summary
Researchers Deng Yong and Feng Xuemin from the State Grid Fujian Electric Power Dispatch and Control Center wrote an article in the 10th issue of "Electrical Technology" magazine in 2018, pointing out that with the advancement of dispatch automation system technology and the promotion and application of remote operation, the realization of programmed operation in dispatch automation systems has broad application prospects.
First, this paper proposes two typical schemes for implementing programmed operations in a dispatch automation system. A comparison shows that deploying programmed operation functionality at the dispatch master station offers several advantages, including fast implementation speed, low construction cost, wide application range, and minimal post-implementation maintenance. Second, it introduces solutions to key issues such as security measures for programmed operations at the dispatch end, operation ticket reasoning, and AIS switch operation confirmation. Third, it elaborates on the functional architecture and operation process of the dispatch end's programmed operating system. Finally, the system was piloted in a certain region, ensuring both operational safety and improved operational efficiency, achieving excellent application results.
In order to improve the efficiency of power grid switching operations, reduce operational safety risks, and improve the safety operation level of substations, more and more substations in China are piloting application-based operation[1]. With the promotion and application of remote operation[2], the control system can realize programmatic operation without repeatedly checking basic data such as remote control point table and remote control link. Relying on the integrated system error prevention[3] already realized by the control system and the real-time data of the whole network EMS, the operation verification of the programmatic operation process can be fully covered by all substations that support remote operation. Therefore, the realization of programmatic operation in the dispatch automation system has broad application prospects.
With the pilot application of programmed operation functions, research on programmed operation has gradually deepened. References [4-6] compared several schemes for implementing programmed operation and ultimately chose to implement it in substations. References [7-9] analyzed key and difficult issues related to programmed operation, such as operation ticket mode, substation expansion, and busbar operation, and proposed solutions. References [10-11] introduced specific schemes for implementing programmed operation in smart substations and conducted pilot applications in actual substations.
In summary, current research on programmed operation focuses on its implementation within substations, but suffers from drawbacks such as inflexible operation ticketing mechanisms and poor applicability to switching operations involving special wiring configurations and abnormal operating conditions. While some articles touch upon programmed operation implementation schemes for dispatch automation systems, none have proposed feasible and specific implementation plans.
Based on current research findings on programmed operation in substations, this paper proposes a specific implementation scheme for programmed operation in dispatch automation systems.
1. Implementation scheme of programmatic operation of the scheduling terminal
In recent years, China has vigorously developed intelligent operation, cold standby operation, and secondary operation at the dispatching terminal, accumulating considerable experience in remote operation at the dispatching terminal. This paper, considering the technical requirements of programmed operation for primary and secondary equipment, proposes the following two implementation schemes for programmed operation in dispatch automation systems.
1.1 Option 1: Deploy a programmatic operation function mode on the scheduling master station (hereinafter referred to as master station mode)
In master station mode, the programmed operation function is deployed on the dispatch terminal. The dispatch terminal is responsible for functions such as ticket generation, control command issuance, programmed operation logic verification, and interlocking. The substation is only responsible for executing remote operations and sending relevant operation information, as shown in Figure 1.
Figure 1 Main Site Mode
1.2 Option 2: Deploy a programmed operation function mode at the substation end (hereinafter referred to as substation mode)
In substation mode, the programmed operation function is deployed at the substation level. The dispatching terminal is responsible for initiating programmed operation commands, issuing the initial and target states of the operated equipment, and calling the programmed operation tickets from the substation. The substation is responsible for ticket generation, logic verification, and interlocking of programmed operations. The dispatching terminal monitors the execution process of programmed operations in real time and can understand the cause of interruptions through information exchange. Substation mode requires the substation to have programmed operation capabilities and can be considered an extension of the programmed operation function within the substation.
1.3 Comparison of Implementation Schemes
Comparative analysis of the two implementation schemes above shows that Scheme 1 has the following advantages:
1) Fast implementation and low construction cost. Relying on remote operation applications of substations, the programmed operation function is built uniformly at the main station. Compared with the substation model of deploying programmed operation functions in each substation, the construction cost is lower and the practical application can be promoted faster.
Figure 2 Subsite Mode
2) Wider range of applications. It can realize advanced programmed operations involving inter-substation interaction, such as line cross-station programmed operation and line reclosing activation/deactivation.
3) Facilitates later maintenance. Compared with the substation mode, the master station mode makes it easier to upgrade and modify the system functions and is more adaptable to different types of substations.
