Vuoksa Cascade

The story of the most powerful cascade of the Karelian Isthmus

Seventy years ago, on August 16, 1947, the Svetogorskaya HPP was put into operation after the previously launched Lesogorskaya HPP. These two important events made possible the organization in 1949 of the Vuoksa Cascade, the most powerful source of energy on the Karelian Isthmus today. The Lesogorskaya HPP and Svetogorskaya HPP, which are part of the chain of HPPs known as the Vuoksa Cascade, are located on the Vuoksa in the Vyborgsky district, west of St. Petersburg. The most powerful river of the Karelian Isthmus, the Vuoksa flows from Lake Saimaa in Finland into Lake Ladoga.

There are four power stations on the Vuoksa in total, with the two upper ones located in Finland. Use of the river for the operation of hydropower plants is regulated by agreements between Finland and the USSR concluded in the 1970s and 1980s. Russian stations are the main source of energy supply for the Karelian Isthmus, with an annual output exceeding 1 billion kWh.

Moving home

Both Russian stations, with their unusual history, are closely related to the military history of the USSR. Until 1940, the Lesogorskaya HPP was located on Finnish soil; then it was called Rouhiala. Finnish specialists began construction in 1934, the first unit was commissioned in March 1937, and by the end of that year the hydroelectric power plant had reached its full capacity. The original name of the station was changed in 1940, after it became part of the USSR after the Winter War between the Soviet Union and Finland. During World War II, the station was partially destroyed. Restoration work began almost immediately after the liberation of the Leningrad region, and on December 19, 1945, the HPP was put back nto operation.

Today, the installed capacity of the Lesogorskaya HPP is 118 MW, and its average annual power generation is 613.38 million kWh. The Svetogorskaya HPP is located downstream of Vuoksa near Svetogorsk. Just like the Lesogorskaya station, it ended up in the USSR in 1940 after the Winter War. Its construction began in the late 1930s as a Finnish project. After eastern Karelia was taken by the USSR, the project was reworked and construction continued. In August 1941, the HPP was captured by the advancing Finnish troops, and Finnish engineers continued construction on the Soviet project. In April1944, they conducted a test run of the equipment. However, a few months later, the unfinished hydroelectric power station was retaken by Soviet troops, and Russian workers completed it in 1947.

The station was integrated into the structure of the Vuoksa Cascade in 1949 and at the same time its name was changed from Enso HPP to its current one. Today, its installed capacity is 122 MW, and the average annual power generation is 554.6 million kWh.

A time of renewal

Ten years ago, in 2007, Power Machines signed an agreement with the company TGC-1 for the reconstruction of the stations of the Chain of Vuoksa HPPs. This project has become one of the most significant for our company in recent years. Since commissioning, the units of both stations had operated for more than half a century, and the question of their replacement was overdue. Eight new hydroelectric units were required: four per HPP. Our company carried out designing, production, testing and delivery of the equipment, and conducted installation supervision and commissioning.

Assemblies for the hydroelectric units were produced at the Leningrad Metal Plant and Elektrosila plants. The new equipment at both stations was identical, which permitted the strict scheduling of outflow and even load distribution.

The first modernized unit of the Svetogorskaya HPP was put into operation at the end of 2009. The turbines and generators were replaced by more powerful ones: 30.5 MW instead of 23.25. A special scheme for the turbine installation inside a concrete block made it possible to place it in existing building structures.

To achieve higher performance, the flow section of the Lesogorskaya HPP was altered – this required laborious drilling and blasting operations. The number of impeller blades was also increased and a unique turning mechanism was introduced. As a result, the maximum capacity of the turbine has been increased by more than 30% compared to the old unit. Additionally, the plants have become much more environmentally friendly: the design of the new turbines has eliminated the possibility of technical oil getting into the flow section.

The reconstruction of the Vuoksa Cascade was completed on December 18, 2013, on the eve of Energy Day, when the last of the eight Lesogorsk units was commissioned with full honors and celebrations.