A sunspec signal search method

Abstract

A SunSpec signal search method comprises the following steps: S1, determining a signal search period according to the periodicity of a SunSpec system signal; S2, dividing the signal search period into a single-period signal detection time and a single-period system sleep time; S3, starting a low-frequency timer in the single-period system sleep time, and the timer still normally operates in a low-power sleep state; meanwhile, other parts of the system are in the sleep state; S4, performing signal detection and analysis in the single-period signal detection time to determine the data characteristics of the current received signal; S5, when the data characteristics of the current received signal do not meet the signal characteristics, a next signal search period is re-started; otherwise, the low-power search state is exited, and complete signal search and signal demodulation work are performed. The method can quickly detect the arrival of a SunSpec system effective signal, greatly reduce the invalid working time of the system, and effectively reduce the detection power consumption.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a low-power SunSpec signal search method. Background Technology

[0002] Power line communication (PLC) is a communication technology that uses power lines as a medium to achieve data transmission. Digital signals are modulated and transmitted in carrier form, then modulated again by a PLC transceiver before being loaded onto the power line for transmission. Reception is the reverse process.

[0003] A photovoltaic (PV) power generation system consists of PV strings formed by multiple PV modules connected in series. These strings are then connected to an inverter to convert DC to AC for grid-connected power generation. Considering that series-connected PV modules can generate a DC high voltage of 600V–1000V, which could pose a risk of personal injury and fire, PV fast shutdown devices compliant with SunSpec standards can achieve rapid shutdown at the module level in emergency situations.

[0004] The SunSpec Fast Shutdown Protocol is a PLC protocol specifically designed for the fast shutdown function of photovoltaic systems. The SunSpec protocol specifies that the modulation method uses B-FSK (Binary Frequency Shift Keying), and the B-FSK modulation principle is as follows: Figure 2 As shown, SunSpec specifies two carrier frequencies: Fm = 131.25kHz and Fs = 143.75kHz, which fall within the CENELEC B / C / D bands for narrowband communication. Additionally, SunSpec specifies two types of valid commands to be transmitted: shutdown commands and normal operation commands. The complete transmission cycle for one command is 1070.08ms.

[0005] However, the power line channel transmission environment is extremely harsh, with various complex noises, strong narrowband interference, and poor frequency selectivity. These factors greatly hinder reliable signal transmission, requiring effective technologies to ensure efficient and robust signal transmission and guarantee the safe and reliable operation of photovoltaic systems.

[0006] Against the backdrop of global development towards green, environmentally friendly, and low-carbon practices, how to significantly reduce power consumption and search power consumption in the SunSpec system without affecting normal system operation is an important research direction and topic.

[0007] Therefore, designing a high-performance system signal search method that ensures reliable signal search and has low power consumption, thereby ensuring reliable signal detection in the SunSpec system and laying a solid foundation for accurate demodulation of the subsequent SunSpec system, is a problem that the SunSpec system based on spread spectrum B-FSK modulation needs to solve. Summary of the Invention

[0008] To address the challenge of low-power, high-performance signal detection in the SunSpec system, this invention provides a low-power, fast, and accurate SunSpec signal search method.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A SunSpec signal search method includes the following steps:

[0011] S1. Determine the signal search period Tsearch based on the periodicity characteristics of the SunSpec system signal;

[0012] S2. The system divides the signal search period Tsearch into a single-cycle signal detection time T1_det and a single-cycle system sleep time T1_sleep.

[0013] S3. During the single-cycle system sleep time, the system starts a low-frequency timer, which continues to operate normally in the low-power sleep state; at the same time, all other parts of the system are in sleep state, thereby minimizing system power consumption.

[0014] S4. During the single-cycle signal detection time, the system performs multiple signal detections and analyses, and finally determines the data characteristics of the currently received signal.

[0015] S5. If the data characteristics of the currently received signal do not meet the signal characteristics, restart the next signal search cycle; otherwise, exit the low-power search state and carry out complete signal search and signal demodulation.

[0016] In one embodiment, step S1 includes:

[0017] The signal search period Tsearch is less than the SunSpec effective signal transmission time ABC (168.96ms), which ensures that the effective signal transmission time will not be missed under any circumstances.

