pickTo:At present, there are many user side substations in China. Due to the long construction time, almost all equipment has shown an aging trend. Therefore, it is necessary to carry out intelligent transformation. With the development of automation technology, transforming traditional substation systems into comprehensive automation systems has become an inevitable choice. This article will combine with a certaintraditionalThe current situation of 66kV substation andAnalysis of the comprehensive automation system of the substation, exploration of its intelligent transformation measures, and implementationUnmanned 66kV substation.

Keywords66kVsubstation；Integrated automation system;; intelligentizationreform; Unmanned operation;

0. Introduction

Driven by the rapid development of society, ChinaEnterprise productionThe dependence on electricity energy in China is gradually increasing, and there are greater contradictions in the supply of electricity for production and daily life. In order to ensureenterpriseIn production and daily life, there is sufficient electricity and energy, and the management of substations should be strengthened to ensure more stable operation and ensure the supply of electricity and energy.

1. Current operation status of substation

In recent years, China'straditionThe high occurrence rate of substation failures leads toResident life, enterprise productionIt has been greatly affected, which requires in-depth analysis of the fault problems and causes within the power system. It is found that the main cause of the fault problems is due to equipment aging and inadequate maintenance. Based on the analysis of the actual situation,traditionThe faults that occur in substations are quite serious, difficult to maintain, and can lead to long-term power outages, greatly affecting the daily lives of urban residentsProduction and operation of enterprisesAt present, substations are mainly managed through unmanned substation mode, and real-time monitoring can be completed without the need for on duty personnel. This is because modern substation equipment with high technological level is installed, and only a small number of staff assistance is needed to complete the operation, which can achieve remote management and control. For the unmanned management mode, the staff in the control center only need to use scientific means to timely detect problems in the operation of the substation and carry out maintenance and handling in a timely manner.

2. Advantages and Problems of Substation Integrated Automation System

2.1.System Advantages

Compared with the traditional secondary system of conventional substations, the comprehensive automation system of substations makes the operation and maintenance management of substations more convenient, safe and reliable, which can greatly improve the work efficiency of substations and promote the modernization development of the power grid system. With the development of computer technology, network technology, and communication technology, and the improvement of automation level, the secondary system of substations has basically achieved comprehensive automation of substations. Through the comprehensive automation system, relay protection can be self checked and mutually inspected, with functions such as fault recording, event recording, operation monitoring, and control, reducing operation and maintenance costs and improving the safe and reliable operation level of substations.

2.2.Existing problems

With the development of the power system, there are more and more substations, which brings with it equipment failures. Based on the analysis of the location of the failure, the reasons are analyzed, and according to the location of the comprehensive automation system failure in the power grid substation in recent yearsRelevant information indicates thatThere are many faults in the station control layer, accounting for45.39%； Next is the spacing layer, accounting for 30.50%; Next is the network layer, accounting for 12.76%;Next is the remote control system, which accounts for11.35%.

lStation control layer malfunction

The main reasons for the majority of station control layer failures are hardware failures in the backend system, incorrect parameter settings in the backend system, and software failures in the front-end processor.

(1)The hardware failure of the backend system is manifested as frequent crashes of computer equipment. The main reason is that the device has been running for too long and has experienced a certain degree of aging, resulting in damage to the motherboard and hard drive. In addition, hardware devices such as displays in the backend system are also severely damaged.

(2)The parameter setting error in the backend system is manifested as unclear definition of message names, and inconsistency between the main and sub screen displays and the actual situation. Mainly due to the huge amount of information in automation systems, new and modified/Caused by inadequate transmission during the acceptance of the expansion project. In addition, non-standard message names are also the main reason for such defects.

