Cooperative noise masking secure communication method and system based on converter ripple communication

Abstract

The application discloses a kind of based on converter ripple communication's collaborative noise masking secure communication method and system, applied to including at least two power electronic converters and the power transmission line connected to its power electronic system;Source converter superimposes information signal in power control loop, and forms information carrier in power transmission line by pulse width modulation;Sink converter synchronously superimposes collaborative noise signal in power control loop, and injects collaborative noise carrier with the same frequency as information carrier in power transmission line, so that information carrier and collaborative noise carrier are superimposed to form hybrid carrier on power transmission line;Sink converter constructs noise transfer characteristic estimation model using collaborative noise signal injected by itself, and carries out collaborative noise carrier component elimination processing to recover information carrier;The application does not need to add new communication line or special encryption hardware, and can realize the improvement of power electronic system communication security.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of power electronics and information security, specifically relating to a cooperative noise masking secure communication method and system based on converter ripple communication. Background Technology

[0002] With the widespread integration of power electronic devices such as new energy power generation, energy storage, and electric vehicle charging equipment, the scale of power electronic systems is constantly expanding and their topologies are becoming increasingly complex. Modern power electronic converters, in addition to performing power conversion, also need to undertake functions such as state monitoring, coordinated control, and real-time protection linkage, leading to an exponential increase in the demand for information exchange within the system. Therefore, constructing an efficient and reliable data communication mechanism has become crucial for ensuring the stable operation of the system.

[0003] To meet the information exchange needs of power electronic systems, energy information synchronization modulation technology has emerged. This technology superimposes data modulation during power modulation, allowing voltage or current ripple to carry data information, thereby achieving coordinated energy and information transmission. Because this technology reuses existing power transmission lines, it eliminates the need for independent communication lines or dedicated modules, significantly reducing system complexity and cost.

[0004] Currently, various implementation schemes have been developed, focusing on modulation and demodulation methods, communication rate enhancement, and application scenarios. For example, some research has proposed a frequency-hopping differential phase-shift keying (FPS) method. The FH-DPSK modulation method combines FSK and DPSK modulation to digitally modulate the PWM carrier. Chinese Patent CN112994419A proposes a composite modulation method combining pulse width modulation and orthogonal frequency division multiplexing (OFDM) modulation, using OFDM to convert serial data into multiple subcarriers for parallel transmission. Chinese Patent CN114785117A proposes a three-degree-of-freedom power information fusion PWM control method, which improves communication bandwidth utilization and increases ripple communication rate by jointly modulating the duty cycle, frequency, and phase of the PWM signal. Chinese Patent CN110855359A proposes an LED driver that simultaneously realizes DC power line communication and visible light communication, achieving data transmission through PWM modulation and supporting bidirectional communication. Chinese Patent CN114825656A proposes a wireless power and data synchronization transmission system and data modulation method to realize information transmission across wireless power transmission links.

[0005] However, while energy-information synchronization modulation technology improves system integration, it also brings communication security challenges. Because this technology essentially broadcasts information over power transmission lines, the communication signals exhibit open propagation characteristics at the physical layer. This means that the communication signals are easily intercepted by other nodes on the same physical line or by external eavesdropping devices, thus posing a communication security risk. Existing security encryption methods mostly employ key-based algorithms to encrypt data at the protocol or application layer. These methods have the following significant limitations: 1. Significant computational overhead: This type of method relies on key management and computational resources, which may increase the computational burden in embedded power electronic control systems.

[0006] 2. Traditional encryption methods mainly operate at the data bit level and fail to fully utilize the physical channel characteristics of power electronic systems to improve communication security.

