Application and Analysis of Distributed Database Technology in Power Enterprises Liu Qiong, Lu Su, Li Lin (School of Electrical Engineering, Wuhan University, Wuhan 430072, China), for example, the application of distributed database technology in various systems of power companies Detailed analysis, and on this basis, proposed to build a distributed database of power systems. 1 The business units of Baibai Power Enterprise have established relatively independent systems and realized network communication with each other. To obtain information sharing is an important symbol of the current acceleration of power system automation and informationization process. This is also planned as a power sector. produce. The basis for planning and other decisions. The use of distributed object communication mechanism is a relatively advanced information management technology. It is based on the concept of “brick and tile†of layered components. 131. The combination of centralized database technology and computer network technology. Since the mid-1970s, this technology has developed rapidly. From the 1990s to the present, distributed databases have entered a practical stage. The field of distributed databases is rapidly evolving not only at the level of research and prototyping, but also at the level of industrial products and real-life applications. 2 Distributed Database (DDB) Technology 2.1 Concept The so-called distributed database system divides the database into a subset of logical associations, distributes them on computers in different locations and provides data access capabilities to fully manipulate these subsets. Database system. Data distribution is designed to address locality of processing, availability and reliability of distributed data, workload distribution, storage costs, and availability. Several specific indicators are: distribution transparency, distributed units, data duplication, remote database access, remote process-to-process communication, and distributed transaction recovery. The design of a distributed database consists of four phases: the design of the global model, the design of the segmentation, the design of the location allocation, and the design of the physical structure of each site. The global schema and physical structure can be designed in the same way as the conceptual and physical schemas in a centralized database. Therefore, the uniqueness of distributed database design is the segmentation design and distribution design. 2.2 Based on the characteristics of distributed database system Reliability Through the redundant replication between nodes, the entire system can still guarantee data integrity when the single node is destroyed, and the reconstruction of the node can be reliably realized. By copying the application logic, after a single node is destroyed, its tasks can be smoothly taken over by other nodes until the node is restored. At the same time, since each child node is an autonomous system, when the child node loses contact with the central node, the child node can still achieve most of the functions. The data distribution goal of distributed database is node autonomy and collaboration optimization, and through proper data redundancy replication, most applications can obtain data from remote nodes, improve processing efficiency, and reduce network overhead. Modern application systems will inevitably face problems of system expansion and adjustment during their operation. At this point, the distributed database system provides a consistent extension interface and a dynamically scalable system architecture, and the system can be smoothly upgraded and reconstructed. At the same time, the distributed database system also provides load balancing functions to achieve reasonable and full utilization of system resources. A distributed database system provides site independence of data. For applications, DDB blocks the distribution of data and accesses all data in the same way. Operational support for heterogeneous databases is achieved by providing a unified data model and its API to the application. Through the grid-based (GRID)-based distributed computing technology, the entire system can distribute a large-scale computing application (such as the optimal analysis of the power grid) to each sub-node for processing, making full use of the processing power of the sub-nodes, significantly shortening calculating time. Support and integration of data warehouse and data mining The distributed system architecture itself provides the basis for building large data warehouses, and provides further data mining, namely online analysis processing (Online Application Process referred to as 0LAP) and decision support (DSS). A simple and transparent development interface. These aspects can be easily integrated into a single system. Based on the distributed database, applications such as expert systems, geographic information systems, and virtual enterprise networks can be seamlessly and smoothly integrated. 3 The application status of distributed database in power system 3.1 The particularity of power system automation technology The database application technology of power system has its special industry characteristics: real-time requirements of power system monitoring control and data acquisition system (SupervisoryControlAndData Acquisition System for short) The data availability problem of the traditional management information system (ManageInformatioriSystem, MIS for short) requires the improvement of its underlying database technology. At this point, the distributed database can complete the task of converting data into information and providing it to power system management users in time for decision support. 3.2 Grid Dispatching Automation System The power grid dispatching automation system was launched in the 1960s. It is a new computer-based power grid control technology. It has become the pillar to ensure the safety, stability and economic operation of the power system and the basis for realizing its management modernization. After nearly 40 years of development, the power grid dispatching automation system evolved from the original centralized SCADA to the distributed SCADA/EMS/DMS. The updated power grid dispatching automation master station system is taken as an example to discuss its database construction. Adaptive interconnect communication for each application subnet in the enterprise network. In this way, different nodes of the same network or different applications of the heterogeneous network can establish a relative client/server communication system by treating each other as an external logical application environment, that is, transparently customizing the application object communication process based on different applications, thereby achieving openness. Mission and network interconnection. Based on the design requirements in the Technical Specifications for Power Grid Dispatching Automation System, the large-scale commercial relational database management system MSSQLSever is used to store and manage system information and data in the database, and to provide database access interfaces for various non-real-time information systems. In order to meet the expansion requirements of the system for openness and real-time database, the following measures are taken: introducing hierarchical and object-oriented concepts, defining data according to their respective characteristics and storing