Latvenergo Group generates most of the electricity at three largest Daugava HPPs in Latvia, ensuring an environmentally friendly way of electricity generation They operate on water – a renewable energy resource.
Although the installed capacity of generation facilities at hydropower plants is high, their ability to generate electricity depends on the water inflow in the Daugava River. Daugava HPPs operate at full capacity during the spring flooding season, which lasts for about one to two months annually. Water inflow in the Daugava River during the spring flooding may more than 10 times exceed the water inflow during low water periods (mainly in summer). During the spring flooding, Latvenergo Group is able to cover the entire customer demand for electricity and trade the excess on the electricity exchange. Outside the flooding season, Daugava HPPs provide for a possibility to accumulate water and generate electricity when the demand and prices on the power market increase.
Plavinas HPP and Riga HPP can also operate in synchronous compensator mode (adjusting the voltage in high-voltage electric networks), allowing the transmission system operator to ensure a certain voltage quality.
In 2016, Daugava HPPs generated 2,449 GWh of electricity, which constitutes 52% of the total electricity output of the Group. Due to higher water inflow in the Daugava River, the amount of electricity generated was 36% higher compared to the previous year.
Latvenergo Group continues with gradual overhaul of the old hydropower units at Daugava HPPs. The main purpose of the reconstruction project is to replace the outdated hydroturbines and increase the installed capacity, efficiency rate and electricity output. This promotes reliable, efficient, sustainable and competitive operation of Daugava HPPs within the overall energy system and liberalised electricity market.
Out of the 23 Daugava HPPs hydropower units, twelve are already modernised. The process of the hydropower unit reconstruction is scheduled for completion in 2022, and the total reconstruction costs of the 11 hydropower units yet to be reconstructed are expected to exceed EUR 200 million. The plans are to complete the reconstruction of one Plavinas HPP and one Kegums HPP hydropower unit in summer Other Reconstruction of hydropower units 2017, and one Plavinas HPP and one Kegums HPP as well as two Riga HPP hydropower units in spring 2018.
Plavinas HPP plays a very significant role in the Latvian energy system – with ten hydropower units, whose total installed capacity is 894 MW, it is the largest hydropower plant in the Baltics and one of the largest in the European Union.
Plavinas HPP began operation in 1968. This structure is unique – it was proven for the first time that it is practically possible to build a medium head power plant on soft ground.
During 1991–2001 overhaul of five hydropower units was carried out. The process of hydropower unit reconstruction was continued during 2007-2010, in this period, another three hydropower units were overhauled. Along with the reconstruction of the hydropower units, the plant efficiency improved and the amount of electricity generated from renewable sources was also correspondingly increased.
In 2016, Plavinas HPP generated 1,386 GWh of electricity, which is 57% of the amount generated by the Daugava HPPs.
Riga HPP started operation in 1974/1975, and it is the youngest of the Daugava hydropower plants. It has 6 hydropower units with the total capacity of 402 MW.
In Riga HPP, great attention is paid to the safety of hydro-technical structures: the safety of the earth dam has been improved; constant restoration is carried out for the concrete surfaces of the Riga HPP structures and buildings.
In 2016, the Riga HPP generated 588 GWh of electricity.
Kegums HPP was constructed during the first period of independence of Latvia, and the year 1939, when its first hydropower unit was put into operation, can be considered the beginning of the Latvian power engineering, also marking the beginning of the history of Latvenergo Group.
In fact, this structure is a complex of hydropower plants, since it consists of two plants constructed in different periods. The first of them is located on the right bank of the Daugava River, while the second was built on the left bank, installing three new hydropower units which were commissioned in 1979.
During 1998-2001, the reconstruction of all four hydropower units of the first Kegums plant was carried out, and their control systems were automated.
The total capacity of Kegums HPP is 240 MW, and in 2016 it generated 475 GWh of electricity.