By Arturs Tiesnieks, Latvenergo, Riga, Latvia,
and Jay Etherton, GE Power Systems, Melbourne, Florida, USA
Improving power system reliability and efficiency is a key objective of the Baltic states. Latvenergo is therefore installing a state-of-the-art energy management system to modernize the network that serves over one million people.
Latvia’s state-owned power company, Latvenergo, recently joined its counterparts in neighbouring Estonia and Lithuania in updating ageing, Soviet-era control systems with a GE state-of-the-art energy management system to improve power system reliability. Movement toward privatization and a free electricity market in the Baltic region is spurring efforts by the national power companies to find ways to become more competitive.
Latvenergo, a state joint stock company and one of the Baltic region’s largest companies, provides power to more than one million customers in Latvia and participates in the Baltic Interconnected Power System, a 330 kV transmission network integrating the power supply systems in Latvia, Estonia, Lithuania, Russia and Belarus. Power transfers from the independently operated power systems are coordinated by the DC Baltija dispatch centre located in Riga, Latvia’s capital.
Latvenergo’s three hydroelectric plants on the Daugava River – Kegums HES, Plavinas HES and Riga HES – and two thermoelectric plants in Riga – Riga TEC-1 and Riga TEC-2 – have a total capacity of 2046 MW and produce about 68 per cent of the energy consumed in Latvia. More than 70 per cent of the power supply comes from the hydropower stations, whose annual power production fluctuates between 1800 GWh and 4600 GWh, depending on the river’s water volume. Power is imported from Estonia, Lithuania, Russia and Belarus during off-peak hours and exported to Lithuania during peak periods.
The company’s transmission network consists of more than 5000 km of 330 kV and 110 kV high voltage overhead lines, 26 km of 110 kV cable lines and 127 330 kV and 110 kV substations.
Figure 1. Latvenergo participates in the Baltic Interconnected Power System, which integrates Latvia, Estonia, Lithuania, Russia and Belarus
Seven distribution network subsidiaries deliver power to Latvenergo’s customers via medium and low voltage aerial lines, cables and transformer substations.
Latvenergo is engaged in a large-scale effort to modernize its entire power system infrastructure to become more efficient in the production and delivery of electricity. The company was recently reorganized into three strategic divisions for generation, transmission and distribution, and significant investments are being made in state-of-the-art information technologies in all parts of the business. New systems are currently being implemented for enterprise resource planning, energy management, geographical information/distribution management, customer service and billing, and automated energy meter data acquisition.
Figure 2. Latvenergo’s Riga TEC-1 thermoelectric power plant
Improving power quality and reducing power losses are two of the company’s transmission network priorities. To improve the reliability of power transmission to Latvian consumers and to the Baltic power grid, Latvenergo is replacing its existing data acquisition system at its national control centre in Riga with a GE Network Solutions XA/21 supervisory control and data acquisition/energy management system (SCADA/EMS).
More than 20 years old, the existing system is obsolete and requires manual switching of circuit breakers to control power dispatch. Maintenance of the system was becoming more and more expensive, requiring specially trained people and hard-to-find spare parts. Most importantly, the old system was unable to support any data exchange with modern control systems in the power plants and substations or with other control centres, and made it very difficult to develop and implement any kind of power network optimization applications.
Following a competitive bid process, Latvenergo selected the GE Network Solutions XA/21 product based on its superior technology. The installation process for the project – the company’s first with an American company – began in June of 2000. The new system is expected to be fully operational by July 2002.
The XA/21 system is simultaneously being installed at Rigas ET, a Latvenergo distribution subsidiary in Riga, and at DC Baltija, a joint venture of the three Baltic power companies, Latvenergo, Eesti Energia and Lietuvos Energia. Availability testing is due to begin in the summer of 2002 at Rigas ET. DC Baltija’s new system became operational in May 2002.
Figure 3. The new SCADA/EMS system allows data exchange between the national control centre and power plants and substations
The XA/21 system was also installed several years ago in the national control centres at Eesti Energia and Lietuvos Energia.
The XA/21 system enables real-time monitoring, control and optimization of power generation and high voltage transmission networks. The system consists of data acquisition and control, power network applications, a database and a graphic user interface, which provide the basic framework for day-to-day operation and maintenance of the generation and transmission grid. Fully configurable for specific functions, it can be scaled from a single-node system up to dozens of processing nodes interconnecting geographically dispersed systems, providing the flexibility to expand the system to meet growing operational needs. The system’s distributed processing architecture also allows it to be integrated into a utility’s enterprise system to provide unified data across the business using a single system image with a single point of maintenance.
While the basic SCADA system is the same for all three projects in Latvia – Latvenergo, Rigas ET and DC Baltija – the features and functionality vary based on the application. At Rigas ET, for example, the system has user interface, SCADA and datalink features, but no power network applications, and is designed to interface with a geographical information system, while the DC Baltija SCADA/EMS system also has a subset of power network applications and primarily receives data via links to the SCADA systems of the national power companies. DC Baltija, Latvenergo and Rigas ET all have ICCP data-link functionality, while Latvenergo and Rigas ET also have Elcom 90 data-link functionality.
Latvenergo elected to install a relatively standard version of the XA/21 system for transmission applications to gain the benefits of field-tested software and to avoid the cost of additional custom software development. In addition to the XA/21 system, Latvenergo has an interconnected dispatcher training simulator node as well as an emergency control centre system.
Figure 4. The system provides the framework for day-to-day operation and maintenance of the power network
The new system includes an emergency backup control centre in a second location in Riga to be used in the event the main control centre becomes disabled. This system is a duplicate of the primary XA/21 system in functionality.
In addition to delivery of the XA/21 system itself, 21 remote terminal units (RTUs) were delivered by GE Energy Services for installation and commissioning at the Latvenergo control centre. RTU installation support and supervision were provided by Sigma Telas, a local regional supplier of RTU services located in Lithuania.
Building the system
Within several months of the initial contract signing, Latvernergo began building its database and displays in Riga, using a small, preliminary development system provided by GE. This information was continuously fed to the GE Network Solutions operation in Melbourne, Florida, USA, for integration into the larger system under construction there. The periodic submittal of the customer’s database from the development system to the main XA/21 system in Melbourne allowed GE to batch in customer inputs for schematic and syntactic verification, exporting from the development system and importing to the XA/21 system. This ensured syntax, point linkages, and sizing were verified and corrected in time for factory acceptance testing.
During the project, Latvenergo personnel attended training in Melbourne to become knowledgeable about the various software subsystems and user interfaces. Training covered XA/21 program development, data-link applications, database/display building, XA/21 tools/utilities, historical applications system basics/architecture, and power network applications.
Once the total system software integration and pre-acceptance testing were completed in the autumn of 2001, GE and Latvenergo conducted factory acceptance testing to ensure that the system was fully functional and met Latvenergo’s requirements prior to shipping to the customer site. One of the biggest challenges encountered with the project was the Latvian localization character set to be supported by the system. This became a ‘learn and resolve as you go’ task as it applied to applications such as user interface, operating systems, XA/21 software, Oracle, and the database. Latvenergo played a significant role in supporting GE through this process and in the understanding of the Latvian localization character set.
The system was shipped to Riga in December 2001 for installation at the Latvenergo control centre. Site acceptance testing of the system to ensure that it was working and interfacing properly was completed in January and February 2002, with site acceptance testing discrepancy resolution successfully completed in April 2002. Latvenergo personnel are now in the process of commissioning the system’s 21 RTUs in preparation for availability testing to ensure system stability. Then, the old system will be decommissioned and the new XA/21 system will assume the monitoring and control of Latvenergo’s transmission system.