NXP State Grid Single-Phase Meter Solution

With the rapid development of electronic energy meter technology, the intelligence and informationization of power grids have become an inevitable trend. Therefore, there is a huge potential market demand for smart meters. In order to better build and develop the national grid , the State Grid Corporation of China promulgated the new "Smart Energy Meter Series Standards" in September 2009 to regulate and standardize the development of the power meter industry. The new smart meter standards put forward new requirements for the design and production of smart meters. The State Grid single-phase meter DDS-GW solution was created to meet the requirements of the new State Grid standards. The

State Grid single-phase meter DDS-GW solution uses NXP's low-power LPC1100 series Cortex-M0 microcontroller as the main control chip, which is designed in full accordance with the State Grid Corporation's smart meter series standards and meets the "Smart Energy Meter Function Specifications". It integrates multiple functions such as metering, local fee control, zero-line anti-theft, instantaneous/agreed/timing/daily freezing, event recording, etc., and has RS485 communication interface and infrared communication interface.

System Structure

The State Grid single-phase meter DDS-GW uses NXP's 32-bit Cortex-M0 microcontroller LPC1100 as the main control chip, plus metering unit, fee control, RS485, infrared communication, data storage, LCD display and other functional modules. The system structure of the State Grid single-phase meter is shown in the figure below.



Solution Advantages


High-performance Cortex-M0 processor - tailor-made for the power industry

Traditional single-phase energy meter solutions mainly use 8-bit microcontrollers as the main control chip, but with the increasing standards of smart energy meters, traditional solutions will be limited in hardware resource utilization and software design. The State Grid single-phase meter DDS-GW uses NXP's 32-bit LPC1100 series Cortex-M0 microcontroller as the main control chip. This microcontroller is specially designed by NXP for single-phase meters in the power industry. It is based on the Cortex-M0 core, with a main frequency of up to 50MHz, 3 serial ports, 1 I2C ^interface , 1 SPI interface and 128K on-chip Flash, and supports three low-power modes: sleep, deep sleep and deep power-down. The LPC1100 series microcontroller has rich peripheral resources and high-performance computing processing capabilities, which improves the design flexibility of hardware and software, and is an ideal choice for the design of single-phase meters in the State Grid. [page]

Fee control function: RC522 card reader module

MF RC522 is a low-voltage, low-cost, small-size contactless card reader chip launched by NXP for the "three meters" [1] application. It supports ISO/IEC1443 Type A (communication rate 212kbit/s and 424kbit/s) and MIFARE ^® communication protocol. MF RC522 integrates multiple communication interfaces such as SPI, I2C ^and UART, which is convenient for MCU programming control. [1] Refers to electricity meter, water meter and gas meter.

Technical specifications


and technical standards

Its performance indicators comply with the requirements of GB/T 17215.321-2008 "Particular requirements for AC current measuring equipment Part 21: Static active energy meters (Class 1 and Class 2)"; the

communication protocol complies with DL/T 645-2007 "Multi-function energy meter communication protocol"; and

it complies with State Grid Corporation's Q/GDW 354-2009, Q/GDW 355-2009, Q/GDW 364-2009, Q/GDW 365-2009 and other series of enterprise standards.


Basic functions and featuresElectric

energy metering function: metering of forward active energy, reverse active energy, and combined active energy;

Time-sharing metering function: metering of total, peak, peak, flat, and valley electricity;

with multiple electricity price functions such as multi-rate electricity price and tiered electricity price;

Freezing function: supports instantaneous freezing, timed freezing, hourly freezing, daily freezing, and other freezing methods for freezing active energy and active power data; supports switching of time zone tables, time period tables, and tiered electricity price tables;

Fee control function: has a local fee control function that can switch the power on and off for electricity users. There are alarm amounts and overdraft threshold amounts. When the alarm amount or overdraft threshold amount is reached, the energy meter should be able to remind the user by sound, light, or other means or control the load switch to interrupt the power supply. Only after the electric energy meter confirms the information of the renewed electricity fee payment can the power supply be restored by closing the switch;

the fee control switch is internally controlled when the maximum current is within 60A, and externally controlled when the maximum current is above 60A;

local fee control is implemented by contactless card, which complies with the safety technical specifications of State Grid Corporation on information exchange;

there are multiple event recording functions: power-off record, programming record, time calibration record, cover opening record, meter clearing record, switch closing record, electricity purchase record, etc. to ensure the safety of the electric energy meter and the traceability of events;

alarm function: support LED , buzzer and LCD display alarm;

display function: the electric energy meter can display a variety of information on the LCD screen through automatic rotation display and manual button display, with rich display information;

password locking function: if the password is entered incorrectly for 3 times in total, the electric energy meter will be automatically locked, and it will be automatically unlocked 24 hours after the password is locked; power failure wake-up function: support display button, cover opening and contactless card insertion and other wake-up methods;

with zero line anti-theft function;

there are multiple communication interfaces: RS485 and infrared.

The actual picture

of the State Grid single-phase meter test board DDS-GW V1.00 Demo is shown in the figure below.