Part 1 Overview
With the development of science and technology, realize the automation of distribution network has become a trend in the development of electric power system. Distribution network, as the last link in transmission and distribution system, its degree of automation is closely related to the quality and reliability of power supply. For this reason, this is making a simple discussion about the necessity and implementation solution of distribution automation network.
Distribution transformer is an electrical equipment to distribute power to low voltage user directly, its operation data is an important part of the whole distribution network basic data. Therefore, it is necessary to monitor its operation parameters and states. In this paper, we discuss using GPRS as a means of communication to establish the distribution transformer monitoring system. The theory of GPRS bandwidth can reach 171.2Kbit/s, the actual application of bandwidth at about 40～100Kbit/s, to provide TCP/IP connection on channel can be used in various application such as INTERNET connection and data transmission. GPRS uses the packet switching technology, each user can take multiple wireless channels at the same time, and a wireless channel can be shared by multiple users, which makes the resource effectively used. GPRS allows user to send and receive data in the end-to-end packet switching mode, without no need to use circuit switching mode network resource. GPRS is always online, charged according to flow, and thus provides a high-efficient, low-cost wireless packet data service. Especially adapt to intermittent, sudden and frequent, node and scattered, small and medium-sized flow of data transmission, also suitable for the occasional large amount of data transmission.
Part 2 Networking System Solution
Solution 1: Client and Server are connected to the network directly
The monitoring center use the INTERNET public network connection such as ADSL, using public fixed IP service. This kind of solution applies to INTERNET operators at first for broadband service such as ADSL, and the center has a public fixed IP. DTU link to the center directly. Recommend this solution because of its reliable and stability operation. This network solution is simple, stable, but not enough security, the server exposed in the INTERNET directly.
Transformer monitoring unit collecting the data of transformer, and transmit data to the server through the DTU directly, including three-phase voltage, three-phase current, three-phase power(load), three-phase reactive power, three-phase unbalanced current, power factor, Harmonic, pulse table electric degrees and the temperature of the transformer, and so on, through monitoring the working condition of the transformer can optimize the running of the distribution network, and alarm when a failure occurs, trouble clearing timely to reduce outage time, reduce economic loss, reduce the inconvenience caused to users and improve the quality of power supply.
Solution 2: Client and Server are settled in a intranet
The solution is the safest, the client and server settled in a intranet, and they communication through a special channel between them.
Enable the serial port application, the router is equal to an ordinary DTU, distribution transformer meters through RS232/485 interface to connect to the data collector, collector can also connect with the DTU module through RS232 interface. DTU receives the data and transmission to the load monitoring system of power grid companies data center through the network, realize the real-time online connection between terminal data and data center system.
Part 3 Solution characteristics
1. The transmission equipment adopt GPRS wireless access network. At present, the GPRS network technology is already very mature. After 10 years of development by domestic operators, the network has covered all over the country, even the remote faraway mountain areas. Therefore, the network building will not face the difficult problem because of dispersed power supply monitoring points.
2. The transmission module supports multiple online trigger ways, including SMS, ring and data and so on, customer can control the online or offline of the equipment according to their own, and will send SMS alarm information to maintenance personnel automatically when the equipment malfunction or abnormal. Reliable network connection, intelligence prevention drops, support online detection, support online maintenance, auto redial when offline to ensure the equipment always online.