A synchronous ring network system for grid-type energy storage converters

Abstract

This application provides a synchronous ring network system for grid-type energy storage converters, specifically relating to the field of power electronic system control and communication network synchronization technology. The system includes: multiple energy storage converters, each equipped with a synchronous ring network controller. These controllers are connected end-to-end via communication interfaces to form a ring communication network. Two energy storage converters serve as master control devices. Each master control device's controller generates a single second pulse synchronization signal, and both signals are transmitted simultaneously in the ring network. Each master control device's controller is configured to receive and compare the two second pulse signals in real time via the ring network. When the deviation exceeds a preset threshold, the timing of subsequent signal transmissions is adjusted to correct the deviation. This application, while ensuring high reliability of the ring synchronization network, fully leverages the parallel potential of the dual-master redundant architecture in high-precision clock synchronization scenarios at the physical layer, ensuring seamless redundancy of the synchronization reference and the unified maintenance of dynamic high precision.

Description

Technical Field

[0001] This application relates to the field of power electronic system control and communication network synchronization technology, and in particular to a synchronous ring network system for a grid-type energy storage converter. Background Technology

[0002] The application of energy storage technology plays a crucial role in solving large-scale power storage and dispatch, significantly contributing to the stability and flexibility of the power system. With the continuous increase in the scale of wind and solar power generation, the power system faces substantial fluctuations. Energy storage technology balances supply and demand on the generation, grid, and user sides, greatly improving the reliability of wind and solar power generation. Its application scenarios can be categorized into generation-side energy storage, transmission-side energy storage, and user-side energy storage. In generation-side energy storage, its main applications are secondary frequency regulation and renewable energy storage. In transmission-side energy storage, it primarily alleviates transmission and distribution congestion, delays the expansion of distribution equipment, power supply, peak shaving, and primary frequency regulation. On the user side, it is mainly used for peak shaving, capacity cost management, improving power quality, and enhancing power supply reliability. In practical applications, how to more efficiently utilize energy storage, and the optimization of large-scale energy storage layout and settings, are key to project design and better operation. In the ever-developing energy storage power stations, the characteristics of large single-unit capacity, high energy conversion efficiency, high safety, simple system coordination and control, and strong grid support provide important guarantees for the safe and stable operation of the power system.

[0003] Existing power conversion system (PCS) ring synchronization networks typically employ a single clock source architecture where a single master control device generates the synchronization signal, and the remaining devices act as slave devices for synchronization. The drawback of this architecture is that when the master control device fails or the link is disconnected, the entire ring network loses its synchronization reference, causing the system to malfunction.

[0004] In the general reliability design of industrial control systems, redundant architectures with dual master control devices serving as hot backups for each other have been explored. However, such dual-master redundancy schemes are mostly applied to system-level power scheduling or energy management layers, and the technical problem they address is the reliability at the control decision level, rather than the high-precision clock synchronization problem at the physical or data link layers.

[0005] To improve system reliability, a dual-master redundancy architecture is introduced into the energy storage converter ring network synchronization scenario, i.e., setting up two master control devices as backups for each other. This will inevitably introduce the following technical challenges: In the specific scenario of a ring synchronization network, if both master control devices are in operation and each independently generates a second pulse synchronization signal for transmission in the ring network, a dual time reference conflict will occur—two synchronization signals with time deviations are received simultaneously from the node, making it impossible to determine which one to use as the reference for clock calibration; the bidirectional transmission of the two signals in the ring network may also cause mutual interference, which will lead to a deterioration in synchronization accuracy.

[0006] The core idea behind existing technologies for resolving dual time base conflicts is usually to select a single valid source from among redundant clock sources. This avoidance-based approach fails to fully realize the parallel synchronization potential of dual-master redundant architectures in energy storage converter ring network synchronization scenarios, especially hindering the effective coordination of dual synchronization signals and limiting the improvement of system reliability. Summary of the Invention

[0007] To address at least one drawback of the prior art, this application provides a synchronous ring network system for a grid-type energy storage converter, comprising: Multiple energy storage converters, each equipped with a synchronous ring network controller, are connected end to end in sequence through a communication interface to form a ring communication network; Two of the multiple energy storage converters operate as main control devices in the ring communication network; the synchronous ring network controllers of the two main control devices each generate a second pulse synchronization signal, and the two second pulse synchronization signals are transmitted simultaneously in the ring communication network. Each of the master control devices is configured to receive and compare the two second pulse synchronization signals in real time through the ring communication network. When the deviation between the two second pulse synchronization signals exceeds a preset threshold, the transmission time of the subsequent second pulse synchronization signal is adjusted to correct the deviation.

