High-Voltage Switch Innovation for Electric Power Systems
Simulation is being used at Pinggao Group to help ensure stable energy storage. The company uses multiphysics simulation, simulation apps, and digital twins to better understand and improve the design of electric power system components. The apps have been downloaded thousands of times throughout the company's engineering teams.
By Renji Hao
November 2025
Electric power systems make up the foundation of modern society. These complex systems contain a variety of equipment used for electric power generation, transmission, transformation, and distribution, as well as for electric power overflow protection. High-voltage switches (Figure 1), the key components for the operation of a power system, are capable of switching or disconnecting circuits within a rated voltage range in order to distribute and control electric power according to the power consumption demands of different regions and equipment. They must not only withstand extremely high voltages and large current surges but also achieve stable, long-term operation in order to maintain the normal functioning of the power grid.
The internal voltage of high-voltage switches can reach up to 1100 kV, and the switches must be able to cut off currents exceeding 100 kA in an extremely short amount of time. During the process of cutting off the current, an arc with energy up to 100 MW is generated, accompanied by various physical phenomena, such as discharge, heating, and ablation, posing significant challenges to the insulation design of high-voltage switches. Wang Zhijun, the director of the Institute of Basic Technology at Pinggao Group, said, "Traditional design methods based on experiments are expensive and time consuming, with each experimental test requiring approximately 10 million RMB (~1.4 million USD) and lasting several weeks." Moreover, the measurement of electric signals is easily affected by the high voltage of the equipment, resulting in inaccurate results. These methods can no longer meet the demands of high-voltage switch R&D. To address these issues, Zhijun and his team at Pinggao Group have turned to simulation to improve processes and designs.
Pinggao Group Co., Ltd. is a subsidiary of the State Grid Corporation of China and an important member of China Electrical Equipment Group. Pinggao Group focuses on the development and production of high-voltage and ultra-high-voltage electrical equipment. Different teams at the company use simulation to explore in depth the factors that affect the performance of high-voltage switches as well as to optimize switch designs and predict the operational status of equipment.
Optimizing High-Voltage Switch Designs to Avoid Insulation Failure
During the long-term operation of high-voltage switches, the charged particles in the insulating gas and the carriers in the insulating material undergo directional movement under the influence of a DC electric field and end up accumulating on the surface of insulators and other components. When the aggregated charge reaches a certain amount, partial discharge phenomena may occur, resulting in insulation failure, which significantly affects the safe and stable operation of high-voltage switches.
With the COMSOL Multiphysics® simulation software, Pinggao Group identified DC insulation criteria applicable to different working conditions as well as areas of field strength concentration and insulation weak points. This information is valuable in insulation design for DC equipment. A key aspect of gathering this information was looking at the physics phenomena involved in a DC insulation problem, and with the software, the team was able to assess multiphysics couplings between electromagnetics, heat transfer, structural mechanics, and other physics phenomena. The team also used simulation to look at the electric field distribution on the disk insulator under DC voltage, as shown in Figure 2.
Based on this research, Pinggao Group developed the world's first 1100 kV SF6 insulated wall bushing, which is used to isolate and protect DC cables from insulation when passing through walls, floors, or building structures. This wall bushing has been safely operating for 5 years and significantly improves the capacity, efficiency, and stability of power transmission systems.
In addition to the accumulation of charged particles, another cause of insulation failure in high-voltage switches is the inevitable generation of metal particles. These particles result from wear and tear that occurs during the installation of the high-voltage switch, thermal expansion and contraction of the cylinder that encloses different high-voltage switch components, and long-term operation. The movement of the particles under the combined effect of the electric field and the insulating gas flow field is extremely complex, difficult to predict, and challenging to observe with the naked eye. If these particles adhere to the insulator surface, it will lead to changes in the surrounding electric field, triggering gas breakdown and affecting the insulation performance of the insulator. To address these issues, Pinggao Group used multiphysics simulation to evaluate the forces acting on the particles and their moving trajectory (Figure 3).
To better understand the forces acting on the particles, the team considered the factors of gravity, SF6 gas resistance, Coulomb force, electric field gradient force, and friction. The jumping direction and displacement of the particles were simulated in order to investigate the relationship between particle mass, shape, and jump height. This information provided guidance for the design of a particle trap (Figure 4), which is used to minimize the impact of metal particles on the insulation performance of high-voltage switches.
The team created multiple models for different particle trap designs, and the optimized trap design has since been completed and applied to Pinggao Group's gas-insulated transmission line (GIL) products. GILs are used for power transmission subject to harsh conditions like high altitude, low temperature, and long transmission distance because of their advantages of large transmission capacity, low power loss, compact structure, and high reliability.