them according to their types; classifying data in the same table and establishing ID alignment identifiers for them , primary key and index. Real-time databases are combined with commercial databases. The real-time database backup is established in the commercial database, and the two are kept in sync; the open database link (ODBC) and the developed universal "soft bus" interface technologies are used to provide historical and real-time data services for each application. The system's database service program uses large commercial MSSQLServer, its functions include: creating and modifying databases, quickly accessing and managing data; defining system parameters, plant and RTU data characteristics; monitoring, modifying, defining data types and their structures online, Expand database size; fast copy, backup, failback, and automatic login and restart of the database; provide common database access and application interfaces; support concurrent access to data, and protect database security, consistency, and integrity. From the above analysis, it is not difficult to conclude that such a typical system structure uses a distributed structure, a centralized database. 3.3 Power Enterprise Management Information System The information management system of the power enterprise is a new database management system. Each business department is divided into a system independent database for the customer's power enterprise network to integrate the architectural mode. Each sub-database management system manages the data of the department. In addition, the global shared data is automatically uploaded to the core database, that is, the data is merged and summarized. Take the Wuhan Power Supply Bureau as an example. Wuhan Power Supply Bureau has jurisdiction over more than 700 square kilometers of power transmission, transformation, distribution, and use in Wuhan. It has jurisdiction over Hankou, Hanyang, Wuchang and Qingshan Branches, and its AM/FM; IS aims to realize the processing of regional data in four places. Secure real-time data sharing. AM/FM (Automated Mapping/FacilitiesManage) is a computer graphics and text interaction system based on equipment and production technology management on geographic information. It is also a computer application software system that combines graphics technology with database management technology. Due to the wide area of ​​its jurisdiction and the distribution of jurisdictions, it is decided that the AM/FMAGIS system of Wuhan Power Supply Bureau must adopt a multi-level distribution structure: that is, the first-level server is located in the municipal bureau, and the secondary servers are located in each branch office; The secondary server can work independently for each branch office from the primary server; each server works in its own domain and implements cross-domain communication between the office and the office through the TCP/IP protocol; each branch has its own graphics server and database server. It is not necessary to request a response from a remote server through the metropolitan area network of the power supply bureau, and the clients of each office only perform work requests for entry and modification to their respective servers. In this way, the load flow of the metropolitan area network can be greatly reduced, and the burden on the massive data processing of each server can be alleviated. In the actual construction of the system, the data distributed processing design idea is to install the SQL Server database server for the central office and the four branches respectively, and form a distributed database application system as a whole; the organization can query all the branch office data but cannot perform data maintenance. The system function is divided into two major modules: each branch office can only maintain the data of the branch office. For each data table, create a conditional view in each branch to generate a record set that belongs only to the local office; convert the maintenance of the local user data table to maintain the view. Each branch office can query other local maintainable data in the local database (but cannot maintain it). Using the replication mechanism of SQLServer, a two-way replication mechanism is established between the branch office and the city office, and the replication mechanism is continuous (sub-bureau and branch office). A replication relationship is not established. A database named WHBB is created on all five SQL Server servers. The data in each database is divided into two parts: non-shared and shared. The shared data is maintained and consistent by the four regional bureaus in the WHBB database. The table that holds the data is called the publication form. The specific implementation scheme is that the four branches have mutually different and unique unit codes. All published tables in the WWPB database have a primary key. The structure of the published table on all servers is the same, and the information registered in the field data dictionary is also the same. The information in the table data dictionary is in addition to the "publishing conditions". The same applies to the fields, and the "Publishing Conditions" field describes the code of this unit. Create all published tables in the application data for the five distribution points, ensure that the "Publishing Conditions" field for all distribution points is set correctly, and then create a publishing view in the application database for all distribution points. Every time you modify the table structure, you need to rebuild the publishing view. After creating a normal user, you need to reassign the user rights after modifying the structure of the table that the normal user can access or after reconfiguring the user to configure the menu. The distributed AM/FMA IS system of Wuhan Power Supply Bureau has achieved the expected technical indicators after nearly one year of trial operation. Investigate the automation construction process of other power companies. This system is the first management information system based on computer metropolitan area network and multi-level server distributed database technology. 3.4 Development Proposal Building a distributed database system in the power system requires the following considerations: (down to page 153) / fill out the details table æ’å…¥ insert, modify and delete data in the database ç‹™ above for insert data, to To modify or delete data, just modify the contents of sqlstrirg to the corresponding SQL statement. 5 Conclusion In the development process of the air conditioning design system of Zhejiang National Sample Refrigeration Co., Ltd., the method of accessing the database based on ODBC API function is adopted, which not only ensures the integration with the AutoCAD environment, but also realizes the database access function of the system. On the one hand, the function will increase the difficulty of programming. On the other hand, because the ODBC API function is directly called, the database access performance can be improved, and at the same time, it has high flexibility. In practical applications, it can be used in combination with the interface and engine provided by the development tool, such as the CDatabase class in VC++, which can improve performance and improve efficiency. Lcd Touch Screen,Ips Lcd Display,Projector Lcd Display,1.54 Inch Tft Lcd Shenzhen Yetai Optoelectronics Technology Co.,Ltd. , https://www.yetailcd.com