CN112766674B - An intelligent review system for substation technical renovation and overhaul projects based on 3D GIS - Google Patents

Abstract

The invention relates to an intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS. The system architecture is a three-layer architecture logical framework based on the data layer, service layer and application layer. Specifically: the data layer is based on business The source of the data divides the data into substation three-dimensional scene data and substation business application data; the service layer adopts a microservice architecture and is divided into three-dimensional scene services and data interface services according to the service application scenarios; the application layer adopts The modular structure includes a three-dimensional scene basic application and a smart substation review application. Compared with the existing technology, the present invention has the advantages of making the review work of substation technical renovation and overhaul projects more efficient, standardized, and accurate.

Description

An intelligent review system for substation technical renovation and overhaul projects based on 3D GIS

Technical field

The present invention relates to the field of evaluation of substation technical renovation and overhaul projects, and in particular to an intelligent evaluation system for substation technical renovation and overhaul projects based on three-dimensional GIS.

Background technique

According to the three-dimensional GIS modeling work requirements of substations and in accordance with unified standards, a three-dimensional panoramic holographic model is constructed to continue to explore new information management application models and provide an advanced and practical technical means to improve the operating efficiency of power companies and enhance the decision-making service capabilities of smart applications. As the starting point, we rely on new technical means to support the transformation and innovation of management models and operating methods. Applying 3D GIS technology in the review of substation technical renovation and overhaul projects can restore the real situation of on-site substation equipment and view the power grid equipment environment online in real time, which can improve the accuracy and efficiency of the review of substation technical renovation and overhaul projects.

However, the current PMS2.0 system power grid graphics is a two-dimensional graphics platform without three-dimensional substation model data, which cannot accurately express the three-dimensional spatial information of power grid equipment. It does not meet the requirements for three-dimensional GIS modeling of substations. In addition, during the review process of substation technical renovation and overhaul projects, It is impossible to view the on-site status of the corresponding power grid equipment and the three-dimensional model comparison results, and it is impossible to accurately evaluate the project.

Contents of the invention

The purpose of the present invention is to provide an intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS in order to overcome the above-mentioned shortcomings of the existing technology and promote the evaluation work of substation technical renovation and overhaul projects to be more efficient, standardized and accurate.

The object of the present invention can be achieved through the following technical solutions:

An intelligent review system for substation technical renovation and overhaul projects based on 3D GIS. The system architecture is a three-layer logical framework based on the data layer, service layer and application layer, specifically:

The data layer divides the data into substation three-dimensional scene data and substation business application data according to the source of the business data;

The service layer adopts a microservice architecture and is divided into three-dimensional scene services and data interface services according to the service application scenario;

The application layer adopts a modular structure, including three-dimensional scene basic applications and substation smart review applications.

Further, the three-dimensional scene basic application includes a three-dimensional scene editing module and a three-dimensional data management module, and the substation intelligent review application includes a substation three-dimensional scene browsing module, a business data integration module and a project intelligent review module.

Further, the three-dimensional scene services include paging services, editing services, attribute services, synchronization services, relationship services, version services and ledger services, and the data interface services include relationship mapping services, PMS data access services, SACDA Data access services, power grid primary equipment online monitoring data access services and unified video system monitoring video access services.

Further, the project intelligent review module includes a substation information panel, an in-station camera information panel and a project information panel. The substation three-dimensional scene browsing module is used to browse the three-dimensional substation scene through three modes: flying, driving and walking. The business data integration module is used to access and display PMS2.0 data, power grid primary equipment online monitoring data, SCADA data and unified video data.

