Yugoslavia Develops a New Distribution Management System
By Nenad Katic, Elektrovojvodina
Elektrovojvodina, the largest power distribution company in Serbia and Yugoslavia, delivers 7,000 GWh of electric energy per year to 800,000 consumers. The market economy, cost pressures and increased customer demands require the company to increase efficiency and automate network operations.
In an effort to expand its distribution management system (DMS), Elektrovojvodina has introduced more automation and advanced technologies in the last few years. The aim was to optimize utilization of the existing electricity network and to minimize the high investment costs in network reinforcing. Remote network control, load management and user automation provide the company and the its customers with benefits such as:
better quality and
Elektrovojvodina is located in Novi Sad, the province of Vojvodina, North of Serbia. The winter peak load is almost 1,500 MW. Power is distributed by 55 substations 110/20 (35) kV with 2,630 MVA rated power, 90 substations 35/10 (20) kV with 1,000 MVA rated power and by 8,600 substations 20 (10)/0,4 kV with 4,000 MVA rated power. The distribution network consists of 110, 35, 20, 10 and 4 kV overhead and cable lines totaling 20,000 km in length.
The company employs 3,500 people in a whole range of areas such as power, distribution, telecommunications, distribution management system, electric installation construction, research, information systems and business. The total assets of the company has an estimated value of more than (U.S.) $1 billion.
The Area Control Center (ACC) in Novi Sad controls the high-voltage network and the 10 Regional Control Centers (RCC) control the medium- and low-voltage network.
There appeared to be some problems in the power distribution system in past years. The electric energy consumption increased 20 percent in the last five years, mostly in the low-voltage network used for home heating and small business and also at some large commercial and industrial customers.
This situation was caused by the low price of electric energy as well as the high price and shortage of other energy supplies. Household appliances used for heating with high power loads–thermal storage electric heaters, huge electric boilers and others with power loads ranging from 6 to 24 kW–caused overloading of transformers and lines in the distribution network.
Industrial electric energy consumption decreased. The expectation for the next period is that household consumption will stagnate or slowly decrease and that industry consumption will rapidly increase.
Existing problems in the power distribution network are a result of local overloading of transformers and lines and non-controlled consumption, although the average utilization of the existing network is not more than 60 percent.
Investment costs for building the new power lines and substations are very high and the company`s investment fund is limited. The management of the company analyzed this situation and decided to advance the development and implementation of modern technologies for better utilization of the existing network.
The flexible and efficient operation and control of the electricity distribution network are essential for the commercial and technical success of any electricity distributor. The efficient operation and control technologies include management of many lines, substations and switches of the physical distribution network, interaction with customer services, financial services, metering and other support services.
In a distribution company, each aspect of network management is vested in a number of different departments, and their tasks in some of them have been computerized usually in isolation. Sharing information among the islands is difficult and laborious. Consistency and accuracy of data is difficult to achieve, and the overall efficiency of the distribution organization suffers.
The DMS is a solution that integrates the full spectrum of distribution automation and information management functions. DMS provides an environment that integrates the “islands of automation” in an integrated set of applications modules which together bring benefits to all parts of a distribution management business. The distributed client/server information base is the foundation of the DMS that serves all the users and a communication network that controls the exchange of information. DMS includes advanced applications such as:
supervisory control and data acquisition,
automated management and facilities management,
network analysis and operation management,
distribution outage management and
planning and engineering management.
The conception and global architecture of DMS is currently being developed in Elektrovojovdina.
The application processing with DMS is distributed to the user workstations in different departments. DMS is based on the UNIX operating system, which provides the flexibility for accommodation of technological advances and evolving user requirements.
DMS Global Architecture
A global architecture of DMS includes:
Information database management–a client/server architecture and a relational database such as ORACLE, which allows the system to be spread across several control centers or consolidated into a single one.
Data processing and operating system, with use of open standards that provide a framework for transparent exchange of data between different user environments. Man machine interface gives the operators the procedures and the tools to interact with the system.
Communication management, to monitor and manage the communication network using different transmission media such as power-line carriers, radio and telephone communications. Configuration management configures available equipment. Fault detection management records and detects faulty operation of equipment.
Application management includes activities in the control room (SCADA, network analysis, DSM, outage management, and planning and engineering management).
Interfaced systems interface with the customer information system, management information system and with foreign information systems out of the company.
Energy management system (EMS) which connects with the EMS in higher control centers.
The front-end functions of the SCADA include remote control, data acquisition and handling of alarms and events. In addition, it maintains a connectivity model of the network and provides the graphical interface to the system, supporting the display and manipulation of the geographic and schematic network diagrams, with background maps, diagram navigation and network coloring.
