Prefabricated Boost Transformer Substation Solution for Photovoltaic Power Plants in Skid-Mounted Design

The Rockwell Energy modular prefabricated step-up substation integrates medium-voltage switchgear, step-up transformers, and low-voltage distribution into a steel frame that has been factory-assembled and undergone routine testing.

Upon arrival at the site, it can be “put into operation immediately”—shortening the grid connection cycle from the 3–6 months typically required for conventional substations built on-site to about 2 weeks. The amount of civil construction is reduced by 70%, and the open-air natural air-cooling system allows the transformer to operate at full capacity without derating.

1. Why do photovoltaic projects lose revenue at the step-up substation stage?

• Mismatch in construction schedules: While components and inverters can be installed within a few weeks, the 35kV civil engineering and step-up substation takes 3 to 6 months, making it the sole critical path for grid connection.
• Remote sites: weak construction capabilities, numerous concurrent operations, and uncontrollable on-site installation quality.
• Phased expansion: Each phase repeats the civil engineering cycle, making capacity expansion uneconomical.
• On-site operations and maintenance are challenging: power stations are scattered, and there’s a shortage of maintenance personnel.

Taking a 100 MW power plant as an example, each month of delay results in a loss of approximately 1% of annual power generation (this is a rough estimate; the actual figure will depend on project-specific calculations).

II. Standard Product Platform (Committed Values, Not “Examples”)

The capacity is selected according to the standard series during the engineering design phase; the platform value will be delivered as promised.

III. Traditional Civil Construction vs. Rockwell Energy Skid-Mounted Systems (Quantitative Comparison)

4. Engineering Configuration and Grid-Connection Support

• Primary System: Incoming line (ring main/switchgear cabinet, SF6-insulated) → Step-up transformer (oil-immersed) → Low-voltage distribution (400–800V, multiple configurations including circuit breakers/fuse disconnect switches), supporting either string inverter combiner or direct connection to centralized inverters;
• Grid-connection protection and setting value services: Transformer protection, feeder overcurrent protection, and grid-connection protection are configured according to IEC 60255. A set of factory-delivered setting value sheets is provided, and communication interfaces with the substation control AGC/AVC (IEC 61850 / Modbus) are reserved to meet the grid’s requirements for active and reactive power regulation.
• Reactive power support (optional): SVG or capacitor banks can be integrated according to the requirements of the connection point, and the compensation capacity shall be verified based on the PCC voltage requirements.
• Environmental support: shade canopy, temperature control, fire alarm linkage, and full-site monitoring.

V. Acceptance Criteria (Verifiable, Anchored to Standard Clauses)

Six: Why Choose Rockwell Energy?

• Routine factory tests for each skid-mounted unit: Complete test list provided, with report delivered along with the goods.
• One-stop grid connection protection: Setting value adjustment, testing, and AGC/AVC interface integration are all handled by a single provider, reducing conflicts and disputes among multiple vendors.
• Regional Delivery Records: Available for customer reference in the African, Southeast Asian, and Mongolian markets.
• Digital Operations and Maintenance: Remote monitoring via IEC 61850 / Modbus, with alarm integration into the power plant SCADA system.