CN112462847A

CN112462847A - Method for improving power-off time keeping precision of distribution automation equipment

Info

Publication number: CN112462847A
Application number: CN202011184837.8A
Authority: CN
Inventors: 张杭; 王道军; 张燕
Original assignee: Nanjing Intelligent Software Technology Co ltd; Nanjing Intelligent Apparatus Co ltd
Current assignee: Nanjing Intelligent Software Technology Co ltd; Nanjing Intelligent Apparatus Co ltd
Priority date: 2020-10-29
Filing date: 2020-10-29
Publication date: 2021-03-09

Abstract

The invention provides a method for improving power-off time keeping accuracy of distribution automation equipment, which comprises the steps of writing a real-time clock after receiving a time keeping command, triggering and updating a low-priority task of an RTC (real time clock), recording the current clock firstly in the task, writing the current clock into an RTC chip through an SPI (serial peripheral interface) or an I2C bus when the clock has sudden change in seconds and the time consumption does not exceed 5mS, judging that the total time consumption does not exceed 10mS after writing the RTC chip, and re-executing if the time consumption exceeds 5 mS. When the equipment is powered on, the time is read from the RTC chip when the clock of the RTC chip jumps, the equipment only allows the clock to be interrupted after being started, and the execution time is less than 0.1 mS. After the method is adopted, the error of writing the RTC chip in normal operation of the device is less than 10mS, the clock error read from the RTC chip after electrification is less than 5mS, and the error of writing and reading is not more than 15 mS. The time keeping error will depend only on the error of the RTC chip.

Description

Method for improving power-off time keeping precision of distribution automation equipment

Technical Field

The invention relates to the field of power distribution equipment, in particular to a method for improving the power-off time keeping precision of power distribution automation equipment.

Background

The accuracy requirement of the distribution automation equipment on power failure punctuality is higher and higher, and the requirement of some application scenes is less than 0.5S.

To meet the requirement of high precision time keeping, in addition to requiring higher precision for the clock of the RTC chip, the delay of the received time keeping command written into the RTC chip needs to be strictly controlled, and in addition, the delay and the time of reading the clock from the RTC chip need to be strictly controlled.

The minimum resolution of the RTC clock is typically seconds or 0.1 seconds, which results in an inherent error on the order of seconds or 0.1 seconds when a write or power up read of a tick command is received, resulting in a time keeping out of tolerance.

Disclosure of Invention

The invention provides a method for improving the power-off time keeping precision of distribution automation equipment to solve the problems in the prior art, wherein the error of writing into an RTC chip is less than 10mS when the equipment is in normal operation, the clock error read from the RTC chip after the equipment is powered on is less than 5mS, and the error of writing and reading is not more than 15 mS. The time keeping error will depend only on the error of the RTC chip.

After receiving a time tick command (the minimum resolution of the command is 1 mS), the invention firstly writes a real-time clock (the resolution is 1 mS). Triggering a low priority task that updates the RTC. In the task, firstly, a current clock (resolution mS) is recorded, when the second of the clock has sudden change and the time of use does not exceed 5mS (ensuring that the clock cannot be interrupted by a task with high priority and long time of use), the current clock is written into an RTC chip through an SPI or an I2C bus, the total time of use is judged to not exceed 10mS after the current clock is written into the RTC chip, and if the total time of use exceeds 10mS, the current clock is executed again, so that the time of writing into the RTC chip and the error of the real-time clock can be ensured. In the whole process, no high priority or off-interrupt is used to complete, since writing to the RTC chip is about 1-2mS (according to SPI or CLOCK frequency of I2C), and the off-interrupt affects the execution of high priority tasks such as sampling, protection, etc.

When the device is powered on, time is also read from the RTC chip, and the time needs to be read when the clock of the RTC chip jumps in consideration of inherent errors. The device only allows the clock to be interrupted after being started, and the execution time is less than 0.1mS, so that the influence of the interruption on the time for updating the system clock by the clock mutation is extremely small, and the time required by the device to execute is about 2mS, and the clock error read by the whole RTC chip is not more than 5 mS.

In summary, after the invention is adopted, the error of writing into the RTC chip by the device during normal operation is less than 10mS, the clock error read from the RTC chip after power-on is less than 5mS, and the error of writing and reading is not more than 15 mS. The time keeping error will depend only on the error of the RTC chip.

Drawings

Fig. 1 is a flowchart of a time tick command after being received.

Fig. 2 is a flow chart of the device when it is powered on.

Detailed Description

The invention will be further explained with reference to the drawings.

After receiving the time tick command (the minimum resolution of the command is 1 mS), the present invention writes the real time clock (resolution 1 mS) first as shown in fig. 1. Triggering a low priority task that updates the RTC. In the task, firstly, a current clock (resolution mS) is recorded, when the second of the clock has sudden change and the time of use does not exceed 5mS (ensuring that the clock cannot be interrupted by a task with high priority and long time of use), the current clock is written into an RTC chip through an SPI or an I2C bus, the total time of use is judged to not exceed 10mS after the current clock is written into the RTC chip, and if the total time of use exceeds 10mS, the current clock is executed again, so that the time of writing into the RTC chip and the error of the real-time clock can be ensured. In the whole process, no high priority or off-interrupt is used to complete, since writing to the RTC chip is about 1-2mS (according to SPI or CLOCK frequency of I2C), and the off-interrupt affects the execution of high priority tasks such as sampling, protection, etc.

When the device is powered on, as shown in fig. 2, time is also read from the RTC chip, and the time needs to be read when the clock of the RTC chip jumps in consideration of inherent errors. The device only allows the clock to be interrupted after being started, and the execution time is less than 0.1mS, so that the influence of the interruption on the time for updating the system clock by the clock mutation is extremely small, and the time required by the device to execute is about 2mS, and the clock error read by the whole RTC chip is not more than 5 mS.

While the invention has been described in terms of its preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1. A method for improving the power-off time keeping precision of distribution automation equipment is characterized by comprising the following steps:

1) after receiving a time tick command, writing a real-time clock firstly, triggering and updating a low-priority task of the RTC, in the task, firstly recording the current clock, when the clock has sudden change in seconds and the time consumption does not exceed 5mS, writing the current clock into an RTC chip through an SPI or an I2C bus, judging that the total time consumption does not exceed 10mS after writing the current clock into the RTC chip, and if the total time consumption does not exceed 10mS, re-executing;

2) when the equipment is powered on, the time is read from the RTC chip when the clock of the RTC chip jumps, the equipment only allows the clock to be interrupted after being started, and the execution time is less than 0.1 mS.

2. The method of improving power distribution automation equipment power outage timekeeping accuracy of claim 1, wherein: the minimum resolution of the time tick command in the step 1) is 1 mS.

3. The method of improving power distribution automation equipment power outage timekeeping accuracy of claim 1, wherein: the resolution ratio of the real-time clock and the current clock is 1 mS.