(3)The main manifestations of front-end computer software failures are unexplained crashes and application crashes. Usually, it can be restored by restarting.

lInterval layer fault

The equipment failure in the interlayer is mainly caused by two aspects. The frequent occurrence of intermediate layers is due to secondary loop problems. The communication status cannot correspond well with the actual situation due to poor insulation points or inadequate auxiliary contacts after each operation of the equipment. Another issue is caused by the measurement and control device, manifested in hardware facilities, where communication interruptions often occur due to internal plugin or module problems. There are relatively few problems with the software of the measurement and control device, but the defects that occur are quite serious. If the scheduled values are lost and the on-site inspection is not in place, it is easy to cause operational accidents. There were also incidents of measurement and control devices crashing on site, causing remote control commands to be unable to execute and operate normally. Power off and restart the measurement and control devices to restore normal operation.

lNetwork equipment malfunction

According to relevant information, the current network communication equipment problems are not too serious, but if they occur, they can lead to serious problems, which may cause interruptions in the data collection work of substations or substation equipment. So it is necessary to handle such faults in a timely manner. Analyzing and studying the causes of network equipment failures is often due to poor product quality, especially hardware issues with various network communication devices such as hubs and switches.

3. Acrel-1000Solution for Integrated Automation System of Substation

3.1.Program Overview

The Acrel-1000 substation comprehensive automation monitoring system consists of two layers of equipment, namely the station control layer and the interval layer, in terms of logical functions, and is connected using a layered and open network system. The station control layer equipment includes a monitoring host, which provides a human-machine interface for station operation, realizes the management and control of equipment in the interval layer, forms a whole station monitoring, and communicates with remote monitoring and dispatch centers; The interval layer is composed of several secondary subsystems, which can independently complete the on-site monitoring function of interval layer equipment in the event of station control layer and station control layer network failure.

Based on the specific situation of the project, the design scheme has high reliability, easy expansion, and friendly human-machine interface, with good performance price ratio. The monitoring system consists of two parts: the station control layer and the interval layer, and adopts a layered distributed network structure. The station control layer network adoptsEthernet based on TCP/IP protocol. The station control layer network adopts a single network dual machine hot standby configuration.

3.2.Substation Integrated Automation SystemIntelligent transformation

3.2.1.Reconstruction of station control layer issues

Station control layeradoptAcrel-1000 substation comprehensive automation system realizes monitoring and management of power equipment. And integrate new computer technology, network technology, communication technology, information processing technology, power distribution automation technology and other technologies at home and abroad to achieve functions such as telemetry, remote signaling, remote control, and remote adjustment. Meet all the requirements of users for the protection, monitoring, and power quality of the power system.

Acrel-1000 Substation Integrated Automation SystemadoptSingle network dual machine hot standby configuration, under normal circumstances, the host is in working state and the slave is in monitoring state. Once the slave detects an abnormality in the host, it will replace the host in a short period of time to achieve the functions of the host. simultaneouslysystemMeet the following requirements:

Average wuguzhang interval time at the station control layer（MTBF is greater than or equal to 20000 hours, and the average wuguzhang interval time of interval level measurement and control devices is greater than or equal to 30000 hours;

The workstations at the station control layerCPU average load rate: less than or equal to 30% during normal operation (within any 30 minutes), and less than or equal to 50% during power system failure (within 10 seconds);

Average network load rate: under normal conditions (arbitrary)Less than or equal to 20% within 30 minutes, and less than or equal to 40% within 10 seconds of power system failure;

3.2.2.Renovation of Interval Layer Issues

Configurable in the substation distribution systemThe AM5SE series microcomputer protection device has the following advantages, effectively balancing the economic benefits brought by the equipment with the technical content and quality issues of the product itself.

In terms of product design, the device has a unified hardware, including a power moduleCPU module, input/output module, control circuit module, analog signal acquisition, communication module, etc; The overall design adopts a modular approach with strong universality, allowing for flexible configuration of protection functions for different primary equipment on the same hardware platform, achieving protection and measurement functions for substations and equipment with voltage levels of 35kV and below. This includes protection and automatic control functions for 35kV incoming lines/main transformers (generally with a capacity of 2000kVA or above)/PT/busbars, 10kV incoming lines/feeders/distribution transformers (generally with a capacity of 2000kVA or below)/high-voltage motors/high-voltage capacitors/busbars/PT and other equipment.

