10kV Power Supply Design of a Large-scale Mixed-use Project and Application of User-side Intelligent Power Distribution System

Xu Shuang

Ankerui Electric Co., Ltd. Shanghai Jiading 201801

1 Project Introduction

This project is a large-scale commercial complex, including a 260m super high-rise office building, a 100m office building, a 100m hotel and office building, as well as a commercial podium and an underground garage. The total construction area of ​​the project is about 344,000 m2, and the construction area and building height of each part are shown in Table 1.

Table 1 Project Profile

Project area

I District Tower

Tower II Tower

III District Tower

IV area podium

V area underground

Nature of use

Office

Hotel, office

Office

Business, catering

Station, garage

Number of layers

56 layers

26th floor

26th floor

8 floors

3 floors underground

building height

260m

100m

100m

34m

-12.9m

construction area

120,000 m2

50,000 m2

35 thousand m2

88,000 m2

5.1 million m2

2 Determination of power supply capacity

2.1 Several considerations for transformer installation capacity calculation

The design of the medium-voltage power supply system shall be based on the characteristics of the project, and shall be based on the national design specifications and local power supply design regulations to determine a reliable, safe, economical and reasonable solution. The load rating of a large-scale mixed-use project is generally one class. When a 10kV voltage class is used for power supply, most of the two 10kV power supplies (dual power supply) are used to enter the line, and the single bus is operated in segments, and a tie switch is provided. Normally, two-way power supply operates in parallel and serves as hot spares. When one-way power supply fails, the switch is manually/automatically operated to supply the entire load (or primary and secondary loads) from the other power supply. When the power supply capacity of the two channels cannot meet the requirements, multiple groups of power supply lines can be used (each group is dual-channel). Therefore, the calculation of electrical loads is the most basic task of power distribution design, and it is the basis for determining the overall power supply plan, substation planning, distribution system design, and power distribution plane design. The general steps are to use the transformer per unit area installation index for estimation in the early stage of project design; use the load density index for initial calculation in the preliminary design stage to correct the estimated value; use the coefficient method for detailed calculation in the construction drawing stage to calculate the initial calculation Correct the value. Factors that influence the load calculation: air conditioning plan, layout and function of the building, reliability factors, and economic factors.

When calculating the transformer installation capacity, this project follows the following principles:

2.2 Transformer installation capacity

The project office building area is relatively high, accounting for about 50%, should be a reasonable determination of the office building's transformer capacity, as far as possible to avoid the Party A mentioned the existing projects. Therefore, in the calculation of office building load, the value of the middle subsidence is used.

The actual transformer installation capacity of this project is 29100kVA, and a total of 20 transformers are installed. The average transformer installation capacity per unit area is 84 VA/m2. See Table 2 for the installation capacity of each transformer.

Table 2 Transformer installation capacity per unit area

Power range

construction area

(m2)

Installation capacity

(kVA)

Unit area installation capacity (kVA/m2)

Hotel (including cold machine)

33019

4000

121

Commercial (excluding cold machines)

88533

8900+2080

124

Office (excluding cold machines)

174370

9800

56

Garage, station building

50919

1120

twenty two

Freezer room (non-hotel part)

262903

3200

12

3 power supply design

The transformer installation capacity of this project is 29100kVA, which has exceeded the power supply capacity of 10kV voltage level. For the power supply capacity of the 10kV power supply, there are different regulations for the power supply departments, which are generally 8000-16000kVA. In the early stages of the project, a scheme for using 2 sets of 10kV power supply to enter the line is determined. The power grouping scheme is shown in Table 3.

Table 3 10kV power grouping scheme

Program

The first group of medium pressure

The second group of medium pressure

Group characteristics

plan 1

I District Office, III District Office,

Zone IV commercial (local), freezer room

District II Hotel, Office, Business District IV (District), Catering,

Underground garage, station building

Power supply in the nearest area to avoid 10kV line crossing

Scenario 2

I District Office, District II Hotels,

District II Office, District III Office

Chiller plant,

District IV Business, Catering,

V area underground garage, station building

Easy to operate independently in business, there is a 10kV line crossing

Option 3

I District Office, II District Office,

District III office, freezer room

District II Hotels,

District IV Business, Catering,

V area underground garage, station building

Take into consideration the convenience of local area power supply and operation management

The grouping of two 10kV power supplies mainly considers three principles: similar power supply distances, similar functions, and two sets of power supply capacities are balanced as much as possible. Finally, the power grouping scheme is determined as scheme 3, 2 medium voltage total configurations are set, the total transformer installation capacity of A-1# is 13000kVA, and the total transformer installation capacity of B-1# is 16100kVA. The power supply scheme adopts 2 sets of power inlets, each set of 2 10kV power supplies. The 2 power supplies work at the same time. When the 1st power supply loses power, the other power supply carries all the loads (or primary and secondary important loads) and supplies power. The system is shown in Figure 1.

