HP-PV is feasible from both technical view and economic view; For a PV system in isolated micro-grid, stability is the core issue, and relative equipments and technologies are in emergent need.

17 THANK YOU! Dr. Wang Yibo Institute of Electrical Engineering