To enhance the safety, reliability, and stability of the 35kV substation operations, reduce maintenance costs, and improve economic benefits, and to provide high-quality power services to our customers, we have decided to implement comprehensive automation upgrades at the 35kV substation. This will involve the application of automatic control technology, information processing and transmission technology, and computer hardware and software technology to monitor, coordinate, control, and manage the operations of the 35kV substation, partially replacing conventional secondary systems and reducing the need for on-site staff to monitor and control the substation's operations. This will make the substation safer, more stable, and more reliable. Additionally, we will further explore the effects of the comprehensive automation system post-implementation and gradually develop and perfect the 35kV substation's comprehensive automation system.
Renovation Plan
This renovation employs a centralized grouping screen approach, with the main transformer protection, 35kV incoming line protection, 10kV feeder protection, and 10kV capacitor protection devices all installed within the protection screen. The metering devices combine centralized grouping screens with decentralized installation. The existing protection screens and related equipment remain unchanged to ensure the ongoing operation of the current setup. The new DC equipment, main transformer protection screen, line protection screen, and communication screen are first installed in the new location, and after successful debugging, the outgoing lines and main transformer protection and control systems are gradually integrated into the new system. This method ensures a smooth transition between old and new equipment while potentially reducing downtime.
Technical Measures to Be Noted in This Renovation
The primary challenge in this renovation lies in the concurrent operation of new and old equipment during the process. Consideration must be given to the connection of various power sources between the renovated and unrenovated equipment. Ensure that the unrenovated equipment operates reliably during the renovation of the 10kV cabinet control cables. When working on the control power, closing power, alarm power, and 10kV voltage cables, wear insulating gloves and boots. Remove and replace cables only after verifying their correctness one by one and wrapping them with insulating tape to prevent grounding. When connecting two cables, ensure a secure connection. After the renovation of each compartment, carefully inspect and verify the correctness of the involved new and old control cables.
Steps for the Comprehensive Automation Transformation of a 35kV Substation
1) Based on the on-site conditions of the substation, draw the electrical design drawings for the main transformer protection and control cabinet; the 35kV line protection and control cabinet electrical design; the 6kV line capacitor protection and control cabinet electrical design; and the general-purpose protection and control cabinet electrical design. The content of the design drawings includes: overcurrent protection, three-phase single-stroke reclosing, low-frequency load shedding, and low-voltage load shedding. Measurements for 3-phase voltages, 3-phase currents (measured by CT), and P, Q, COS power factors, with remote measurement error of 0.5%. Features include switch input, pulse input, AC220V power supply, weight gas trip, weight/light gas signals, and transformer over-temperature signals.
2) Customized protective cabinets based on design drawings, requiring: ①Each protective device is equipped with a local exit hard pressure plate and a soft pressure plate for the protection exit; ②The operating mode includes interlock functions for on-site micro-computer operation, remote dispatch operation, and local equipment operation; ③The system features remote maintenance capabilities.
3) The 35kV substation is equipped with a distributed configuration of primary equipment. Protection is fully implemented using micro-computer protection systems, with the protection and measurement devices centralized in the main control room. Each protection unit operates relatively independently, capable of independently executing its protective functions and transmitting protection information to the monitoring system via communication interfaces.
4) Measurement: Protection utilizes different current transformers, including measuring CTs and protection CTs. The protection function is independent of the monitoring system's functions; all protective devices are equipped with multiple setpoints.
5) Switch control is achieved through protection. In traditional systems, manual switch control is performed by the control panel, resulting in redundant wiring connections and increased cable installations on-site. In this system, manual switch control is handled by the protection associated with each switch. Control commands are directly sent from the field bus to the protection, which, upon receiving the command, executes control based on pre-set programs, such as checking for no voltage or synchronization, etc. Switches and knives without installed protection are still controlled by the control module within the system.