Furthermore, the substation information panel is used to query information about the substation operation and maintenance unit, maintenance team, voltage level, operation date, operation number, operation status, duty mode and layout mode;

The camera information panel in the station is classified and displayed according to the substation location area. The location area includes the capacitor room, switch room, equipment area, station environment and main control room. The camera information panel in the station is selected and positioned by clicking the mouse. View the corresponding camera model in the three-dimensional scene of the substation. In the three-dimensional scene of the substation, the selected camera model is highlighted in the center. Click the three-dimensional camera model in the three-dimensional scene with the mouse to open the real video picture of the camera in the station; the project information panel Used to query and download the details of substation technical renovation and overhaul projects, project estimates, annual/item investments, technical renovation/overhaul objects, equipment main materials, scrap materials, scale results and project attachments, and the project information The panel displays the review elements of substation technical renovation and overhaul projects by category, provides functions for reviewing one by one, filling in review opinions step by step, and exporting review reports with one click. It also provides yellow, red, and green color reminders for the review status of the review elements of technical renovation and overhaul projects. , among which, green represents approval, red represents rejection, and yellow represents pending review;

The project information panel, by obtaining the name of the primary equipment of the power grid in the list of technical renovation/overhaul objects clicked by the mouse, locates the location of the primary equipment of the power grid in the three-dimensional scene of the substation, and displays the ledger data associated with the selected primary equipment of the power grid. Online monitoring data, SCADA data and video surveillance data.

Furthermore, the system includes a client, an application server and a database server. The client is connected to the intranet through a router and a firewall in turn. The application server and database server are connected to the intranet respectively. The application server It is also connected to the PMS system, SCADA system, power grid primary equipment online monitoring platform and unified video system. The client is in the application layer, the application server is in the service layer, and is used for the deployment of three-dimensional platform services. The database The server is in the data layer and is used to store three-dimensional scene data of the substation and business application data of the substation.

Further, the application server provides three-dimensional scene services and data interface services through load balancing and service agents, and obtains PMS data from the PMS system, SCADA data from the SCADA system, and online monitoring of primary equipment from the power grid through the data interface services. The platform obtains online monitoring data of primary equipment in the power grid and video surveillance data from the unified video system.

Further, the PMS2.0 data includes power grid primary equipment ledger data, substation information, substation technical renovation and overhaul project details, project estimate, annual/item investment, renovation and overhaul objects, equipment main materials, and old materials for demolition , scale results and project attachments, the SCADA data includes voltage, current, active and reactive power data, the online monitoring data of primary power grid equipment includes oil chromatography, oil pillow oil level and circuit breaker partial discharge data, the Video surveillance data includes on-site video surveillance images of substations.

Furthermore, the map image data includes terrain data, vector data and image data, the model and point cloud files include model data, point cloud data and picture data, and the business scenario data is stored in a relational database. .

Further, the operating systems of the application server and database server are both Windows operating systems.

Compared with the prior art, the present invention has the following advantages:

1) Based on the virtual reality production management platform, this invention expands the business scenarios for the review of substation technical renovation and overhaul projects, meets the demand for three-dimensional scene display inside the substation during the project review process of substation technical renovation and overhaul projects, and at the same time satisfies the wisdom of substation projects. Review the need for reliable controls;

2) The shared interface of the present invention is standardized and can support friendly calling of the interface for third parties that meet technical requirements, enabling access to PMS data, power grid primary equipment online monitoring data, video monitoring data and SCADA data, ensuring the source of three-dimensional data maintenance Unique, improve data maintenance efficiency and data accuracy, while ensuring the timeliness, integrity and accuracy of business data, data acquisition is unique and comprehensive, and highly reliable;

3) The application layer adopts a modular structure design, which achieves low coupling between modules, facilitates application adjustment and upgrade, and has high scalability. The service layer adopts a microservice architecture design, which reduces the dependence between services and realizes service integration. Load balancing and distributed deployment improve efficiency.

Description of drawings

Figure 1 is a schematic diagram of the application architecture of the system of the present invention;

Figure 2 is a schematic diagram of the data architecture of the system of the present invention;

Figure 3 is a schematic diagram of the deployment architecture of the system of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention.

Example

The present invention provides an intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS. It adopts service-oriented (SOA) application architecture design. While dividing business applications, it also performs fine-grained division of services supporting applications and extracts public uses. Services, such as scene services, editing services, attribute services, map services, and synchronization services, are further divided into business-related services, such as equipment ledger services, relationship mapping services, online monitoring data reading services, video surveillance access services, etc.