In terms of product quality, the device has obtained type test reports and electromagnetic compatibility inspection reports through third-party type testing at the National Relay Protection and Automation Equipment Quality Supervision and Testing Center. It has passed radiation emission limit testing, conducted emission limit testing, radio frequency electromagnetic field radiation immunity, electrostatic discharge immunity, radio frequency field induced conducted disturbance immunity, electrical fast transient pulse group immunity, slow damping oscillation wave immunity, surge immunity, power frequency magnetic field immunity, AC and DC voltage sag interruption, etc10 electromagnetic compatibility testing certifications, among which the fast transient, electrostatic discharge, and surge anti-interference performance all meet the requirements of level IV.

In terms of interface resources, the device has12 analog channels, selectable for protection current, measurement current, and voltage input; The AC voltage input port should be able to connect phase voltage, as well as connect voltage, zero sequence voltage, or unbalanced voltage, and adapt to various PT connection methods. The protection current and measurement current channels can be connected to three-phase current separately; The other two AC current channels can be connected to zero sequence current, unbalanced current, or line current. It has zero sequence current and zero sequence voltage measurement functions, and cooperates with the power monitoring system to achieve small current grounding line selection function.

3.2.3.Data communication problem transformation

The comprehensive automation system of the substation needs to collect information on equipment in the station for centralized analysis and management. Due to interface issues between different system units and products, we willCommunication interfaces for various system unit devicesThe protocol conversion device converts it into an open and unified interface standard, allowing users to choose the appropriate interface according to their own needs.

4. System functions

4.1.real-time monitoring

Acrel-1000 Substation Integrated AutomationThe system visually displays the operating status of distribution lines in the form of a distribution diagram, monitors real-time electrical parameter information such as voltage, current, power, and power factor of each circuit, dynamically monitors the closing and opening status of circuit breakers, isolation switches, ground knives, and related fault, alarm, and other signals of each distribution circuit.

4.2.Alarm Handling

The monitoring system has an accident alarm function. Accident alarm includes circuit breaker tripping and protection device action signals caused by abnormal operation; Pre warning alarms include general equipment displacement, abnormal status information, analog or temperature exceeding limits, etc.

1) Accident alarm. When in the accident state mode, the accident alarm immediately emits an audible alarm (the alarm volume can be adjusted arbitrarily), and the display screen of the operator workstation changes color and flashes to indicate that the device has changed position. At the same time, a pop-up window displays a red alarm text. The alarm is divided into real-time alarm and historical alarm, and the historical alarm text has the function of selecting, querying, and printing.

2) For each measurement value (including calculated values), four specified operating limits (physical lower limit, alarm lower limit, alarm upper limit, physical upper limit) are set by the user sequence and defined as pre alarm and accident alarm, respectively.

3) The alarm methods have various forms of expression, including pop ups, flashing screens, etc., but not limited to the above methods. Users can add or modify alarm information according to their own needs.

4.3.Regulation and Control

The operator controls the electrical equipment that needs to be controlled. The monitoring system has operation monitoring function, allowing monitoring personnel to implement monitoring on the operator workstation to avoid misoperation.

The operation control is divided into four levels:

First level control, on-site maintenance control of equipment. Having high priority control. When the operator remotely connects the on-site equipment/When the local switch is placed in the local position, all other control functions will be locked and only on-site operations will be performed.

Second level control, backup control for the interval layer. The switching between it and the third level control is completed in the interval layer.

Third level control, station control layer control. This level of control is completed on the operator workstation and has remote capabilities/Switching of station control layer.

Fourth level control, remote control, low priority.

