Main Components of Substation-Power Transformers

In this series of Posts we are going to Explore Main Components of Substation. We will focus on a 380 kV substations or Bulk Supply Points (BSP) that are most common in Saudi Arabia. A substation is designed to manage the transmission and distribution of electrical power at high voltages. These include several key components that ensure efficient, reliable, and safe operation. Here are the main components typically used in a 380 kV substations/BSPs in KSA:

Main Components of Substation-Power Transformers

Power Transformers

This post will overview different types of Transformers mostly used inside substations in KSA. In our next posts we will overview other Major components used inside substations.

Related posts you may like are as follows

Following Types of Transformers we most commonly use in 380kV substations in KSA

380KV Power/Auto Transformers (SGT)

In KSA, 380 kV substations commonly use autotransformers for stepping down voltage levels from 380 kV to lower levels like 132 kV/115kV/110kV & 13.8 kV. These transformers are essential for voltage transformation and provide the necessary power transfer between different voltage levels. Normally in 380kV substations inside KSA Auto Transformers are named as Super Grid Transformers SGT. The Most common Rating used is 500MVA where Client is Saudi Electricity Company and 750 MVA where Client is SWCC or Saudi ARAMCO.
The main Suppliers of Power Transformers in KSA (Approved by SEC) are following

Hitachi Energy Chongqing Transformer Company Limited, China
HD HYUNDAI ELECTRIC, Korea
Nantong Hyosung Transformer Co. Ltd, China
Siemens Energy, China
Iljin Electric Co, Korea
TBEA Shenyang Transformer Group Co., Ltd, China
Grid Solutions SAS

Note: there are no Local Manufacturers of SGTs in KSA

132KV Power/Auto Transformers (GT)

Transformers used for stepping down Voltage from 132kV/115kV/110kV to 33kv/13.8kV are referred as Grid Transformers. These are most widely used in 132kV substations. Most common Power transformers in SEC substations are below GTs are

50/67 MVA 132/33kV or 50/67 MVA 132/13.8kV

80/100MVA 132/33kV or 80/100MVA 132/13.8kV

Up to 100MVA transformers following suppliers are Approved from SEC

Saudi Power Transformers Company (SPTC) Local Transformer Manufacturer in KSA
Voltamp, Oman
Hitachi Energy Chongqing Transformer Company Limited, China
HD HYUNDAI ELECTRIC, Korea
Nantong Hyosung Transformer Co. Ltd, China
Siemens Energy, China
TBEA Shenyang Transformer Group Co., Ltd, China
Grid Solutions SAS
Iljin Electric Co, Korea

Grounding Transformers

A grounding transformer is a type of transformer that we use to provide a grounded (neutral) point to a power system that otherwise does not have a neutral. This is particularly necessary for systems that are otherwise ungrounded, such as delta-connected systems, where there is no direct path to ground for fault currents. The grounding transformer creates a reference point to ground, which helps stabilize the system voltage during transient conditions and facilitates protective relaying and fault detection.

In KSA zigzag grounding transformer is mostly used when tertiary winding of SGT is Loaded.

A zigzag grounding transformer consists of two sets of windings per phase, wound on a common core leg. The windings connected in a way that they cancel out the magnetizing flux under normal operating conditions but provide a path for zero-sequence currents during ground faults.

Grounding Transformer suppliers worldwide accepted in KSA are as follows

HD HYUNDAI ELECTRIC, Korea
Hyosung, Korea
Končar – Distribution and Special Transformers Inc. Croatia

Station Service Transformer (SST)

A Station Service Transformer (SST), also known as an Auxiliary Transformer, is a critical component in substations and power plants. Its primary function is to step down high voltage from the main power supply (such as 380 kV, 132 kV, or 69 kV) to lower voltage levels suitable for powering the auxiliary equipment and systems within the substation or power plant.

The SST provides electrical power at a lower voltage (480 V, or 230 V) to run various auxiliary systems in a substation or power plant. These systems include lighting, HVAC (heating, ventilation, and air conditioning), control and protection systems, battery chargers, communication systems, and other essential equipment.