[0018] In one embodiment, step S2 further includes:

[0019] The single-cycle signal detection time T1_det is greater than the transmission time of 4 modulation bits (20.48ms), thereby ensuring that the detection signal simultaneously covers the carrier signals Fm and Fs;

[0020] Furthermore, step S4 also includes:

[0021] Step S41: Based on the frequency resolution requirements, determine the data sampling clock fs and the single signal detection data length N, and define three peak feature counts peak1_num, peak2_num and peak3_num, and initialize them all to 0;

[0022] Step S42: Perform a Fast Fourier Transform (FFT) on the received N-point time-domain signal to obtain the frequency domain characteristics of the data;

[0023] Step S43: Calculate the total energy of all frequency signals and the energy of the frequency points corresponding to carrier signals Fm and Fs;

[0024] Based on the frequency points corresponding to the SunSpec modulated carrier signals Fm and Fs, the subcarrier indices in the frequency domain are as follows:

[0025]

[0026] Wherein, Subm is the subcarrier index in the frequency domain where the carrier signal Fm is located, and Subs is the subcarrier index in the frequency domain where the carrier signal Fs is located.

[0027] Step S44: Determine whether the carrier signal Fm or Fs meets the energy threshold requirement. If the carrier signal Fm meets the threshold requirement, increment the single signal characteristic peak count Peak1_num by 1. If the carrier signal Fs meets the threshold requirement, increment the single signal characteristic peak count Peak2_num by 1. Otherwise, increment the single signal characteristic indicator count Peak3_num by 1.

[0028] Step S45: Continue processing the subsequent N-point time-domain signals;

[0029] Step S46: Repeat steps S42-S45. When the number of signal searches reaches the preset number Nvalue, perform a comprehensive judgment on the multiple signal detection results to determine whether a signal is detected in the current period, and output a signal indicator Flag_signal. The judgment rules are as follows:

[0030] If Peak1_num > Thr & and Peak2_num > Thr, then Flag_signal = 1; otherwise, Flag_signal = 0.

[0031] Where Thr is the threshold for the number of times a valid signal can be detected.

[0032] When Flag_signal is 1, it means that a valid signal has been detected;

[0033] When Flag_signal is 0, it means that no valid signal was detected.

[0034] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the SunSpec signal search method.

[0035] The beneficial effects of this invention compared to the prior art are as follows:

[0036] This invention provides a low-power SunSpec signal search method that dynamically balances signal detection and system sleep time. While ensuring reliable signal detection performance, it significantly reduces power consumption during signal detection, achieving high system efficiency and energy saving. This invention combines Fast Fourier Transform (FFT) analysis to extract and analyze the frequency domain characteristics of the received signal and implements multiple comprehensive decision processing schemes to adapt to the complex power line noise and interference channel environment of the SunSpec system. This enables accurate and reliable signal detection in the SunSpec system, effectively assisting in the reliable reception of SunSpec system data.

[0037] The scheme also has the advantages of simple implementation, low computational cost, excellent performance, and high reliability.

[0038] Theoretical analysis and specific experiments show that the low-power SunSpec signal search method proposed in this invention can not only quickly detect the arrival of valid signals in the SunSpec system, but also significantly reduce the system's ineffective working time, effectively reducing the detection power consumption of the SunSpec system and meeting the requirements of low-power system design. Attached Figure Description

[0039] Figure 1 This is a flowchart of a SunSpec signal search method according to a specific embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of B-FSK modulation of the SunSpec system in a specific embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the SunSpec PLC transmission signal frame structure according to a specific embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram illustrating the design of SunSpec signal detection time and sleep time parameters in a specific embodiment of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0044] like Figure 1As shown, a specific embodiment of the present invention provides a low-power SunSpec signal search method, which realizes low-power detection and search of the system's SunSpec signal, providing a basis for normal demodulation at the subsequent receiver. The SunSpec signal search method includes the following steps:

[0045] S1. Determine the signal search period Tsearch based on the periodicity characteristics of the SunSpec system signal;

[0046] S2. The system divides the signal search period Tsearch into a single-cycle signal detection time T1_det and a single-cycle system sleep time T1_sleep.

[0047] S3. During the single-cycle system sleep time, the system starts a low-frequency timer, which continues to operate normally in the low-power sleep state; at the same time, all other parts of the system are in sleep state, thereby minimizing system power consumption.

[0048] S4. During the single-cycle signal detection time, the system performs multiple signal detections and analyses, and finally determines the data characteristics of the currently received signal.

[0049] S5. If the data characteristics of the currently received signal do not meet the signal characteristics, restart the next signal search cycle; otherwise, exit the low-power search state and carry out complete signal search and signal demodulation.

[0050] The low-power SunSpec signal search method provided by this invention can adapt to the complex environmental requirements of DC photovoltaic communication systems, realize reliable and accurate detection of SunSpec system received signals, provide a foundation for subsequent SunSpec data demodulation, and provide a basis for normal demodulation at the subsequent receiving end.

