Hua-style prefabricated substations

1. Product Overview

The Longnice Hua-style prefabricated substation is a factory-assembled, base-mounted package that brings together a high-voltage compartment, a low-voltage compartment and a step-up transformer on a single structural frame. It is intended mainly for step-up duty in renewable-energy generation, where the transformer raises the output of the inverters or generators to the collection voltage of the plant.

Unlike a conventional enclosure-type package substation, the transformer is arranged outside the enclosure. Heat generated by the transformer is therefore carried away by natural air circulation instead of accumulating inside the compartments, which keeps the temperature rise inside the housing within the limits set by the applicable standards and reduces the demand on forced ventilation. The transformer is connected to the housing through side bushings and a short busbar run, and a central partition divides the enclosure into the high-voltage and low-voltage compartments, so the two functions remain electrically and physically separated.

2. Configuration
Transformer: oil-immersed or dry-type step-up transformer, mounted externally on the common base frame and connected to the enclosure by side bushings and a short busbar run.
High-voltage compartment: medium-voltage incoming and protection switchgear, closed off by the central partition.
Low-voltage compartment: low-voltage incoming, distribution and control equipment.
Enclosure: steel housing on the common base frame, complete with doors, locks and ventilation openings; lifting provisions are provided on the frame.
Earthing: a common earthing terminal is provided for the complete assembly.
3. Standards and Compliance

The unit is designed, manufactured and tested in accordance with the following standards; where a project specifies the equivalent international standard, the corresponding IEC publication applies.

Prefabricated substations: GB/T 17467 (IEC 62271-202)
Power transformers: GB 1094 series (IEC 60076 series)
Oil-immersed transformers: GB/T 6451
Dry-type transformers: GB/T 1094.11
Medium-voltage switchgear and controlgear: GB/T 3906 (IEC 62271-200)
Low-voltage switchgear and controlgear assemblies: GB/T 7251.1 (IEC 61439-1)
Degrees of protection provided by enclosures: GB/T 4208 (IEC 60529)
Grid connection of renewable plants: GB/T 19964 (photovoltaic) and GB/T 19963 (wind power)

Rated voltage, rated capacity, impedance voltage, temperature rise, vector group and degree of protection are confirmed for each project and stated on the nameplate. Routine tests are carried out on every unit before delivery, and type-test reports are available on request.

4. Typical Applications
Step-up service in ground-mounted and distributed photovoltaic power stations.
Step-up service in onshore wind farms and combined wind-photovoltaic stations.
Collection and boosting points in energy-storage plants and large new-energy bases.
Projects that need a compact, factory-assembled step-up package on a prepared outdoor foundation.