6) The comprehensive automation of the 35kV substation takes approximately one month to complete. After completion, an empty-load test is conducted, grounding is shaken, measurements are taken, and various electrical tests are passed before power is supplied. The operation is going well.
The main functions achieved after the comprehensive automation system transformation of the 4 35kV substation.
The renovated substation's integrated automation system features primarily: protective functions; switching operations and manual control of switches locally and remotely; collection and processing (measurement via CT) of AC/DC power; collection and processing of electrical pulse quantities; collection and processing of switch quantities; and switches, knife switches.
Control; accident alarms and incident logs; data collection; protection and substation automation information collection; data preprocessing including: statistics, computation, and sampling; control and regulation functions; event sequence recording and incident reconstruction; operational alarms; display and human-machine interaction operations; report creation, display, and printing; time correction; web browser.
5 Comprehensive Automation System Transformation Effects
Since the transformation and commissioning of the substation automation system over a year ago, it has significantly improved the power supply environment and achieved excellent results.
1) Enhanced safety and reliability through optimized design combinations, which has reduced external connections and minimized failure rates. To date, the system has operated without fault for 8,760 hours, timely monitored and reported electrical faults 16 times, and automatically implemented protective measures.
2) Easy to maintain, the device is microprocessor-based, fully standardized and modular, with a simple structure and built-in fault diagnosis capabilities. It can promptly identify issues during operation, and the system wiring is straightforward, making maintenance convenient.
3) The占地面积 has been reduced, with the hardware components utilizing large-scale integrated circuits, resulting in a compact structure, small size, and strong functionality. The obtained data and signals are shareable, reducing the number of components. Additionally, the 6kV equipment is directly installed on the switchgear, saving a significant amount of control cables and cabinets, thereby reducing the footprint. After the renovation, the number of switchgears has been reduced to 6. To date, the total reduction in material and maintenance costs amounts to over 46,000 yuan.
4) The level of real-time calculation and control has been enhanced. On-site equipment automatically collects signal and measurement data, ensuring completeness and accuracy. The microcomputer unit and back-end system can perform real-time calculations, analysis, and data processing. The system can be automatically controlled and also operated by on-duty staff through a microcomputer. It features remote control capabilities, with detected operating conditions and data sent to dispatch in real-time, enabling remote control and thereby improving the level of calculation and control.
5) The utilization of microcomputers and databases has enhanced the level of automation in substation operation management. The system's automation and remote control functions provide a reliable technical condition for the realization of unmanned operation in substation.
Ankore Acrel-1000 Substation Integrated Automation System
6.1 Project Overview
The Acrel-1000 Substation Integrated Automation Monitoring System is composed of a station control layer and an interlayer equipment layer in terms of logical functions, connected through a layered, open network system. The station control layer equipment includes a monitoring host, which provides an operator interface for in-station operations and enables management and control of interlayer devices, forming comprehensive station monitoring and facilitating communication with remote monitoring and dispatching. The interlayer consists of several secondary subsystems and can still independently perform local monitoring functions for interlayer devices even if the station control layer and its network fail.
In response to the specific engineering requirements, the design offers high reliability, easy scalability, and a user-friendly interface. The performance-to-price ratio is superior. The monitoring system is composed of two parts: the station control layer and the interval layer, utilizing a hierarchical distributed network architecture. The station control layer network employs an Ethernet using the TCP/IP protocol. The station control layer network is configured with a single network and dual hot-standby machines.
6.2 Application Venue:
End-user distribution, operation monitoring, and control management systems for power utilization in public, industrial, and residential buildings, etc., applicable to voltage levels below 35kV.
6.3 System Structure
6.4 System Features
6.4.1 Real-time Monitoring
The Acrel-1000 Substation Integrated Automation System visually displays the operation status of distribution lines in the form of a primary distribution diagram, real-time monitoring electrical parameters such as voltage, current, power, and power factor for each loop. It dynamically supervises the opening and closing states of circuit breakers, isolators, and ground switches in various distribution loops, as well as related fault and alarm signals.
