Variable Renewable Energy Integration today's model vs. electric network of future

Transcription

1 Variable Renewable Energy Integration today's model vs. electric network of future

2 Today's electric power grid in Pakistan N E P R A GENERATION TRANSMISSION DISTRIBUTION Electric power distribution system in Karachi W A P D A G E N C O HYDRO ELECTRIC POWER PLANTS GENCO-I GENCO-II GENCO-III GENCO-IV GENCO-V IPPs NTDC National Transmission and Dispatch Company 14 x 500 kv & 38 x 220 kv GS. TLs of 5110 km 500 kv & 9686 km 220 kv. D I S C O IESCO LESCO FESCO PESCO MEPCO GEPCO HESCO SEPCO QESCO TESCO KE KE has 11 kv distribution capacity of approximately 7,000 MVA using a network of 22,000 PMTs and substations in an area spanning more than 2,500 square miles, and serving more than 20 million consumers in Karachi and parts of Baluchistan. KE generation KE transmission KE distribution

3 THE FUTURE The utility and grid of the future are expected to be much more dynamic and active, rapidly evolving, heterogeneous and customer centric. Sources: World Resource Institute & MIT Utility of the Future Report

4 Grid Modernization Today Large centralized generation From Consumers to Prosumers Tomorrow More VRE More data Long distance T&D More distributed resources Source: IEEE

5 Potential for wind and solar in Pakistan Source: Global Wind Atlas At 50 m height, Karachi has wind power densities of W/m² and wind speeds of m/s Source: ESMAP/AEDB On an average, Karachi has horizontal solar radiation levels of kwh/m²/day

6 MW Current status of DG in Pakistan Solar energy is gaining momentum in Pakistan 1.1 GW of projects under AEDB supervision Capacity of solar DG installations NM implementation cases w.r.t. licenses issued to them and capacity addition up to June 2017 The graph shows only large scale grid connected installations 28* 278* Current trends PKR per watt with no battery backup for DG. Storage costs make solar more expensive: dry batteries > lead acid. 1 kw inverter PKR 25, kw grid tied PV system can cost up to PKR 100,000. State of Industry Report *July 2018

7 C H A L L E N G E S Translating to local regulations The challenges of integrating high penetrations of renewable energy technologies into the grid are less well recognized in part because they require interdisciplinary research in such areas as power systems analysis, communications, power electronics, economics, operations research, and industrial organization. The challenges result from needed changes to achieve federal and regulatory objectives for a low carbon energy system. Power Systems Engineering Research Center AEDB and NEPRA have established a DG code and rolled out NM throughout all DISCOs. Policies have been made by NEPRA (Alternative and Renewable Energy) DG and NM Regulations of 2015 to initiate load flow studies and advanced planning. Single phase inverter meeting the specifications shall be accepted for 5 kw solar distributed generator Each DISCO shall establish net metering facilitation cell Process applications for net metering up to 10 kw without any study Each DISCO to install a PV plant at their HQ to set an example and provide necessary training

8 Variability and uncertainty of VRE Challenges Intermittent supply of energy (VRE produces energy when resources are available variable and uncertain). Power system planning and risk management with VRE, intermittent energy storage, demandresponsive loads, RE standards, and GHG emission policies. Forecasting (renewable resources and load). T&D planning: unpredictable line & PMT loading Interface between the grid and VRE: basic power quality (harmonics, voltage, frequency, PF) for equipment interconnection; power electronic devices at high power ratings need to be controlled and regulated. Need advanced controls & technologies to integrate wind and solar while maintaining grid stability and reliability

9 High levels of VRE: technical challenges New challenges in a modern grid Increasing levels of two-way power flow VRE (solar and wind) More use of communications, controls, data, and information, e.g. smart grids Other new technologies: electric vehicles, distributed storage and flexible loads Becoming highly distributed: more complex to control

10 High levels of VRE: technical challenges Coordinate flexible loads (active DR). Use storage for excess VRE production. Utilize geographic diversity. Solutions Expand the transmission system. Utilize flexible conventional generation. Increase sharing among NTDC areas. Source: B. Kroposki et al., Achieving a 100% Renewable Grid Operating Electric Power Systems with Extremely High Levels of Variable Renewable Energy, Challenges and solutions Protection coordination: loss of high SC current may affect protection schemes. Solution: Synchronous condensers and new protection schemes. Unintentional islanding: need methods to protect against unintentional islanding. Solution: new artificial intelligence options. Black-start: ability to restore system from outage. Solution: new system restoration methods. Distributed controls. Solution: new control architectures and management systems

11 Power system stability Increasing penetration of variable renewable energies brings challenges to the traditional power system Challenges Solutions Transient and dynamic stability: loss of system inertia could reduce ability to respond to disturbances need ride-though capabilities in VRE. Frequency regulation: need primary, secondary, and tertiary response from VRE. Volt/VAR regulation: need ability to locally change voltage to stay within nominal limits. Using smart inverters with advanced functionality. Mimic synchronous generator characteristics. Provide active power, reactive power, voltage, and frequency control.

12 Challenge: control and optimization of millions of devices As we migrate from a centrally controlled, synchronous generator-based grid to a distributed, inverter-based system Research Needs Control theory Advanced control and optimization algorithms Embedded controllers in devices Linkage to advanced distribution management systems (ADMS) Validation of concepts and deployment we need smart inverters with advanced functionality to maintain grid stability and improved optimization for millions of controllable devices in the grid. Source: NREL & ARPA-E, Source: E. Dall Anese et al.,

13 F U T U R E KE has processed DG applications for 600 kw+ as per NEPRA s NM polices KE has installed 296 kw solar PV system at the corporate headquarters KE has rolled out smart metering with AMI for all grid stations and distribution transformers Decentralization Digitalization De-carbonization