By Carl R. Goeckeler, P.E.
Over the years, Kansas City Power & Light (KCP&L) has been very successful in its distribution automation projects, realizing significant cost savings and improving service to its customers. This success is due in part to a proactive effort to implement distribution automation for practical applications. An important part of these projects is making sure the applications support industry standard protocols.
Several years ago, KCP&L co-funded EnergyLine’s development of special software tools that support capacitor automation. The capacitor automation design uses a two-way fixed network system, programmable capacitor controls and WinMon, a powerful graphical user interface. The system already has exceeded original expectations and has been a valuable tool to limit losses and stabilize the KCP&L system.
But the existing fixed network has limitations. It is only available in the metro area due to economic restrictions. Nearly 90 percent of the load is within the metro area, but the number of square miles covered by the existing communications solution is less than 20 percent of the entire service territory. Also, the existing fixed network system is limited to the PG&E protocol, an older master/slave protocol originally developed by Pacific Gas & Electric in an attempt to provide a universal platform for performing supervisory control and data acquisition (SCADA).
KCP&L Adds DNP to Protocol Suite
The PG&E protocol served the basic needs of the capacitor automation project, but there were significant reasons to use a more robust protocol. Suppliers continue to add DNP to their products, and users continue to deploy this protocol. It has become the electric utility industry de facto standard.
KCP&L chose the DNP3.0 protocol for the following reasons:
“- DNP uses “report by exception” instead of traditional polling. Users may more effectively and economically manage communication.
“- DNP offers breadth and depth of protocol implementation. For example, report formats support time stamping for actual times in controls and relative to events.
“- KCP&L hopes to lower development costs of DNP applications by finding solutions for other utilities who will share development costs and benefits.
“- Future distribution automation projects with DNP will more likely be off-the-shelf instead of customized.
“- Standardizing on DNP eliminates the need for protocol converters.
Consequently, KCP&L and SchlumbergerSema have begun a project to implement the DNP3.0 protocol through their systems for the metropolitan area. SchlumbergerSema will add the DNP3.0 protocol to its communication infrastructure, and KCP&L will add a DNP option to the LiveData platform underlying WinMon, allowing full integration with KCP&L’s SCADA system. No custom data interfaces need to be written because LiveData will continue to present operational information directly to WinMon. With no changes to the SCADA interface required, implementation of the new application can be made quickly with no impact on operational systems.
KCP&L Studies Expanded DA Coverage
The KCP&L territory outside the fixed network is widespread and sparsely populated, making the operating cost per customer more difficult to control than in the metropolitan area. Distribution automation offers an opportunity to reduce operating and maintenance costs and improve reliability for these outlying regions.
The KCP&L rural districts use a 34-kV sub-transmission system to deliver power to approximately fifty 34/12-kV substations. These substations currently have no automation and no communication infrastructure. KCP&L operators rely on trouble calls from customers on circuits where reclosers may have tripped or where voltage regulators need attention.
KCP&L realized the economic and operating benefits of automating capacitors based on the successful metropolitan automation and hoped to find similar benefits in outlying areas. Proper selection of a communication system was key to this success. Based on the knowledge obtained in the metropolitan network, KCP&L developed a communication “wish list” for these additional areas. The desired communication system would provide:
“- Economical build-out by using existing public communications infrastructure,
“- Two-way communications with wide coverage,
“- Security, reliability and cost effectiveness,
“- Broad bandwidth,
“- Scaleable solution for large deployment,
“- Support of the DNP3.0 protocol,
“- Web-based option for monitoring and user notifications, and
“- Ability to access devices from SCADA and energy management systems (EMS).
KCP&L studied various communications options and compared these with the above “wish list.” The providers offered interesting solutions, but failed to meet some of the basic practical and economic requirements. It was obvious no single provider could meet all the needs, so the challenge was to find the most economical and effective communications solution.
KCP&L discovered the Telemetric communication solution while participating in the 2001 DistribuTECH Conference and Exhibition in San Diego, Calif. Telemetric uses the digital control channel of cellular telephony to achieve both low cost and wide coverage. This solution uses the existing towers and radio systems of local cellular providers.