As shown in Figure 1, the platform builds a typical three-layer architectural logic framework based on the data layer, service layer, and application layer to realize the browsing and management of three-dimensional substation scenes under different business scenarios;

The application layer adopts a modular structure design to achieve low coupling between modules and facilitate application adjustments and upgrades, including 3D scene basic applications and substation smart review applications, including substation 3D scene browsing modules, business data integration modules and project smart reviews The module is mainly used to implement functions such as power station roaming, site inspection, ledger management, equipment defect hazard viewing, equipment live status rendering, equipment operation monitoring data viewing, equipment abnormal alarm viewing, in-station video monitoring viewing, and substation smart review.

Among them, the project intelligent review module includes the substation information panel, the station camera information panel and the project information panel. The substation three-dimensional scene browsing module browses the substation three-dimensional scene through three modes: flying, driving and walking. The business data integration module is used for PMS2.0 data, Access and display of online monitoring data of power grid primary equipment, SCADA data and unified video data.

The substation information panel is used to query information about the substation operation and maintenance unit, maintenance team, voltage level, operation date, operation number, operation status, duty mode and layout mode;

The camera information panel in the station is classified and displayed according to the location area of the substation. The location area includes the capacitor room, switch room, equipment area, station environment and main control room. The camera information panel in the station can be selected and positioned by clicking the mouse to the corresponding camera model in the three-dimensional scene of the substation. View, in the 3D scene of the substation, the selected camera model is highlighted in the center. Click the 3D model of the camera in the 3D scene with the mouse to open the real video picture of the camera in the station; the project information panel is used to review technical renovation and overhaul project details and project estimate documents. , annual/item investment, technical transformation/overhaul objects, equipment main materials, scrapped materials, scale results and project attachments can be inquired and downloaded. The project information panel displays the review elements of technical transformation and overhaul projects by classification, providing one-by-one review, The function of filling in the review opinions step by step and exporting the review report with one click provides yellow, red, and green color reminders for the review status of the project review elements. Green represents review approval, red represents rejection, and yellow represents pending review. In the project information panel, click the name of the equipment in the technical renovation/overhaul object list to locate the location of the equipment in the three-dimensional scene of the substation. Select the equipment to view the ledger information, online monitoring information, SCADA information and on-site camera monitoring video associated with the equipment. .

The service layer adopts a microservice architecture design, which reduces the dependence between services and enables load balancing and distributed deployment of services. According to different service application scenarios, the service layer is divided into two categories: three-dimensional scene services and data interface services. 3D scene services mainly include paging services, editing services, attribute services, synchronization services, relationship services, version services, ledger services, map services and file storage management services. Data interface services include relationship mapping services, PMS data access services, and SACDA Data access services, power grid primary equipment online monitoring data access services and unified video system monitoring video access services.

The data layer divides the data into substation three-dimensional scene data and substation business application data according to the source of business data. Three-dimensional scene data mainly includes unstructured data and structured data; substation business application data mainly includes equipment-related data.

As shown in Figure 2, the data in the system can be divided into three-dimensional scene data and substation business application data according to different sources of data. According to different storage methods, 3D scene data can be divided into business scene application data that can be stored in a structured manner and unstructured scene model files and other data.

Three-dimensional scene data mainly includes business scenarios and application data, models and point cloud files, and geographical image data. Among them, business scenarios and application data mainly include scene paging information, basic model information, basic point cloud information, basic ledger information, business function information, etc. Data such as scene pagination and basic ledgers that are frequently accessed by the client use an in-memory database. (Redis) method is stored in memory to improve the efficiency of data access. Models, point cloud files, geographical image maps and other unstructured files are stored in the file storage system, which supports distributed deployment of services. After the client obtains the accessed files, it will cache the unstructured files locally, improving again. The efficiency of reading this file.

Substation business application data mainly completes the access of related data in other systems. According to the different data access methods and display forms, the interface data can be divided into surveillance video data and ledger and operation monitoring data. Operation monitoring data is cached in memory in the form of relational mapping, and surveillance video data is directly accessed through the access method provided by the unified video platform.

