Interconnected Microgrids Challenges and Solutions Dr Farhad - PowerPoint PPT Presentation

System of Interconnected Microgrids Challenges and Solutions Dr Farhad Shahnia

Overview  Microgrids  Importance of Microgrids to Australia  Microgrid Projects in WA  On-going Research Topics  A New Research Avenue : System of Interconnected Microgrids  Application and Benefit  An Example  Research Questions to be Addressed 2

Microgrid Microgrids are defined as  interconnected networks of loads and resources (distributed energy resources-DERs)  can function in grid-connected or islanded modes Microgrids are a way for utilities to:  Reduce loss, emissions, cost of energy  Upgrade aging systems  Build sustainable futures 3

Importance of Microgrids to Australia 4

Importance of Microgrids to Australia 5

Importance of Microgrids to Australia 6

Microgrid Projects in WA http://reneweconomy.com.au/w-plans-australias-biggest-solarstorage-micro-grid-onslow-39857/ http://www.energymatters.com.au/renewable-news/renewables-microgrid-wa-em5793/ https://onestepoffthegrid.com.au/p2p-energy-sharing-start-brings-brooklyn-microgrid-smarts-australia/ 7 http://www.energynetworks.com.au/news/energy-insider/what-could-customers-save-standalone-systems-microgrids

On-going Research Topics Structure: Energy Sources:  AC microgrids  Inertial Sources  DC microgrids  Converter-dominated microgrids  AC-DC microgrids Power Sharing among Sources: Control Techniques:  Sharing based on source ratings  Decentralized  Centralized  Sharing based on economics  Hierarchical  Distributed Control 8

A New Research Avenue Considered possibilities:  Grid-connected microgrids  Islanded (isolated/standalone/off-grid) New possibility: Temporary Interconnection of Neighboring Islanded Microgrids or Microgrid Clusters 9

Application and Benefit Application: • Remote large towns with no access to a utility feeder • Presence of two or more microgrid owners (operators) in the town Importance (Benefit): • Reducing load-shedding possibility due to unexpected overloading of the microgrid • Reducing renewable energy curtailment due to unexpected excessive generation • Improving the self-healing, reliability, and resiliency of the electrical system of remote town 10

An example 11

Research Questions to be Addressed • Q-1: What are the criteria based on which the necessity of interconnection is defined? • Q-2: How to select the most suitable neighboring microgrid? • Q-3: What must be the suitable structure and topology of the microgrids to enable the coupling? 12

Research Questions to be Addressed • Q-4: How to synchronize the selected microgrids? • Q-5: How to prevent an interconnection, which may cause instability for the system of coupled microgrids, after their interconnection? • Q-6: When to isolate a system of coupled microgrids into its contributing microgrids? • Q-7: How should the interconnected system operate? 13

Q-1: Defining Criteria on the necessity of interconnection Centralized Approach • Active and reactive power generation of each source Decentralized approach • A frequency-based technique E Pashajavid, F Shahnia , A Ghosh (2017) Development of a self-healing strategy to enhance the overloading resilience of islanded microgrids, IEEE 14 Trans Smart Grid 8(2):868-880

Q-2: S electing the suitable neighboring microgrid(s)? Decision-Making • Fast but not optimal Optimization • Optimal but slow A Arefi, F Shahnia (2017) Tertiary controller-based optimal voltage and frequency management technique for multi-microgrid systems of large remote towns, IEEE Trans Smart Grid in-press F Shahnia , S Bourbour, A Ghosh (2017) Coupling neighboring microgrids for overload management based on dynamic multi-criteria decision-making, 15 IEEE Trans Smart Grid 8(2):969-983

Q-3: Suitable Structure and Topology Planning Study • Cost • Frequency of interconnection • One or more system of coupled micreogrids 16 16

Q-3: Suitable Structure and Topology Power Exchange Highway: • Three-phase ac link • Single-phase ac link • DC link Interconnecting Switch: • Conventional Circuit breaker • Power electronics-based switch • Back-to-back power converters 17

Q-4: Synchronization Open, DR UPC , PDL CC, DR OMT On/Off Selected ISS MGs MG Central Controller ISS Synchronization Controller Module Network Synchronize, Controller Close, Open, DR CC, DR Synchronize, Close, DR MG- N -1 MG- N MG- k MG-1 (a) MG-2 S Bourbour and F Shahnia (2016) A suitable mechanism for the interconnection phase of temporary coupling of adjacent microgrids,” IEEE PES Innovative Smart Grid Technologies Asian Conference (ISGT-Asia), 18 Melbourne.

Q-5: Stability Analysis Small-signal stability analysis • Will the system of coupled microgrids become stable after their interconnection? Transient Analysis • Will the overloaded microgrid become unstable before the synchronization is achieved and they are coupled? F Shahnia , A Arefi (2017) Eigenanalysis-based small signal stability of the system of coupled sustainable microgrids, Int Journal of Electrical Power & Energy Systems 91:42-60 F Shahnia (2016) Stability and eigenanalysis of a sustainable remote area microgrid with a transforming structure, Sustainable Energy, Grids & Networks , 19 8:37-50

Q-6: Isolation of microgrids Defining Criteria to detect • Interconnection necessity has been alleviated. • Generation/demand imbalance • Faults 20

Q-7: Dynamic Operation Challenges: • Level of allowed voltage and frequency variations • Primary controllers of DERs fighting against each other • Central controllers of microgrids fighting against each other • Communication link failure • Coordination of energy storages (e.g. batteries) with interconnection • Power trade among interconnected microgrids *F Shahnia , R Chandrasena, S Rajakaruna, A Ghosh (2014) Primary control level of parallel distributed energy resources converters in system of multiple interconnected autonomous microgrids within self-healing networks, IET Gen. Trans. & Dist. 8(2):203-222 E Pashajavid, F Shahnia , A Ghosh (2017) Provisional internal and external power exchange to support remote sustainable microgrids in the course of power deficiency, IET Gen. Trans. & Dist. 11(1):246-260 T Mehr, A Ghosh, F Shahnia (2017) Cooperative control of battery energy storage systems in microgrids, Int Journal of Electrical Power & Energy Systems 87:109-120 21

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