Sevan–Hrazdan Cascade
Sevan–Hrazdan Cascade is a complex of hydroelectric power plants on the Hrazdan River and its tributaries between the Lake Sevan and Yerevan in Armenia. They use irrigation water flow from the Lake Sevan and streams waters of Hrazdan River that gives an opportunity to irrigate 70% of Armenian agricultural lands. The cascade is owned by the International Energy Corporation, a subsidiary of RusHydro.
History
The first small-scale Yerevan Hydroelectric Power Station was built in 1923.In 1932, it was replaced by Yerevan-2 HPS. The construction of the current cascade started in 1936, when the Kanaker HPS was opened. That time it was planned to built the whole cascade by 1947. In 1940, construction of the Sevan HPS started but due to World War II, construction was suspended and the HPS became operational only in 1949. The largest HPS, Argel HPS, was opened in 1953, followed by Arzni HPS in 1953, Yerevan-3 HPS in 1955, Hrazdan HPS in 1959 and Yerevan-1 HPS in 1962. The original plan included also construction of three more HPSs—Upper Argavand HPS, Lower Argavand HPSand Noragavit HPS—but these plants were never built.
In 2003 the cascade was given to Inter RAO UES in return for US$25 million debt by Armenia. For operation of the cascade, the IEC was incorporated. In 2011, Rushydro bought the IEC from Inter RAO. In November 2015 it was published that Rushydro plans to sell the IEC.
In 2019 newspaper reported, that Rushydro is going to sell at $2.7 million cascade to Tashir group, the owner of electricity distributions networks in the country. Buyer has to settle all debts running at $55.13 million by the end of September 2019.
Technical description
The length of the Sevan–Hrazdan Cascade is about and it consists of seven hydroelectric power stations, with total nominal capacity of 565 MW. The HPSs are Sevan, Hrazdan, Argel, Arzni, Kanaker, Yerevan-1 and Yerevan-3—all run-of-the-river type. The cascade produces about 10% of Armenia's electricity.The operation of the Sevan–Hrazdan Cascade is dependent on amount of water supply from the Lake Sevan and it is suitable for the daily peak generation. Five HPSs operate all year long and two HPSs work only during the irrigation season when additional water is available in the system. Therefore the power generation during the winter is limited.
The water is transported from the Lake Seven to the HPSs through open diversion canals and tunnels. Most of these canals were built in 1960s and are now under poor conditions and require rehabilitation.
Power plants
| Power Plant | Year | Number of Units | Installed Capacity | Available Capacity | Unavailable Capacity | Coordinates |
| Yerevan-3 HPS | 1960 | 1 | 5 | 5 | 0 | |
| Yerevan-1 HPS | 1962 | 2 | 44 | 22 | 22 | |
| Kanaker HPS | 1936 | 6 | 100 | 87.5 | 12.5 | |
| Arzni HPS | 1956 | 3 | 70.6 | 70.6 | 0 | |
| Argel HPS | 1953 | 4 | 224 | 168 | 56 | |
| Hrazdan HPS | 1959 | 2 | 81.6 | 81.6 | 0 | |
| Sevan HPS | 1949 | 2 | 34.2 | 24 | 10.2 | |
| Total | 20 | 559.4 | 458.7 | 100.7 |
Source: IEC, Asbarez
Sevan Hydroelectric Power Station
The Sevan Hydroelectric Power Station, is the upper power station of the cascade. It is an underground power station locating below the surface. It has two turbines with a total nominal capacity of 34.2 MW and the factual capacity of about 24 MW. Its nominal annual generation is 130 GWh, but the factual generation for the last years has been about 15 GWh. The water intake of the Sevan HPS was renovated in 2010.Hrazdan Hydroelectric Power Station
The Hrazdan Hydroelectric Power Station, known as Atarbekyan during the Soviet years, is located between the Sevan and Argel stations. It has two turbines with a total installed capacity of 81.6 MW. Its nominal annual generation is 375 GWh, but the factual generation for the last years has been about 40 GWh.Argel Hydroelectric Power Station
The Argel Hydroelectric Power Station, is located between the Hrazdan and Arzni stations. It is the largest power plant of the cascade. It has four turbines, supplied by LMZ, with total installed nominal capacity of 224 MW and available capacity about 168 MW. Its nominal annual generation is 870 GWh, but the factual generation for the last years has been about 200 GWh. The plant is important for ensuring the frequency of the Armenian power system, ensuring the emergency supply to the Metsamor Nuclear Power Plant, and supplying peak-load capacity.In May 1995, landslides caused by heavy rains destroyed one of the plant spillways and blocked the Hrazdan River channel. It was restored and reopened in 2000 and 2006 correspondingly.
Arzni Hydroelectric Power Station
The Arzni Hydroelectric Power Station is located between of the Argel and Kanaker stations. It has three turbines with total installed capacity of 70.6 MW. Its nominal annual generation is 300 GWh, but the factual generation for the last years has been about 80 GWh.Kanaker Hydroelectric Power Station
The Kanaker Hydroelectric Power Station is located next to the Rusal Armenal aluminum smelter in the Kanaker-Zeytun District of Yerevan, in between of the Arzni HPP and the Yerevan-1 HPP. It has a total installed capacity of 100 MW which consists of four turbines with capacity of 12.5 MW each and two turbines with capacity of 25 MW each, all supplied by LMZ. The nominal installed capacity is !00 MW and the factual capacity is 87.5 MW. Its nominal annual generation is 425 GWh, but the factual generation for the last years has been about 110 GWh. The plant is important for providing the peak-load capacity as also supplying Yerevan with irrigation and industrial water.The plant was rehabilitated in 1993–1995, a project financed by USAID, Energy pour l’Armenie and Aznavour pour l’Armenie. In 1995, the unit 5 and in 2000, the unit 6 were shut for the renovation, financed by the loan from KfW. These units were reopened in 2003. The renovation was carried out by Alstom Power Generation.
Yerevan Hydroelectric Power Station-1
The Yerevan Hydroelectric Power Station-1 is located between the Kanaker and Yerevan-3 stations, at the central Kentron District of Yerevan. It has two turbines with the total installed nominal capacity of 44 MW and available capacity of 22 MW. Its nominal annual generation is 210 GWh, but the factual generation for the last years has been about 50 GWh. It supplies the center part of Yerevan.Yerevan Hydroelectric Power Station-3
The Yerevan Hydroelectric Power Station-3 is located in Yerevan. It has one turbined with installed capacity of 5 MW. Its diversion channel and penstock are part of the Artashat irrigation channel.Rehabilitation project
Most part of the Sevan–Hrazdan Cascade is in bad condition. Since its establishment there had not been held any big repairs. There is a rehabilitation project going on the Sevan–Hrazdan Cascade that is predicted to be completed in 2017. The main goal of the rehabilitation project is to re-establish the initial capacity of the cascade. The planned works for the rehabilitation project include a complete reconstruction of Yerevan-1 HPP. Sevan HPP, Hrazdan HPP, Argel HPP, Arzni HPP, and Kanaker HPP will have a new electrical equipment, such as new accumulators and generators. Also the hydro units of Argel HPP, Hrazdan HPP and Kanaker HPP will be replaced.As there is a plan to dredge Yerevan-1 dam right on the biological environment—there is also a high-level risk because of increased turbidity. Another negative impact may be expected due to works and equipment transportations, which would cause pollution and noise, resulting in a social indignation. The rehabilitation process will not include any further expansion or creation of new facilities—all the work items are approved according to the plan.