A*STAR Funded IEDS Project - Microgrid Energy Management System. by H B GOOI

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1 A*STAR Funded IEDS Project - Microgrid Energy Management System by H B GOOI 4 Aug 2009

2 Outline Introduction - Distributed Generators and Microgrids Proposed Microgrid Energy Management System (MEMS) MEMS at Lab for Clean Energy Research (LaCER), NTU Possible IES Project Idea - Integrating Thermal & Electrical Energy System

3 Centralized Generation Usually very large capacity generators over hundreds of MWs Usually located far away from load centers Waste heat discharged into rivers or sea Low energy conversion efficiency: 30-40% Distributed Generation Usually very small capacity generators: a few kws to a few MWs Usually located at load centers - can avoid T&D cost & losses Waste heat can be recovered for heating & cooling High energy conversion efficiency: over 80% with CCHP Emerging: renewables such as solar, wind, marine, etc

4 Microgrids Microgrids are low voltage networks, which include loads, energy storage systems, and several small distributed modular generation systems, providing both power and heat Microgrids can operate in isolated or interconnected mode Benefits Improve efficiency by combined heat and power (CHP) Enhance local reliability, improve power quality, and provide lower costs of energy supply, etc Other potential societal benefits Protect vital public utilities Offer a place for integrating small-scale renewables (reduce emissions)

5 Singapore Power System High voltage network 66 kv and above Medium voltage network 22 kv and 6.6 kv Low voltage network 400 V Energy Management System (EMS) manages 66-kV, 230- kv and 400-kV generation and transmission system Distribution Management System manages 22-kV and 6.6-kV distribution system

6 Singapore Market Operation Key players Regulator (EMA) Power system operator (PSO) Market operator (EMC) Electricity retailers Gencos Transco (SP PowerGrid) Market support services Wholesale electricity traders Contestable consumers Non-contestable consumers MEMS would enable non-contestable consumers to participate in the market as a single entity.

7 Is Singapore Ready for Microgrid? Government support and its national policy framework Energy research at institutions and universities Global cry on CO2 emission and demand for energy efficiency Deregulated power market and its promotion by the government Advanced telecommunication infrastructures Software and hardware capabilities More firms choose to own DGs in the form of trigeneration (CCHP), e.g. pharmaceutical plants of Pfizer and Schering Plough Industrial parks, science parks, HDB residential blocks could serve as launching pads

8 What MEMS Can Offer? All loads in district are aggregated Renewable and traditional generation systems CHP, CCHP Central control of heat and air conditioning MEMS would collect data and make decisions for control & optimization

9 Features What MEMS can offer? The MEMS will be responsible for decisions When to commit and dispatch each generator When to store energy Purchase and sale with upstream networks Manage load priority and security of microgrid Incorporate renewable sources and control DERs Combined electricity, hot water and air conditioner (district cooling) loads Handle offers/bids submitted by DGs and price responsive elastic loads Participate in the wholesale energy and reserve market.

10 Microgrid Energy Management System (MEMS) Advantages Open up scope for new services and new opportunities Improve energy efficiency as a single entity Potential thermal energy utilization Responsive to changes in market Power management at district (distribution) level Process optimization and improve reliability Could offer islanding operation and enhance power quality

11 Smart Meters for MEMS Singapore EMA and PA are working out smart meters (based on wireless technology) which could be exploited for MEMS Features of smart meters Time-of-the-day pricing Daily reading of consumption periods Daily retail settlement Daily wholesale settlement Innovative pricing and service packaging Consumers can plan their consumption Interruptible and elastic loads Consumers can choose to buy/sell electricity when they have storage or own generation What it can offer for MEMS Collect information and help to make collective decision Optimize the use of installed DERs, elastic loads, storages, heating and cooling Allow consumers to plan their consumption or MEMS to take control MEMS can take decision to generate own electricity when the market prices are high with its storages or own generation

12 A*STAR Intelligent Energy Distribution System (IEDS) Projects at NTU Power Converter & Grid Architectural Design for Future Intelligent Energy Distribution Networks (S$0.96 million), PI: Andrew Loh. Microgrid Energy Management System (S0.96 million), PI: Gooi HB. Open Architecture for Intelligent Power Quality Monitoring & Evaluation System (S$0.6 million), PI: Choi SS. Design of a Voltage Collapse Monitoring Instrument using Local Information (S$0.48 million), PI: Haque MH. Intelligent Trading/Metering/Billing System for Future Smart Distribution System (S$0.48 million), PI: Wang P. Total Grant is S$3.48 million.

13 MEMS OBJECTIVES To design software algorithms and control schemes for minimizing schedule cost or maximizing revenue of MEMS while ensuring its secure operation. Economic aspect: Predict total customer loads and perform economic scheduling of distributed energy resources (DERs). Security aspect: Monitor & control MEMS. To design hardware controllers and demonstrate how proposed prototype can coordinate and schedule one or more DERs and price-sensitive loads. To develop a web-based GUI and incorporate sensing and communication devices for interfacing with local DERs and loads, distribution networks and market operators.

