Chung-Ang University scientists are developing a system for smart grids and smart homes to use energy more efficiently.

Home energy management systems (HEMSs) efficiently manage energy consumption of home appliances by scheduling when washing machines should start and strategically turning air conditioners (ACs) on and off. In general, a HEMS works to minimize electricity bills while also taking the user’s preferences and comfort into account.

Usually, hand-crafted models that use abstract equations to represent appliances and distributed energy resources are used to program HEMSs. But these models and optimization methods are not very versatile and give suboptimal solutions. An alternative is to use centralized machine learning, where data from thousands of users is collected, sent to a central server, and used to train a model from the ground up. This strategy, however, may prove costly, computationally complex, and susceptible to hacking.

To tackle these problems simultaneously, Associate Professor Dr. Dae-Hyun Choi and PhD student Sangyoon Lee from Chung-Ang University, South Korea, have proposed a novel data-driven strategy. The researchers have developed a framework for HEMS based on federated deep reinforcement learning (F-DRL), combining the advantages of various machine learning techniques. Their study was published in Volume 18, Issue 1 of IEEE Transactions on Industrial Informatics in January 2022.

The key word to note in F-DRL is ‘federated,’ which indicates a decentralized form of machine learning. In the proposed framework, each home has a HEMS connected to various appliances and devices, which collects data about its users’ energy consumption and tries to optimize a schedule for the appliances by creating a local model. These local models are all uploaded to a global server, which averages them to produce a global model. Afterwards, each HEMS replaces its local model with the global model and proceeds to train it once again using local data. This process is repeated several times, progressively improving the accuracy of both global and local models. “In a conventional centralized DRL model, the global server must have access to the data of all local devices to generate the model of the global system. This results in data privacy concerns for local devices,” explains Dr. Choi, “However, in our federated DRL method, the system does not require the sharing of user data because only the parameters of local and global model are exchanged. In turn, this helps prevent local data leakages and protects the users’ privacy.”

The researchers tested their approach through simulations, showcasing its optimal performance when scheduling the operation of various appliances at different homes. “To the best of our knowledge, this is the first HEMS framework based on federated DRL that can manage the energy consumption of multiple smart homes and ensure the comfort of the consumers while taking their preferences into account in a distributed manner,” observes Dr. Choi. In addition to its low computational complexity and relatively fast training process, the proposed framework can easily support the addition of more appliances in each house.

Dr. Choi envisions a more comprehensive version of this framework that also considers electric cars and energy trading between households. We certainly have our fingers crossed for the secure optimization of energy consumption in future.