This paper presents a method for the linearization of the non-linear power flow equations, which can be used in mixed integer linear optimizations. The power flow equations are linearized around an operating point using the Taylor approximation. The linearization implies an approximation error, which can be reduced iteratively by modifying the operating point. In addition to existing approaches, controllable assets like voltage regulated transformers or phase shifters are integrated into the linearized grid constraints. The model is exemplarily applied to an operation planning model of distributed energy resources considering grid restrictions. The results show that this approach reduces the approximation error significantly and that it is robust for different real distribution grids as well as for different generation and load scenarios.