Because of the role of substation power supply in substations, it is very important, like the heart of a person, especially the emergence of intelligent substations and digital substations, and more reliable power supply is needed to support them.
In the past, there was insufficient attention to the power supply of substations, which led to the occurrence of accidents that caused power loss in all stations due to power supply. This led to a boom in research station power supply, the domestic mainstream manufacturers have introduced their own power solutions, the most notable is the current station AC and DC power supply integration solutions.
2 Introduction to various modes and comparison of advantages and disadvantages
1.1 Small Integration Model and Large Integration Model
The small integrated mode is a system in which a DC operation power supply (including the AC input power supply before the charging module is switched), a dedicated UPS power supply, and a communication power supply are used, and a DC power bus is shared to realize unified monitoring. The core is: sharing of battery packs; establishing integrated monitoring. In particular, it is to cancel the special battery packs and charging equipments for communication power supply, cancel the UPS special battery packs, and replace the DC/DC and power inverters directly with the DC bus to obtain the power supply. The typical representative of this model is ADT’s “Uninterrupted Power Supply DC and AC Uninterruptible Power Supply System”.
The advantage of this mode is that canceling the communication power supply/UPS battery pack is beneficial to professional management, and on the other hand it is in line with the development trend of environmental protection.
The disadvantages of this mode are:
1. The AC power system is not integrated, and the power supply technology and management solutions for the station are incomplete.
2. The core idea is limited to battery sharing and there is no ideological motivation for continuous development. Just think: How will this model evolve when battery sharing is achieved?
Status Quo: Currently, it is reliable to cancel the battery pack for communication power supply directly connected to the operating DC bus, and whether the indicators can meet the requirements of the power supply bureau is more controversial.
The integrated mode is based on the small integrated power supply and integrates the AC power system. The core ideas are: unified design, production, commissioning and maintenance of station power supply and some design optimization; establishment of an integrated monitoring platform to enhance the power professional management capabilities.
The current integrated power model has been developed in two stages:
1. Intelligent AC/DC integration system. Smart AC + Smart DC + Inverter + Communication DC/DC Power Supply.
2. Digital AC/DC integration system. The integrated monitoring pair can realize IEC61850 communication, allowing the station power system to be seamlessly embedded in the digital substation system.
The big integration model is a complete solution for station power supply, and this model has been tended to be recognized in China at present.
1.2 Comparison of Digital Solutions in Large-scale Integration Model
There are still differences in implementing digital solutions in the big integration model. The typical representative is the digital AC/DC integrated power supply system of Shenzhen Taiang Electronics and the digital integrated power supply system of XJ Power.
The main difference is:
XJ power digital power mode focuses on the integrated monitoring with IEC61850 interface.
The core idea of digital substations is summarized into two points: Core ideas 1. Upward release of digital transmission of information, which is considered to be the basic idea of digital substations. On this basis, the application of IEC 61850 statutes is the only solution to the general problems of communication. Core ideas 2. IEC 61850 protocol interface. To realize the digital transmission of upstream information, Shenzhen Taiang adopts two major measures: 1. All switches are intelligent and modular, integrating switches, sensors, and intelligent circuits. On the one hand, it strengthens the intelligent monitoring function of feeders, and can monitor the switch position, accident trip contact, load current, and can set alarms, leakage currents, and set alarms. On the other hand, there is no secondary wiring outside the module, only the digital core of the communication interface. 2, centralized function decentralization. Mainly for DC system insulation monitoring, using feeder module leakage current and setting alarm function, combined with bus insulation monitoring information, unified integrated monitoring platform for comprehensive logic analysis, so that the conventional complex insulation monitoring secondary line disappears; for battery inspection A large number of secondary wires adopt a method of configuring one acquisition module at each layer so that there is no secondary wiring across the screen.