Simulation Apps Benefit the Entire Organization
In the process of using multiphysics simulation for high-voltage switch product design, Pinggao Group found that the development and maintenance of multiphysics simulation models require a deep understanding of the underlying physical principles of the products and the numerical methods used in simulations. Additionally, team members required training on how to use simulation, and design optimization required the simulation personnel to perform modeling calculations that could be repetitive. To help simplify design processes and make it easier for team members to understand and use simulation, Pinggao Group decided to build its own custom simulation apps based on its existing models, which take the form of easy-to-use user interfaces with a set number of parameters.
Pinggao Group has developed over 50 simulation apps using the Application Builder in COMSOL Multiphysics®. The apps were compiled into standalone executable files using COMSOL Compiler™, which enables different teams to run the apps independently. The customized apps are simple, user friendly, and enable users to quickly verify the feasibility of a new design by inputting a small number of parameters and obtaining simulation results. The apps cover a wide range of critical technical areas, including electromagnetic heating analysis, insulation performance evaluation, mechanical design, and failure analysis.
One of the apps that Pinggao Group created is used to calculate the temperature change that occurs in the busbar of a high-voltage switch because of electromagnetic heating (Figure 5). By inputting geometric dimensions, material properties, and operating conditions into the app, the team can compute results such as the magnetic flux density, current density, temperature distribution, and airflow velocity distribution. The temperature rise of the busbar under operating conditions can be simulated to determine whether the busbar structure meets the temperature rise requirements.
“By automating the preparatory and results visualization processes, we can significantly reduce labor requirements and speed up product development," said Zhijun. "The extensive experience and techniques we have accumulated over the years in product development are integrated into the simulation apps, helping eliminate knowledge barriers and difficulties in the simulation modeling process. This makes it easier for engineers and technicians across different departments within the organization to use simulations to validate the design, manufacturing, and operation and maintenance of products.”
Pinggao Group has established an internal web browser, called "Simulation App Store", where engineers can easily and quickly access the apps, upload and download simulation data and results, and share project information within teams. In the web browser, the simulation apps are categorized based on different design parameters, such as electric field, power, and stress, which helps users in different departments quickly find suitable, customized simulation apps. Currently, the simulation apps have been downloaded thousands of times throughout the company's engineering teams.
Digital Twins of Real-World Electric Systems
When it comes to power equipment, relying solely on historical data to predict and analyze the future performance of the equipment is inaccurate due to the uncertainty of load conditions and the diversity of operating environments. Moreover, during the operation of power equipment, different physical fields, such as thermal, electric, and magnetic fields, interact with each other, and the effects of those interactions can be difficult to predict. Multiphysics simulation can be combined with online monitoring data to build high-fidelity models that can then be turned into digital twins that are synchronized with the power equipment and updated in real time.
A digital twin is an interactive mapping model that integrates information technologies such as sensing, computing, and simulation to achieve full-scale and full-life-cycle interactions between physical and virtual spaces. Digital twins can be used to analyze the changes in physical objects and thus offer a way to better monitor them, predict their behavior, and optimize them so that they meet functional and application needs.
With the COMSOL® software, Pinggao Group has successfully achieved a digital twin model with full-life-cycle digital management and state inversion for metal-enclosed gas-insulated switchgear (GIS) disconnect switch equipment, which is a commonly used type of high-voltage switch. Pinggao Group is able to use the digital twin to diagnose and evaluate the state of high-voltage switches. For instance, when an abnormal state occurs, it is possible to locate the problem and identify the causes via the digital twin. These models have been deployed to the Zhongzhou UHV Converter Station, which is part of an electricity transmission system in China.
The digital twin model of the high-voltage switch collects real-time operational data from the power equipment via sensors, and this data is automatically used as input in a simulation app called "GIS Isolation Switch Fast Simulation App with Local Overheating State Inversion Function". As a result, the simulation time of the temperature and electric fields in high-voltage switches has been reduced to seconds. A digital twin model of the GIS disconnecting switch is shown in Figure 6, with real-time operational data on the left and the simulation results on the right. The simulation results are used to analyze and monitor the operational status of the power equipment, enabling state inversion and the identification of abnormal operating conditions.
Continuing the Use of Simulation at Pinggao Group
Pinggao Group plans to continue integrating multiphysics simulation into its development processes in order to help product designers develop high-voltage switches with better performance.
“For the critical issues encountered during the development of high-voltage switches, we have been able to find corresponding features and solutions in the COMSOL software, which has provided significant support for our development work," said Zhijun. "The simulation apps have further enhanced the application and value of simulation technology within the organization.”
Pinggao Group is also going to explore further applications of simulation in the development of renewable energy applications, including for energy storage and integrated energy systems.