Abstract: Shanghai Metro's first line officially began operation on April 10, 1995. It was the third urban rail transit system to be put into operation in mainland China after the Beijing and Tianjin Metro, and is currently the longest urban rail transit system in China. This paper mainly introduces the architecture of the metro power distribution system and the application of the force control software platform in the integrated automation system of the Shanghai Metro Line 2 substation.
I. Introduction
As of June 30, 2011, Shanghai's metro network had 11 lines and 275 stations in operation, with an operating mileage of 420 km (excluding the Maglev line), ranking first in the world. Shanghai Metro Line 2, Shanghai's second underground railway line, began operation on June 11, 2000. The line starts from Xujing East Station in Qingpu District, passes through Nanjing Road (known as China's No. 1 Street), crosses the Huangpu River, reaches Zhangjiang High-Tech Park in Pudong New Area, and continues through Tangzhen, Chuansha, and other places, finally reaching Pudong International Airport, Shanghai's major airport connecting the city to the outside world. It can be said to be a link between Shanghai's past and future.
Line 2 is 60 kilometers long and has 30 stations. It operates for 18 hours and 11 minutes a day and has a daily passenger flow of 1.3 million, making it the longest single-line rail transit line in China in terms of operating mileage and passenger flow.
II. Project Overview
2.1 Current Situation
The supporting project for the Hongqiao Integrated Transportation Hub (the western extension of Metro Line 2, from Songhong Road Station to Zhuguang Road Station) runs from Zhuguang Road in Qingpu District to the already operational Songhong Road Station on Line 2. The route is as follows: Zhuguang Road Station—Xumin Road—Axis Avenue—Hongqiao West Station of the Hongqiao Integrated Transportation Hub—Hongqiao East Station—Tianshan Road—Songhong Road Station. The line is 8.58 km long, entirely underground, and includes 3 stations: Hongqiao Airport East Station, Hongqiao Airport West Station, and Zhuguang Road Station.
The Line 2 West-West Extension Project includes two traction step-down hybrid substations located at Zhuguang Road Station and Hongqiao East Station, respectively. Two step-down substations are located at Hongqiao West Station and in Ventilation Shaft No. 4 of the section. Five follow-type step-down substations are located at Hongqiao East Station, two at Hongqiao West Station, Zhuguang Road Station, and in Ventilation Shaft No. 2 of the section.
2.2 System Design Objectives
The design objectives for the integrated automation system of the substation in the Xixi extension project of Line 2 are as follows:
★ Control, monitoring, linkage, interlocking, and blocking functions for equipment in each substation; automatic switching; and acquisition functions for current, voltage, power, electricity consumption, and other various information quantities.
★Each substation can dynamically display the main wiring diagram of the substation and the communication status of devices such as microcomputer measurement and control, protection units, and information acquisition units connected to the integrated automation system;
★Each substation uses a window mode to display fault and alarm information within the substation, as well as the time of occurrence of the fault and alarm;
★ Trend charts of key parameters for each substation, as well as daily, monthly, quarterly, and annual reports of key parameters;
★ Communicate with the pSCADA platform of the dispatch center to transmit information such as substation operation, accidents, and warnings to the pSCADA dispatch or local maintenance computer; receive control commands issued by the pSCADA dispatch or local maintenance computer.
2.3 System Design Principles
★Fast Response
From the perspective of the power industry, the system design process should meet the requirements of rapid response, with software screen switching time ≤1s; network communication rate within the substation ≥100Mbps; and event resolution within the substation ≤5ms.
★Openness
The system platform features a modular, distributed architecture with excellent openness, supporting secondary development by users and allowing customers to customize settings according to their specific needs. It supports data interfaces with various mainstream devices and real-time databases, and integrates with third-party systems through standard relational database interfaces (such as ODBC and OLEDB).
★Safety and stability
In the operation of rail transit systems, the safety and stability of the power system plays a crucial role in the normal operation of trains. The system platform has a strict access control mechanism and functions for fault handling and event log query.
2.4 System Requirements
This system primarily performs the following functions: The substation integrated automation system platform can control, monitor, link, interlock, and lock various equipment in the substation, as well as automatically switch on/off, and collect data on current, voltage, power, electricity consumption, and other information. The system needs to have protocol forwarding capabilities to aggregate data from various substations to the higher-level power dispatching pSCADA system using a unified protocol.
Important equipment can not only achieve hard-wired linkage, interlocking, and locking through secondary circuits, but also complete the above functions in the configuration using integrated automation software, realizing functions such as logic judgment, calculation, and relay.
III. System Architecture
Based on the above functional requirements, the system architecture is shown in the figure below.
