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 post-fault supply restoration under abnormal conditions. The use of SOPs for the operation of medium voltage (MV) distribution networks was investigated. Three aspects were studied, which include the control of an SOP, benefit analysis of using SOPs and distribution network voltage control with SOPs. Two control modes for the operation of an SOP, which is based on back-to-back voltage source converters (VSCs), were developed. The operating principle and performance of the back-to-back VSC based SOP under both normal and abnormal network operating conditions were analysed. It was found that during the change of network operating conditions, smooth transitions between the two controls modes were needed. Using soft cold load pickup and voltage synchronization processes can achieve the smooth mode transitions. A steady state analysis framework to quantify the operational benefits of a MV distribution network with SOPs was developed, which considers feeder load balancing, power loss minimization and voltage profile improvement. The framework also considered traditional network reconfiguration and the combination of both SOP control and network reconfiguration to quantify the benefits. It was found that in the case study using only one SOP can achieve a similar improvement in network operation compared to the case of using network reconfiguration with all branches equipped with remotely controlled switches. The combination of both SOP control and network reconfiguration can achieve the optimal network operation.