According to the national grid construction strategy and the initiative for a robust power grid, rural power grid intelligence is being piloted as a key project to drive innovation and advancement in power distribution technologies. This year, in July, the State Grid drafted and proposed the latest technical standards to standardize intelligent distribution terminals. But what exactly do these new standards entail?
To accelerate the development and renovation of the distribution network, promoting its transformation and upgrade, the National Energy Administration released the "Distribution Network Transformation and Reform Action Plan (2015-2020)." This plan emphasized significant investments in the distribution network, with total spending from 2015 to 2020 projected to be no less than 2 trillion yuan. Through implementation, by 2020, the intelligence level of the distribution network will be significantly enhanced, with power supply reliability reaching 99.99%, effectively addressing the issue of weak urban and rural grids.
**Figure 1 Distribution Network**
In recent rural power grid renovations, the State Grid has been upgrading various power supply devices across large areas. Among these, JP cabinets, which stand for integrated power distribution cabinets for transformer stations, will also undergo upgrades. As shown in Figure 2, JP cabinets are ubiquitous and can be found almost everywhere around us.
**Figure 2 Rural Network Transformation JP Cabinet**
The focus of these new national grid standards naturally falls on our main character today—the "intelligent distribution terminal," as seen in Figure 3:
**Figure 3 Intelligent Distribution Terminal**
Firstly, the Latest Technical Requirements for Intelligent Distribution Terminals
Based on the operational characteristics of the rural power grid, the State Grid Corporation drew upon previous construction and usage experiences of agricultural networks, standardizing the technical requirements for intelligent distribution terminals. These detailed requirements cover environmental conditions, power supply, functionality, technical specifications, and reliability. Previously, agricultural network intelligent low-voltage distribution boxes were designed, manufactured, managed, and maintained according to the Q/GDW 614-2011 "Functional Specifications and Technical Conditions for Agricultural Network Intelligent Low-Voltage Distribution Boxes" and Q/GDW 615-2011 "Functional Specifications and Technical Conditions for Intelligent Distribution Terminals." The newly proposed intelligent distribution terminal technical requirements are as follows:
1. **Environmental Requirements**
For more details on temperature and humidity requirements, refer to Table 1.
**Table 1 Ambient Temperature and Humidity**
2. **Power Requirements**
AC three-phase four-wire power supply is used. Even during system faults (such as two-phase power failure in a three-phase four-wire system), the terminal can operate normally using AC power. Specific power supply technical parameters include:
- Rated voltage: AC220V/380V, 50Hz;
- Permissible deviation: -30%~+30%;
- When the terminal is powered on/off or the power supply voltage rises or drops slowly, it should not malfunction or trigger incorrectly. After power is restored, it should automatically resume normal operation.
- Data saved is not lost after power restoration, and the internal clock continues to run normally.
3. **Functional Requirements**
The terminal's functions consist of basic and extended application functions. Basic functions are mandatory, while extended functions are optional. The basic features include:
- Distribution monitoring function
- Switch acquisition
- Reactive power compensation control function
- Residual current action protector monitoring function
- Low-voltage switch position information collection function
- Power information monitoring function
- Three-phase unbalanced management function
- Transformer condition monitoring function
- Environmental status monitoring function
- Data logging and remote transmission
- Maintenance function
- Data statistics function
- Local indication function
- Time function
- Security protection
- Plug and Play automatic configuration
4. **Technical Indicators**
- Software architecture requirements: Open with third-party software portability.
- Hardware architecture requirements: Strong computing and storage capabilities, easy to add new business functions. The CPU should be dual-core with a main frequency above 600MHz, memory above 512MB, and FLASH above 1GB, all industrial-grade chips.
- Analog quantities:
- Measurement range:
- Voltage: 0.7~1.3UN; 0~264V;
- Current: 0~6A;
- Frequency: 45Hz~55Hz.
- Measurement accuracy:
- Voltage: ≤±0.5%;
- Current: ≤±0.5%;
- Frequency: ≤0.01Hz;
- Active power: ≤±1%;
- Reactive power: ≤±1%;
- Power factor: ≤±1%;
- Apparent power: ≤±1.0%;
- Electrical metric: ≤1.0%.
Input status quantities:
- Support single-point remote signaling;
- Power supply 24V;
- The software anti-shake time can be set from 10 to 60,000 milliseconds, with event recording resolution no more than 10 milliseconds.
5. **Reliability**
The MTBF of the equipment should be no less than 50,000 hours; the service life of the terminal should be 8-10 years.
Secondly, ZLG Zhiyuan Electronics' Cortex-A9 Embedded Solution-Based Application
Grid transformation covers vast areas, necessitating equipment that is low-cost, highly stable, and adaptable to harsh environments. ZLG Zhiyuan Electronics' Cortex-A9 series core board products, with their abundant interface resources and industrial-grade quality, are ideal for serving as the main controller in intelligent distribution terminals. The display control unit primarily includes functions such as numeric display control, matrix keyboard, data download, data upload, status indicator control, partial data monitoring, data analysis, and processing.
Below is an application example of ZLG Zhiyuan Electronics' industrial control core board in an intelligent distribution terminal:
**Figure 4 Intelligent Power Distribution (Variable) Terminal Core Board Application Example**
The block diagram of ZLG Zhiyuan Electronics' Cortex-A9 embedded solution is as follows:
**Figure 5 Block Diagram Based on Cortex-A9 Embedded Solution**
The latest technical standards proposed by the State Grid are system requirements: developability and support for third-party software migration. ZLG Zhiyuan Electronics' Cortex-A9 industrial control core board supports embedded Linux systems and standard Ubuntu systems with secondary development and software portability to ensure system security and stability. The remaining indicators are shown in Table 2 and compared with the M6708-T parameters:
**Table 2 Comparison of Technical Parameters of Intelligent Distribution Terminals**
Through the data in the table above, ZLG Zhiyuan Electronics' Cortex-A9 core board not only meets all the indicators of the new standard but also offers more advantages and function extensions, as shown below:
- LVDS, LCD, HDMI, and other display interfaces provide options;
- Two-way USB interface, which can be expanded to five channels of USB via HUB to accommodate simultaneous use of multiple peripherals like mice, keyboards, and USB drives;
- Two-way CAN bus, the data bus that X86 systems cannot directly access;
- Two-way IIC, which can be used for data monitoring;
- Three-way multiplexed SPI to enrich the data bus for acquisition and control;
- Two-channel SD cards, providing one WIFI module and one TF card, with single-channel TF cards supporting up to 32G (currently up to 64G);
- One standard SATA 2.0 interface, a feature only supported by quad-core boards to meet user data storage expansion needs;
- Two Mini PCIE interfaces, one channel supports Wi-Fi, ZigBee, LAN MiniPCIE modules; the other channel can support 2G/3G/4G WAN MiniPCIE modules.
These features make ZLG Zhiyuan Electronics' Cortex-A9 core board an excellent choice for intelligent distribution terminals, ensuring both compliance with standards and additional flexibility for future enhancements.
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