Abstract
Soft Open Points (SOPs) are power electronic devices installed in place of normally-open points in electrical power distribution networks. They are able to provide active power flow control, reactive power compensation and voltage regulation under normal network operating conditions, as well as fast fault isolation and supply restoration under abnormal conditions. Two control modes were developed for the operation of an SOP, using back-to-back voltage-source converters (VSCs). A power flow control mode with current control provides independent control of real and reactive power. A supply restoration mode with a voltage controller enables power supply to isolated loads due to network faults. The operating principle of the back-to-back VSCs based SOP was investigated under both normal and abnormal network operating conditions. Studies on a two-feeder medium-voltage distribution network showed the performance of the SOP under different network-operating conditions: normal, during a fault and post-fault supply restoration. During the change of network operating conditions, a mode switch method based on the phase locked loop controller was used to achieve the transitions between the two control modes. Hard transitions by a direct mode switching were noticed unfavourable, but seamless transitions were obtained by deploying a soft cold load pickup and voltage synchronization process.
Highlights
The widespread use of distributed energy resources, e.g., distributed generations (DG), energy storage and controllable loads, is anticipated in many countries but this can lead to operation problems including excessive fault level as well as violations of thermal and voltage limits [1,2]
Medium voltage (MV) distribution networks are usually operated in a radial configuration
It consists of two MV feeders which are extracted from an IEEE 33-bus distribution network [19] and a back-to-back VSC based SOP placed between the feeders
Summary
The widespread use of distributed energy resources, e.g., distributed generations (DG), energy storage and controllable loads, is anticipated in many countries but this can lead to operation problems including excessive fault level as well as violations of thermal and voltage limits [1,2]. Open points (NOPs) are built, connecting adjacent feeders, to provide alternative routes of electricity supply in case of planned or unplanned power outages [4] Such network configuration allows the use of simple and inexpensive protection schemes as well as providing fast fault isolation to limit the propagation of network faults. A closed loop configuration is advantageous over a radial one because the load can be balanced between feeders resulting in better voltage profiles and improved reliability of power supply [7]. Such loop configuration increases the risk of wide area failures because any single network fault can be propagated quickly over a wide area. The importance of the soft cold load pickup and voltage synchronization process, which are essential for a smooth transition between control modes during the change of network operating conditions, was investigated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