The sources and access methods of equipment ledger information and monitoring data in the platform are as follows:

Power grid primary equipment ledger data, equipment-related defects, hidden dangers, maintenance plans and other business data, as well as technical renovation and overhaul project data, specifically including ledger data, defect data and hidden danger data, are obtained through the PMS2.0 system backup library and use data integration way to access the platform;

Equipment operating data, such as voltage, current, active power, reactive power and other data, are integrated with the equipment operating data in the SCADA system through system integration, specifically including operating data, alarm data and abnormal data;

The primary equipment of the power grid monitors abnormality, defects, faults and other data online, and obtains relevant data through the online monitoring platform, including oil chromatography, oil conservator oil level, and circuit breaker partial discharge data, and accesses the platform through system integration;

The video data monitored in the site is connected to the video surveillance data of the unified video platform in a system integration manner.

After completing the layering of the entire platform architecture (application layer, service layer, data layer) and subdividing the business functions in the application layer and the service support in the service layer, the deployment architecture needs to be considered. Facilitate distributed deployment, which is also one of the main purposes of layering. Deploy different modules on different servers and work together through remote calls. Distribution means that more computers can be used to complete the same function. The more computers, the more CPU, memory, and storage resources, and the greater the amount of concurrent access and data that can be processed, thereby providing more users with Serve.

The deployment architecture shown in Figure 3 includes clients, application servers and database servers. The servers can be virtual hosts divided on the cloud platform. The clients are connected to the intranet through routers and firewalls in turn, and the application servers and database servers are connected to In the intranet, the application server is also connected to the PMS system, SCADA system, power grid primary equipment online monitoring system and unified video system. The client is in the application layer, the application server is in the application layer, and is used for the deployment of three-dimensional platform services. The database server is in the data layer. , used to store the three-dimensional scene data of the substation and the business application data of the substation. The application server uses Nginx to implement the service agent and load balancing of the application, and provides three-dimensional scene services and data interface services through load balancing and service agents, and obtains PMS data from the PMS system and SCADA data from the SCADA system through the data interface service. Obtain the online monitoring data of the primary equipment of the power grid from the online monitoring system of the primary equipment of the power grid, and obtain the video monitoring data from the unified video system.

The application server service adopts double-click hot backup and distributed deployment to achieve high availability of the service. The database uses the master-slave backup function to achieve highly reliable operation of the database. The data storage adopts distributed file storage to ensure the safe storage of files.

The smart review and control application for substation technical renovation and overhaul projects is a three-dimensional hierarchical display of the power grid overview, substation panorama, and equipment status based on monitoring big data. It displays the geographical location of each substation on a 3D GIS map and intuitively displays the entire network in a three-dimensional scene. Big data analysis results such as alarms, defects, loads, and equipment charging status. When advancing to the 3D scene of the substation, the 3D equipment model is used to correlate diversified data information to form an intuitive visualization effect, and provide an intuitive distribution of different statuses such as equipment alarms, defects, and maintenance throughout the station. Using equipment online monitoring data and in-station video monitoring data, through data analysis and processing, intelligent review and management of substation projects can be realized.

Three-dimensional model library management is divided into: equipment model information management, civil engineering model information management, and decoration model information management according to different types of equipment. The 3D model management can be classified and displayed by device type, voltage level, and category. Users can view models of related devices based on filter conditions. When previewing the model, they can view the model's attributes, components, animation, electrical and other information. Users can also import new equipment models or replace existing equipment models through the model import function. 3D model component management is mainly responsible for splitting and naming management of equipment model components. Three-dimensional parts management is divided into split management and naming management, and equipment parts can be added, modified, and deleted. Three-dimensional point cloud management is the management and maintenance of point cloud data obtained during the collection process. Laser point cloud data is divided into substation, cable channel and overhead line point clouds according to the type of corresponding equipment. Point cloud management includes analysis, processing and upload maintenance of point cloud data, download and preview of point cloud data and point cloud management. Functions such as integration and display of data and device models in the scene. Multi-dimensional browsing can be performed in 3D scene browsing. Scene browsing conforms to the browsing methods commonly used in 3D operations and supports browsing and roaming operations with mouse and keyboard shortcuts. Roaming and browsing in the three-dimensional scene supports multiple modes. Depending on the browsing location, it can support flying, driving and walking modes. You can also choose the automatic mode. In the automatic mode, the browsing speed in the scene can be automatically adjusted according to the height of the field of view. .

