Diesel Generator and Transformer Integrated Power Supply Solution: Building a High-Reliability Power Distribution System

Writer： Hengfeng you electric Time：2025-11-10 views：times

In modern power supply systems, the combination of diesel generators and transformers forms the core of high-reliability power supply systems. This hybrid power supply system can effectively cope with various complex working conditions and ensure continuous power supply during emergencies such as grid failures or natural disasters. With the development of UHV grids towards intelligence and high efficiency, as key equipment for power plants to step up voltage to UHV levels for transmission, their performance directly affects grid transmission efficiency and safety. This article will explore the power distribution solution combining diesel generators and transformers in depth, providing a comprehensive analysis from technical principles and system design to practical applications.

I. Technical Basis of Diesel Generator and Transformer Integrated Systems

1.1 System Working Principle and Composition
The power supply and distribution system combining transformers and diesel generators achieves efficient distribution and management of electrical energy by converting the output voltage of diesel generators to voltage levels suitable for transmission and use. The system mainly consists of core components such as diesel generator sets, step-up transformers, distribution transformers, control systems, and protection devices.

As an emergency or primary power source, diesel generators automatically start when grid power is interrupted, providing necessary power support. Transformers undertake the task of voltage conversion, ensuring electrical energy is transmitted and distributed at the most appropriate voltage levels. The collaborative work of both creates a new hybrid power supply mode with stable performance and strong adaptability.

1.2 System Connection Methods and Technical Considerations
There are two main working methods for connecting diesel generators to distribution transformers: direct connection and connection through switching transformers. The direct connection method has a simple structure and low cost, suitable for occasions with relatively stable loads; while connection through switching transformers offers higher flexibility and control accuracy, especially suitable for loads with high power quality requirements.

In terms of generator paralleling, there are mainly two methods: precise synchronization paralleling and self-synchronization paralleling. Self-synchronization paralleling has more advantages in ease of use and automation implementation, but there is a certain inrush current during the paralleling process. Adopting a control scheme based on switching transformer technology can effectively reduce the inrush current during self-synchronization paralleling, lower paralleling risks, and ensure long-term efficient and stable grid operation.
 

II. Key Equipment Selection and Technical Parameters of Diesel Generator and Transformer Integrated Systems

2.1 Key Points for Diesel Generator Selection
Diesel generator selection requires comprehensive consideration of multiple factors such as installation environment, load characteristics, and operating requirements. In plateau areas, specially designed plateau-type diesel generators should be selected to ensure rated output power can be maintained in low-oxygen environments. For example, the diesel generator specifications used in the Tibet Changdu City Nongli Lake Reservoir project are CXXXDX, XXXkW, X.XkV, cosΦ=0.X, plateau-type design.

Key selection parameters include:

• Rated power: Determined based on maximum load demand, with appropriate margin reserved

• Rated voltage: Matches the transformer voltage level

• Power factor: Usually 0.8-1.0

• Starting characteristics: Meet motor starting current impact requirements

2.2 Transformer Selection Guide
As the core equipment for power conversion, transformer selection directly affects the efficiency and reliability of the entire system. Dry-type transformers are widely used in hybrid power supply systems due to their good fire performance, easy maintenance, and strong environmental protection.

Table: Core Selection Parameters for Dry-Type Transformers

Additional considerations for selection:

• Load characteristics: For impact loads (such as motor starting), select models with overload capacity ≥1.5 times

• Energy efficiency standards: Comply with the latest national standard GB 20052-2024 energy efficiency, select level 1 for long-term operation

• Cooling method: Natural air cooling (AN) for small capacity (<800kVA), forced air cooling (AF) for large capacity/high temperature environments

• Environmental protection and safety: Non-epoxy resin models (recyclable materials), fire rating F1 (950℃/3h non-flammable)

For UHV application scenarios, such as 1000kV step-up transformers for power plants, it is necessary to follow the DL/T 1409-2015 technical specification, which strictly specifies technical parameters, structural design, insulation requirements, test detection, etc., to ensure stable operation of equipment under complex working conditions.

III. Design and Implementation Plan for Diesel Generator and Transformer Integrated Systems

3.1 Main Wiring Scheme Design
The main wiring design of the diesel generator and transformer integrated system needs to be comprehensively considered based on factors such as load, number of power sources, and operation mode. For occasions with high reliability requirements, a wiring method with dual 10kV power sources diesel generators can be used.

Typical wiring schemes are as follows:

1. Mains priority: Two mains power sources are first transferred through a dual power transfer switch

2. Generator backup: Mains outlet and generator outlet are then switched through ATS for the second time

3. Interlocking logic: Ensure that the generator and mains do not supply power simultaneously, preventing non-synchronized paralleling and backfeeding to the mains

For complex scenarios such as large hydropower stations, the electrical main wiring design is the main part of electrical design. When the number of hydropower station installed units is large and the unit capacity is not very large, the connection form between the generator and the main transformer is relatively diverse, and a reasonable wiring method must be determined through comprehensive technical and economic comparison.

