The Future of Distribution Management Systems as the Decisive Enabler of the Transactive Energy Paradigm
By Panayiotis (Panos) Moutis
Distribution Management Systems (DMS) have been at the center of attention since the mid-1990s as an extension of the Energy Management Systems (EMS) to the distribution networks (DNs). EMS, as computer applications (in most cases SCADA systems), were employed to robustly operate, manage, protect and monitor the transmission system and the central generation, due to the size and complexity of the infrastructure involved. That said, DMS had, at first, a very narrow range of functionalities, mainly of monitoring DNs and providing an interface with the overlying EMS. However, the ever-increasing penetration of Distributed Generation (DG) and the deregulation of energy markets changed this status. Nowadays, all major industrial companies such as ABB, General Electric, Siemens, Schneider and others, each offer their own DMS platform featuring numerous applications for the operation and control of DNs. In this sense, DMS are deployed widely, in order to facilitate the transition to the Transactive Energy paradigm.
Despite the wide commercialization of DMS, recent research on the topic has remained vast and in-depth at various levels of such platforms. The research aims to incorporate functionalities that will improve the performance of DNs, enhance them with additional capabilities and optimize the operation and profit of all participating stakeholders.
From the viewpoint of fundamental operation methods, the electricity dispatch problem has been and will be a major consideration. The unbundling of the energy markets, the demand for fair treatment of all resources (plans and action to reduce/revoke of subsidies or special tariffs for renewables), the diversity of the DG types, the opportunity of exploiting redundant storage from Electric Vehicles (EVs) and the ever persistent problem of the load demand uncertainty (even more crucial and less normalized at the scale of DNs) justify the concerns for a robust and cost-effective approach on day-ahead and intra-day scheduling in medium and low voltage networks. The DN-level system operators will be required to act as the aggregators of all local energy assets, thus be expected to trade them upstream in the markets. To this end, DNs may be viewed as clusters of microgrids. Viewing the DNs as such clusters with diverse objectives is a uniquely commercial scope, so as to answer pragmatically through it the market problems. At the same time, the potential of EVs participating actively in the electricity demand/supply within DNs has been addressed a separate functionality of modern DMS, because driving patterns and emissions (related to the mobility issues of EVs) affect the solution of the electricity dispatch problem in a particular manner.
Despite the fact that the electricity dispatch does consider technical limitations and power quality standards, reliability events can occur and variability of both demand and supply may be well outside the forecasted values. Hence, ancillary services have to be scheduled and controlled by the DMS for online treatment. That said, although voltage control is deemed as an issue rectified by local measures, it becomes system-wide. Especially if we wish to avoid unnecessary action of transformers equipped with on-load tap changers; excessive activation of such equipment, which leads to their wear, has been noticed in DNs with high penetration of renewables, due to the volatility of the output of the latter. With these points in mind, the cooperative action of all the installed DG along a DN to keep bus voltages well between the standardized limits will be coordinated by DMS. As an alternative to the above control actions, online DN reconfiguration (changing the topology of distribution lines by disconnecting and reconnecting parts of them to neighboring feeders) may also achieve minimization of losses (related similarly to the voltage profile treatment) and improve overall reliability. Due to the fact that such actions interfere with multiple DNs and concern multiple objectives, reconfiguration is discussed to be realized at high-level, i.e. again through DMS.
The critical role of the DMS in the applications discussed above, which are greatly diverse, as also the requirement for any DMS to be readily deployed to any DN globally, raises questions about implementation, protocols and standards for the information exchange among and the control of the various actors and participants. The discussion on applying certain standards in the management of microgrids (lately leading to the development of the first drafts), explicitly implies that DMS will be required to follow similar guidelines. At the same time, the ability of adaptation of a DMS to any given metering infrastructure and/or communication architecture and the efficient elaboration of the collected data from the above, are concerns for the operation of such a platform across existing infrastructures. This last observation pertains to the challenge of avoiding the development of customized approaches as also any additional investment in specific integration (not to mention delays in the deployment of DMS).
DMS represent the platform that may readily enable all smart grid approaches and methodologies for the operation, control and management of modern DNs in an effective and efficient way. The research in the field keeps unlocking additional potential and it is expected for DMS to facilitate wide and multilevel customer participation as also revolutionary abstractions of existing smart grid paradigms. Thus, DMS will enhance the performance of the electricity infrastructure by further optimizing its operation and act (at a system level) as the enable for innovative transactive energy applications of remarkably added value for all power system stakeholders.
Panayiotis (Panos) Moutis, Managing Editor of the IEEE Smart Grid Newsletter, is a postdoctoral research associate at Carnegie Mellon University, Pittsburgh, USA, and a technical consultant with 10 years of experience on Renewable Energy Sources investments in Greece. He has published more than 15 papers on topics concerning the management and control of distributed generation and storage resources based on various smart grid paradigms. His research interests lie in the field of virtual power plants, microgrids, distributed resources integration and application of artificial intelligence to power system management and control. He is a senior member of the IEEE Power & Energy Society, IEEE Industrial Electronics Society, IEEE Computational Intelligence Society and IEEE Computer Society.