46MW Run-of-River Hydropower Plant Construction Project
KeRun provided complete power solutions for a 46MW Run-of-River Hydropower Plant in Nepal, overcoming challenging terrain and boosting clean energy.
Nepal is working to balance trade through its “Platinum (Hydropower)” export plan. This project is part of the Nepal Electricity Authority’s (NEA) key planning. KeRun Intelligent Control Co., Ltd. overcame extreme terrain and transportation limitations to provide a complete boosting and distribution solution for two 23MW impulse turbine generator sets, successfully delivering clean hydropower to Kathmandu’s grid, located 70 km away.
Project Introduction and Supply Scope
For a total installed capacity of 2×23MW, we followed N-1 safety criteria and plant power needs. The detailed supply list includes:
A. Main Transformer System
Equipment: Two 28MVA 132kV/11kV three-phase oil-immersed dual-winding step-up transformers.
Quantity Logic:
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Unit Connection: Each 23MW generator directly connects to a 28MVA main transformer.
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Capacity Match: Generator power is 23MW. Assuming a power factor of 0.85, the apparent power is approximately 27MVA. Considering high-altitude derating, we selected 28MVA transformers for an excellent safety margin.
B. Plant Power System
Equipment: Two 800kVA 11kV/0.4kV epoxy resin cast dry-type transformers.
Quantity Logic:
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1 running, 1 standby. These transformers power the dam gate hoists, governor oil pumps, plant lighting, and excitation system. We use dry transformers for fire safety and place them directly inside the plant.
C. Residential Area Distribution
Equipment: Ten 100kVA 11kV/0.4kV pole-mounted oil-immersed transformers.
Quantity Logic:
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Given the scattered nature of residential areas in the mountains, we deploy small capacity transformers distributed widely.
D. High and Low Voltage Complete Equipment
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11kV Side: 14 units of KYN28-12 metal-clad switchgear (including generator outlet circuit breaker, PT cabinet, excitation transformer cabinet).
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132kV Side: We provide matching relay protection panels and outdoor circuit breaker control cabinets.
4. Design Logic and Principles
Hydropower in Nepal faces core challenges like “thin air” and “geologically active regions.”
1. High Altitude Insulation Correction Logic
Principle: At 2,800 meters, air pressure is thin, causing a decrease in breakdown voltage. Standard 132kV equipment insulation is insufficient at this altitude.
Solution: We upgraded the insulation of the 132kV transformer bushings and external insulation. We designed the creepage distance and air clearance based on a 4,000-meter altitude standard. The actual withstand voltage level reaches an equivalent of 170kV in plain areas, eliminating “mountain corona” discharge issues.
2. Seismic Damping Logic
Principle: Nepal lies on the boundary between the Indian and Eurasian tectonic plates, resulting in high seismic intensity.
Solution: We use a “six-point positioning” hard connection for the transformer body, and we fit the oil tank with a horizontal shock-absorbing base. Our calculations passed a 0.5g horizontal acceleration seismic simulation, ensuring the equipment experiences no displacement or tilting during an 8-magnitude earthquake.
3. Extreme Cold Start Logic
Principle: Winter temperatures can drop to -15°C, reducing transformer oil flowability.
Solution: We chose naphthenic transformer oil with a pour point of -45°C and equipped the transformer with an intelligent control box featuring automatic heating functions to prevent freezing of secondary circuit components.
Nepal Market Research and Technical Insights
KeRun fully understands the uniqueness of the Nepalese market:
Transportation Limitations Research
Research: The road from Chinese ports to the project site is winding, and bridge weight limits are 40 tons.
Solution: We designed the 28MVA main transformer with a “slimmed-down” approach. We made the radiators and oil tanks detachable to keep the transport weight under 35 tons, ensuring safe passage over fragile bridges.
NEA Grid Connection Standards
Research: Nepal’s grid frequency is highly unstable (48.5-51.5Hz).
Solution: Our magnetic circuit design uses a low magnetic flux density (1.65T). Even with frequency drops, the core will not saturate and overheat, preventing transformer shutdowns that could stop the entire plant.
Product Advantages and Selling Points
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“Snow Domain Custom” Insulation: We designed it for the climate near the southern slopes of the Himalayas, featuring UV-resistant insulation bushings.
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Zero Maintenance Breathing System: We use a maintenance-free dual-stage silica gel dehumidifier, ideal for high humidity foggy areas. The silica gel does not require replacement for three years, reducing the operational burden for local staff.
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Modular On-Site Assembly: We designed the transformers for “foolproof” flange connections. Even in mountain gorges with no large cranes, installers can quickly assemble the components using simple gantry cranes.
Procurement Considerations
Nepal, being a landlocked mountainous country, has a long and unpredictable logistics chain. To protect both parties’ interests, we apply strict export terms:
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Prepayment Policy: A 30% prepayment is required within 10 business days after contract signing.
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Reason: This covers the procurement of copper, silicon steel, and other bulk materials, as well as custom components like high-altitude bushings.
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Balance Payment Before Shipment: The remaining 70% balance must be settled after the equipment passes the FAT (Factory Acceptance Test). Only then can shipment be arranged.
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Reason: Custom high-altitude equipment cannot be sold to other clients once manufactured.
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Delivery Terms: Only FOB or EXW are supported.
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Reason: We handle precise manufacturing and port shipment within China. The cross-border logistics from Chinese ports to Nepal involve complex agreements through India, so we recommend that the buyer arranges a specialized logistics provider in Nepal.
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Why Choose KeRun Intelligent Control for Nepal?
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Master of High-Altitude Physics: Many manufacturers from plains fail to understand Paschen’s Law, causing their equipment to fail in the mountains. KeRun has over 500 transformers operating in the Tibetan Plateau and can replicate our successful “Tibet solution” for Nepal.
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Extremely Compact Size Control: We understand the narrow mountain roads in Nepal. We know how to design transformers that are as compact as “compressed biscuits” without sacrificing performance, ensuring they fit into trucks without getting stuck.
Value-Added Services: Himalayan Energy Architect
We provide not only hardware but also strategic support for Nepal’s energy security:
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Cross-Himalayan Grid Interconnection Consulting: As part of China’s power grid ecosystem, KeRun offers top-level consulting on the “China-Nepal Interconnection Project.” We ensure that the 132kV equipment we deliver can seamlessly connect with China’s Tibet grid or India’s grid, enhancing the strategic export value of the plant.
