1. Overview: Distribution transformers are crucial equipment in power distribution networks and form the most basic unit of power supply. Monitoring distribution transformers is of great significance for distribution automation management, line loss analysis, load forecasting, and power demand management. 2. Introduction to the Distribution System: Distribution transformers (abbreviated as distribution transformers) are devices in the distribution network that directly distribute electrical energy to low-voltage users. They serve as the boundary between the low-voltage (10kV) distribution network and the user's 380/220V distribution network. Distribution transformers are installed on utility poles, in distribution rooms, and prefabricated substations. They are characterized by being dispersed, having diverse geographical environments, wide coverage, numerous users, and being easily affected by user capacity expansion and urban construction. 3. Functions of the Distribution Transformer Real-Time Monitoring System: Through real-time monitoring of distribution transformers, the operating status of the transformers can be promptly grasped, preventing severe overload leading to equipment burnout, severe three-phase load imbalance leading to accelerated transformer damage, uneconomical operating conditions caused by long-term light load operation, and low power factor and high line loss caused by a large number of inductive loads. Real-time monitoring, data collection, analysis, processing, and control of distribution transformer operation allows for timely adjustments to transformer operating status, rational allocation of transformer capacity, and adjustment of low-voltage intelligent reactive power compensation control, ensuring safe, stable, and efficient operation of distribution transformers. Comprehensive, scientific, and accurate real-time monitoring of distribution transformers provides reliable operational data and historical information for distribution automation management, effectively reducing line losses and providing accurate data for load forecasting, line loss analysis, and demand-side management (DSM); accurately combating electricity theft; guiding capacity expansion installations based on load forecasting; providing scientific data for analyzing electricity consumption, electricity consumption characteristics, and load growth trends in planning work such as system capacity expansion and distribution transformer location selection; simultaneously improving work efficiency, reducing labor costs, and scientifically enhancing the automation level of distribution management. 4. Problems and Requirements of Distribution Transformer Real-Time Monitoring Communication Networks a. Problems with Distribution Transformer Real-Time Monitoring Communication Networks? Distribution transformers are characterized by a large number of devices, harsh operating environments, uneven geographical distribution, and dispersed locations due to their installation locations and other factors. Based on the above characteristics, fiber optic communication, wired cable, and power line carrier communication networks are not feasible in terms of either technology or cost-benefit ratio. Communication networking for real-time distribution transformer monitoring has been a persistent obstacle to its promotion and implementation. b. What are the communication requirements for real-time distribution transformer monitoring? Distribution transformer monitoring involves a large amount of data, but the real-time requirements are not very high. Monitoring terminals should have storage capabilities, eliminating the need for each terminal to occupy a single channel for communication with the main distribution transformer management station. It needs to have a point-selection call communication function, allowing distribution transformer administrators to call real-time data from the monitoring terminals at any time. For special alarm signals that exceed limits and affect distribution transformer operation, the monitoring terminals must promptly upload the data to the main distribution transformer management station. The main station and terminals should be easy to construct, install, and maintain, with low operating costs. Ideally, a transparent transmission channel or compatibility with multiple communication protocols should be provided. 5. Comparison of Distribution Transformer Real-Time Monitoring Communication Networks and Solutions 5.1 Current Communication Systems Traditional distribution monitoring systems use communication methods such as public telephone exchanges, wireless data transmission radios, and fiber optics. Public Telephone Exchange (PTB) Solution: PTBs are quite widespread; they are present wherever people work and live. PTBs can be used for both voice calls and data transmission, but they suffer from long dialing redundancy times and difficult link maintenance. Wireless Data Transmission Radio Solution: Wireless data transmission radios are suitable for data monitoring with dispersed communication points, making them ideal for distribution transformer monitoring. They have dedicated data transmission frequency bands, operating at 220MHz to 240MHz. However, initial activation requires a fee to the local radio management committee, followed by annual frequency occupancy fees, resulting in high network costs. Communication distance is limited (maximum 50km in plains areas) and is significantly affected by buildings and mountains. Professional maintenance is required, leading to high construction and maintenance costs. From field operation, fiber optic communication offers more stable data and stronger anti-interference capabilities. This method requires a large initial investment, with very high costs for optical communication equipment and significant engineering implementation difficulties. 