In principle, interval level control and equipment on-site control are used as backup or maintenance operation methods. To prevent misoperation, step-by-step operation is required under any control mode, including selection, returning to school, and execution. Operator and supervisor passwords and line codes should be set at the station level to ensure the safety and correctness of the operation. For any operation method, ensure that the next step is only performed after the previous operation step is completed. Only one control method is allowed to be effective at a time.

The devices included in the control include:35kV and below circuit breakers; 35 kV and below isolating switches and grounding switches with live moving mechanisms; Station power 380V circuit breaker; Main transformer tap; Remote reset and remote switching connection piece of relay protection device.

5. Acrel-1000Transformation Plan for Substation Integrated Automation System

5.1.system architecture

The substation of this project adopts66kVSingle circuit mains power input lineConnected to the power grid through a single busbarThe 12500kVA main transformer is stepped down to 10kV for the distribution of various circuits in the station.

5.2.Equipment selection

The substation renovation of this project mainly focuses on the protection of the main transformer and the inside of the stationThe 10kV switchgear secondary and monitoring system backend will be renovated. The small current grounding line selection device cannot be replaced immediately, so this renovation will utilize the old equipment.

The main transformer protection screen cabinet is set up in the electrical monitoring room, and is installed on the screen cabinet1 differential protection device AM5SE-D2, 1 high backup protection device AM5SE-TB, 1 low backup protection device AM5SE-TB, 1 non electric protection device AM5SE-FD, 1 high side measurement and control device AM5SE-K, 1 low side measurement and control device AM5SE-K, 1 transformer temperature controller ARTM-8, and other control equipment such as transfer switches, pressure plates, and air switches.

Line protection screen according to10kV segmentation principle, divided into two screen cabinets, 1#4 line protection AM5SE on the 10kV line protection measurement and control screen-F，2#4 line protection AM5SE on the 10kV line protection measurement and control screen-Add one old small current grounding line selection device to F.

The monitoring host is configured according to the single network dual machine scheme, with one monitoring host screen installed in the station and one operation console installed in the duty room,Under normal circumstances, the host is in a working state, while the slave is in a monitoring state. Once the slave detects an abnormality in the host, it will quickly replace the host and fulfill its functions..

5.3.On site comparison before and after renovation

The power outage time for the substation renovation of this project is onlyWithin 24 hours, the secondary cables of the microcomputer protection group cabinet for this renovation were sorted out according to the original secondary drawings, considering cable laying. During the design phase, the position of the back terminal was kept unchanged, and only the internal wiring of the device to the cabinet was adjusted. At the same time, the position of the switch and pressure plate was installed near the side of the device according to the original on-site design.

The on-site situation before and after the renovation is shown in the following figure. During the design phase of this renovation, the original drawings were strictly followed, considering the convenience of construction. During the construction phase, the cables were sorted and point-to-point according to the construction specifications, and the high and low voltage circuits of the main transformer on site were checkedRemote control testing was conducted on each 10kV outgoing circuit, and the transformation and power transmission were successfully completed within 24 hours.

Substation before renovation

Post renovation substation

6. Conclusion

The comprehensive automation renovation project of substations is an old substation renovation project. Through the comprehensive automation renovation of substations, real-time and unified substation data and dispatch room data can be achieved, making remote control more accurate. Each signal data can be stored in the substation comprehensive automation system, so that in the future, when the power grid fails, real-time transmission data and past action signals can be called for analysis, bringing convenience to accident signal judgment.

References

[1]Li XintianComprehensive automation transformation measures for 35kV substations [J]. Science and Wealth, 2021

[2] Liu Xiaoling, Li Yong Discussion on Comprehensive Automation System of Substation [J]. Science and Technology Information, 2016, (03).

[3] Huang Xiaorong, Liu Jing A Brief Discussion on the Comprehensive Automation System of Substations [J]. Shanxi Electronic Technology, 2016, (15).

[4] Yao Zhigang, Fang Wei. Analysis and Implementation of 35kV Substation Renovation[J]Journal of Electrical Technology,2002(8).