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Today's power distribution control center manages the day-to-day operation of distribution network to ensure uninterrupted power supplies to the end customers. Today there is limited automation in distribution networks which results in lack the holistic visibility of real-time situation for an operator. With the advent of Smart Grid, there is an increase in development of next generation sensors, controllers and standard based system integration tools. This is expected to make the grid operations and monitoring more complex but will bring in more opportunities and challenges too. In this article we try to figure out the changes and challenges expected in a Smart Grid Distribution Control Center and its operations.

Current state of power distribution control centers

• Systems -- describes the available systems in today's distribution control center to manage and operate distribution grid.

  From the Operational Technology point of view, in a traditional distribution utility control center there are Operation Technology (OT) systems such as Supervisory Control And Data Acquisition (SCADA), Distribution Management System (DMS), Outage Management System (OMS) available today, to deal with 'fault' and 'outages' and day-to-day operations. These systems are mainly stand-alone in nature with limited or no integration with one another. As a result lots of manual interventions are required from control center operator to co-relate the incidents in these stand-alone systems and understand the situation to arrive at comprehensive decision. Due to these manual interventions more time is taken to arrive at a conclusive decision for situations needing immediate attention. This decision making capacity also varies from operator to operator and the decision is entirely driven by the operators' understanding of the sequence of events in the systems leading to sub-optimal/faulty decisions at times. Any inaccurate conclusion may result in further loss of time and money to the utility. So despite having the information, today's utility control center operations depend on the operator's capability to analyze the data and to come to a comprehensive decision.

• Operational Responsibilities -- describes the distribution control center operator's responsibilities to manage and operate the distribution grid.

  An operator/dispatcher of today's control center are mainly responsible for following functions:

  • Maintaining and Controling of Grid

  • Dynamic Load Management

  • Fault Management

  • Outage Management

  The current system operation at control center is relatively simple and completely dependent on the operator's capability of understanding the situation based on his/her experience. Operator sees the information in form of data/alarms in different systems and comprehends the current situation based on past experience and decides on certain assumption to handle the situation. The monitoring, analysis and control in the current system is manually driven by control center system operators.

Expected changes in a Smart Grid power distribution control center

Traditional distribution control center operations comprise of mainly monitoring and control of limited numbers of substations, transformers and feeders. Even with this limited capability, the traditional utility control center was able to function satisfactorily.

But with the Smart Grid movement, new generation of smart sensors, meters and IEDs are becoming increasingly popular. From control center perspective there is a need to support these new generation sensors and devices as well as the new Smart Grid eco system, comprising of distributed generation, electric vehicles, energy storage devices etc. With all these new breed of devices, technologies and systems, the overall utility value chain will see a change in the way power is managed and delivered. Smart Grid development will require a completely new concept of Smart Grid control center which will use the new infrastructure that integrates Information Technology (IT), Operation technology (OT) and other support systems in the utility to maximize business value and deliver high reliability. This integration will facilitate the Smart Grid control center operator to carry out efficient, reliable and flexible operation of entire Smart Grid eco system.

With the investment flowing in from all sectors, to change the age-old utility into a 'smart utility', there is a growing need to convert the 'old utility distribution control center' into a 'Smart Grid control center'.

• Integrated System Environment -- provides the platform in Smart Grid distribution control center where OT-IT and support systems can talk to each other in common language to manage and operate distribution grid.

The Smart Grid Distribution control center must have an 'interoperable' OT-IT and support systems. Some of these systems may even be present in today's utility but presently working in a standalone mode. NIST (National Institute of Standard and Technology, USA) has recommended two standards, CIM (Common Information module) and MultiSpeak for Smart Grid interoperability between OT, IT and support systems.

Utilities has OT systems such as SCADA,DMS, OMS and IT systems such as WMS (Work Management System), EAMS (Enterprise Assets Management System), GIS (Geographical Information System), AMI/MDM (Advance Metering Infrastructure/Meter Data Management), DRPM(Demand response Program Management), MWFM (Mobile Work Force Management), CIS (Customer Information System) etc. to manage their operations in control center and back office. What is missing is the integration of these systems on common platform which can enable real-time event correlation, bring-in predictive analytics and forecasting capabilities, perform condition based monitoring, automate fault & outage management and enhance demand management to empower operator with information for better decision making and responding to situations needing immediate attention in timely and correct manner. Fig-1 shows the high level architecture of how the Smart Grid distribution control center will look like.