In summary, the main station mode has obvious advantages in both short-term construction and long-term maintenance. This paper adopts Scheme 1 to realize the programmatic operation of the scheduling terminal.
2. Key technologies for implementing programmed operations on the scheduling terminal
2.1 Security Measures for Programmed Operations at the Scheduling Terminal
In the programmed operations of the scheduling end, the operations are automatically implemented by the system. Therefore, it is particularly important to take measures to ensure the security and reliability of the programmed operations. This paper mainly considers the following three aspects.
1) Verification of abnormal signals in programmed operations
In the programmed operation process, items that traditionally required manual judgment of primary and secondary abnormal signals are now automatically judged by the system according to the programmed operation lockout library. The lockout library should consider both safety and reliability requirements. Safety means that the operated object and its related primary and secondary equipment should be in normal operating condition when executing the programmed operation to ensure the safety of the programmed operation process. Reliability means that the object of the programmed operation can reliably operate to the corresponding target state while ensuring the safety of the primary and secondary equipment, and there should be no false lockouts.
2) Preventing errors in procedural operation processes
The programmed operation calls the function of the integrated anti-misoperation system of the main station [2]. On the one hand, it realizes the anti-misoperation interlocking of equipment operation based on the topological relationship between electrical equipment; on the other hand, it adopts the same five-prevention logic expression as the station end, combined with topological anti-misoperation, to ensure the correctness of programmed operation.
3) Assessment of procedural operation in place
The programmed operation should realize the automatic judgment of the equipment operation in place. Based on the remote signaling change, the system automatically collects telemetry or associated video information to assist in the judgment of the equipment operation in place[12], and realizes the judgment of the programmed operation in place according to the preset logic.
2.2 Intelligent Reasoning Scheme for Programmed Operation Tickets
The intelligent reasoning scheme for programmed operation tickets is based on the conventional operation ticket expert system. It adopts a general cognitive model and performs network topology analysis [13]. It combines the general logic of programmed operation, such as the mechanism of the programmed operation lockout library and the judgment condition of the equipment operation in place, to realize intelligent reasoning of operation tickets. The following two aspects need to be noted in the topology analysis.
1) For the programmed operation tasks of equipment decommissioning involving mode arrangement, in order to solve the problem of mismatch between real-time topology and draft topology caused by pre-written programmed operation tickets, the normal mode of substation is incorporated into the system logic. The system automatically generates tickets based on the currently controlled normal mode.
2) For procedural operations such as maintenance work or specified operation sequences, dynamic adjustments to the special methods can be achieved through human-computer interaction.
2.3 AIS Equipment "Dual Confirmation" Implementation Scheme
In order to meet the safety requirements for operation, and considering that the current AIS disconnector double confirmation automatic judgment technology is not yet mature, this paper adopts the substation video auxiliary system [13] for remote confirmation.
The specific plan is as follows: 1) Before the programmed operation, the operator checks whether the video corresponding to the relevant equipment interval is clear; 2) During the programmed operation, the system automatically sends a video linkage command to the video auxiliary system, the video auxiliary system automatically locates the programmed operation equipment, and displays the programmed operation equipment video for the operator to confirm.
3. Implementation of Programmatic Operations in D5000
3.1 System Architecture
The D5000 programmed operating system functional architecture is divided into three layers: the user layer, the system application layer, and the substation execution layer, as shown in Figure 3.
1) User layer. Users of the programmed operation function include controllers and maintenance personnel who are authorized to remotely operate the control system via the terminal. Controllers or maintenance personnel carry out programmed operations through the corresponding human-machine workstation.
2) System Application Layer. The application for programmed operation of the control system is developed and deployed based on the integrated platform of the control system, including the control operation ticket system, the five-proof server, the remote operating system, the security certificate management system and the video auxiliary system, to complete core functions such as programmed operation ticket generation, operation security verification and digital security authentication.
Figure 3. Schematic diagram of the functional architecture of the D5000 programmable operating system
3) Substation execution layer. The control system automatically sends programmed operation commands to the remote control unit (RTU) via the dispatch data network; after receiving the programmed operation commands, the RTU sends them to the corresponding measurement and control device to execute the programmed operation; after each operation, the RTU uploads the telemetry and tele-signaling status sent by the measurement and control system to the control master station system; the control master station automatically performs telemetry and tele-signaling status determination based on the programmed operation application.
3.2 System Functions
The D5000 programmed operating system provides the following system functions related to programmed operation applications on the scheduling end.
