Today, IEEE1588 (or PTP) has been developed to V2 version, and the overall application is still very promising, after all, compared with expensive satellite timing, land time synchronization technology is still more reliable and more economical.
However, in many practical applications of private networks, many customers are gradually using PTP timing solutions. However, many timing products cannot be guaranteed in terms of accuracy. SYN2402 Portable Small 1588 Master Clock
For measurements with digitized substations, synchrophasor measurements require a UTC time source with an accuracy of 1us, which can be obtained by providing a GPS receiver for each station as the primary reference time. The collection and transmission of equipment data in the site is generally carried out through the LAN and it is precisely because of the use of the LAN mode that provides an opportunity for the application of the IEEE1588 standard in the power system, and because there is already a boundary clock switch that can realize the IEEE1588 function on the market, it is feasible to replace the existing IRIG-B technology with IEEE 1588 technology from the technical and application environment analysis. Moreover, the distance between the various electrical equipment in the power plant, including voltage transformers, current transformers, voltage transformers and various monitoring equipment, is usually within the range of one kilometer to two kilometers, which is just the scope of the local area network to which the IEEE1588 standard applies.
Now, the company's time synchronization technology can traverse any IP network, so that users can rely on its original self-owned slave technology to accurately recover time information without any modification to the existing network, realize accurate time synchronization of the entire network, and ensure that it is highly consistent with the master clock time. At present, its time synchronization accuracy can reach the level of 1ns and 100ns according to different network conditions, which can well meet the needs of various devices for accurate timing. With accurate time synchronization of servers, network equipment, computers, etc., it can maximize its own value, accurately know the time and sequence of each transaction, ensure the fairness and impartiality of the transaction, and promote the effective development of various tasks. The company's series of time-frequency products and solutions, old customers have repeatedly repurchased, and new customers have come to order. The company's time synchronization technology, so that users do not need to change the network, do not need to replace the ordinary switch to the 1588 switch to achieve accurate time synchronization, the prospect is very broad, interested can search for the leader in the icon, minutes to help you easily solve any problems related to accurate time synchronization. SYN2402 Portable Small 1588 Master Clock
1. Basic overview of time synchronization of power system
With the deepening of the research on the IEC 61850 standard, the significant difference between the digital substation and the conventional substation is that the traditional current voltage transformer and circuit breaker at the process layer will be replaced by electronic current voltage transformer and intelligent circuit breaker. In the digital substation, the degree of data information sharing and the real-time nature of data will be greatly improved. The IEC61850 standard divides the clock accuracy function requirements of intelligent electronic devices into 5 levels (T1-T5), of which the T5 level used for measurement has an accuracy of 1US.
Nowadays, IEEE1588 has begun to be widely used in small local area networks, and although the stability is good, the accuracy is not high. In addition, when it comes to long-distance applications, there are obstacles to the asymmetry of the transmission link path. SYN2402 Portable Small 1588 Master Clock
At present, the global positioning system is used in the substation automation system a lot, and the GPS synchronization equipment uses pulse signals to time through hard wiring, which has the characteristics of high precision and low cost, and its related technology has been very mature. However, the development trend of digitalization of substations has replaced the secondary hard wiring in the station with serial communication lines, so the IEC61850 standard introduces a simple network time protocol as a network timing protocol. SNTP is a simplified standard for the Internet Network Time Protocol. Under a certain network structure, the timing accuracy of NTP can reach the T1 level (1 ms), and the error range in the WAN is 10 100 ms. The network application of NTP SNTP is relatively mature, but it is difficult to achieve T3 level accuracy of 25us. SYN2402 Portable Small 1588 Master Clock
IEEE 1588 released in 2002 defines a precision time protocol PTP for distributed measurement and control systems, and its network timing accuracy can reach sub-US level, which has attracted the attention of researchers in industrial fields such as automation and communications. In view of the high-precision distributed network timing characteristics of IEEE1588, the 10th working group of IEC TC57 is ready to introduce IEEE1588 into IEC 61850 after the switches and Ethernet chips that support IEEE1588 have mature commercial applications. Therefore, it is of great significance to study the specific application of IEEE1588 in digital substation.
2. Introduction and implementation of IEEE1588
IEEE1588 (Precision Time Protocol) is a network timing mode that adapts to the time synchronization of intelligent substations. The standard was originally proposed as a precision clock synchronization protocol standard dedicated to industrial control and measurement, with the goal of providing sub-subtle synchronization accuracy applications. Later, the standard attracted attention in the field of automation, especially in the field of distributed motion control, and related organizations such as telecommunication and power systems also showed strong interest in it. At present, in terms of digital substations, IEEE1588 is the first choice for time synchronization.
SYN2402 Portable Small 1588 Master ClockIt is a master clock that supports IEEE1588-2008 V2, uses GPS Beidou as the clock reference source, has nanosecond time transmission accuracy, supports dozens of PTP slave clock devices, and is a small PTP master clock with high cost performance.
3. Features and advantages of IEEE1588
IEEE1588 implements master-slave synchronization and has the following features compared with other network timing schemes.
1)The exact value of the time at which the sync packet is sent is not included in this packet, but in the follow-up packet, so that the transmission time and time measurement of the packet do not affect each other.
2) After the master obtains accurate information through the timescale generator at the bottom layer, it sends a follow up packet, which accurately reflects the sending time of the sync packet. The slave uses a time scale generator to accurately measure the time at which a SYNC message is received. This accurate moment is guaranteed because the time label information is "stamped" close to the physical layer. Similarly, Delay Req and Delay Resp packets can be accurately timestamped at the time of transmission. (3) Compared with the master-slave clock offset measurement, the master-slave communication path delay measurement is not performed periodically, but is only executed once at a longer time interval, so that the network load and the processing task of the terminal equipment can be reduced.
It is precisely because of this combination of software and hardware that the uncertainty of the protocol stack delay is eliminated, so that the IEEE1588 protocol synchronization can achieve sub-subtle accuracy.
SYN2402 Portable Small 1588 Master Clock
Compared with the traditional pulse, irig-b and other hard timing methods, IEEE 1588 can automatically correct the distance of the line, which greatly simplifies the allocation and synchronization of time between various devices within the site compared to irig-b. In addition, because the IEEE 1588 standard can be used to use network pairing, the internal dedicated timing twisted pair can be reduced, so the stability of the system can be improved, and the cost is more affordable than the solution using irig-B. Therefore, the IEEE1588 network timing mode will replace the traditional hard timing mode with its incomparable flexibility and become the most important communication mode of the power system.
IV. Concluding remarks
Many industrial, test and measurement, and communications applications require high-precision clock signals to synchronize control signals, capture data, and more. The IEEE 1588 Precision Time Protocol (PTP), applied in standard Ethernet, provides a way to propagate master clock timing to many nodes in the system.