• Operational Responsibility -- describes the Smart Grid distribution control center operator's responsibilities to manage and operate the distribution grid.

In Smart Grid with introduction of new emerging technologies, advance communication & computing infrastructure and energy resources such as renewable generation, energy storage, electric vehicles increases the complexity of system operations. The operator will have challenges in hand to perform real-time monitoring, analysis and control in Smart Grid control center environment.

The Smart Grid control center will have advance systems and applications for monitoring and operations which will help the system operators to deliver power efficiently, reliably and safely. In an integrated (OT, IT and support system integration) Smart Grid eco-system the utility control center operators shall have one consolidated environment to view a complete picture of current network conditions. This will help him to quickly analyze and respond to the situations.

The integrated single user interface with comprehensive view of distribution network will have GIS based maps for visualization of events and conditions. It will also have the dashboards and applications to monitor, control and manage the distribution network. The control center operator can log into the single operator console with single sign-on that manages the entire distribution operations. An operator no longer needs to monitor the conditions of network in SCADA system, makes the appropriate changes in OMS, use the DMS system to run the advance applications and access the crew management system to assign the work orders. The integrated single console allows operator to access all these systems through single interface to perform their jobs.

Let's see an example how an operator will act in Smart Grid control center during fault resulting multiple customer outages. A fault on feeder causes major outages (say, 30 Distribution Transformers and 200 Customers). Feeder tripping alarm is alerted on operator console from SCADA system. Operator acknowledges the alarms and FLISR (Fault Location Isolation and Service Restoration) application of DMS executed to locate, isolate the faulty section and restore the um-impacted sections. The relevant isolation is simulated and only 2 Distribution Transformers (say) are found out (out of 30 initially affected) with 8 customers under outage. The operator will ping the customer meters for confirmation of outage via MDMS or AMI head-end system and will generate the work orders on 2 Distribution Transformers, looks into GPS enabled GIS maps to locate the appropriate crew nearby and assign the work orders to crew member. In this integrated environment the appropriate message for outage communication is flashed/ sent to respective stakeholders with details of cause of outage and ETR's (estimated time of restoration). The integrated system will track and display the update status of restoration activities on operator's dashboard. Once the restoration is complete the operator pings the customer smart meter for confirmation and after receiving the confirmation from meter, closes the work order. This increases operation efficiency as the operator has to interact with one integrated system instead of looking for information in different systems with potentially different data. This eventually reduces outage duration, improves operation efficiency and high reliability.

Apart from responsibilities described above, the a Smart Grid control center operator will also be responsible for the followings functionalities -

• Peak-Demand Management

• Demand Response Program Management

• Power Quality Management

• Reactive Power Management

• Loss Management

• Predictive Outage Management

• Predictive Maintenance Management

• Mobile workforce Management

Smart Grid control center operational hierarchy

From the characteristic described above, it is quite clear that, the responsibility of control center operators are going to increase in many folds. Therefore there will be a need to change the operational hierarchy level for efficient operation from Smart Grid control center. Fig2 shows the 3-tier hierarchy level in a Smart Grid control center, with their responsibilities -

The operator responsibility pyramid shown above has three categories of operator Super, Master and End.

• End Operators are competent enough to perform daily operations to manage the load, outage and fault in distribution network which is similar to today's control center operator's job. They will be responsible to address outage, fault and assign the work to crew members for restoration activities. They will also perform the load shedding and load management activities for reliable operation of grid.

• Master Operators are competent to deal with the peak demand, power quality management, reactive power management and perform outage predictions. They will be responsible to manage the conditions during the peak demand situation and see that the peak demand is shaved to secure bandwidth by performing several actions as per demand response programs. Also responsible for power quality monitoring and maintaining the good voltage profile in distribution network. Analyze data and perform condition based monitoring to prepare and alert the predictive outages and asset conditions.

• Super Operators are competent to perform demand response programs and take necessary step in executing it to have safe, reliable and efficient operations meeting the organization business and operations strategies. They will also be responsible for operations and actions of Master and End operators. Super operator will monitor the Master and End operator activities and have privileges to override their actions.

Conclusion

The future utility Smart Grid distribution control center will be the 'heart', which has to support the entire distribution utility Smart Grid operations and management. The success of the Smart Grid will depend on the capabilities of the control center and the operators. The integrated environment in control center and simple usage of it through the single operator console through single sign-on will enable the smooth operations in complex environment. The three tier categorization of operator responsibility will bring the transparency, clarity and safe operations aspect in managing the Smart Grid distribution control center.