Power flow control in networks using controllable network transformers

The drive for higher reliability has motivated many utilities to move towards a more meshed system. Two control areas are often connected together with tie-lines. Power flow through the tie-lines connecting two control areas is difficult to control. This lack of controllability of power flow is one of the major issues in the modern grid. It causes asymmetric stress on the grid assets. This makes some grid assets more vulnerable to failure than others and therefore decreases the overall system reliability. Presently utilities can achieve very limited power flow control using devices like load tap changing (LTC) transformers and phase shifting transformers (PST). Controllable network transformers (CNT) were introduced as a simple, low cost solution to the power flow problem. This paper develops a theoretical analysis for the operation of CNT in a meshed network. It also shows the various possible applications of the CNT. Experimental validation of the working principle of a small scale prototype CNT is also provided.