• Zhejiang Zhilu Transmission and Distribution Equipment Co., Ltd

Comparison of Typical Design Schemes for 10kV Combined Substations

Abstract

1. Introduction

2. Classification of Typical Design Schemes

2.1 Ring Main Unit (RMU) - Based Scheme

• Electrical Wiring: This scheme uses RMUs in the high - voltage section, featuring a ring - type power supply network. Multiple substations can be connected in a ring, enabling power transfer and backup in case of a fault. The RMU typically includes load switches, circuit breakers, and fuses for fault isolation and protection.

• Equipment Selection: Vacuum or SF6 - insulated RMUs are commonly used, offering high - reliability switching and arc - extinguishing capabilities. Transformers are usually dry - type with capacities ranging from 200kVA to 1600kVA, suitable for medium - scale loads.

• Advantages: Simple wiring, low investment cost, and easy operation. It provides good power supply reliability through ring - network operation and can quickly isolate faults, minimizing power outages.

• Disadvantages: Limited short - circuit current - breaking capacity compared to some other schemes. It may require additional protection devices for complex network conditions.

• Application Scenarios: Ideal for urban residential areas, small - scale commercial complexes, and rural power grids with relatively stable and moderate loads.

2.2 Double - Busbar Scheme

• Electrical Wiring: The high - voltage section adopts a double - busbar configuration, allowing for flexible power transfer and parallel operation. Each circuit can be connected to either of the two busbars, and bus - coupler breakers enable switching between busbars.

• Equipment Selection: High - performance circuit breakers (e.g., vacuum circuit breakers with large - breaking - capacity) are installed to handle high - current operations. Transformers often have higher capacities (up to 2500kVA or more) to meet large - scale load demands.

• Advantages: High reliability and flexibility. In case of busbar or equipment failure, power can be quickly transferred to the other busbar, ensuring continuous power supply. It also facilitates equipment maintenance without interrupting the entire power system.

• Disadvantages: Higher investment cost due to the complex busbar system and additional switching equipment. The control and protection systems are more complicated, requiring more professional operation and maintenance.

• Application Scenarios: Suitable for large - scale industrial parks, commercial centers, and important public facilities where uninterrupted power supply is of utmost importance.

2.3 Single - Busbar Sectionalized Scheme

• Electrical Wiring: The high - voltage busbar is divided into two sections by a bus - sectionalizing breaker. Each section can operate independently or be connected through the sectionalizing breaker. This design provides a balance between reliability and cost.

• Equipment Selection: Similar to the RMU - based scheme, vacuum - insulated switchgear is commonly used. Transformers are selected according to the specific load requirements of each section.

• Advantages: Moderate investment cost, improved reliability compared to single - busbar non - sectionalized schemes. When one section fails, the other section can continue to supply power, reducing the impact of faults on the overall system.

• Disadvantages: Less flexible than the double - busbar scheme in terms of power transfer and parallel operation. There may be limitations in handling large - scale load fluctuations.

• Application Scenarios: Widely applied in medium - sized industrial enterprises, schools, and hospitals, where a certain level of reliability is required within a reasonable budget.

2.4 Compact Integrated Scheme

• Electrical Wiring: This scheme highly integrates high - voltage, transformer, and low - voltage sections into a compact structure. The internal wiring is optimized to minimize the overall size while maintaining electrical safety and performance.

• Equipment Selection: Miniaturized and high - integrated electrical equipment, such as compact vacuum circuit breakers and high - efficiency dry - type transformers, are used. The low - voltage section often adopts modular distribution panels for easy expansion.

• Advantages: Occupies less space, which is beneficial for urban areas with limited land resources. Quick installation and low construction cost due to its pre - assembled nature.

• Disadvantages: Limited capacity expansion potential compared to some other schemes. The maintenance space may be relatively narrow, increasing the difficulty of equipment inspection and repair.

• Application Scenarios: Appropriate for urban distribution networks in densely populated areas, temporary construction sites, and locations with strict space limitations.

3. Comparative Analysis of Key Design Elements

3.1 Electrical Wiring and Power Supply Reliability

3.2 Equipment Investment and Operation Cost

3.3 Structural Layout and Space Utilization

4. Application Recommendations

• Urban Residential Areas: The RMU - based or compact integrated schemes are preferred due to their cost - effectiveness, relatively simple operation, and suitability for medium - scale, stable loads.

• Industrial Parks: For large - scale industrial parks with high - reliability requirements, the double - busbar or single - busbar sectionalized schemes are more appropriate, as they can handle large load fluctuations and ensure continuous power supply.

• Temporary or Space - Constrained Projects: The compact integrated scheme is an ideal choice, providing quick installation and efficient space utilization.

5. Conclusion