Qingdao Chengyang Grand Theatre Power Distribution Project (Substation) Solution

I. Overview of the Power Distribution Engineering Substation for the Grand Theatre

As an important cultural landmark and artistic venue in northern Qingdao, the Qingdao Chengyang Grand Theatre relies on a safe, stable, efficient, and intelligent power distribution system to support each of its performances. Facing the theater's complex electrical load requirements (high-power stage lighting, precision sound systems, heavy machinery, and air conditioning in densely populated audience areas) and nearly stringent power supply reliability demands, Hengfengyou Electrical tailored a substation solution and successfully delivered the core power distribution solution. This article will provide an in-depth analysis of this critical engineering project.

II. Design Standards and Requirements for the Grand Theatre Substation

1. Safety and Reliability: The design must comply with current national and local electrical design standards to ensure the safe, stable, and continuous operation of the power supply system, safeguarding the safety of personnel and equipment. Particular emphasis must be placed on meeting the reliability requirements for critical loads such as fire protection, emergency lighting, and stage equipment.

2. Sufficient Capacity: Meet the load requirements of all electrical equipment (stage lighting, sound systems, mechanical equipment, air conditioning, lighting, office equipment, fire protection, security systems, etc.) in the theater for the current period and a certain future period, and reserve appropriate development capacity (Hengfengyou Electrical recommends 40%).

3. Power quality: Ensure stable voltage and frequency, effectively suppress harmonics (especially those generated by stage dimming equipment), and meet the power quality requirements of precision equipment (sound systems, control systems).

4. Energy efficiency: Select high-efficiency, energy-saving equipment (transformers, lighting fixtures, motors, etc.), and design reasonable operating modes to reduce operational energy consumption.

5. Intelligent Management: Establish a comprehensive power monitoring and energy management system to enable remote monitoring, metering, analysis, alarms, and partial control functions, thereby improving management efficiency and fault resolution speed.

6. Easy Maintenance: Select equipment appropriately, ensure clear layout, and provide clear labeling to facilitate daily inspections and maintenance.

III. Core Content of the Grand Theater Substation Solution

1. Load Analysis and Calculation for the Grand Theater Substation

A. Detailed Load Statistics:

Stage Area: Stage lighting (front lighting, overhead lighting, side lighting, follow spot lighting, effect lighting, etc., considering the load and harmonic characteristics of dimming silicon cabinets), stage machinery (lifting platforms, moving platforms, hoists, curtains, etc., motor-driven equipment), sound systems (amplifiers, processors, etc.), LED screens, stage supervision systems, orchestra pit equipment, etc.

Auditorium: General lighting, emergency lighting, air conditioning fan coils, seat ventilation, security surveillance, evacuation signage.

Backstage Area: Makeup room lighting and outlets, rehearsal hall lighting and equipment, office area lighting and office equipment, air conditioning.

Public Areas: Lobby, corridors, restroom lighting and outlets, advertising light boxes, air conditioning.

Equipment Rooms: Chiller units, chilled water pumps, cooling pumps, cooling tower fans, air conditioning unit fans, supply and exhaust fans, fire pumps, domestic water pumps, elevators, and self-use power for the substation.

Fire Protection System: Fire alarm control panel, fire pumps, sprinkler pumps, smoke exhaust fans, fire-resistant rolling doors, emergency lighting, and evacuation signage system power supply.

Security System: Surveillance center equipment, cameras, access control, and patrol systems.

Others: Kitchen equipment, commercial tenant reserves, etc.

B. Load Classification:

Critical Loads (Highly Important): Fire protection equipment (fire pumps, sprinkler pumps, smoke exhaust fans, core power supply for fire alarm systems, fire elevators, emergency lighting, and evacuation signage systems), core loads for stage performances (main stage lighting, main sound reinforcement systems, stage machinery control system power supply, stage supervision communication systems). Dual power supply (two independent utility power circuits) with end-of-line switching + diesel generator backup (Cummins + Stanford).

Critical Loads (Important): Main passenger elevators, domestic water pumps, lighting for main corridors and critical equipment rooms, security monitoring center, theater management core system. Typically supplied by dual circuits with end-of-line switching.

Secondary loads: ordinary passenger elevators, air conditioning systems (non-critical areas for performances), general area lighting, office power, etc. Typically uses dual-circuit power supply.

Tertiary loads: general-purpose electrical equipment. Single-circuit power supply.

C. Load calculation: Uses the demand factor method and utilization factor method for detailed calculations to determine transformer capacity, circuit breaker specifications, and cable sizes. Special attention is given to the nonlinear characteristics and impact of stage lighting loads.
 

2. Power Supply Plan for the Grand Theatre:

A. Dual-circuit mains power supply: Two independent 10kV power sources from different substations or different busbar sections of the same substation.

This is the foundation for ensuring high reliability.