[0051] The system parameters used in this embodiment are defined as shown in the table below:

[0052] Table 1 SunSpec Communication System Parameters

[0053]

[0054] Therefore, the SunSpec signal modulation method is as follows Figure 2 As shown, the SunSpec system's fast shutdown PLC protocol uses a periodic signal command method, and its frame format is as follows: Figure 3 As shown.

[0055] This preferred embodiment specifically includes the following steps:

[0056] S1. Based on the periodicity characteristics of the SunSpec system signal, design a reasonable signal search period Tsearch;

[0057] According to the SunSpec system signal cycle in Table 1, the ABC transmission duration is approximately 168.96 ms, and the static duration (no signal transmission time) is approximately 901.12 ms. Therefore, a normal signal cycle is 1070.08 ms.

[0058] Therefore, the signal search period Tsearch is less than the SunSpec effective signal transmission time ABC (168.96ms), which ensures that the effective signal transmission time will not be missed under any circumstances.

[0059] Preferably, in this embodiment, the signal search period Tsearch is set to 151.04ms.

[0060] S2. The system divides the signal search period Tsearch into a single-cycle signal detection time T1_det and a single-cycle system sleep time T1_sleep.

[0061] The single-cycle signal detection time T1_det is greater than the transmission time of 4 modulation bits (20.48ms), thereby ensuring that the detection signal simultaneously covers the carrier signals Fm and Fs;

[0062] Preferably, in this embodiment, the signal search period Tsearch is designed to be 151.04ms, the single-cycle signal detection time T1_det is designed to be 23.04ms, and the single-cycle system sleep time T1_sleep is designed to be 128ms. Figure 4 The diagram further illustrates the design of low-power SunSpec signal detection time and sleep time parameters. Through the above-mentioned periodic signal detection and system sleep design, the power consumption of the system can be effectively reduced, while the arrival of signals can be quickly detected.

[0063] S3. During the single-cycle system sleep time, the system starts a low-frequency timer, which continues to operate normally in the low-power sleep state; at the same time, all other parts of the system are in sleep state, thereby minimizing system power consumption.

[0064] In this preferred embodiment, the low-frequency clock f is designed to be 32.768kHz, thereby ensuring low power consumption operation of the system. Moreover, the timing accuracy requirements are relatively low, with no special requirements. Even if the crystal oscillator fluctuation is 100-300ppm, it can meet the requirements.

[0065] S4. During the single-cycle signal detection time, the system performs multiple signal detections and analyses, and finally determines the data characteristics of the currently received signal.

[0066] Step S41: Based on the frequency resolution requirements, design a reasonable data sampling clock fs and a single signal detection data length N, and define three peak feature counts peak1_num, peak2_num and peak3_num, and initialize them all to 0;

[0067] According to the modulation bit transmission time Bit Period(T) S Given the FSK carrier modulation frequencies Fm (131.25kHz) and Fs (143.75kHz) specified by the SunSpec system (5.12ms), select a reasonable receiver sampling rate f. s (kHz) and the single signal detection data length N; preferably, in this embodiment, the receiver sampling rate f s The design is for 1000kHz, and the single signal detection data length N is designed to be 640.

[0068] Step S42: Perform a Fast Fourier Transform (FFT) on the received N-point time-domain signal to obtain the frequency domain characteristics of the data;

[0069] Step S43: Calculate the total energy of all frequency signals and the energy of the frequency points corresponding to carrier signals Fm and Fs;

[0070] Based on the frequency points corresponding to the SunSpec modulated carrier signals Fm and Fs, the subcarrier indices in the frequency domain are as follows:

[0071]

[0072] Wherein, Subm is the subcarrier index in the frequency domain where the carrier signal Fm is located, and Subs is the subcarrier index in the frequency domain where the carrier signal Fs is located.

[0073] Step S44: Determine whether the carrier signal Fm or Fs meets the energy threshold requirement. If the carrier signal Fm meets the threshold requirement, increment the single signal characteristic peak count Peak1_num by 1. If the carrier signal Fs meets the threshold requirement, increment the single signal characteristic peak count Peak2_num by 1. Otherwise, increment the single signal characteristic indicator count Peak3_num by 1.

[0074] Step S45: Continue processing the subsequent N-point time-domain signals;

[0075] Step S46: Repeat steps S42-S45. When the number of signal searches reaches the preset number Nvalue, perform a comprehensive judgment on the multiple signal detection results to determine whether a signal is detected in the current period, and output a signal indicator Flag_signal. The judgment rules are as follows:

[0076] if(Peak1_num>Thr&&Peak2_num>Thr)Flag_signal=1;

[0077] else Flag_signal = 0;

[0078] Thr is the threshold for the number of times a valid signal can be detected.

[0079] When Flag_signal is 1, it means that a valid signal has been detected;

[0080] When Flag_signal is 0, it means that no valid signal was detected.

