EVNPECC4 accompaniesTrung Nam Group to finish the largest wind power plant project in Vietnam

On October 31^st, 2021 in Ea Nam Commune - Ea H'Leo District - Dak Lak Province, Ea Nam Wind Power Plant with a capacity of 400MW was successfully connected to the grid with 84/84 turbines. This is the largest capacity wind power project installed in Vietnam which has been successfully energized. The plant was invested by Trung Nam Dak Lak 1 Wind Power Joint Stock Company (belonging Trung Nam Group) and designed by Power Construction Consultancy Joint Stock Company 4 (EVNPECC4).

This project was included to the amended Power Master Plan VII following Document No. 795/TTg-CN dated June 25^th, 2020 by the Prime Minister and approved by the People’s Committee of Dak Lak Province by Decision No. 3282/QĐ-UBND on December 31^st, 2020. According to Mr. Ngo Giang Dong - Project Manager, this is the key wind power project of Dak Lak province, following Decision 39 of the Prime Minister about wind power development and Resolution 55 of the Politburo about the national energy development strategy. Dak Lak Provincial People Committee agreed to deploy in Resolution 14-NQ/TU about the development of renewable energy of the province. Hence, the investor determined to put the full force to advance the power generation before October 31^st, 2021.

Ea Nam wind power plant with total capacity of 400 MW, is the largest operating onshore wind power project in Vietnam. Presently, the turbine used for this project (E138 and E160 with capacity of 4.2MW and 5, 5MW) - the largest capacity in Vietnam and provided by Enercon.

Implemented by EVNPECC4 - the leading unit in energy investment consulting, particularly in renewable energy sector in Viet Nam, this project has reached the record of progress in survey and design. The project consultancy team of more than 50 engineers and experts, together with the investor, worked continuously for almost one year to complete the project dossier from the technical design, design of the construction drawing, and solved all arising problems in the construction site in order to meet the deadline.

The project was being implemented at the technical design stage. However, with great intention to meet the deadline and ensure the quality of design documents, the EVNPECC4 power system calculation team reviewed the technical calculations of the FS stage, especially updated the power system configuration, verified calculations, made technical proposals to help the Investors reduce investment costs and save project implementation time. Consequently, the construction work on COD was speeding up. Those technical proposals included convincing the EVN to change the technical solution and eliminate the need to upgrade or replace the 30.5 Ohm series capacitor - 2000A at Di Linh 500kV station to a higher rated current. This resulted in saving the investment cost of roughly VND 200 billion as well as shortening the time in reaching an agreement with the 500kV power grid operation management agencies.

As 84 turbines were arranged in different geological conditions, some of them were placed directly on the bedrock, while others required a pile foundation up to 40 meters deep. The piles used for the project included high-intensity prestressed piles (PHC), D1000mm - D1200mm drilling piles. Turbines’ based foundations were designed with 450-600 armoured ferroconcrete diameter of 22.0m-26.8m, depending on geological conditions and turbine capacity at each location.

The connection of wind turbines - with almost 100 kilometers of 33kV tranmission lines including many branches of over 10km and the installation of the wind turbines that far from the substation obstructed the ability to adjust their reactive power. Turbines locating far from the connection point can reach the voltage values of over their abnormal operating range (90-110% of nominal voltage at the generator terminal), leading to operation under to Fault Ride Through mode (FRT Capability), and trip the generator after a period of overvoltage or undervoltage operation. Engineers of the R&D Center had studied and known that this phenomenon would occur due to the voltage discrepancy on wind turbines with long-distance connection to the connection point at the substation. Acknowledge this issue is, new problem arising issue for the wind power plants, unlike conventional power plants. Simulation was conducted by software and EVNPECC4 proposed solutions including equipping reactive power compensation devices such as SVC or STATCOM, and operation mode for the turbines based on their positions.

There were 22 of 33kv tranmission lines connecting the turbines to the 500kV substation, including many sections that have to go underground to get through to 220kv lines, 500kv, and enter 500kv substation (shared approximately 16 circuits). That number of combining underground cables which were also very closed to each other would reduce the load capacity of the lines. Therefore, to reduce equipment costs and ensure transmission capacity, the criteria for suitable the underlying cables and how to optimize the installation as well as the distance in the layout were calculated and measured by specialized software for underground cable calculations to achieve the most accurate and effective results.

The project has total investment cost of 16,500 billion VND with expected annual generation yield of approximately 1,173.6 GWh. Once project operates, the investor shall contribute over 3.000 billion of corporate income tax to the province's budget and 250 billion VND of VAT each year. Ea Nam Wind Power Plant will play an important role in reducing air pollution and greenhouse gas emissions and creating jobs for hundreds of local workers, making a significant contribution to the socio-economic development of Ea H'Leo district as well as Dak Lak province.