6.4.2 Alarm Handling
The monitoring system features an alarm function for accidents. The accident alarms include circuit breaker trips and protective device operation signals caused by abnormal operations; pre-alarm notifications cover general equipment changes, abnormal status information, over-limit of analog or temperature values, etc.
1) Incident Alarm. When the system is in an incident state, an audio alarm is immediately triggered (alarm volume adjustable), indicated by a color change and blinking on the operator's workstation display, along with a red alert message popping up. Alarms are categorized as real-time and historical, with the historical alert messages featuring selectable query and printing capabilities.
Incident alarms are manually triggered, with confirmation required each time. Once an alarm is confirmed, the sound and flash will cease.
During the alert reporting phase, the next alert signal is allowed to enter, meaning the current alert does not override the previous alert content. The alert handling has the functionality to be defined or exited on the main computer.
2) For each measurement value (including calculated values), the user sets four specified operating limits (physical lower limit, alarm lower limit, alarm upper limit, and physical upper limit) sequentially, which are defined as pre-alarm and accident alarms, respectively.
3) Trip circuit breaker to a certain number of times or pull circuit breaker to a certain number of times, trigger an alarm and prompt users to conduct maintenance.
4) Reporting Procedures.
Alert methods come in various forms, including pop-ups, screen flashing, audio-visual alarms, voice, SMS, and phone calls, among others. Users can add or modify alert information according to their needs.
6.4.3 Adjustments and Controls
Operators perform control operations on electrical equipment requiring control. The monitoring system features an operation supervision function, enabling supervisors to supervise from the operator's work station, thus preventing any accidental misoperations.
Operation control is divided into four levels:
Local equipment maintenance control, with priority control rights. When the operator places the remote/local switch of the local equipment in the local position, it will lock all other control functions, and only perform on-site operations.
Level control, interlayer backup control. The switch between the third-level control is completed at the interlayer.
Level 3 Control, Station Control Layer Control. This level of control is completed at the operator's workstations and features a remote/station control layer switch.
Level 4 Control, Remote Control, Priority.
In principle, interlayer control and on-site equipment control are used as backup or maintenance operation methods. To prevent erroneous operations, step-by-step procedures must be followed under any control mode, i.e., select, return, and execute. Operators and supervisors' passwords, as well as line codes, should be set at the station level to ensure the safety and accuracy of operations. For any operation mode, the next step should only be initiated after the previous operation step is completed. Only one control mode is allowed at a time.
Equipment under control includes: Circuit breakers for voltages of 35kV and below; Disconnectors for voltages of 35kV and below, as well as earthing switches with electric mechanisms; Station power 380V circuit breakers; Tap changers for main transformers; Remote reset and remote switching links for relay protection devices.
3) Scheduled Control: Operators perform scheduled control operations on electrical equipment, setting start and shutdown times to complete the scheduled control.
4) Control output of the monitoring system. The control output terminals are passive terminals, with a capacity of 110V (220V) for DC and 5A, and 220V for AC, 5A.
6.4.4 User Permission Management
The system has been equipped with user permission management functionality. Through user permission management, unauthorized operations can be prevented, and permission groups with different operational permissions can be defined (such as administrators, maintenance staff, on-duty team, etc.). Usernames and passwords can be added within each permission group, ensuring reliable protection for the system's operation, maintenance, and management.
7 System Hardware Configuration
8 Conclusion
The application of the 35kV substation microcomputer integrated automation system represents a significant technical advancement in the power supply system. Currently, the system operates stably and reliably. In today's rapidly evolving technological landscape, the integrated automation system for substation is gradually replacing the cumbersome and complex traditional control and protection systems with its systematic, standardized, and future-oriented approach. The promotion and application of the integrated automation system in 35kV substations will undoubtedly have a profound impact on enhancing the safety, stability, and reliability of substation operations, as well as reducing maintenance costs.