Users can use the mouse and keyboard to perform roaming operations in the scene. By holding down the left mouse button and dragging in the scene, the user can drag the three-dimensional scene to browse. The height of the field of view in the scene can be adjusted through the scroll wheel operation to realize the scene control. Perform zoom operations, hold down the middle button of the mouse and drag to adjust the scene perspective. In the scene, the roaming function in the three-dimensional scene can also be realized by using the shortcut keys WASD and the up, down, left, and right direction keys.

In three-dimensional scene positioning, multiple scene positioning methods need to be provided, such as bookmark positioning, coordinate positioning and other positioning methods. 3D scene management includes:

Management of device objects: Grouped according to device type, a classification tree list of all device objects in the three-dimensional scene is displayed. In device object management, you can determine whether the device is in the current scene based on the device node status, or you can set the device by checking the box. The equipment can be visible or hidden in the scene, and the equipment can also be selected and positioned through the tools provided in the list.

Management of device layers: All types are grouped and displayed according to type. Each device type corresponds to a device layer. Users can perform optional and visible setting operations on a certain type of device based on the device layer.

3D scene node management: Displays device node information in the current scene to facilitate device management and debugging.

In a three-dimensional scene, you can use scene editing tools to add, delete, and adjust equipment and facilities in the scene. You can add a new model to the 3D scene through the new operation. After selecting the model, you can left-click on the appropriate position in the scene to create the model, or right-click to cancel the creation of the model. After the model is created, you can use the model adjustment tool to adjust the model in the scene. position, height and direction, etc. You can also delete the model after selecting it in the scene.

Scene operation tools are provided in the 3D scene to facilitate more clear and intuitive display of model equipment data in the 3D scene. For example, the platform provides highlighted display of 3D models, visible and hidden control of 3D model equipment, adjustable transparency of model equipment, setting of terrain transparency, 3D scene measurement tools, etc.

The main station system of the 3D GIS smart review platform deploys services based on the server resources of the provincial-level technical renovation and overhaul intelligent project establishment platform. The relevant business data is uniformly accessed from the relevant business systems by the municipal-level technical renovation and overhaul intelligent project establishment platform, and is sent to the main station system on demand. Share the following data:

Equipment ledger data, equipment-related defects, hidden dangers, maintenance plans and other business data and technical renovation and overhaul project data provided by PMS2.0, specifically equipment ledger data, substation information, technical renovation and overhaul project details, project estimate, Yearly/item investment, renovation and overhaul objects, equipment main materials, demolished materials, scale results and project attachments;

The SCADA equipment operating data, such as voltage, current, load and other data, is integrated with the equipment operating data in the SCADA system through system integration, specifically including voltage, current, active power and reactive power data;

The power grid primary equipment online monitoring platform provides oil chromatography and other online monitoring abnormalities, defects, faults and other data, specifically including oil chromatography data;

The in-station surveillance video data provided by the unified video platform specifically includes on-site video surveillance images of the substation.

According to the business requirements of 3D data sharing application construction, the hardware configuration is divided into unstructured file management server, database server and application server. Among them, the unstructured file management server is used for storage, management and calculation, and manages and stores model information data on a substation basis; the database server is used to store model record data, model graph associated data and model-related business data; the application server is used Deployment of 3D platform services, such as scene services, file management services, attribute services, etc.

According to the service and application deployment configuration requirements, the minimum configuration requirements for server and client software and hardware are as follows:

The minimum hardware configuration requirements for the server are as follows:

The minimum hardware configuration requirements for the client are as follows:

Operating system and software configuration requirements:

The application server and database server operating systems are Windows operating systems, and Windows 10 is recommended;

The client operating system requires Windows 7 and above, and the browser version is IE9 and above.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any worker familiar with the technical field can easily think of various equivalent methods within the technical scope disclosed by the present invention. Modifications or substitutions shall be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (6)

