Achieving high-precision time synchronization of various devices in the power system is crucial to ensuring the stable operation of the power system. The following are some common and effective methods:

1. Global Satellite Navigation System (GNSS) Timing:

• Principle and Application:

Global satellite navigation systems, such as my country's Beidou Satellite Navigation System (BDS) and the United States' Global Positioning System (GPS), send signals containing precise time information to the ground through satellites. The equipment in the power system is equipped with corresponding satellite timing receiving devices to receive satellite signals and extract time information from them as the time reference of the equipment. For example, in a substation, Beidou or GPS timing devices are installed to provide high-precision time synchronization signals for relay protection devices, automatic monitoring systems and other equipment in the station to ensure that these devices operate under a unified time reference.

• Advantages And Limitations:

The advantage is that it can provide high-precision time synchronization, with time accuracy ranging from nanoseconds to microseconds, and has a wide coverage range and is not restricted by geographical conditions. However, there are certain limitations. For example, satellite signals may be blocked or interfered, resulting in signal weakening or loss, affecting the accuracy of time synchronization. In addition, the compatibility and reliability of different satellite navigation systems also need further consideration.

2. Atomic Clock Timing:

• Principle And Application:

Atomic clocks are devices that generate high-precision time signals based on the stable frequency of atomic energy level transitions. Common atomic clocks include rubidium atomic clocks and cesium atomic clocks. In the power system, atomic clocks are used as time reference sources, and the high-precision time signals generated by atomic clocks are transmitted to various devices through time synchronization equipment. For example, in some important power dispatching centers or hub substations, high-precision rubidium atomic clocks are installed as master clocks to provide time synchronization services for power equipment in the entire region.

• Advantages And Limitations:

Atomic clocks have extremely high time stability and accuracy, and can maintain high-precision time output for a long time. However, atomic clocks are relatively expensive, have high maintenance costs, and are large in size, which may be difficult to install in some power equipment with limited space.

3. Network Time Protocol (NTP) and Precision Time Protocol (PTP):

• NTP Principle And Application:

NTP is a time synchronization protocol based on network transmission, which transmits the time information of the time server to the client device through the network. In the power system, a time server is set up, and its time source can be GNSS timing or atomic clock timing. Other devices act as clients and communicate with the time server through the network to obtain accurate time information and synchronize. For example, in the office network of a power company, computers, servers and other devices can synchronize time with the time server through the NTP protocol to ensure the consistency of time in the office system.

• PTP Principle And Application:

PTP is a more accurate time synchronization protocol. It can achieve sub-microsecond or even nanosecond time synchronization accuracy through a combination of hardware and software. The PTP protocol uses switches, routers and other devices in the network to transmit time information, and ensures the accuracy of time synchronization through precise timestamp calculation and correction mechanisms. In the automation control network of the power system, such as the process layer network of the smart substation, the PTP protocol can provide high-precision time synchronization for protection devices, measurement and control devices and other devices.

• Advantages And Limitations:

NTP protocol is simple to implement and has low cost. It is suitable for occasions where time accuracy is not extremely high. PTP protocol has high accuracy, but has high requirements for network equipment and software, and the implementation cost is relatively high. At the same time, factors such as delay and jitter in the network transmission process may affect the accuracy of time synchronization.

4. Fiber-Optic Timing:

• Principle And Application:

Time synchronization is performed using the stable transmission characteristics of optical fiber. By setting up time synchronization equipment at both ends of the optical fiber, one end sends the time signal, and the other end receives and performs time calibration. Fiber-optic timing can use two-way time transfer technology, that is, the devices at both ends send and receive time signals at the same time, and the round-trip time of signal transmission is calculated to eliminate the influence of transmission delay and achieve high-precision time synchronization. For example, between the substations at both ends of a long-distance transmission line, optical fiber can be used for time synchronization to ensure the time consistency of the devices at both ends.

• Advantages And Limitations:

Fiber-optic timing has the advantages of high accuracy and strong anti-interference ability, and is not affected by electromagnetic interference and weather conditions. However, the cost of laying optical fiber is high, and the optical fiber needs to be regularly maintained to ensure the stability of its transmission performance.

5. Redundant Configuration Of Time Synchronization Equipment:

• Principle And Application:

In order to improve the reliability of the time synchronization system, redundant configuration of time synchronization equipment is usually adopted in the power system. For example, multiple time servers are set up. When one server fails, other servers can automatically take over the time synchronization task to ensure that the system's time synchronization is not affected. At the same time, multiple time synchronization interfaces can also be configured on the device side. When one interface has a problem, it can switch to other interfaces to obtain time information.

• Advantages And Limitations:

Redundant configuration can effectively improve the reliability and fault tolerance of the time synchronization system, but it will increase the cost and complexity of the system, and requires reasonable planning and management.