Microgrids and Power Quality

Michael Starke, Ben Ollis, Josh Hambrick, Madhu Chinthavali Electrical Engineering Systems Research Division Oak Ridge National Laboratory

ORNL is managed by UT-Battelle, LLC for the US Department of Energy ORNL Research TRL 9 • Funded by Department of Energy Systems Test and Deployment TRL 8 – Building technologies Systems Development – Renewable integration TRL 7 – TRL 6 Technology – and microgrids Demonstration TRL 5 Technology • Target technology readiness at TRL 4 different levels Development TRL 3 – Fundamental science to deployments Feasibility Assessment of technology with industry partners TRL 2 Basic Research TRL 1 What is a Microgrid?

“A microgrid is a discrete energy system consisting of distributed energy sources (including demand management, storage, and generation) and loads capable of operating in parallel with, or independently from, the main power grid” – General Microgrids What Makes up a Microgrid?

Separation Separation What Makes up a Microgrid?

Controllable Controllable Generation Generation

PV alone is not a good microgrid asset. What Makes up a Microgrid?

Loads Loads What is Needed to Make a Microgrid Successful?

• Clear expected functionality of the microgrid Defined Functionality – Should the microgrid be able to island successfully without a blackout? – Blackout ok and blackstart is expected upon that condition? • Enough local and controllable generation and Generation Capacity resource capacity – Standard generators? – Power electronic resources (PV, energy storage, fuel cells?) • Multiple levels of controls Coordinated Control – Devices and controls that support the control and coordination to meet this functionality – Communications to support optimization and device coordination Layers of Controls (Inverters) Primary Control – Secondary Control – – Converter and generation system level controls – Microgrid controller works with assets that are done automatically in response to to ensure voltage and frequency of measurements system are regulated. – Typically fast in nature – Typically slower in nature Typical Structure of Inverter based Devices

Controller • Controller – - Measurements I/O – Lowest level is field programmable gate array (FPGA) - Inverter controls or digital signal processors (DSP) - PWM generation – Very fast computation and signal - Fault detection generation in 1-10 us range - System state decision (normal • Interface – conditions) – Real-time layers that support interaction to controller and Interface usually performs the communications interface and - Communication layer state representations - System state decision making – Can be done on the controller (normal conditions) level, but controller is resource - System coordinator limited

Main Message: These systems can be complicated! Microgrids Transitioning to Power Electronic Resource

Power electronic systems do not have inertia. Need different controls.

Power Electronic Resources

Fuel Cell

Battery Systems

PV Systems Power Quality Magnitude • A measurement of the ‘fitness’ of the power Frequency delivered • For US electric grid, usually like to think of a voltage sine IEEE/IEC NFPA/NEMA UL wave operating at 60Hz IEC 61000 NEMA LA 1 UL 96A IEEE 519 NEMA LS 1 UL 1283 • Many standards are available IEEE 1159 NEMA PE1 UL 1449 IEEE 1433 NFPA 70 to support defining power IEEE 1531 NFPA 780 quality and technology IEEE C2 IEEE C62.41 solutions IEEE 1433 IEEE 1564

Theo Laughner, Intro to Power Quality, TVA Presentation, 2017

11 Why is Power Quality Important? • Poor Power Quality Impacts: – Premature failure of devices • Capacitors • Motors • Transformers and cables – Energy efficiency with increased heating and losses • Can Trigger Tripping of Devices – Computers – Relays • Can Lead to C