Figure 1 System Architecture Diagram
3.1 Communication Network
The integrated automation communication network within the substation adopts industrial-grade fiber optic Ethernet, improving the bandwidth and anti-interference capabilities of communication within the substation. An industrial-grade fiber optic Ethernet switch is configured in the station-level monitoring room to connect the fiber optic Ethernet interfaces of different equipment groups, meeting the communication technology requirements for control, measurement, and protection of the substation's integrated automation system, and fully satisfying the overall automation requirements of the substation.
In each substation, serial port server equipment is provided for 33kV, DC1500V and 0.4kV switchgear according to the needs of the site. The equipment is installed in the switchgear and is used to convert the RS485 signals of the control unit in the cabinet into Ethernet signals and summarize them to the monitoring platform in the station-level monitoring room.
3.2 Control System
The control signal panel in the substation is equipped with ABB's AC500 series controller. This device not only has an industrial-grade, fast dedicated core processor and a large capacity of RAM, but its system also provides a programmable interface. Using a simple structured script language, users can perform numerical calculations, logical operations, and control output functions.
3.3 Station-level monitoring
Each substation-level monitoring system uses PowerControl Technology's power monitoring software as its system platform, which can monitor the operating status of the monitoring units in each switchgear in real time and realize functions such as control, monitoring, and acquisition of current, voltage, power, and electricity consumption of various equipment in the substation.
ForceControl Power Monitoring Software perfectly combines general configuration software and power professional technology. It is a professional power system automation configuration software developed using advanced computer software programming technology. It is suitable for master station systems such as county-level dispatch automation, centralized control station automation, substation integrated automation, power plant electrical monitoring (ECS), enterprise power supply and distribution automation, hydropower station integrated automation, and building power distribution automation.
Because each substation has multiple devices with different data communication protocols, each substation is equipped with a PowerControl Technology pFieldcomm data acquisition gateway to achieve unified data aggregation. Substation data is converted into the Power 104 protocol and transmitted to the central dispatching system pSCADA platform in the central dispatching room via the pFieldcomm gateway.
The ForceControl pFieldComm series industrial communication gateway adopts a high-performance embedded computing platform. Its service kernel software can run on either a desktop or embedded operating system, making it a communication service platform independent of specific hardware interfaces. It features multiple communication acquisition and forwarding protocol libraries, enabling the acquisition of data from multiple subsystems. This allows for centralized data aggregation, classification, and preprocessing, simplifying the conversion of heterogeneous protocols and the networking process. Heterogeneous protocols are easily integrated and can be converted to standard protocols (such as OPC) for networking with other systems.
IV. System Functional Characteristics
4.1 Real-time comprehensiveness
The system can display the operating status of system equipment in a vivid and intuitive way through real-time animation. The substation main wiring diagram can dynamically display the status of each switch in real time according to the on-site operating conditions. It can display data such as current, voltage, electrical energy, power, active power, reactive power, and power factor in real time, realizing the four remote functions of the power system.
Figure 2 Main wiring diagram
Figure 3. Data display of remote sensing data.
Figure 4 Remote signaling status screen
Powerful reporting and trend curve functions: Various duty reports, operation reports, alarm reports, and daily/monthly/yearly reports can be easily generated from stored historical data. All data can be displayed using real-time and historical trend curves.
4.2 Safety and Reliability
Strict access control is implemented in operation. Operational-level operators access the system through workstations. Regardless of the initial startup or logout of the workstation, users will be directly taken to the system login screen or completely exit the operating system. General users are not allowed to access any operating system commands.
The system should provide audit trail functionality, recording all user operations and providing a basis and means for investigating system security issues; the system should also have a transaction log function. Various records (operations, alarms) should be searchable according to user requirements, by station name, object, nature, time, etc.
The system alarm supports multiple alarm output methods, and can output alarms to mobile phones, PDAs, and PCs via audio alarms, SMS, and email.
4.3 Integration and Openness
This system supports the simultaneous acquisition of real-time data from multiple field devices using different communication protocols, and stores the data in the system's real-time and historical databases according to pre-configured system requirements. It supports power CDT, DNP, standard Modbus protocol, power standard IEC101, 102, 103, and 104 protocols, as well as ABB's AC500 device proprietary protocol and AVERA (ALSTOM)'s Courier protocol.
It has WebServer functionality, which allows users to remotely browse various real-time and historical data within the system, such as main connection diagrams, system diagrams, real-time data queries based on integrated protection devices and bay layers, as well as historical SOE, operation events and system events queries, and browsing of telemetry historical curves and load curves.
V. Summary
With the rapid development of urban transportation, subways have become an important mode of travel for residents due to their convenience and speed. This system, combining advanced computer technology, automatic control theory, and data acquisition and communication platforms, provides strong support for the construction of digital cities.
