Lessons learned: interfacing existing external systems to new EMS

Hydro-Quebec is in the process of renewing its SCADA/EMS. Part of this work involves interfacing existing external systems that perform various applications such as state estimation, power flow and stability limit calculations to the new SCADA/EMS. These systems run on various platforms and operating systems. They were developed in-house or by different vendors. When initiated, in 1995, the primary goal of the interface subproject, was to minimize the modifications to the existing systems and the customization of the new SCADA/EMS. It sought to find standard interface components: protocol, exchange format, data dictionary, etc. At that time, standards such as ICCP and models such as CIM were immature. An in-house protocol both at the application and at the communication level was found best. Such a protocol was defined jointly with the vendor, based on the principles of the IDEC protocol. This article presents the challenges met from our decisions of developing in-house solution and from our initial goals. The article describes these challenges in terms of protocol, data formats and data modeling. It discusses the lessons we have learned and what we would do differently, especially in the light of standard development.