[0007] Therefore, it is necessary to explore a secure communication mechanism that utilizes the physical channel characteristics of power electronic systems to enhance communication security during the signal generation and propagation stages, in order to address the communication security issues of energy information synchronization modulation technology. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention proposes a cooperative noise masking secure communication method and system based on converter ripple communication.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, the present invention provides a cooperative noise-masking secure communication method based on converter ripple communication, comprising the following steps: S1 Address Confirmation Stage: The source converter sends address identification information on the power transmission line through the information modulation principle. Other converters connected to the power transmission line perform address matching according to the address identification information. The converter that matches the address identification information is the destination converter for this communication. S2 filter training phase: The source converter remains silent, while the sink converter injects a cooperative noise signal into the control loop through information modulation principle and injects a cooperative noise carrier into the same power transmission line; at the same time, the cooperative noise carrier is sampled, and then the sink converter inputs the sampling result of the cooperative noise carrier and the cooperative noise signal into the adaptive algorithm to estimate the transmission characteristics from the cooperative noise signal injection end to the sampling end of the power transmission line, thereby obtaining the noise transmission characteristic estimation model; S3 Data Transmission Stage: The source converter injects an information carrier carrying the data to be transmitted, and the sink converter synchronously injects a cooperative noise carrier. The information carrier and the cooperative noise carrier are superimposed on the power transmission line to form a mixed carrier. The sink converter uses the noise transmission characteristic estimation model to estimate the cooperative noise carrier component and eliminates it from the mixed carrier, thereby obtaining the recovered information carrier. Demodulation of the recovered information carrier yields the data transmitted by the source converter. Specifically, the information modulation principle is as follows: when the converter does not send baseband data, it only uses the power reference output by the control loop to compare with the carrier signal to generate a pulse width modulation signal; when the converter needs to send baseband data, it first modulates the baseband data to be sent through the modulator, then superimposes the modulated signal onto the original power reference, and finally compares the superimposed modulated power reference with the carrier signal to generate a PWM signal carrying data information, thereby forming corresponding voltage and / or current ripple in the connected power transmission line; The source converter is specifically a converter that performs the function of transmitting information, and the sink converter is specifically a converter that performs the function of receiving information. The information carrier is the voltage and / or current ripple generated by the source converter through the information modulation principle, and the cooperative noise carrier is the voltage and / or current ripple generated by the sink converter through the information modulation principle.

[0010] Furthermore, in step S2, the adaptive algorithm includes the LMS algorithm or the RLS algorithm.

[0011] Furthermore, in step S3, the information carrier is a periodic signal with a fixed frequency, whose amplitude and / or phase change with the data to be transmitted, and adopts a data modulation method of differential phase shift keying, amplitude shift keying, or quadrature amplitude modulation.

[0012] Furthermore, in step S3, the cooperative noise carrier and the information carrier have the same frequency, and the amplitude and phase of the cooperative noise carrier remain constant within a preset coding period and change within different coding periods.

[0013] Furthermore, the amplitude of the cooperative noise carrier is selected within a preset range, so that different modulation symbols form an overlapping region in the signal decision space of the non-cooperative node after being superimposed with the cooperative noise carrier.

[0014] In a second aspect, the present invention also provides a power electronic communication system, comprising: a source converter, a sink converter, and a power transmission line electrically connecting the source converter and the sink converter; wherein the source converter and the sink converter are configured to perform the secure communication method described above.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention achieves enhanced security for communication signals at the physical layer of power transmission lines. It creates a physical masking effect through the superposition mechanism of information carrier and cooperative noise carrier, achieving enhanced communication security without the need for additional independent communication lines or dedicated encryption hardware. 2. Other converters or external monitoring devices that do not participate in the coordination mechanism can only observe the superimposed mixed signal, making it difficult to obtain the coordination noise parameters and their transmission characteristics, thus making it difficult to reliably recover the original information carrier and improve the system's anti-eavesdropping capability; 3. This invention is applicable to power electronic systems where the source converter and sink converter are electrically connected to the same power transmission line. It is compatible with multi-converter parallel systems, cascaded converter systems, or point-to-point structures. It achieves physical layer security enhancement without changing the original power transmission architecture, and has good engineering feasibility and application value. Attached Figure Description

[0016] Figure 1 A schematic diagram illustrating the information modulation principle of the source converter and the sink converter; Figure 2 A schematic diagram of a cooperative noise-masked secure communication system based on converter ripple communication; Figure 3 This is a schematic diagram of a cooperative noise-masking secure communication process based on converter ripple communication. Figure 4 This is a schematic diagram of the noise estimation and cancellation processing structure of the sink converter; Figure 5 A schematic diagram illustrating the superposition of an information carrier and a cooperative noise carrier to form a mixed signal; Figure 6 A schematic diagram of the modulation symbol decision space under the influence of cooperative noise; Figure 7 The figure shows the experimental results of the modulation symbol decision space of different nodes under the influence of cooperative noise. Figure 7 (a) Modulation symbol decision space diagram obtained after noise estimation and cancellation processing of the sink converter; Figure 7 (b) is the modulation symbol decision space diagram obtained by other converters that do not participate in the coordination mechanism directly demodulating the mixed signal on the power transmission line. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0019] In a first aspect, the present invention proposes a cooperative noise masking secure communication method based on converter ripple communication. The above method is applied to a power electronic system including at least two power electronic converters and power transmission lines connecting the converters. During the communication process, the converter that performs the information sending function is the source converter, and the converter that performs the information receiving function is the sink converter.