1. An intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS. It is characterized in that the system architecture is a three-layer architecture logical framework based on the data layer, service layer and application layer, specifically: The data layer divides the data into substation three-dimensional scene data and substation business application data according to the source of the business data; The service layer adopts a microservice architecture and is divided into three-dimensional scene services and data interface services according to the service application scenario; The application layer adopts a modular structure, including three-dimensional scene basic applications and substation smart review applications; The three-dimensional scene basic application includes a three-dimensional scene editing module and a three-dimensional data management module. The substation intelligent review application includes a substation three-dimensional scene browsing module, a business data integration module and a project intelligent review module; The project intelligent review module includes a substation information panel, a station camera information panel and a project information panel. The substation three-dimensional scene browsing module is used to browse the three-dimensional substation scene through three modes: flying, driving and walking. The business data The integrated module is used to access and display PMS2.0 data, power grid primary equipment online monitoring data, SCADA data and unified video data; The substation information panel is used to query information about the substation operation and maintenance unit, maintenance team, voltage level, operation date, operation number, operation status, duty mode and layout mode; The camera information panel in the station is classified and displayed according to the substation location area. The location area includes the capacitor room, switch room, equipment area, station environment and main control room. The camera information panel in the station is selected and positioned by clicking the mouse. View the corresponding camera model in the three-dimensional scene of the substation. In the three-dimensional scene of the substation, the selected camera model is highlighted in the center. Click the three-dimensional camera model in the three-dimensional scene with the mouse to open the real video picture of the camera in the station; the project information panel Used to query and download the details of substation technical renovation and overhaul projects, project estimates, annual/item investments, technical renovation/overhaul objects, equipment main materials, scrap materials, scale results and project attachments, and the project information The panel displays the review elements of substation technical renovation and overhaul projects by category, provides functions for reviewing one by one, filling in review opinions step by step, and exporting review reports with one click. It also provides yellow, red, and green color reminders for the review status of the review elements of technical renovation and overhaul projects. , among which, green represents approval, red represents rejection, and yellow represents pending review; The project information panel, by obtaining the name of the primary equipment of the power grid in the list of technical renovation/overhaul objects clicked by the mouse, locates the location of the primary equipment of the power grid in the three-dimensional scene of the substation, and displays the ledger data associated with the selected primary equipment of the power grid. Online monitoring data, SCADA data and video surveillance data. 2. An intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS according to claim 1, characterized in that the three-dimensional scene services include paging services, editing services, attribute services, synchronization services, and relationship services. Version service and ledger service. The data interface services include relationship mapping service, PMS data access service, SACDA data access service, power grid primary equipment online monitoring data access service and unified video system monitoring video access service. 3. An intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS according to claim 1, characterized in that the system includes a client, an application server and a database server, and the client sequentially passes through a router and a firewall. Connected to the intranet, the application server and database server are connected to the intranet respectively. The application server is also connected to the PMS system, SCADA system, power grid primary equipment online monitoring platform and unified video system. The client is in In the application layer, the application server is in the service layer and is used for the deployment of three-dimensional platform services. The database server is in the data layer and is used to store three-dimensional scene data of the substation and business application data of the substation. 4. An intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS according to claim 3, characterized in that the application server provides three-dimensional scene services and data interface services through load balancing and service agents, and Through the data interface service, PMS data is obtained from the PMS system, SCADA data is obtained from the SCADA system, power grid primary equipment online monitoring data is obtained from the power grid primary equipment online monitoring platform, and video monitoring data is obtained from the unified video system. 5. An intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS according to claim 1 or 4, characterized in that the PMS2.0 data includes power grid primary equipment ledger data, substation information, substation technology Details of the overhaul project, project estimate, yearly/item investment, renovation and overhaul objects, equipment main materials, scrapped materials, scale results and project attachments. The SCADA data includes voltage, current, active and reactive power data, The online monitoring data of the primary equipment of the power grid includes oil chromatography, oil pillow oil level and circuit breaker partial discharge data, and the video monitoring data includes on-site video monitoring images of the substation. 6. An intelligent review system for substation technical renovation and overhaul projects based on three-dimensional GIS according to claim 3, characterized in that the operating systems of the application server and database server are both Windows operating systems.