B. Power Supply Method:

Option A: Dual power supply + automatic transfer switch (ATS): Both mains power sources are connected simultaneously, with one as the primary and the other as the backup. In the event of a failure in the primary power supply, the ATS automatically switches to the standby power supply, with the switching time meeting the requirements for critical loads (typically <15 seconds). Suitable for critical loads.

Option B: Dual Power Supply + Busbar Segmentation + On-Site Emergency Power Supply: Two independent 10kV busbars are installed, each powered by a separate utility power supply. A bus tie switch is installed between the two bus sections. A large-capacity diesel generator set is also configured as an emergency power supply to provide power to particularly critical loads. When both mains power sources fail, the diesel generator automatically starts and connects to the emergency bus via the ATS. This is the optimal solution for applications with extremely high performance reliability requirements.

C. Upper-level power supply capacity and lines: Ensure that the upper-level substation has sufficient capacity, and that the incoming line specifications meet requirements for current carrying capacity, short-circuit capacity, and voltage drop.

3. Selection and layout of the grand theater substation:

A. Location selection: Close to the load center (stage area, air conditioning machine room, etc.) to reduce low-voltage distribution distance and losses. Consider convenience for incoming and outgoing lines, equipment transportation channels, ventilation and heat dissipation, flood prevention, distance from flammable, explosive, and vibration sources, and ease of operation and maintenance management. Located in a dedicated distribution room.

B. Layout Design: Complies with safety standards (clearance distances, access pathways), with clear functional zones (high-voltage room, transformer room, low-voltage distribution room, control room/duty room). Consideration is given to equipment handling, installation, and maintenance space. Comprehensive measures are implemented for ventilation, heat dissipation, lighting, fire protection (gas extinguishing system), pest control, and moisture prevention (dehumidifiers). Special attention is given to the location of dedicated distribution cabinets in the stage area.
 

4. Selection of Main Equipment for Substations:

A. 10kV High-Voltage Switchgear:

Type: KYN28A-12 and other mainstream metal-clad, draw-out type switchgear.

Circuit Breaker: Vacuum circuit breaker with reliable breaking capacity.

Protection: Equipped with a microcomputer-based comprehensive protection device, providing overcurrent, instantaneous trip, zero-sequence, overvoltage/undervoltage, and transformer temperature protection, with communication interfaces.

Metering: Dedicated metering cabinets are installed.

Operation: Equipped with a complete anti-misoperation interlocking system (five-prevention).

B. Distribution Transformers:

Type: SCB14 energy-efficient epoxy resin cast dry-type transformers (fire-resistant, environmentally friendly, low-noise, suitable for indoor use).

Capacity: Determined based on load calculations and demand factor, considering N+1 redundancy or reserved expansion space. Two SCB14-2500kVA-10/0.4kV epoxy resin cast dry-type transformers are installed, capable of operating in parallel to limit short-circuit current.

C. Low-voltage distribution cabinets:

Type: Select GCK or similar modular, drawer-type switchgear cabinets for ease of maintenance and expansion.

Frame circuit breakers (ACB): For feeder, bus tie, and high-capacity feeder circuits, use Schneider Electric Masterpact™ MTZ series, featuring three-stage protection and communication functionality.

Molded case circuit breakers (MCCB): For feeder circuits, use Schneider Electric Compact NSX series, with sufficient breaking capacity, modular design, and support for digital functionality.

Miniature Circuit Breakers (MCB): Schneider Acti9 iC60 series are selected for end-of-line distribution.

Critical Circuit Configuration: Dual Power Source Switching Device (ATS).

Power Quality Management:

Dynamic Reactive Power Compensation Device (SVG/SVC): Rapidly compensates power factor, suppresses voltage fluctuations and flicker, particularly addressing the impact of reactive power generated by stage lighting equipment.

Active Power Filter (APF): Real-time detection and active mitigation of harmonic currents (particularly 3rd, 5th, and 7th harmonics generated by stage thyristor dimming, LED power supplies, and variable frequency drives), significantly improving THDi and ensuring the reliable operation of sensitive equipment.

Surge Protective Device (SPD): Installed at all levels of distribution to effectively protect against lightning and operational overvoltages.



D. Emergency Power Supply System:

Diesel Generator Sets: Capacity sufficient to meet the startup and operational requirements of all critical loads (accounting for motor startup impact). Equipped with automatic startup, automatic transfer, and automatic shutdown functions. Low-noise, low-emission design, with exhaust systems compliant with environmental protection standards. Fuel reserves meet regulatory requirements (typically ≥24 hours).

Uninterruptible Power Supply System (UPS): Provides millisecond-level seamless switching and high-quality power supply for critical control equipment (such as stage control systems, low-voltage equipment rooms, fire control rooms, and certain important lighting systems). Configured according to load capacity and backup time requirements.

DC Operating Power Supply System: Provides reliable operating and control power for high-voltage switchgear, relay protection devices, and signal systems.