Distribution SCADA technology is already installed in the 10 regional control centers (RCC) in Elektrovojvodina, but the RTUs are installed in only 40 percent of the substations. The installation of RTUs and remote control of all substations are complete. The important substations are planned for the next five years. The new SCADA technology was developed by the Institute “Mihajlo Pupin” from Beograd in cooperation with Elektrovojvodina engineers. It is based on PC-technology with full graphics and man-machine interface with connection to the DMS relational database.
The installation of the EMS for remote control of the transmission network in Vojvodina has started in the Novi Sad area control center. The EMS will enable real-time connection with all SCADA systems in Regional Control Centers and will have applications for integrated control, supervision and survey of the distribution network. In this way, the complete distribution network will be under control and supervision.
Distribution operation management provides a set of tools that address common network analysis functions and additional tools in order to help operations personnel make important decisions about the distribution network. These tools include: network power flow analysis, voltage calculations, connectivity analysis and interactive network modifications, “what if” scenarios with fault reconfiguration strategies, line loss minimization with optimum network configuration strategies, short circuit calculations and voltage and reactive power regulation.
Network analysis and operation management was developed in cooperation with the Faculty of Technical Sciences in Novi Sad. The pilot installation is managed by the RCC in Novi Sad served by two substations with 40,000 consumers. The network operation management installations are planned in all RCCs in the next three years. DSM includes two-way data communication using the electricity power network and provides capability for remote meter reading and load control.
It includes peak-load forecasting and the formulation and execution of load control strategies. With remote intelligent metering, automatic readings can be performed as frequently as required, making flexible tariff switching and dynamic pricing possible. Home automation systems allow direct control of individual electrical devices and open possibilities for “end-to-end” control of the electricity network.
The two-way communication system using electric power network technology is in the beginning stages of development in Elektrovojvodina, and some experiments and testing have already been done. Load management using radio telecontrol (RTC) technology has been developed in Elektrovojvodina in the last five years in cooperation with the Faculty of Technical Sciences in Novi Sad.
The RTC system has been implemented in the five RCCs with 5,000 consumers. The implementation of the new RTC level, based on microprocessor receivers and PC-based central units, started in Novi Sad this year. The RTC system manages direct control of the large electric appliances (boilers, large heating appliances) in households, and indirect control is planned for the next five years. In this way, it will be possible to control from 50 to 100 MW of peak power in the distribution network.
Distribution outage management and restoration module embodies all aspects of trouble-call entry, allowing better response to consumers` complaints and queries, allowing calls to be used to aid outage analysis and priority of faults. The repair crew resource management facility ensures that the correct repair crews are dispatched to faults and optimize repair crew utilization.
This module is in the beginning stages of installation and implementation. GISs enable the automated mapping and facilities management technologies. GIS is founded upon spatial analysis concepts and can determine physical relationships between various entities. It is coupled with a relational database management system to provide the necessary link between spatial and facilities data.
Basic functions are partitioned or continuous map processing, digitization and registration, file and map analyzing and map drawing. This module also is just in the beginning stages of development and implementation.
The work order management module contains all of the functionality required to prepare, check and execute work orders, producing all of the necessary hard-copy documentation. It incorporates all of the required safety procedures of a utility and helps to ensure that standard working practices are followed.
This module is incorporated in the DMS pilot installation in Novi Sad. The distribution planning module supports network analysis, load forecasting and the interface with existing or proposed applications. It is an interactive and engineering oriented environment and provides the ability to perform applications such as capacitor siting, feeder balancing, optimal substation siting and sizing, feeder routing and conductor sizing, automated relay setting and long-term spatial load forecasting.
This Module is Being Developed
DMS modules and applications development will be performed by the Elektrovojvodina engineers in cooperation with the Faculty of Technical Sciences in Novi Sad and other Electrical Institutes in Serbia and abroad.
The technical and economic analysis has been made for the development of advanced technologies. The investment costs in the next three years will be about (U.S.) $20 million, but the expected benefits in the next 10 years are more than five times the cost. The investment will be repayable in the first two or three years.
Application of these new technologies will increase the efficiency of the existing network and postpone the building of new facilities. The remote network and load control will stabilize the power system exploitation and lessen overloading, losses and faults. The DMS development will raise the efficiency of work in each aspect of network management and contribute to technical and commercial success of the company.
If you would like to see more articles on this topic, circle R.S. 109.
For more information on this article, circle R.S. 111.