[0081] In this preferred embodiment, a reasonable threshold Thr for the number of times a valid signal is detected is set. This threshold is usually designed based on the noise impact and the data length of a single cycle. In this embodiment, Thr = 2 is used.

[0082] S5. If the data characteristics of the currently received signal do not meet the signal characteristics, restart the next signal search cycle. Otherwise, exit the low-power search state and perform a complete signal search and demodulation operation.

[0083] Through the above-described signal search method and mechanism design, the power consumption of the power system search can be reduced to about one-sixth of the normal search power consumption, thereby significantly reducing the system's search power consumption and demonstrating the effectiveness and practicality of the method of the present invention.

[0084] The above describes the complete steps and related search mechanism of the low-power SunSpec signal search method. It can be seen that the low-power SunSpec signal search method of this invention can effectively reduce system power consumption while quickly detecting and identifying the arrival of signals, thereby effectively assisting in the reliable reception of SunSpec system data.

[0085] Theoretical analysis and specific experiments show that the low-power SunSpec signal search method proposed in this invention can not only quickly detect the arrival of valid signals in the SunSpec system, but also significantly reduce the system's ineffective working time, effectively reducing the detection power consumption of the SunSpec system and meeting the requirements of low-power system design.

[0086] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.

Claims

1. A SunSpec signal search method, characterized in that, Includes the following steps: S1. Determine the signal search period Tsearch based on the periodicity characteristics of the SunSpec system signal; S2. Divide the signal search period Tsearch into a single-cycle signal detection time T1_det and a single-cycle system sleep time T1_sleep; S3. During the single-cycle system sleep time, a low-frequency timer is started, and the timer continues to operate normally in the low-power sleep state; at the same time, all other parts of the system are in sleep state. S4. Within the single-cycle signal detection time, perform signal detection and analysis to determine the data characteristics of the currently received signal; S5. If the data characteristics of the currently received signal do not meet the signal characteristics, restart the next signal search cycle; otherwise, exit the low-power search state and carry out complete signal search and signal demodulation.

2. The SunSpec signal search method as described in claim 1, characterized in that, Step S1 includes: The signal search period Tsearch is less than the effective signal transmission time ABC of SunSpec.

3. The SunSpec signal search method as described in claim 1 or 2, characterized in that, Step S2 further includes: The single-cycle signal detection time T1_det is greater than the transmission time of 4 modulation bits, thereby ensuring that the detection signal simultaneously covers the carrier signals Fm and Fs.

4. The SunSpec signal search method as described in any one of claims 1 to 2, characterized in that, Step S4 specifically includes: Step S41: Based on the frequency resolution requirements, determine the data sampling clock fs and the single signal detection data length N, and define three peak feature counts peak1_num, peak2_num and peak3_num, and initialize them all to 0; Step S42: Perform Fast Fourier Transform (FFT) on the received N-point time-domain signal to obtain the frequency domain characteristics of the data; Step S43: Calculate the total energy of all frequency signals and the energy of the frequency points corresponding to carrier signals Fm and Fs; Based on the frequency points corresponding to the SunSpec modulated carrier signals Fm and Fs; Step S44: Determine whether the carrier signal Fm or Fs meets the energy threshold requirement. If the carrier signal Fm meets the threshold requirement, increment the single signal characteristic peak count Peak1_num by 1. If the carrier signal Fs meets the threshold requirement, increment the single signal characteristic peak count Peak2_num by 1. Otherwise, increment the single signal characteristic indicator count Peak3_num by 1. Step S45: Continue processing the subsequent N-point time-domain signals; Step S46: Repeat steps S42-S45. When the number of signal searches reaches the preset number Nvalue, perform a comprehensive judgment on the multiple signal detection results to determine whether a signal is detected in the current period, and output a signal indicator Flag_signal; the judgment rules are as follows: If Peak1_num > Thr & and Peak2_num > Thr, then Flag_signal = 1; otherwise, Flag_signal = 0. Where Thr is the threshold for the number of times a valid signal can be detected; When Flag_signal is 1, it means that a valid signal has been detected; When Flag_signal is 0, it means that no valid signal was detected.

5. The SunSpec signal search method as described in claim 4, characterized in that, In step S43, based on the frequency points corresponding to the SunSpec modulated carrier signals Fm and Fs, the subcarrier indices in their respective frequency domains are as follows: in, The subcarrier index in the frequency domain where the carrier signal Fm is located. The subcarrier number in the frequency domain where the carrier signal Fs is located.

6. The SunSpec signal search method as described in claim 4, characterized in that, In step S4, the threshold Thr is set to 2.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the SunSpec signal search method as described in any one of claims 1 to 6.

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