5.2 CDMA 1X Communication Solution: The emergence of China Unicom's CDMA 1X network provides a new solution for power distribution monitoring systems. CDMA 1X technology, based on CDMA mobile packet service, provides users with IP or X.25 mobile packet connectivity. It boasts numerous advantages, primarily its high level of wireless technology, with stringent and complete standards for the air interface and core network signaling protocols, and interoperability with the Internet. In particular, the first phase of 2.5G CDMA 2000 can provide users with high-speed (up to 371Kbps) and variable-speed (actual speeds between 80 and 120Kbps) data transmission, facilitating internet access anytime, anywhere. Using CDMA 1X networks for data transmission in power monitoring systems can significantly reduce the initial investment in communication systems, shorten the time spent debugging during project implementation, and lower maintenance costs. This communication method is particularly economical for widely distributed, sparsely populated distribution network systems (such as rural power grids). 6. Distribution Network Monitoring System Based on CDMA 1X Network 6.1 Composition of the Distribution Network Monitoring System Based on CDMA 1X Network The real-time monitoring system for distribution transformers consists of three parts: a distribution transformer management master station; a distribution transformer monitoring terminal (distribution integrated measurement and control instrument); and a CDMA 1X communication channel. The distribution integrated monitoring system, developed by Zhuhai Yite Company, integrates distribution transformer monitoring, reactive power compensation control, CDMA remote meter reading, and data analysis and processing. The system uses the "ET3000 Distribution Integrated Monitoring System" as the distribution transformer measurement and control management software, the ETPD series distribution integrated measurement and control instrument as the distribution transformer monitoring terminal, and Hongdian H7612 and H7661 CDMA DTUs as the data transmission channel. The CDMA 1X network is provided by Zhuhai Unicom, ensuring reliable network operation and good technical service. 6.2 Main Functions of the Distribution Integrated Measurement and Control System? Telemetry function, energy metering function, statistical function, remote signaling function, and remote control function? The low-voltage intelligent reactive power compensation function and remote communication function are described in section 6.3. The actual operation and optimized design of CDMA 1X communication are highlighted. The most significant feature of CDMA 1X communication is its data-based billing; however, reasonable control of communication traffic can effectively save operating costs. The ETPD power distribution integrated monitoring system developed by Zhuhai ETE High Technology Co., Ltd. successfully applies data flow control technology and CDMA module timed reporting and SMS activation technology, ensuring reliable data while effectively reducing operating costs. Data flow control technology in power distribution transformer monitoring aims to monitor the operating status of power distribution transformers and improve power quality. Power distribution transformer monitoring is basically divided into two processes: assessment and monitoring. It requires understanding abnormal data and status of power distribution transformer operation. For stable operating data, as long as it is within the allowable range, communication uploading is not necessary. Based on the application, a scientific "data flow controller" is designed for the communication control of the power distribution integrated monitoring and control instrument. This controller allows users to control data flow by setting the dead zone value and dead zone crossing time limit of the "data flow manager," and to determine the upper and lower limits. The dead zone value and dead zone crossing time limit of the "data flow manager" are continuously transmitted from the main station to the power distribution integrated monitoring and control instrument. The adoption of "data flow controller" technology reliably ensures system operation while effectively reducing operating costs. The timed reporting application technology eliminates the need for a heartbeat function to maintain connection in the distribution transformer monitoring system, which does not have high real-time requirements. Instead, timed reporting is used. When the distribution integrated monitoring and control instrument needs to transmit data, it directly activates the CDMA module for communication. When the master station needs to communicate, it activates the CDMA module via SMS to communicate with the distribution integrated monitoring and control instrument. This eliminates the need for maintaining connection data volume and saves operating costs. 7. Conclusion: Under the current circumstances of energy shortages, systemic power shortages, nationwide power rationing, and orderly peak-shifting, both the State Grid Corporation of China and the Southern Power Grid Corporation of China require the comprehensive promotion of power demand-side management to meet users' requirements for power quality and reliability. This necessitates accelerating the automation level of distribution low-voltage load control and management. Simultaneously, new demands are placed on the scientific management of distribution low-voltage monitoring and management and the intelligence of power demand-side management (DSM): the necessity of accurate, scientific, and effective distribution low-voltage monitoring to reduce line losses is becoming increasingly prominent. The ETPD integrated power distribution monitoring system, which adopts CDMA 1X communication, will play a significant role in the scientific management of low-voltage power distribution monitoring with its advanced technology, precise measurement accuracy, and scientific design and manufacturing. It will ensure the safe, economical, and reliable operation of the power distribution network and play an important role in the automated management of low-voltage power distribution.