[0020] The information modulation principles of the source converter and the sink converter are as follows: Figure 1 As shown, when the converter does not transmit baseband data, it only compares the power reference output from the control loop with the carrier signal to generate a pulse width modulation (PWM) signal. When the converter needs to transmit baseband data, it first modulates the baseband data to be transmitted through a modulator, then superimposes the modulated signal onto the original power reference, and finally compares the superimposed modulated power reference with the carrier signal to generate a PWM signal carrying data information, thereby forming corresponding voltage and / or current ripple in the connected power transmission line. In this invention, the voltage and / or current ripple generated by the source converter through the aforementioned information modulation principle is defined as the information carrier, and correspondingly, the voltage and / or current ripple generated by the sink converter through the aforementioned information modulation principle is defined as the cooperative noise carrier.

[0021] The specific communication system structure is as follows: Figure 2 As shown, in this embodiment, a DC microgrid system is used as an example for explanation. The output terminals of the source converters share a DC bus and communicate at the output terminals; the input terminals of the load converters share a DC bus and communicate at the input terminals; the DC bus serves as the power transmission line connecting each converter. The information carrier generated by the source converter and the cooperative noise carrier generated by the sink converter both propagate through the power transmission line and are superimposed on the line to form a hybrid carrier.

[0022] The secure communication method described in this invention employs a time-division communication structure, such as... Figure 3 As shown, a complete communication cycle includes the address confirmation phase, the filter training phase, and the data transmission phase, executed sequentially, as follows: S1: Address Confirmation Phase The source converter transmits address identification information on the power transmission line through the information modulation principle. The address identification information propagates along the power transmission line with the power flow. Other converters connected to the power transmission line perform address matching based on the received address identification information. The converter that matches the address identification information is determined as the destination converter for this communication.

[0023] S2: Filtering Training Phase After the sink converter is determined in the address confirmation phase, the filter training phase begins. During this phase, the source converter remains silent; simultaneously, the sink converter behaves as follows: Figure 4 As shown, the sink converter injects a cooperative noise signal into the control loop using the information modulation principle, and also injects a cooperative noise carrier into the same power transmission line. Simultaneously, the sink converter samples the cooperative noise carrier in the power transmission line, and inputs the sampling result of the cooperative noise carrier and the cooperative noise signal together into an adaptive algorithm (e.g., LMS algorithm or RLS algorithm) to estimate the transmission characteristics from the cooperative noise signal injection point to the sampling point of the power transmission line, thus obtaining a noise transmission characteristic estimation model for subsequent noise cancellation.

[0024] S3: Data Transmission Phase After completing the filtering training, the data transmission phase begins. In this phase, the source converter and sink converter enter a bidirectional cooperative mode: the source converter injects an information carrier carrying the data to be transmitted into the power transmission line using the aforementioned information modulation principle; simultaneously, the sink converter maintains strict time synchronization and also injects a cooperative noise carrier into the same circuit transmission line using the same information modulation principle. The information carrier and the cooperative noise carrier superimpose on the power transmission line, and the principle of superposition is as follows... Figure 5 As shown, a hybrid carrier is formed: Let the information carrier be The cooperative noise carrier is Then the hybrid carrier on the power transmission line It can be represented as: Among them, the information carrier transmitted by the source converter The signal is a periodic signal with a fixed frequency, whose amplitude and / or phase change with the data to be transmitted. Specific digital modulation methods can include Differential Phase Shift Keying (DPSK), Amplitude Shift Keying (ASK), or Quadrature Amplitude Modulation (QAM). The cooperative noise carrier transmitted by the sink converter has the same frequency as the information carrier, but its amplitude and phase remain constant within a preset coding period, changing between different coding periods. By reasonably setting the amplitude range of the cooperative noise carrier, it is possible to ensure that different modulation symbols, after being superimposed on the cooperative noise carrier, generate overlapping regions in the signal decision space of non-cooperative nodes. This physical layer aliasing effect fundamentally destroys the characteristic structure of the signal, thereby greatly increasing the demodulation difficulty for unauthorized nodes.

