Distributed Power Flow Controller

In modern power systems, there is a great demand to control the power flow actively. Power flow controlling devices (PFCDs) are required for such purpose, because the power flow over the lines is the nature result of the impedance of each line. Due to the control capabilities of different types of PFCDs, the trend is that mechanical PFCDs are gradually being replaced by Power electronics (PE) PFCDs. Among all PE PFCDs, the Unified Power Flow Controller (UPFC) is the most versatile device. However, the UPFC is not widely applied in utility grids, because the cost of such device is much higher than the rest of PFCDs and the reliability is relatively low due to its complexity. The objective of this thesis is to develop a new PFCD that offers the same control capability as the UPFC, at a reduced cost and with an increased reliability. The new device, so-called Distributed Power Flow Controller (DPFC), is invented and presented in this thesis. The DPFC is a further development of the UPFC. It has been shown that the DPFC fulfills all three of the listed goals. This thesis starts with the review the state-of-art of current PFCDs, followed by the research at the DPFC device level, including the operation principle, the modeling and control, and experimental demonstrations. At the end, the thesis presents the research at the system level, which includes the DPFC applications to improve power system controllability and stability, and the feasibility of the DPFC for real networks