Emergency Power Grid Recovery in Ukraine

KeRun delivered hybrid power equipment for Ukraine’s emergency power grid recovery, ensuring reliable winter power supply in conflict zones.

Project Scope and Supply Range

For the two 22.2 MW hydro-generator units, we designed a classic “one-generator-one-transformer, high-voltage bus” main connection scheme:

A. Core Step-Up System

• Equipment: Two 25 MVA 110 kV/10.5 kV three-phase oil-immersed dual-winding on-load tap-changing power transformers.

• Quantity Logic:

  • Capacity matching: The generator power is 22.2 MW with a power factor of 0.9, making the apparent power approximately 24.6 MVA. We selected 25 MVA standard transformers, achieving 100% matching without waste.

  • Unit connection: We connect each generator directly to one main transformer, stepping up 10.5 kV generator voltage to 110 kV transmission voltage.

  • On-load tap changer: Considering the large power fluctuations between dry and wet seasons, we configured a ±8×1.25% OLTC to stabilize output voltage.

B. Station Service and Auxiliary System

• Equipment: Two 630 kVA 10.5 kV/0.4 kV epoxy resin cast dry-type transformers.

• Quantity Logic:

  • Mutual backup: One transformer powers the station gate oil pumps, lighting, and excitation systems, while the other remains on standby. If the main supply fails, the backup transformer automatically switches in to prevent a total station blackout and runaway accidents.

C. High- and Low-Voltage Switchgear

• Generator outlet side: 16 sets of KYN28-12 (10 kV) metal-clad withdrawable switchgear (including generator outlet breakers, PT cabinets, and excitation transformer cabinets).

• 110 kV high-voltage side: One set of 110 kV GIS interface cabinet.

  • Logic: Due to the limited flat land in the high-altitude canyon area, we recommended using a compact GIS solution instead of building a large outdoor switchyard. Our equipment perfectly matches the GIS interfaces.

Design Logic and Principles

In Ukraine, the focus of the project was not on aesthetics, but on “Survival” and “Compatibility.”

1. “New Wine in Old Bottles” Voltage Compatibility Logic

• Current Situation: The electrical grid in the target area was designed according to the Soviet-era 150kV standard (different from Europe’s 132kV or China’s 110kV).

• Solution: We kept the 150kV voltage interface parameters to ensure direct connection with existing old high-voltage lines, while adopting IEC 60076’s energy-efficient standards internally. This avoided the high cost and time required to replace the entire transmission line, enabling an “in-situ replacement.”

2. “Anti-Fragmentation” Defense Design Principle

• Current Situation: The substation faced the threat of shell fragments and shockwaves.

• Solution: We increased the transformer oil tank wall thickness by 40% (from the standard 10mm to 14mm). The radiators were designed as detachable and independently arranged (connected by flexible oil pipes). If a radiator is punctured by shrapnel, the valve will automatically close, ensuring the main oil tank remains unaffected and the transformer can still operate for a short period.

3. “Fast Installation” Logic

• Current Situation: The power had to be restored before the harsh winter set in, and the site lacked large lifting equipment.

• Solution: We used aviation plugs (Plug-and-Play) for all secondary wiring, eliminating the need for on-site wire stripping. Each transformer was designed with lifting ears, allowing for easy installation by a single truck-mounted crane within 4 hours without the need for complex pulley systems.

Product Features and Local Insights for the Ukrainian Market

• Unique 150kV System:

  • Research: We identified that the region’s 150kV system is one of the few in Ukraine. Using 110kV equipment would result in a failure, while using 220kV equipment would be both expensive and cause under-voltage operation.

• Severe Frequency Fluctuations:

  • Research: Due to the ongoing conflict, the Ukrainian grid often disconnects, with frequency fluctuating between 45Hz and 52Hz.

  • Technical Insight: Ordinary transformers can overheat and saturate at low frequencies (<48Hz). We used high-permeability silicon steel (Hi-B) and reduced the design flux density by 15%, ensuring that the transformer operates effectively even when the grid frequency drops to 45Hz.

• Cold and Muddy Conditions:

  • Technical Insight: Ukraine’s winters are cold and muddy. All outdoor switchgear cabinets were coated with C5-M grade anti-corrosion coating and raised by 500mm at the bottom to prevent snow and mud accumulation.

Why Did Ukraine Choose KeRun Intelligent Control?

• Willingness to Customize 150kV Transformers Quickly: Siemens and ABB were busy with European orders and unwilling to adjust their production lines for a few non-standard 150kV units. KeRun demonstrated the ultimate flexibility of Chinese manufacturing.

• A Business Partner Unaffected by Politics: We focus on infrastructure for the public good and provide purely technical solutions without attaching any political conditions.

• Cost-Effectiveness and Stocked Spare Parts: Our prices are 60% of those of similar European products, and we maintain a spare parts warehouse in Poland, allowing some common components to be delivered to Ukraine’s border within a week via land transport.

Value-Added Services: The Technical Spark for Energy Reconstruction

We don’t just sell equipment; we help rebuild confidence:

• “LEGO-style” Repair Kits: We provided a free “easy-to-replace parts repair kit” (including bushings, seals, and relays) with each transformer. Even in a logistics-disrupted environment, on-site engineers can use these parts to fix 90% of common faults.