Today’s utility business model depends chiefly on big power plants and long transmission lines—and federal and state policies reinforce that model. But as photovoltaics technology advances and...
New Directions in Distribution Management
Advanced systems turn ‘event-driven’ binary schemes into hybrid hierarchical controls.
While the “smart grid” conjures up numerous definitions, there can be little doubt that it signals both a shift of focus to distribution networks, and a revolution in the way they operate.
Over the years, distribution engineers have carefully designed and managed the grid, responding to problems as they develop. By and large, the industry has managed the distribution network in a reactive manner and without significant real-time visibility. As new energy consumers and supply resources appear on the distribution grid, gaining more visibility and control is a necessity for any grid owner.
At the center of the many technologies that are being applied is a complex analytics engine called advanced DMS (distribution management system). The advanced DMS technology, still new to North America, is the tool that unites a host of traditional technologies, such as outage management, SCADA (supervisory control and data acquisition), and operations planning and network analytics. advanced DMS changes the game for both utilities and suppliers, who typically have focused on the transmission system when it comes to information technology. It introduces systems that are less reactive, and driven more by process and real-time state estimation. With only a few systems fully deployed around the world, advanced DMS stands at the cusp of what promises to be a long and exciting expansion of technology solutions for electric distribution networks.
What’s a DMS?
Before digging deeper into the realm of advanced DMS, it’s helpful to establish a common understanding of the basics of distribution management systems. Like many aspects of a smart grid, the term “DMS” has come to be broadly applied: Because of a growing recognition of the need for more automation and control at the medium voltage level, “DMS” has become a popular catch-phrase for almost anything that manages some aspect of a distribution system. That may be fair enough, but for purposes of this discussion, a clear definition of the tool is important. So, let’s begin by outlining the four critical traits of a modern DMS:
• Loadflow Calculations.
• State Estimation.
• Real-Time Systems Integration.
• Fault Calculations.
Also, in thinking about a modern DMS, it’s important to always keep in mind certain differences between transmission and distribution networks.
In fact, many DMS tools on the market today originated as EMS (energy management systems) technology applied to transmission systems. Conceptually the solution techniques are the same (loadflow, state estimation, real-time integration, fault calculations). However, the networks themselves are very different.
Transmission networks are sparse, even pristine. They have very few elements and a high proportion of telemetered data points. Transmission systems don’t change often; once created, managing a transmission model is straightforward. In contrast, a distribution system is a complex, intense, dirty, ever-changing organism. Mathematical techniques that work well for the transmission grid can easily bog down when applied in the distribution context.
Within a modern DMS, loadflow calculations help solve the iterative mathematics of an electric distribution model. Because current