The increasing number of physical objects are being connected to the Internet at an incredible rate, forming the Internet of Things (IoT). This phenomenon not only increases the volume of data on the Internet, but also requires the development of complex software solutions, which need to be thoroughly tested. Testing of IoT systems represents a challenge, since it requires connecting a variety of physical devices to the system. Also, some problems can only be detected if there are a large number of active users in the system, or there are some users generating large data volumes. Simulations and software modeling of system components play an important role in the testing process. They allow to scale the usage of the system at a very low cost, and to perform various testing scenarios. In this paper, software models of components are proposed, which simulate real users' behavior in a home automation IoT system. Using the created models, the high load for the IoT cloud is created, and the system behavior is observed.