Energioptimering genom modellprediktiv styrning : En fallstudie om att kostnadsoptimera en kontorsbyggnads nettolast genom energilagring

Sammanfattning: The shift towards renewable energy sources for electric production implies the need for more demand side flexibility in the use of electricity. In recent years, the spot price of electricity on the NordPool market has started to fluctuate more rapidly and with a greater magnitude than ever seen before. A key factor to this is the changes in production capabilities of cheap renewable energy due to weather changes. A second factor is that the Nordic transmission system is facing challenges in transmitting enough energy from areas with excess electricity production to areas with a shortage on electric energy. Thirdly, Russia launched an illegal invasion on the sovereign state of Ukraine in the early spring of 2022 leading to shortages on fossil fuels which are crucial for electricity production all around Europe. The new market conditions increase the economic incentives to utilize demand side flexibility as a method to decrease the operational energy costs for both small- and large-scale consumers. In this study, the opportunities of utilizing a battery storage system to minimize the cost of electricity by the implementation of Model Predictive Control (MPC) are investigated. The study consists of a case study that simulates how the power flow between the grid, a battery and a building can be optimized by MPC, as well as time scheduled operation. Different control strategies were implemented to include the different market structures that affect the limitations of the system. The simulation model for the system was constructed in MATLAB and utilized its system identification toolbox as well as its mixed integer linear programing capabilities. The results showed that by shifting the power demand by less than 9%, a 13% reduction of the cost for bought electricity can be obtained compared to the same system without an energy storage system. It was also shown that the MPC was able achieve over 40% higher economic savings compared to the time scheduled control structure. The study also propose that similar control strategies can be utilized for different energy storage systems.