Design of Energy Mixer and Router for DC Power Packet Distribution System

Abstract

Energy internet (EI) is introduced recently aiming to improve power system reliability, security and efficiency through advanced information and power electronic technologies. A power packet distribution system (PPDS) is a promising candidate for the EI implementation, as it transfers information alongside the distribution of electric power. The PPDS can be realized for both DC and AC power distribution. This thesis has made four key contributions to the DC-PPDS: (1) A revised PP structure is proposed, which has a reduced footer bit and hence reduction in power switching losses. A routing scheme which does not need footer bits like handshaking protocol is proposed to increase PP distribution efficiency. A new algorithm for PP generation is also proposed capable of generating the PP based on the load power requests and the source power availability. A systematic approach is given to select the energy buffer which is needed to sustain the load voltage. (2) An over-current protection (OCP) scheme based on a simple analog circuit and integrated with the PPDS is proposed to monitor and protect the system during the over-current scenario. The routing algorithm is also modified, which utilizes the information received from the OCP circuit to isolate the faulty loads without interrupting the PP delivery to the other loads. (3) A multiple- energy-source mixer based on a single-inductor, multiple-input and single-output converter structure is proposed to attain power conditioning and voltage regulation simultaneously to send power to various loads at distinct voltage levels. (4) A four-port converter-based mixer is also proposed, which can interface with battery to mitigate intermittency problem of RESs, hence ensure reliable power distribution in islanded mode. The proposed solutions have been verified through experimental results. The PPDS has the potential to be applied in systems where communication and power transfer occur simultaneously.