Research on application of three-port SNOP based on dual closed-loop control in distribution network

In order to strengthen the framework structure of distribution network, promote the agility of its control methods, and improve its intelligent and automation level, Soft Normally-Open Point (SNOP) as a novel power electronic device is installed in distribution network, which can provide accurate control of real and reactive power flow. This paper proposed the dynamic mathematical model of three-port SNOP in dq coordinates, which is able to connect more feeders or AC systems and improve its extensibility and flexibility. The dual closed-loop cooperative control system was adopted to achieve the multiple target control. In order to get the dynamic response characteristics of three-port SNOP, the simulation model was built and tested in the EMTDC/PSCAD platform with different control strategies. The modified IEEE 33-bus power system was used to demonstrate the benefits of SNOP. The simulation results showed that the three-port SNOP with PV control mode and PV control mode have different degree of advantages in balancing feeders load, reducing power loss and improving the node voltage level.