Gobi Power Grid Challenge | Goldhome (Goldhome Successfully Completes On-Site AC Withstand Voltage Test for the Entire 220kV Shizuishan Substation in Ningxia Using Its In-House Developed Series Resonant AC Withstand Voltage Test System
Recently, the high-voltage testing technical team from Goldhome (Wuhan Goldhome) traveled to the newly constructed 220kV substation in Shizuishan, Ningxia. Equipped with their self-developed variable-frequency series-resonant AC withstand voltage test system, the team successfully completed comprehensive AC withstand voltage acceptance tests on the substation's entire set of primary equipment, including the main transformer, GIS (Gas-Insulated Switchgear), high-voltage bushings, and current transformers. All equipment passed the insulation strength assessment on the first attempt, establishing a solid safety foundation for the substation's on-schedule commissioning and fully demonstrating the stability of Goldhome's high-voltage testing equipment and its professional on-site service capabilities under the complex outdoor conditions of Northwest China.
Located in the Gobi Desert region of Northwest China, Shizuishan, Ningxia, experiences significant day-night temperature fluctuations and frequent sandstorms. As a core regional transmission and distribution hub, this 220 kV substation is responsible for supplying power to local industrial loads as well as urban and rural residents. AC withstand voltage testing is the final acceptance test for insulation inspection prior to a substation's commissioning. In accordance with the GB 50150 and DL/T 596 standards, it rigorously evaluates the main insulation strength of all capacitive high-voltage equipment throughout the substation, accurately identifying hidden defects such as moisture ingress, internal bubbles, and installation damage. This is a critical process for preventing insulation breakdown and short-circuit failures after commissioning.
GIS and main transformers at the 220 kV voltage level are high-capacitance test specimens. Traditional power-frequency withstand voltage testing equipment suffers from issues such as bulky size, insufficient on-site power supply capacity, and difficulties in transportation and setup. After multiple rounds of equipment selection and comparison, the project team ultimately chose Goldhome Guodian Huamei's integrated variable-frequency series resonant withstand voltage system. Leveraging the technical advantage of "generating high voltage from a small power source" through resonant technology, the system adapted to the limited on-site construction power supply, significantly reducing the difficulty of on-site operations.
Efficient On-Site Execution: Entire Withstand Voltage Test Passed on the First Attempt
Upon arrival at the site, the Goldhome technical team rapidly completed equipment installation, safety barrier setup, and grounding system installation. They strictly adhered to high-voltage testing safety regulations to demarcate high-voltage hazard isolation zones and implemented a system of continuous supervision and dedicated personnel on duty.
Standardized, step-by-step voltage application ensured controllable data throughout the process
The equipment utilizes a fully automated intelligent variable-frequency control system that automatically searches for the resonance point and applies voltage at a constant rate from zero throughout the entire process. First, the voltage was raised to the conditioning voltage and maintained for an extended period to remove internal metallic impurities from the equipment; then, it was incrementally increased to 252 kV and held steady; finally, it was raised to the rated test voltage of 460 kV and maintained for 1 minute. Voltage, current, and leakage current curves were monitored in real time, with no flashover, abnormal noises, or breakdown observed throughout the process.
Integrated Continuous Testing of Multiple Devices
A single system sequentially completes withstand voltage testing for all equipment categories-including 220 kV main transformers, three-phase GIS bays, high-voltage CTs/PTs, and feeder bushings-eliminating the need to switch between multiple test sets. This significantly reduces on-site testing time, allowing a two-day testing task to be fully completed within a single day.
Adapted for Windy and Sandy Outdoor Conditions in Northwest China
The entire equipment cabinet features a thickened, dust-proof, and corrosion-resistant coating, while the reactors and voltage dividers have fully enclosed insulated structures. Resistant to wind and sand as well as extreme temperatures, the system operates continuously and stably at open-air construction sites in the Gobi Desert, with an extremely low voltage waveform distortion rate and stable, controllable measurement accuracy.
Upon completion of the entire testing process, technicians fully discharged all tested equipment and remeasured the insulation resistance. No significant decline in insulation values was observed before and after testing. All test data was automatically archived and compiled into a standardized test report, passing the joint acceptance inspection by the owner, supervisor, and third-party testing agency on the first attempt. All parties highly commended the stability of Goldhome's equipment, its intelligent operation, and the professional competence of its technical team.
Core Advantages of the Goldhome Series Resonance Withstand Voltage System
Lightweight, modular design for convenient outdoor installation
Featuring a split-type reactor and a compact variable-frequency control cabinet, each unit weighs significantly less than traditional power-frequency test transformers. It can be transported by forklift or manually, making it suitable for the confined outdoor spaces of substations. Testing can begin immediately after quick wiring and startup.
Multiple Electrical Safety Protections
Built-in quadruple protection against overvoltage, overcurrent, flashover, and detuning. Should the test specimen exhibit an insulation defect, the equipment instantly cuts off the high-voltage output while simultaneously triggering audible and visual alarms, thereby preventing accidents involving both equipment and personnel.
Fully Automatic Intelligent Operation, Reducing Operational Barriers
The integrated touchscreen control panel features preset test programs for all voltage levels-220 kV, 110 kV, and 35 kV-and automatically performs voltage ramp-up, timing, voltage ramp-down, and data storage. It supports exporting data to paper,
