Application of Three-layer model in Electric Power Integrated Information System

 

1 Preface

With the rapid development and popularization of interntet/Intranet technology, power systems have been widely used. Compared with traditional information system models, interntet/intranet-based information systems, both Technology and Application (service) methods have obvious advantages. They can adapt to the development, distribution, and management of distributed applications and integrate different business applications, more effective comprehensive use of information resources to expand the scope of information, providing a new mode for Power System informatization. The development and use of the Hanchuan Electric Power Integrated Management Information System have made some beneficial attempts in this aspect.

The Power Integrated Management Information System consists of the WWW information query subsystem, the GIS Management Subsystem for power transmission and transformation, and the SCADA information subsystem. It is developed in B/S (Browser/Server) mode, the browser integrates these three parts so that leaders at all levels can easily understand and master various production and management information and data, which provides an effective means to improve the production management level of power enterprises.

The WWW information query subsystem provides query services for various management information, including production indicators, power supply indicators, security indicators, and financial indicators. The system uses the most advanced ASP (Dynamic Server Page) technology to transplant the integrated management system in the original standalone environment to a web browser, A fully dynamic network query and Management page is generated based on the integrated data dictionary, which ensures data uniformity and security and the adaptability of system expansion in the future, then, you only need to modify the data dictionary to achieve system expansion.

The GIS Management Subsystem of power transmission and transformation provides various information query services for substation, line, tower, and other power equipment related to geographical information. The system combines the desktop Geographic Information System Maplnfo with ActiveX composite documents to query and manage all GIS Geographic Information in a browser.

The SCADA information subsystem can publish the real-time and historical data of various telemetry and remote signals of the SCADA System to the management network in the form of tables, a wiring diagram, and curves, it facilitates relevant leaders and management personnel to understand and master production information and strengthen production management. SCADA sub-systems are developed based on the most advanced distributed network computing model-CORBA (General Object Request proxy architecture), which combines the SCADA system with the management network, you can directly query the relevant data of the SCADA System in a browser.

2. Main System Tasks and features

The main task of Electric Power comprehensive information system construction is to make rational use of existing computer information resources, and face leaders at all levels and staff of various business departments in light of the actual production management conditions of the Power Supply Bureau, it provides a variety of real-time and historical data queries for production, a variety of production geographic information, a variety of office information, and a variety of fast and accurate query methods for managing statistics, to improve the level of production management and information management.

The system has the following main features:

(1) Information Query is performed on the browser in a unified web query mode. All operations are the same or similar to the operations on the Internet at ordinary times. You can use them without training more computer operation knowledge.

(2) In addition to users who need to query Geographical Information, the client computer used for information query only needs to install the operating system (such as Win95 or Win98) and Web browser (such as Internet Explorer ), you do not need to install other applications and do not have high requirements on the client computer, which is conducive to protecting the existing investment in computer hardware. For users who need to query Geographical information, they only need to install a set of software for map operations on their computers.

(3) All programs of the system can be installed on a Web server, which can provide query services for users on the Intranet (Intranet) and even the entire Internet (int6rnet. System maintenance works on a computer, greatly reducing the workload and complexity.

(4) The system can publish real-time data from the SCADA System on the web site in real time, and express the production data collection path maps containing geographic information, it enriches production management methods and helps improve the level of production management.

(5) The system provides the interface platform between heterogeneous databases, can be the original various types of data (such as integrated management of DBF library files, database files of SCA-DA System) it is convenient and quick to switch to the sqij server network database, protecting original information and facilitating various queries in production management.

3. System Design Principles and Methods

3.1 Component Object-based development model

In the traditional C/S development model, the business rules implemented by applications are implemented on the client or in the form of stored procedures or triggers in the backend DBMS. In the early days, this development mode greatly improved the development efficiency and running efficiency of applications. However, with the development of distributed networks, the C/S mode gradually exposes some shortcomings: the client requires a lot of maintenance work, and the user interface is put together with the business logic implemented by the application module, business rules cannot be encapsulated. As the customer's requirements change, a large number of version updates are caused and cannot be easily managed. Because the computing for business processing is mainly performed on the client, for computing such as statistics, You have to repeatedly query the database and send the query results back to the client to complete the computing function, which increases the network burden. To solve this problem, system services can be implemented as functional components to encapsulate business rules. With the development of component technology, we can use component technology to build distributed network data. In this way, we can develop as many high-quality applications as possible at minimal cost. This also helps achieve high consistency, compatibility, and business integrity between applications. Applications: use components to encapsulate business rules, divide component functions, and reasonably deploy component positions to achieve better application performance.

3.2 component-based three-layer development model

After analyzing the service requirements of the Web Database integration system of the power system, we logically split the system into client browser pages that provide user interfaces, the remote service objects that provide business services and the data service objects and database systems that provide Remote Data Services are connected over the network. The system architecture divides the actual programming tasks of an application into component implementation and software integration of the integration component to implement two types of tasks: one type of task is to develop reusable core components (such as business components and database stored procedures), and the other type of task is to integrate the services provided by these core components. We can design a good object model to determine the internal class structure of the object and the interface to be displayed externally, and then construct a specific solution through component assembly. From the perspective of service provision, to split system service requirements into component object services, we can use the layer-3 Development Mode hierarchy shown in figure 1 to divide object functions.

