Time-interval-adaptation-based power line power frequency communication system and method

Abstract

The invention discloses a time-interval-adaptation-based power line power frequency communication system and a time-interval-adaptation-based power line power frequency communication method, which relate to the network structure and signal processing of a power system and belong to technical field of power line power frequency communication. The power line power frequency communication system consists of master station equipment which is positioned in a substation and a remote communication terminal which is positioned on a low-voltage side of a distribution transformer, wherein the master station equipment also comprises a downlink signal driving device and an uplink signal demodulation device. In the method, leading information is adopted in the specified power frequency cycle during power frequency signal modulation; during demodulation, the signal-to-noise ratio of a power frequency distortion signal is improved by accumulating a sampling signal in multiple cycles in a time period of the leading information; the time domain of a modulating signal is determined by performing time frequency analysis on the basis of Wigner distribution; and data demodulation is performed in the time domain through a related detection mode. Because an accurate receiving time period and an optimal judgment moment can be obtained for demodulation, the anti-jamming capacity of the power frequency communication is greatly improved, and the system can adapt to various connection modes of the distribution transformers.

Description

technical field [0001] The invention relates to the technical field of power line frequency communication. In particular, the invention relates to a power line power frequency communication system and method based on time period self-adaptive for power system network structure, communication and signal processing. Background technique [0002] The power line power frequency communication method realizes the transmission of information through the voltage and current distortion near the voltage zero crossing. Since the distorted signal is a low-frequency signal, it can realize long-distance transmission across the transformer station area without additional equipment on the high-voltage line, which is different from using high-frequency Compared with the 10KV power carrier communication for signal transmission, the equipment cost is much lower. Compared with the public wireless network, there is no communication service fee; therefore, the power line frequency communication h...

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Problems solved by technology

The power line is not a dedicated communication line, the channel environment is not ideal, and the power frequency communication method is still difficult to guarantee the communication performance of the industrial power grid. It is basically only used in the meter reading system of the civil power grid; the previous research focuses on the noise of the industrial power grid. In terms of the influence of the modulated signal, the difference in the zero-crossing time of the power frequency communication transceiver terminal voltage is ignored, such as figure 2 The distorted signal and the zero-crossing time difference of the transmitting and receiving end voltage are shown. Due to factors such as power supply line impedance, transformer connection mode, and load, there are differences in the voltage zero-crossing time between the substation and the distribution transformer voltage side, especially in industrial power grids. The electrical load is mainly a high-power motor, and the voltage zero-crossing difference is relatively large; the traditional power frequency communication method is based on the zero-crossing time of the local voltage as the modulation and demodulation time domain of the power frequency communication, which will cause the demodulation period of the power frequency modulation signal to be different from the There are obvious errors in the time domain of the signal existence, coupled with the interference of power grid noise, the performance of power frequency communication is seriously affected

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