A triple active bridge (TAB) DC/DC converter is a multi-port converter that has flexible power flow controls. A TAB converter is capable of bi-directional power transmission, electrical isolation and wide voltage range operation, which are applicable to various equipment. Owing to these characteristics, it has gained popularity as a power converter for an advanced power grid. However, the TAB faces an obstacle in the design of the controller by the nature of 2-input 2-output interference system. As a partial solution to this interference, a novel local decoupling compensator is proposed. To realize stable operation at a wide operating range, it is necessary to estimate the distribution of the interference and the performance of the decoupling compensator in the entire operation range. In this paper, the properties of the interference are measured by conducting experiments on the prototype TAB converter using the interference measurement method, and the effective range of the local decoupling compensator is indicated. Consequently, the validity of the controller design is clarified over a wide operation range.