Flexible Resource Controller: A Price and Voltage-Responsive Device Controller for GridLAB-D Co-Simulations

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Abstract

The Flexible Resource Controller (FRC) is a multiple-objective controller that manages residential heat pumps (HP), electric domestic water heaters (DHW), electric vehicle (EV) charging, and batteries. The first objective is to manage energy use to save customers money-charging storage and EVs when electricity prices are low and avoiding energy use (or discharging the battery) when prices are high, while maintaining thermal comfort. A second objective is to implement reactive power control at the battery inverter based on local voltage levels (Volt-VAr) to minimize voltage excursions outside of acceptable limits. The FRC has been developed for use in transactive energy co-simulations using the GridLAB-D distribution grid simulator to study the impact of price-responsive controls on voltage and other building and grid metrics. It takes as inputs the house thermal properties, weather, and electricity price data, and generates control variables (e.g., hot water temperature setpoint, battery real and reactive power settings) that are sent to the GridLAB-D simulation engine during its execution. The FRC makes use of hourly day-ahead prices (DAP) in addition to optional adjustment of control parameters in response to 5 min real-time prices (RTP). Alternatively, the FRC can adjust control parameters based on a congestion dynamic price (CDP) generated using service transformer power flows. Finally, the FRC can work in a pass-through mode, taking power levels for each device from the transactive energy market (TEM) and passing those on to GridLAB-D. The FRC currently implements simple patterns that shift power usage based on prices. The FRC HP controller implements precooling prior to the evening price peak and then a raised house setpoint temperature during the price peak. The DHW controller lowers the tank setpoint in the afternoon. The EV is charged when prices are lowest during day, evening, or night charging sessions. The battery is set to charge at night and discharge during price peaks. Battery inverter Volt-VAr voltage control is implemented independently of price response, operating at all hours of the day when activated. This document describes the control algorithms that were implemented in the Java programming language and provides an overview of a co-simulation that connects the controller to a GridLAB D distribution grid simulation.

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Energy

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