[0025] The sink converter invokes the noise transmission characteristic estimation model built during the filtering training phase. During the data transmission phase, it performs cooperative noise carrier component estimation and cancellation on the hybrid carrier. Its noise cancellation processing structure is as follows: Figure 4 As shown in the structure outlined in the data transmission stage, since the cooperative noise signal is injected by the sink converter itself, the injected cooperative noise signal is a known signal. It is possible to estimate the cooperative noise carrier component in the received mixed carrier based on the cooperative noise signal, and eliminate the estimated cooperative noise carrier component from the mixed carrier, thereby recovering the original information carrier.

[0026] Specifically, let the estimated cooperative noise carrier component be... The recovered information carrier It can be represented as: When the estimated cooperative noise carrier component With actual cooperative noise carrier When they are close to or equal, we can obtain: This allows for the correct recovery of the original information carrier. Subsequently, by demodulating the recovered information carrier using a demodulator, the data transmitted by the source converter can be obtained.

[0027] After completing the above data transmission and signal recovery process, the masking mechanism of the cooperative noise carrier introduced in this invention on the information carrier is as follows: The spatial distribution of modulation symbol decision under the influence of cooperative noise in this invention is as follows: Figure 6 As shown. In conventional communication without added cooperative noise, different modulation symbols typically have clear distribution areas in the signal decision space, with obvious decision boundaries between each symbol, which can be reliably distinguished by the receiver.

[0028] When a cooperative noise carrier is superimposed on an information carrier, the position of the original modulation symbol in the decision space will shift with the amplitude and phase of the cooperative noise. By reasonably setting the amplitude range of the cooperative noise carrier, different modulation symbols can overlap in the signal decision space of non-cooperative nodes after being superimposed with the cooperative noise carrier. This makes it difficult for converters or external monitoring devices that do not participate in the cooperative mechanism to make a unique decision on the modulation symbol.

[0029] In contrast, the sink converter, due to the known injected cooperative noise signal and its transmission characteristics, can effectively estimate and eliminate the cooperative noise carrier component in the mixed signal, thereby recovering the original information carrier and achieving correct demodulation.

[0030] Therefore, this invention introduces a cooperative noise carrier into the physical layer of the power transmission line, thereby achieving physical layer masking of the communication signal without changing the original communication link structure. This creates an overlapping area in the signal decision space of non-cooperative nodes, resulting in an information asymmetry between the legitimate receiver and the unauthorized eavesdropping node that is "recoverable" and "undecidable," thus significantly improving the system's anti-eavesdropping capability and communication security.

[0031] Secondly, the present invention also provides a power electronic communication system, including a source converter, a sink converter, and a power transmission line for electrically connecting the source converter and the sink converter, the system being configured to perform the above-described secure communication method; the power electronic system includes, but is not limited to, a DC microgrid system, a distributed power supply system, an energy storage system, and an electric vehicle charging system.

[0032] Example: The following is a specific example of the implementation of the secure communication method according to the present invention. The experimental system structure is as follows: Figure 1 As shown, the system has 2 source converters and 2 load converters. The source converters all adopt a bidirectional BOOST circuit topology, and the load converters all adopt a bidirectional BUCK circuit topology. The main circuit parameters are shown in Table 1. Table 1 Main Circuit Parameters Source converter 1 serves as the source converter, and load converter 1 serves as the sink converter. Both are experimentally verified according to the communication process described above. The remaining converters serve as non-cooperative nodes. The source converter transmits communication data using 4DPSK modulation, and the sink converter synchronously injects a cooperative noise carrier with the same frequency as the information carrier.

[0033] Under the secure communication method proposed in this invention, the experimental results of the modulation symbol decision space of different nodes are as follows: Figure 7 As shown, where Figure 7(a) shows the decision space distribution of modulation symbols obtained by the sink converter after noise estimation and cancellation. It can be observed that each modulation symbol still maintains a clear decision region. Figure 7 (b) is the decision space distribution obtained by other nodes that do not participate in the coordination mechanism directly demodulating the power transmission line signal. Due to the superposition of coordination noise, the modulation symbols overlap significantly in the decision space, making it difficult to make a correct decision.