3.2 Protection and Control Strategy
The protection and control of the integrated system are key to ensuring safe operation, mainly including:

• Detection and start: Real-time monitoring of bus voltage, automatic generator start upon bus loss of voltage

• Switching control: Automatic switch to bus after generator reaches rated parameters, automatic switch back to mains after mains recovery

• Protection coordination: Set complete overcurrent, short circuit, ground fault protection to ensure selective coordination

• Impedance control: Dynamically adjust the control parameters of the phase-locked loop by online measurement of grid impedance value to improve system stability

The new high-voltage plant power system solution reduces the path current sent to the bus section and avoids the disadvantage of frequent load imbalance between the two split branches of the traditional split-core isolation transformer scheme by separately connecting the power balance generator to the low-voltage side of the main transformer through a dual-winding step-up transformer.

IV. Solutions for Special Application Scenarios of Diesel Generator and Transformer Integrated Systems

4.1 Plateau Area Applications
The plateau environment poses special challenges to the operation of diesel generators and transformers. Low oxygen conditions affect the combustion efficiency of diesel engines, and high altitude also affects the heat dissipation effect and insulation strength of transformers. For such environments, it is necessary to use plateau-type dedicated equipment and ensure system reliability through measures such as derating or strengthened insulation.

4.2 Hydropower Station Applications
The layout of the main transformer and generator voltage distribution device in the underground powerhouse of a large hydropower station is a key part of the overall layout of the underground powerhouse, which will have a greater impact on the powerhouse layout, civil structure, ventilation scheme and other aspects. In this case, it is necessary to统筹考虑 equipment layout, ventilation and heat dissipation, and maintenance channels and other multiple requirements to optimize the overall layout.

4.3 Nonlinear Load Applications
For nonlinear loads such as frequency converters and rectifiers, traditional transformer designs are difficult to meet the requirements. For such application scenarios, harmonic-resistant transformers with K-factor ≥13 should be selected to prevent overheating and damage caused by harmonics and ensure long-term stable system operation.

V. Stability and Impedance Characteristics Analysis of Diesel Generator and Transformer Integrated Systems

The impedance characteristics of the transformer and diesel generator hybrid power supply system directly affect system stability and power quality. By establishing accurate impedance models, system design and control strategies can be optimized.

Research shows that considering multiple influencing factors such as coordinate rotation transformation process, port impedance, and constant power load, establishing a high-stability impedance model for the transformer and diesel generator hybrid power supply system can significantly improve the accuracy of impedance characteristic analysis results. Example test results show that the fitting degree of positive sequence impedance analysis results can be improved by 20%-30%, and the fitting degree of negative sequence impedance analysis results can be improved by 11%-13%.

This accurate impedance modeling method provides a scientific basis for system stability analysis and control parameter setting, especially in modern distribution systems containing a large number of power electronic devices, its value is more prominent.

VI. Future Development Trends of Diesel Generator and Transformer Integrated Systems

6.1 Intelligent Upgrade
The latest trends in the transformer industry in 2025 indicate that intelligent upgrade has become an irreversible direction. Specific manifestations include:

• Built-in IoT sensors: Real-time monitoring of parameters such as temperature, humidity, partial discharge, etc.

• Remote operation and maintenance: Realize remote monitoring and maintenance through 4G/5G data transmission

• Intelligent diagnosis: Fault prediction and health management based on big data and artificial intelligence

6.2 Compact Design
To adapt to application scenarios with limited space, compact design has become an important research direction for equipment manufacturers. New transformers with a volume reduction of 20% compared to traditional models have been applied in multiple fields.

6.3 New Energy Adaptation
With the continuous increase in the proportion of new energy, diesel generator and transformer systems also need to adapt to this change. Photovoltaic/energy storage dedicated transformers support 150% reverse power tolerance, providing a technical foundation for new energy integration.

Conclusion
The hybrid power supply system combining diesel generators and transformers can build high-reliability, high-flexibility power distribution solutions through reasonable equipment selection, scientific system design, and advanced control strategies. With the continuous development of intelligent, compact, and new energy adaptation technologies, this system will play an important role in a wider range of fields, providing safe, reliable, economical, and efficient power guarantee for all walks of life.

In actual engineering, designers need to select appropriate system architecture and equipment configuration based on specific application scenarios, load characteristics, and reliability requirements to ensure the hybrid power supply system operates in an optimal state and meets users' diverse power needs.