The solution is creative, economical and ideal for control, alarming and receiving analog and digital values. Telemetric converts a 15-digit packet into a binary value (50 bits). Users then can configure up to 36 digital status points from one packet. Since the packet has a limited size, sending the DNP header information is not feasible; therefore, the DNP header information is removed for the cellular transmission and added at the server, preserving the packet as a true DNP3.0 communication. Now, any device with a Telemetric module is accessible as a DNP node. Because of the low cost, KCP&L now can extend SCADA into our distribution automation network as close as possible to our rural customers, and the capital required to deploy this technology is minimized.
KCP&L and Telemetric shared several visions in support of distribution automation at KCP&L and in the industry:
“- Desire to develop a module that could be connected to any DNP3.0 RTU or intelligent electrical device (IED),
“- Desire to support DNP protocol, and
“- Use of full two-way communication using low-cost radios and public networks.
KCP&L made the decision to co-fund a two-part project with Telemetric to implement the DNP communication for its rural customers. Part one-develop and test a module with a cellular radio that speaks DNP. Part two-integrate DNP3.0 communications to the devices with the KCP&L SCADA and EMS systems.
DNP-Remote Telemetry Module
Telemetric and KCP&L have worked together on configuration and testing of a device called the DNP Remote Telemetry Module (DNP-RTM). The DNP-RTM, which is installed within the cabinet of the IED, continuously polls the IED with a serial DNP connection in a master/slave relationship and then reports digital and analog values by exception (See Figure 1). A cellular transmission is only required when the exception report occurs. With the DNP-RTM, KCP&L can monitor various DNP digital points and analog values. Exceeding user-configurable report-by-exception values initiates alarms, and the cellular radio forwards the appropriate packets. In addition, users may configure the DNP-RTM by programming various rule bases. For example, a user can configure the DNP-RTM to report by exception when the voltage falls or rises to given values, or to send an e-mail message to the dispatch center when a capacitor fails.
The DNP-RTM can monitor and control up to 99 points. When a point goes out of range, a call is triggered to report the event. Users can program and configure the DNP-RTM and radio to report various parameters and set points to minimize communication for specific transactions.
KCP&L chose the EnergyLine programmable capacitor control for the initial implementation of the DNP-RTM. KCP&L, Telemetric and EnergyLine worked together to configure and test an EnergyLine 1000 Series Capacitor Control for this application. KCP&L already uses this IED on the existing metropolitan capacitor automation program. The screen shot at left shows the related screen on the Telemetric Web application supporting the product.
Additional controls targeted for this project include EnergyLine’s IntelliCAP PLUS and IntelliTeam, Siemens’ MJ-XL Voltage Regulator Control, and Beckwith Electric’s M-2001B Digital Tapchanger Control.
KCP&L chose the EnergyLine 1000 Series Capacitor Control for initial implementation of the DNP-RTM.
Part two of the project involves integrating the communications with the DNP-RTM into KCP&L’s SCADA and EMS. The Telemetric SCADA-Xchange service acts as a gateway protocol converter that enables access to any Telemetric connected device from the KCP&L SCADA or EMS (See Figure 2). KCP&L currently uses the Telemetric secure Web application to monitor devices. In the future, KCP&L will use WinMon and the LiveData platform to implement this portion of our SCADA system. Since both the EMS and the LiveData platform are bi-directional, this will allow both monitoring and direct control of any Telemetric connected device.
Future KCP&L DA Projects
Throughout the remainder of this calendar year, KCP&L will pursue the strategy to implement the DNP protocol for remote communications in metro areas on the fixed network, and in rural areas with public communications.
The rural automation project is exciting, since this is a new extension of KCP&L’s automation strategy. While cost savings will be used to justify the project, we also expect to improve our level of service to the customers. By automating switched capacitor banks, voltage regulators, line switches and reclosers, KCP&L can identify issues and respond to equipment problems or outages much faster. After the initial implementation, KCP&L will evaluate other components not typically automated such as fixed capacitor banks and fault indicators. By having low-cost communications, we hope to avoid dispatching a truck, while still reducing outage time. This translates into real savings for KCP&L and improved service for our customers.
For the past 27 years Carl Goeckeler, P.E., has worked at Kansas City Power and Light where he initiated their Power Quality program and is also KCP&L’s Distribution Automation Project Leader. Carl led up the Distribution Automation portion of the overall projects that won the Distributech Utility Automation Innovation Award and the “Ultra Award for Information Technology.” In addition, he authored “Understanding and Avoiding Commercial Power Disturbances” a syndicated publication used by electric utilities and customers for providing power quality training.