[0034] Experimental results show that this invention effectively masks the information carrier by introducing a cooperative noise carrier at the physical layer of the power transmission line, making it difficult for unauthorized nodes to reliably demodulate without prior noise information and its transmission characteristics. Simultaneously, the sink converter, relying on its self-constructed noise transmission characteristic estimation model, can effectively eliminate noise components in the mixed carrier, thus ensuring the data recoverability of legitimate communication links. Furthermore, this invention constructs a superposition mechanism of information carrier and cooperative noise carrier on the power transmission line electrically connected to the source and sink converters, creating a mixed masking effect on the power transmission line. This makes it difficult for other converters or external eavesdropping devices not participating in the cooperative mechanism to make a unique decision on the mixed signal. Without increasing computational complexity, additional communication links, or encryption hardware, it improves the system's anti-eavesdropping capability and communication security, achieving physical layer security enhancement of communication signals in power electronic systems. It balances communication concealment with system implementation complexity, possessing good engineering application value and providing a new physical layer secure communication implementation method for power electronic systems.

[0035] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to the above embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A cooperative noise-masking secure communication method based on converter ripple communication, characterized in that, Includes the following steps: S1 Address Confirmation Stage: The source converter sends address identification information on the power transmission line through the information modulation principle. Other converters connected to the power transmission line perform address matching according to the address identification information. The converter that matches the address identification information is the destination converter for this communication. S2 filter training phase: The source converter remains silent, while the sink converter injects a cooperative noise signal into the control loop through information modulation principle and injects a cooperative noise carrier into the same power transmission line; at the same time, the cooperative noise carrier is sampled, and then the sink converter inputs the sampling result of the cooperative noise carrier and the cooperative noise signal into the adaptive algorithm to estimate the transmission characteristics from the cooperative noise signal injection end to the sampling end of the power transmission line, thereby obtaining the noise transmission characteristic estimation model; S3 Data Transmission Stage: The source converter injects an information carrier carrying the data to be transmitted, and the sink converter synchronously injects a cooperative noise carrier. The information carrier and the cooperative noise carrier are superimposed on the power transmission line to form a mixed carrier. The sink converter uses the noise transmission characteristic estimation model to estimate the cooperative noise carrier component and eliminate it from the mixed carrier, thereby obtaining the recovered information carrier. Demodulation of the recovered information carrier yields the data transmitted by the source converter. Specifically, the information modulation principle is as follows: when the converter does not send baseband data, it only uses the power reference output by the control loop to compare with the carrier signal to generate a pulse width modulation signal; when the converter needs to send baseband data, it first modulates the baseband data to be sent through the modulator, then superimposes the modulated signal onto the original power reference, and finally compares the superimposed modulated power reference with the carrier signal to generate a PWM signal carrying data information, thereby forming corresponding voltage and / or current ripple in the connected power transmission line; The source converter is specifically a converter that performs the function of transmitting information, and the sink converter is specifically a converter that performs the function of receiving information. The information carrier is the voltage and / or current ripple generated by the source converter through the information modulation principle, and the cooperative noise carrier is the voltage and / or current ripple generated by the sink converter through the information modulation principle.

2. The secure communication method according to claim 1, characterized in that, In step S2, the adaptive algorithm includes the LMS algorithm or the RLS algorithm.

3. The secure communication method according to claim 1, characterized in that, In step S3, the information carrier is a periodic signal with a fixed frequency, whose amplitude and / or phase change with the data to be transmitted, and adopts a data modulation method of differential phase shift keying, amplitude shift keying, or quadrature amplitude modulation.

4. The secure communication method according to claim 1, characterized in that, In step S3, the cooperative noise carrier and the information carrier have the same frequency. The amplitude and phase of the cooperative noise carrier remain constant within a preset coding period and change within different coding periods.

5. The secure communication method according to claim 4, characterized in that, The amplitude of the cooperative noise carrier is selected within a preset range, so that different modulation symbols form an overlapping region in the signal decision space of the non-cooperative node after being superimposed on the cooperative noise carrier.

6. A power electronic communication system, characterized in that, include: A source converter, a sink converter, and a power transmission line electrically connecting the source converter and the sink converter; wherein the source converter and the sink converter are configured to perform the secure communication method according to any one of claims 1 to 5.

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