14 MEMS SCOPE Support interconnected or islanding operation mode. Design load forecasting algorithms, e.g. ANN, for predicting total load. Engage Unit Commitment (UC) in economic scheduling of DERs. Optimal Power Flow (OPF) recommends maximum customer loads to connect and tap positions of on-line tap changers. Implement recommended tap positions, MW shedding, Var switching and interruptible loads via active management. Perform on-line probabilistic security assessment based on normal operation or sudden disconnection from MV network. Design DC-DC and DC-AC converters for DERs. Implement web-based communication and control for various components of MEMS.

15 Integrated Microgrid DSO MV 1 MVA 22/0.4 kv Transformer IES ` MEMS LV X X X X School of EEE, NTU, 2008 IES IES IES 5 kwp PV Converter Circuit Breaker DC AC IES X HDB Housing Load X AC Grid: 3-phase 400V Converter 5 kw Fuel Cell IES AC X DC X SM X X SM X DSO: Distribution System Operator MEMS: Microgrid Energy Management System IES: Intelligent Energy Sensor SM: Smart Meter MV: Medium Voltage LV: Low Voltage X X X IES SM IES Commercial Load Converter AC DC AC AC 5 kw Wind Turbine Industrial Load DC Energy Converter Storage (Battery, Super- Capacitor or Flywheel)

16 Microgrid on Power Management Software Measurements PMS Programming Monitoring Short Term Load Forecasting Actual Devices Unit Commitment State Estimator Optimal Power Flow System Security

17 Box at Lab Bench Box on Wall Box at Lab Bench Box on Wall Box at Lab Bench Box on Wall Box at ab Bench Box on Wall Box at Lab Bench Box on Wall Box at Lab Bench Box on Wall Box at Lab Bench Box on Wall Box at Lab Bench Box on Wall Box at Lab Bench Box on Wall Level B7 Impedance Bank Impedance Bank Load Impedance Bank Impedance Bank Load Impedance Bank Impedance Bank Load Level B8 Microgrid Network Control Centre

18 Bench 2 Bench 1 Junction box Junction box 32A Motorized ST 32A Motorized ST 2A 2A 2A 2A 100A selector switch 100 A Selector Switch 25mm 2 (90A) Details of Network Control Panel 18 kva Power Source

19 A Sustainable and Efficient Electrical & Thermal Energy System - Thermal energy is captured through solar thermal energy collectors coupled with waste heat recovered from DGs. - Solid state magnetocaloric nanomaterials which possess special magnetic and thermal characteristics can be used in enhancing the efficiency of cooling systems. - An integrated solution which manages cooling/heating, hot water and power in a micro grid via low cost communication networks. - Design and develop an EV energy management system. - Implement metering and billing by landlord and energy sale and purchase by tenants. Proposed by: Gooi HB, Vilathgamuwa DM, Low KS of EEE, Wong TN, Duan F of MAE and Ramanujan RV of MSE

20 A Sustainable and Efficient Electrical & Thermal Energy System - Contd Renewable Energy Sources and Energy Storage A*STAR MEMS Upstream Networks Interruptible Loads Micro Grid Energy Management System Solar Thermal Energy Collector Magnetocaloric Thermal Management System Energy flow Control and/or Communication EV Energy Conversion Micro-turbines

21 Other Related Power Projects National Research Foundation (NRF) Project, Zero Energy Green Water Production and Recycling System Using Membrane Distillation (MD) and Membrane Distillation Bioreactor (MDBR) powered by solar energy (S$10 million), PI: Choo FH Atlantis Resources Corporation & NTU Joint Project - An Efficient System for Underwater Power Generation (S$0.6 million), PI: Tseng KJ.

22 Q & A Session

23 Low Voltage Panel LV System LV Brain Cards Max. Power: 30 kva Rated Voltage: 400 V, 3 Phase System

24 Solar battery charging and grid interfacing inverter system 1. Day time battery is charged from excess energy in solar panel 2. In the night time battery is discharged to supply the load demand 3. Local controlling using dspace DS Power management and high level controlling using ION Power Management Software Power converter Battery bank Demonstration systems solar battery charger and grid interface Solar V 1.1 kw Battery bank 100 V, 128 Ah Simulated grid 220 V rms L-L 3-kW variable load bank

25 Fuel Cell System Acquiring of hydrogen supply to power the 5-KW fuel cell system Design high boost converter topologies for interface Four new families of ZSI are proposed with extended boosting capability particularly for Fuel cell systems Diode assisted Capacitor assisted Continuous current Discontinuous current Diode assisted continuous current qzsi 5-kW Fuel Cell Proposed Hydrogen Storage at S2-B7 Capacitor assisted discontinuous current qzsi vˆ S = ( 1 2D )( 1 D ) DC S 1 S V v ˆ = x M vˆ S 2 vˆ S = 1 ( 1 3D ) DC S V

26 Wind Energy Wind Energy Simulator Rated Power: 7.5 kw Wind Turbine Rated Power: 2.4 kw