5. Substation Distribution System Structure and Protection:

System Structure: Combination of radial and trunk systems. Critical loads (stage core equipment, fire protection, security) are supplied via dedicated radial circuits.

Protection Coordination: Reasonably designed protection settings and time delay coordination ensure selectivity (only the faulty section is isolated during a fault, minimizing the power outage area).

Grounding System: Uses the TN-S system. An independent and well-connected grounding grid is installed, with grounding resistance meeting specifications (typically ≤1Ω). All equipment metal casings, cable trays, pipes, etc., are reliably grounded. The stage area may involve local equipotential bonding.
 

6. Intelligent and Energy Efficiency Management:

Power Monitoring and Energy Management System: Install smart meters (multi-functional electricity meters) on critical circuits (incoming lines, outgoing lines, compensation, generators) in high-voltage cabinets and low-voltage cabinets to collect data such as voltage, current, power, power factor, energy consumption, and harmonics. Set up a communication management unit to upload data to the backend monitoring system via a bus (Modbus).

Monitoring System Implementation: Real-time data monitoring, out-of-limit alarms, event logging, power quality analysis, load curves, report statistics (sub-metering), and remote control (when permitted).

Energy Efficiency Analysis: Identify major energy consumers and optimize operational strategies (e.g., time-based control of air conditioning and ventilation).

Intelligent Lighting Control: Public areas utilize an intelligent lighting control system to achieve scene control, scheduled control, and sensor-based control, thereby enhancing energy efficiency.

7. Special Considerations (Core of the Grand Theater):

Stage-specific power distribution: Set up independent power distribution cabinets for stage lighting, sound, and mechanical systems.

Stage lighting circuits: Ensure sufficient quantity, consider three-phase balanced distribution, and for dimming circuits (silicon cabinets), consider harmonic mitigation and isolation transformer requirements.

Stage Mechanical Circuits: High capacity and reliability. Variable frequency drive equipment considers harmonic and EMC issues. Strict grounding and equipotential bonding are implemented to prevent equipment damage or personal injury caused by stage potential differences.

Harmonic Mitigation: APF and SVG/SVC are centrally configured on the low-voltage side to address harmonic and reactive power impacts from stage equipment.

Electromagnetic compatibility: Sensitive control systems (stage, low-voltage) and interference sources such as variable frequency drives and dimmers will be isolated in terms of wiring and grounding.

Fire alarm interlocking: The power distribution system is interlocked with the fire alarm system (FAS). After a fire is confirmed, non-fire power sources are disconnected, and emergency power is activated.

8. Energy conservation and environmental protection:

Select transformers with a 2-level energy efficiency rating according to GB 20052 standards.

Optimize reactive power compensation to maintain high power factor operation (>0.95).

Use high-efficiency motors and variable frequency control (e.g., air conditioning pumps, fans).

Implement intelligent lighting control to reduce unnecessary lighting energy consumption.

Select environmentally friendly materials (e.g., sulfur hexafluoride-free switchgear, dry-type transformers).

Consider the possibility of utilizing waste heat recovery (e.g., using transformer cooling for winter preheating of fresh air).
 

9. Substation Construction, Commissioning, and Acceptance:

Strictly adhere to design drawings and specifications during construction.

Conduct factory tests and on-site handover tests for critical equipment (including withstand voltage tests, relay protection tests, switch characteristic tests, transformer tests, etc.).

Perform system integration commissioning (including dual power source switching, generator automatic start-up, fire alarm integration, and monitoring system integration).

Power quality testing (voltage, harmonics, flicker) must meet the requirements of standards such as GB/T 14549, GB/T 12325, and GB/T 12326, especially when the load is fully loaded during performances.

Complete handover of completion documents and operational training.

10. Recommendations for substation operation and maintenance

Develop detailed operating procedures and emergency response plans for the distribution system.

Establish comprehensive equipment records and operation and maintenance logs.

Conduct regular preventive testing and maintenance (such as infrared temperature measurement, switch characteristic testing, protection device calibration, battery charge/discharge testing, generator load testing, etc.).

Fully utilize the power monitoring system for daily inspections and data analysis.

Operating and maintenance personnel undergo professional training.

IV. Summary

The distribution solution provided by Hengfengyou Electrical for the Chengyang Grand Theatre is centered on constructing a modern substation based on dual power sources + UPS power, with an efficient SCB14-2500kVA-10/0.4kV epoxy resin cast dry-type transformer as the core, advanced dynamic reactive power compensation and active filtering as safeguards, and intelligent monitoring as the means. It is essential to deeply understand the unique characteristics of stage loads and prioritize power quality management. Additionally, high-reliability design, comprehensive protection measures, strict fire safety integration, and intelligent operation and maintenance management are critical to ensuring the safe, efficient, and seamless operation of the grand theater.