Project 1.3 Status Monitoring, Disturbance Detection, Diagnostics, and Protection for Intelligent Microgrids Dr Wilsun Xu C. Jiang, H. Yazdanpa, Y. Tian & A. Pezol

Problems faced by industry: Project 1 of 3: How to protect MG from short-circuit faults? Overcurrent protections are widely used in various facilities (basis of MG) DGs (distributed generators) create difficulties for over-current protections Can we find a method for DGs to work with the protection scheme? Introduce the concept of fault current restriction for DGs Each DG can only produces a limited amount of short-circuit currents Develop current restriction schemes for 4 types of DGs Proposed solutions and innovations: Potential benefits: Both utilities and DG owners are very interested in finding a simple solution to the problem. This solution does not require changes to utility system The results will lower the interconnection barrier for DGs

Problems faced by industry: Project 2 of 3: How to monitor and diagnose MG conditions? Proposed solutions and innovations: Even with ICT, it is still costly and difficult to monitor loads in a MG Can we monitor the loads at locations where power sensors are not available? The information will help to characterize the load behaviors in a MG and to support demand response and other energy-saving activities Introduce the concept of micro-grid state estimator (MG-SE) The estimator uses measured voltages to estimate loads in a MG The proposed system could solve the sub-metering problem Potential benefits: The problem is of significant interest to commercial facility owners The results will enable more energy-efficient activities in MG & commercial buildings

Project 3 of 3: Home-based MG or “nano-grid” Microgrid Concept Home area network Concept Future Smart Home Energy generation: Solar & natural gas Energy storage: Electric vehicle Energy consumption: Home appliances Nano-grid is a system for managing the generation, storage, consumption of energy in homes. It is build on the concepts of microgrid and home area network. Home-based MG could be the future form of energy use in homes The results will facilitate the energy saving activities of home owners

Proj 1: Propose and confirm solutions for 2 types of DGs Proj 2: Complete technical feasibility study Proj 3: Complete review and formulate research strategy Proj 1: Propose and confirm solutions for other DG types Complete project Proj 2: Complete research work Proj 3: Establish blueprints for nano-grid with research results Proj 1: Technology transfer Proj 2: Complete demo & tech transfer, complete study on sub-metering applications Proj 3: Complete research work and tech transfer

Proposed projects 1.1 Control & operation 1.2: Power management 1.4 Operational strategies of MG 2.1: Cost-benefit 2.3: Demand responses 3.1: HAN (Home area network) 3.3: Automation

Collaboration items - General 1.Establish MG test cases (steady-state, dynamics and transients) 2. Experimental facilities available for the network. Especially on how to access BCIT facility Collaboration items - Specific 1.Experimental studies of fault current restriction schemes 2.MG State estimator: formulation, algorithms and experimental studies 3.Nanogrid: a) MG expertise and HAN expertise b) architecture consideration of nanogrid c) Experimental facility d) Implications to power systems (theme 1)

Project 1 Details: Fault current restriction strategy for DG Every DG shall not contribute to fault current that is higher than k-times of its normal operating current (k=1.2 to 1.5) Synchronous generator We propose crowbar control to limit excitation current Period critical to relay

Project 1 Details: Fault current restriction strategy for DG Inverter-based generator We propose a control that reduces inverter output when sag is detected In traditional control, during voltage sags, inverter current is increased until it reaches the current threshold which is normally set to 1.3~2 I rated. In our control strategy, converter current is reduced in proportional to severity of sag level Operation during low-impedance fault Operation during high-impedance fault

Project 2 Details: Micro-grid state estimator Panel 1Panel 2Panel 3 Load-1Load-2Load-3 X Y Z The currents of Load 1-3 are not known, we may only know the panel 1 current If we know the voltages of buses X,Y and Z and the network impedances, the currents can be estimated The voltages are much easier to measure with the help of distributed plug-in voltage sensors Traditional SE: estimate V using known I or S Microgrid SE: estimate I using known V