Metering system for power plants of Dneprovsky cascade (2002)

March 11, 2003 Elster Metronica introduced a unique Alpha CENTER metering system for all eight Ukranian hydropower plants incorporated in the Dneprovsky cascade. The system includes several thousands of ALPHA meters.

Metering system for power plants of Dneprovsky cascade (2002)

By the end of 2002 ABB VEI Metronica has successfully completed introduction of a unique metering system for Ukranian State company "Dneprhydroenergo" which incorporates eight hydropower plants included in a well-known Dneprovsky cascade: Kievskaya, Dneprovskaya, Kremenchugskaya, etc. The system based on ALPHA CENTER metering system includes thousands of ALPHA A1600/A1300 meters, modern controllers RTU300 series, up-to-date computer equipment needed to organize the workstations, dedicated software and communications equipment (modems, multiplexers, etc.).
"Dneprhydroenergo" is the leader among power generation companies in the Ukraine and plays a noticeable part in covering the on-peak demand, control of frequency and demand within the power pool of the country. The company has 8 hydropower plants, its total installed capacity attains 3906,9 MW.

Purpose of metering system introduction

Before implementing the metering system the means of automation in power plants of the Dneprovsky cascade were practically unavailable. Meter readings were collected manually, and operators-on-duty had to regularly visit substations taking readings and handing them over to "Dneprhydroenergo" metering departments for further processing. Another reason that necessitated the introduction of metering system was associated with a highly important part played by "Dneprhydroenergo" power plants in intersystem connections and frequency control within the related power pool, and the need to cover output and demand balance in daily and maximum demand zones of the load profile in the Ukrainian power pool as a whole.

Implementation of the system made it possible to provide means of automation for commercial and technical electricity metering for all power plants, including monitoring of electricity quality parameters, and improve the on-line demand management, cut power losses and increase accuracy of electricity metering.

Realization of the metering system project allowed to secure accuracy of measurements of output and demand including power flows in intersystem connections of "Dneprhydroenergo" neighboring systems; introduce automated collection, processing and storage of obtained data; organize electricity metering in power plants and assure continuous automated monitoring of their operating modes.

Moreover, due to reduction in power losses, extra revenues were correspondingly received. It means that power losses were reduced not only due to higher metering accuracy and validity alongside with shorter time needed for data collection and processing. Introduction of the system allowed to use basic equipment in the most efficient way and improve maximum demand management, analysis, forecasting and planning of power demand depending upon various tariff zones.

The metering system that was introduced made it possible to resolve the following problems:

• attain higher accuracy, validity, integrity and prompt receipt of data on quantitative and qualitative parameters of generated, delivered and received power;
• receipt and archiving of data on power generation and consumption in "Dneprhydroenergo" grid boundary points;
• assure on-line control of execution of operator’s load profile schedule for each power-generating unit and increase operability of demand management on the whole;
• reduction of working losses;
• automation of functions used to determine output/demand balance;
• obtaining of actual daily, monthly and yearly load profile intervals of power generating units installed in all power plants based on various energy tariff systems, including real-time tariffs;
• protection against unauthorized access;
• creation of common information environment aimed at observance of commercial interests of each entity acting on the electric energy market.

Organization of electricity metering and metering system structure

On the whole, 293 supervised metering points were organized in the power plants of Dneprovsky cascade. To assure higher accuracy, all metering points were equipped with multifunction TOU meters ALPHA A1600/A1300 with an accuracy class of 0,2S and 0,5S designed for TOU tariffs based metering of active and reactive power and demand, as well as for monitoring of electricity quality parameters.

Apart from energy meters, the system includes data collection, processing and transmission units - controllers RTU-314, dispatching centers (workstations) based on Alpha CENTER software, and communications equipment. The system has a two-level structure. The lower level is represented by AMR of all power plants. The higher level – metering system dispatching center (DC) located in the office on the territory of Kievskaya hydropower plant in the city of Vyshgorod.

Metering systems installed in power plants are organized as independent structures which communicate with the dispatching center using dedicated telephone or voice-frequency channels. Power plant data on generated and consumed power is read from controllers RTU-314 by means of modem connected to communication channel. ALPHA A1600/A1300 meters, acting as a primary means of metering, are connected to RTU via digital interface RS-485. Consequently, there are two to four independent communication channels.

A dispatching center (PC based operator’s workstation) organized at every power plant and designed for controller data processing, storing and readout is located in the building where the main control panel is installed (control room of a power plant). Its functions include: presentation of electricity metering parameters in the form of displays, documenting of metering parameters in the form of output reports, presentation of information on current status and configuration of the system, provision of the system security based on a system of passwords etc. Interaction between controllers and the operator’s workstation is performed via interface RS-232. In the case the two controllers are installed, communication is realized using local area network Ethernet via multiplexer HUB. An uninterruptible power supply (UPS) is provided to assure reliable operation of PCs installed at workstations.

So, information from dispatching centers of power plant metering systems is communicated to the main dispatching center in "Dneprhydroenergo", and then to neighboring grids and other energy market entities.

Basic structural components of the dispatching center are represented by the database server, communication server, electricity metering workstations, means of telecommunications (modem pool) etc. Interaction between the dispatching center and power plant metering systems is performed automatically and includes data collection on the level of the power plant, common diagnostics of the system, and system time synchronization. In this case the process of data exchange can be adjusted so as to take place either intermittently, according to preassigned interrogation time, interval and duration, or in compliance with daily schedule of communication sessions, or on operator’s instructions.

Main functions of metering system dispatching center:

• collection of data on power generation, output, demand
• verification of data validity and data processing;
• analysis of output, demand, intersystem power flows;
• generation of database, cumulative data sheets and output reports
• compiling and evaluation of output/demand balance
• system time synchronization in the framework of metering system
• restoration of information by primary data in the event of data corruption
• diagnostics of metering technical condition
• interaction with data management departments of supervisory bodies

The metering system is capable of stage-by-stage upgrading, for instance, at the expense of a larger amount of meters and controllers that may be connected on the level of metering systems of power plants and a larger number of workstations and servers in the central control room. Alongside with this, there exists the possibility to specify and update the types and forms of output reports just in the course of operation.

Conclusion

The implementation of a fully automated electricity metering system laid a basis for reliable and efficient operation of all power plants included in the Dneprovsky cascade and "Dneprhydroenergo" itself known as a major power generation company in the Ukraine.

Perfectly due to the use of the state-of-the-art equipment and software it would be possible to provide comprehensive and highly accurate metering, prompt control of power demand, and consequently improve technical and economic indices of each power plant and reduce power losses.

Introduction of metering system also adds to formation of a unified informational basis for operation and secures commercial interests of any entity acting on the Ukrainian wholesale electric energy market.

11.03.2003