1) Control and Operation Ticket System
It consists of two parts: dispatch instruction ticket application and programmed operation ticket application. The dispatch instruction ticket application has the function of dispatchers drafting, reviewing, and verifying programmed operation instructions; the programmed operation ticket application has the function of generating programmed operation tickets from dispatch programmed operation instructions. The programmed operation ticket is based on the power grid topology of the control system and intelligently identifies programmed operation tasks.
2) Five-prevention verification system
It has functions such as procedural operation for ticket drafting and error prevention verification, pre-drilled error prevention verification, and execution of real-time error prevention interlocking.
3) Remote operating system
The remote operating system features programmed operation execution, automatic interlock signal judgment, and automatic identification of the operating device location. It also provides manual intervention functions such as sequential control execution, sequential control pause, sequential control continuation, and sequential control termination to handle possible abnormal situations in programmed operations.
4) Security Certificate Management System
It provides digital certificate services for procedural operations, authenticates the identities of operators and supervisors, and has dual authentication capabilities.
5) Video-assisted system
This is a video feed of the AIS disconnector operation, for operators to manually confirm after the operation is completed.
3.3 Implementation of Programmatic Operations
1) Integrated procedural vote-drafting process
Upon entering the D5000 control automation system, based on the equipment status requirements of the safety measures in the maintenance application form, the system first drafts the initial and final status dispatch instructions for the specified equipment (such as lines, main transformers, or busbars) in the dispatch instruction ticket application module. Then, the system automatically drafts the corresponding programmed operation tickets according to the dispatch instructions in the programmed operation ticket module.
2) Programmatic operation execution flow
(1) Simulation and rehearsal process
To improve the smoothness of programmed operations, a simulation is performed before executing the programmed operation to identify problems that may affect the safety and reliability of the operation in advance, as shown in Figure 4.
Figure 4. Pre-operation flowchart
The pre-operation simulation phase begins with checking the pre-operation interlock library. Considering the potential interference from accompanying signals, a manual confirmation process for abnormal signals is added. After the interlock library check is passed, the system simulates the operation steps and sequence of the actual pre-operation ticket and performs a five-prevention logic check. Once all checks are passed, the simulation simulation is complete.
(2) Programmatic operation execution process
The formal operation follows the steps and sequence of the programmed operation ticket, automatically issuing and confirming each instruction to be executed correctly until all control instructions are completed. The operation flow is shown in Figure 5.
Figure 5. Execution flow of programmed operations
Programmed operations require checks and five-prevention logic verifications through the programmed operation lockout library. Based on the nature of abnormal signals, the system can prompt for manual confirmation or directly terminate the programmed operation. After the GIS equipment operation is completed, the system will automatically determine whether the operation is in place. The AIS equipment operation requires manual confirmation through video linkage.
4 pilot applications
This paper develops a sequential control function module based on the D5000 control system platform and pilots its application in the Fuzhou control system to achieve programmed operation at the dispatching end. Taking the programmed operation at the dispatching end of the 220kV Helin substation as an example, programmed operations are implemented for the lines, busbars, and main transformers respectively, while the blocking signal library is verified during the programmed operation process.
Pilot results show that: ① The blocking signal library is safe and reliable, the signals inside the blocking library can be blocked reliably, and the signals outside the blocking library will not be blocked erroneously; ② The programmed operation can significantly improve the operation efficiency (as shown in Figure 6), for example, the bus operation and cold standby switching operation is shortened from the original 45 minutes to 2 minutes.
Figure 6 Comparison of operation time
in conclusion
This paper proposes a specific scheme for deploying programmed operation functionality on the scheduling terminal. This scheme has several advantages, including fast implementation speed, low construction cost, wide application scope, and minimal subsequent maintenance. Pilot applications show that implementing programmed operation on the scheduling terminal is safe and reliable, and can significantly improve operational efficiency. Based on the development trend of programmed operation, the paper proposes future research content and directions for reference.
1) At present, smart substations have certain station-side programmed operation functions, but there are shortcomings such as large workload of operation ticket maintenance and inability to flexibly adapt to changes in operation mode. The next stage needs to focus on researching reliable smart ticket generation methods at the station end.
2) In terms of automatic judgment of AIS switch operation, in recent years, research has been carried out on state image monitoring and recognition algorithms such as Hough transform, scale invariant features and image binary method [14], but they are all in the research pilot stage, and their reliability and security are still far from practical application. Therefore, it is necessary to continue to study video data intelligent analysis algorithms to finally realize the automatic judgment of AIS device status.
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