The power supply system shown in Fig. 1 is a typical wiring diagram of the primary load. This scheme is a common scheme for large-scale public construction projects, meets the design specifications, and has high reliability. However, the local power supply department does not allow this type of wiring. The local power supply department requires that: the medium voltage busbars are not allowed to be used as busbar switches; the medium voltage operation mode is one-for-one, manual switching. Then adjust according to the requirements of the power supply department. The design of the power supply system is shown in Figure 2. However, the high reliability of the supply of electricity in the region is 330 yuan/kVA, and the standby capacity of the system shown in Figure 2 is 29100 kVA. According to regulations, it is required to pay a high-reliability charge of 9.6 million yuan. Party A does not accept payment of so much money and hopes to adjust the plan.

Finally, after tripartite negotiation between Party A, the power supply department and the design institute, the power supply scheme was determined as shown in Figure 3, and a two-in-one, medium-voltage power supply scheme was adopted. The main power supply for the 2-way route is derived from one regional substation, and the 1-station backup power supply is derived from another 1-zone substation. The spare capacity is 50% of the total installed capacity of the transformer, that is, 14550kVA. This way, the high-reliability and high-reliability charging will not be paid for too much reserve capacity, and the reserve capacity will not be lost when the 2-way main power supply loses power at the same time. It is still possible to guarantee that the transformer of the general amount of the project is running at full capacity.

4 Intelligent Power Distribution System

4.1 Distribution System Design

According to the power supply scheme determined in Fig. 3, when the backup power supply is put into operation, 50% of the total allocation will be on and off locks, and only 50% of the switches are allowed to be closed to ensure that the 50% transformer can operate at full load. B-1 # total distribution of 10kV power distribution system design shown in Figure 4.

Figure 4 B-1 # total distribution of 10kV power distribution system diagram

4.2 Intelligent Distribution Protection Device Selection

In order to accurately collect the electrical parameter signals and non-electrical energy signals of the power supply system and achieve comprehensive protection and monitoring of the power supply system, the AM6 series protection devices and ASD series switch cabinets of Ankerui Electric Co., Ltd. are properly configured and integrated in one system. Device to ensure the stable and reliable operation of the power supply system, including: AM5-F line protection device is optional for the two main power supply line-side switch cabinets; AM5-M motor protection device is optional for the switch cabinets of the freezer room; on the transformer outlet cabinet Optional AM5-T transformer protection device; general outlet cabinet optional AM5-F line / feeder protection device; PT cabinet optional AM5-U PT monitoring device. The appearance and function of each device are described in Table 4. The detailed functions of AM5 series protection devices can be seen in Table 5.

Table 4 Function List of Protection and Control Devices

Application

model

The main function

Transformer and Distribution System Substation Switchgear

AM5 series

It provides comprehensive protection and monitoring functions for the power distribution system, and can be applied to the protection and automatic control functions of equipment such as lines, bus couplers, distribution transformers, high-voltage motors, and high-voltage capacitors.

ASD series switchgear comprehensive measurement and control device

ASD300

With a system dynamic analog display, switch status indication, high voltage live display, automatic temperature and humidity control, human body induction automatic lighting, voice prompts, electrical parameter measurement, RS485 communication

ASD200

With a system dynamic analog display, switch status indication, high voltage live display, automatic temperature and humidity control, voice prompts, and RS485 communication

ASD100

With a system dynamic analog display, switch status indication, high voltage live display, automatic temperature and humidity control

In the design, the main power switch and the standby power switch are electrically interlocked, and only one of the two switches can be closed. The standby power supply line switch is electrically interlocked with the WH6-WH10 switch. The WH6-WH10 switch is in a disconnected state as a necessary condition for the standby power switch to be closed.