User services, business services, and data services are included in mutually independent objects, with interoperability between objects.

(1) user service layer. The user service layer provides a visual interface for displaying information to users and collecting user data. The user service layer itself does not process business data, but is only responsible for sending requests to the business service layer.

(2) Business Service layer. The business service layer serves as a bridge between users and data services. The business service component object responds to user requests and executes a certain business task. A business task is an operation defined by the requirements of the application system. A business rule is a policy that controls the workflow of a business task. Compared with business tasks, business rules are easier to change. In order to achieve better flexibility, the business rules should be encapsulated in separate components during specific implementation. After the business rules change, you only need to modify the business rules section, at the same time, the external interface of the component remains unchanged. All objects requesting the business rule will use the modified business rule object to get new results.

(3) data service layer. Data Services include data definition, maintenance, access, and update, and management and response to data requests at the business service layer. The data service layer implements all typical data processing activities, including data acquisition, modification, update, and data-related services.

The three-layer development mode application system implements the logical separation and independent encapsulation of diagonal user interfaces, business logic rules, and data services, and meets the requirements of distributed model applications. Services in the three-tier development mode emphasize the logical structure in the conceptual sense, rather than the physical structure in the Component Deployment location, allows components that provide services to reside anywhere on the network physically. Any service object can activate other service objects according to specific functional requirements, service objects can determine the service functions they should have based on their locations in the layer-3 development mode. The layer-3 structure does not mean that in actual applications, only the three objects that interact with each other to provide services. On the contrary, it is possible that the interaction of multiple objects in the system means to provide services at a certain layer.

3.3 advantages of a three-layer Development Model Based on Component Objects

Compared with the traditional centralized application development method, the three-layer Development Mode Based on Component Objects has the following advantages:

(1) encapsulate business rules. The local component objects can be improved when user requirements change, so that the demand changes have less impact on the system.

(2) convenient version management and updates. When user requirements change and object version upgrade, using component objects can minimize version conflict management and maintain downward compatibility, and you can directly download new version component objects through the network, to obtain the new feature.

(3) Deployment optimization. Because the component objects can be deployed on the network, the efficiency, performance, security, and maintenance can be optimized. Some components of an application can reside on the central database server, some are deployed on the department-specific "business" server, and the other part is on the server that is most convenient to users, it even resides on the end user's client. When designing a number of powerful and well-coordinated applications, developers can deploy the applications based on the network and infrastructure. The actual position of the component is transparent to the end user.

(4) manageability. Large and complex projects can be subdivided into simple and secure component projects.

(5) improve reuse efficiency. The component user only needs to understand the interfaces exposed to them, and does not need to know the internal structure of the component and the data used by the component. In this way, we can develop as many high-quality applications as possible at minimal cost. This also helps achieve high consistency, compatibility, and business integrity between applications.

3.4 overall System Structure

The purpose of the integrated power management information system is to query and manage power data in a browser on the Intranet of the Power Supply Bureau. The system needs to download and control all application component objects in a browser. The three subsystems of the power system-SCADA subsystem, GIS system, and comprehensive power management subsystem-are integrated through a browser, it can perform web queries on the data of the three subsystems and manage the WOB (add, delete, and modify) of the data of the three subsystems. At the same time, it is necessary to conveniently expand the system in the future, when adding new functions, it has little impact on all parts of the system.

As mentioned above, the electric power integrated management system is logically divided into three layers: user service layer, business service layer and data service layer. At the user service level, the customer shall be directed to leading customers, production management customers, power supply management customers, security supervision management customers, financial management customers, office management customers, other department customers, and System Administrator customers, different user interfaces are provided to display information to users and collect user data. The business service layer provides the functions of the three subsystems, including real-time SCADA and historical data query, office information query and management, comprehensive management information query and management (including production indicators, power supply indicators, security indicators and financial indicators) the data service layer defines and maintains all data tables, it also responds to data requests of the three subsystems by means of stored procedures, triggers, and SQL Execution statements.

3.5 object structure

We need to construct the following types of component objects to complete the required object services:

(1) user interface components: provides an interactive interface between users and data.

(2) Business logic components: Provides service logic services related to subsystems such as power GIS, SCADA, integrated management, and office management, and receives data and business logic requests from user components, the processed data request is sent to the database interface component, and the data returned by the database is sent back to the user component together with the business logic processing result.

(3) communication components: provides remote communication services between client user component objects and service logic component objects on the server side. Communication components follow the CORBA specifications and the i10p protocol and call remote methods through orb objects.

(4) database interface components: provides various database operation functions, receives data requests from various business logic components, and returns the returned result set of the database to the business logic component.

After more than half a year of operation practice, the electric power integrated management information system developed using this model has the characteristics of high information sharing program, simple use, stable and reliable operation, and strong scalability. It has good practical value. With the continuous development of application systems, the information level will be comprehensively improved in terms of application and application depth.