Table 5 Detailed functions of the power distribution system protection device

use

model

Features

line

protection

Capacitor protection

Motor protection

<2000kW

Plant protection

Parental protection and preparation

PT monitoring

AM5-F

AM5-C

AM5-M

AM5-T

AM5-B

AM5-U

Current acquisition

8

8

8

8

8

0

Voltage acquisition

4

4

4

4

4

4

Switch collection

16

16

16

16

16

16

Relay output

10

10

10

10

10

10

Protective function

Three-stage over-current protection

√

√

Two-stage over-current protection

√

√

√

Two-stage I01 overcurrent

√

√

√

√

Two-stage I02 overcurrent

√

√

Inverse time overcurrent protection

√

√

√

√

√

I01 Inverse Time Overcurrent Protection

√

I02 Inverse Time Overcurrent Protection

√

Overload warning

√

√

√

Overload trip

√

√

√

Control loop disconnection alarm

√

√

√

√

√

Low voltage protection

√

Alarms

PT disconnection alarm

√

√

√

√

√

√

Three-phase reclosing

√

Low-frequency load shedding

√

Accelerated overcurrent

√

√

Overvoltage alarm

√

Overvoltage tripping

√

Stall protection

√

Undervoltage protection

√

Unbalanced voltage protection

√

Unbalanced current protection

√

Zero sequence overvoltage protection

√

Zero sequence overvoltage alarm

√

√

Non-electric protection

√

√

√

Long start-up time

√

Thermal overload protection

√

Negative sequence overcurrent (two segments/inverse time limit)

√

Incoming line preparation/flood preparation

√

FC lockout

√

√

√

4.3 Acrel-2000 User-Side Intelligent Power Distribution System

After a reasonable allocation of protection, measurement and control equipment in the distribution system, according to the power consumption scale of the complex, the distribution of electrical equipment and land area and other aspects of information, the use of hierarchical distributed design of intelligent power distribution system. The system can fly into three layers: station management layer, network communication layer, and field device layer.

The station management layer is located in the central transformer station duty room, including monitoring computers, network switches, printers, UPS, timing devices, remote devices, and Acrel-2000 monitoring software. The station control management computer can be placed on the operation desk of the duty room, or it can be installed in the network cabinet to form a monitoring screen. The network communication layer includes communication collectors, optical transceivers, and other network equipment used to connect with the station control layer. It is installed in the communication collection box, and the communication collection box and field device layer devices are installed nearby and mounted on the wall. The communication layer is a physical layer that links up and down. It is responsible for transmitting the information of the device layer device to the station control layer, and the command of the station layer is sent to the device layer device. The field device layer includes AM5 series protection devices on the low-voltage cabinets, ASD series switchgear monitoring and control devices, multi-functional power meters, temperature controllers, and DC screens. Acrel-2000 monitoring software is based on the Windows platform application software, can simulate the user's power distribution network, providing monitoring, remote signaling, remote control, remote adjustment, alarm, reporting, accident analysis and other functions. The Acrel-2000 distribution system diagram is shown in Figure 5.

5 Power Supply Distribution Analysis

The large-scale complex project encountered two problems in the implementation process, making the initial 10kV power supply design scheme continuously adjusted: First, the local power supply department does not allow the main and standby power supply to operate at the same time, and also charged the backup power supply with high reliability; It is Party A's desire to minimize the cost of power supply systems, and in particular, it does not want to pay for the high reliability of the power supply. In order to meet the requirements of Party A, the power supply department, and the design institute at the same time, we designed a power supply plan that can be accepted by all parties without violating the specification, and finally use the 10kV dual-use and one-stand-alone power supply shown in Figure 3. Program.

Under the power supply scheme of Fig. 3, Acrel-2000 power distribution monitoring system of Ankerui Electric Co., Ltd. was selected, and equipped with Acerui company's microcomputer protection device, switchgear comprehensive measurement and control device, multi-functional power meter and other equipment. Intelligent terminal user substation distribution automation system. The AM5 series of protection and monitoring devices equipped with protection, measurement and control are integrated, and different protection functions can be flexibly configured for different primary equipments. It can achieve comprehensive protection and monitoring functions for voltage and power distribution stations of 35kV and below, applicable to lines and mothers. Joint, distribution transformers, high voltage motors, high voltage capacitors and other equipment protection and automatic control functions. The device adopts advanced and reliable protection principles and algorithms, strong anti-interference performance, high reliability, flexible implementation of protection, and redundant design for communication. The device adopts full graphic programming technology and can logically program the device as required to meet the requirements of most users. If the protection monitoring and control device needs to replace the protection function during use, it is only necessary to update the built-in logic diagram through the maintenance port of the device, and the implementation mode is simple and flexible.

references:

[1] Analysis of a 10kV Power Supply Scheme for a Large-scale Mixed-use Project. Power Supply and Distribution. 2013.11

[2] Ankerui Electric Co., Ltd. Product Selection Manual 2013.1.

[3] Ankerui Electric Co., Ltd. Energy efficiency management system design and installation atlas 2013.11.

About the Author:

Xu Shuang, female, Master, Ankerui Electric Co., Ltd., the main research direction for the intelligent distribution system design, Email: mobile phone QQ