[0008] Optionally, adjusting the transmission time of the subsequent second pulse synchronization signal includes: The second pulse synchronization signal generated by the synchronous ring network controller of another master control device is used as the reference signal, and the second pulse synchronization signal generated at this end is used as the feedback signal. Measure the phase difference between the feedback signal and the reference signal; Based on the phase difference, the transmission phase of the subsequent second pulse synchronization signal at this end is adjusted so that the phase difference converges towards a preset target value.

[0009] Optionally, the synchronous ring network controller of each of the energy storage converters is configured to divide the second pulse synchronization signal, control command and status data to be transmitted in the ring communication network into fixed-length data units, and encapsulate the fixed-length data units in the same slice period into a composite data frame, and transmit the composite data frame serially through the ring communication network in units of the fixed-length data units.

[0010] Optionally, the synchronization ring network controller is further configured to assign a transmission priority to the data unit representing the second pulse synchronization signal, which is higher than that of the data unit representing the control command and higher than that of the data unit representing the status data.

[0011] Optionally, the synchronization ring network controller is further configured to: when there is a target data unit representing the second pulse synchronization signal to be transmitted, if there is a data unit currently being transmitted, terminate the transmission of the current data unit, replace the target data unit with the current transmission position for transmission, and resume the transmission of the terminated data unit from the terminated position after the target data unit has been transmitted.

[0012] Optionally, the synchronous ring network controller includes: The line encoding / decoding module is used to perform line encoding on the fixed-length data unit to be transmitted, and generate encoded data units; A forward error correction module is used to add a forward error correction check code to the encoded data unit so that the downstream synchronous ring network controller receiving the encoded data unit can correct the bit errors generated during transmission based on the forward error correction check code. The automatic retransmission request module is used to receive a retransmission request from the downstream synchronous ring network controller when the downstream synchronous ring network controller detects a bit error that cannot be completely corrected, and to retransmit the corresponding fixed-length data unit according to the retransmission request.

[0013] Optionally, the synchronous ring network controller is further configured to generate two identical copies of the same fixed-length data unit and transmit the two copies in two directions of the ring communication network respectively; after receiving the first arriving copy, the synchronous ring network controller at the receiving end discards the subsequent arriving duplicate copies.

[0014] Optionally, the synchronous ring network controller of each of the energy storage converters includes an analog signal acquisition interface and a digital signal acquisition interface; The analog signal acquisition interface is used to receive analog electrical signals from the main circuit of the energy storage converter or external sensors; the analog electrical signals represent the operating parameters of the energy storage converter. The switch quantity acquisition interface is used to receive switch status signals from the main circuit of the energy storage converter or external devices. The synchronous ring network controller, triggered by the second pulse synchronization signal, synchronously acquires the analog electrical signal and the switch status signal through the analog quantity acquisition interface and the switch quantity acquisition interface, and associates and stores the acquired analog electrical signal, the switch status signal and the corresponding timestamp information.

[0015] Optionally, the analog signal acquisition interface includes multiple analog signal input channels, and the digital signal acquisition interface includes multiple digital signal input channels; The synchronous ring network controller is configured to synchronously acquire analog data at a preset sampling rate through the multiple analog input channels; and synchronously record the status of digital signals at a preset time resolution through the multiple digital input channels.

[0016] Optionally, when the synchronous ring network controller detects a fault event, it reads analog data and switch status within a preset time period before and after the fault event based on the timestamp information, and generates a fault recording file.

[0017] Optionally, each of the energy storage converters' synchronous ring network controllers is configured to: when a communication interruption is detected in a neighboring synchronous ring network controller on one side, generate fault data information, the fault data information including the node information of the synchronous ring network controller itself, the communication interface identifier of the detected communication interruption, and the fault type, the fault type including link disconnection or the neighboring synchronous ring network controller exiting; and forward the fault data information to the main control device through the neighboring synchronous ring network controller on the other side. The master control device is configured to send a forwarding path update instruction to each synchronous ring network controller in the ring communication network after receiving the fault data information. The forwarding path update instruction is used to instruct each synchronous ring network controller to change the data unit originally sent from the side of the communication interruption to be sent to the other side.

[0018] By adopting the above technical solution, this application has the following beneficial effects: This application provides a synchronous ring network system for a grid-type energy storage converter. The synchronous ring network controllers configured in each energy storage converter are connected end-to-end via communication interfaces to form a closed-loop topology. Two master control devices operate in parallel and each independently generates a second pulse synchronization signal, ensuring that two synchronization references originating from different physical nodes exist simultaneously in the ring network. This allows the remaining path and the other master control signal to maintain the continuity of the synchronization reference even in the event of a single-point failure in the link or master control device, eliminating the inherent vulnerability of a single-clock-source architecture. Addressing the time deviation and potential conflicts inevitably caused by clock source differences and asymmetrical transmission paths in the dual-path second pulses, each master control device's synchronous ring network controller is endowed with active monitoring and adaptive adjustment capabilities. Each master control controller receives the two second pulse signals transmitted in the ring network in real time and compares the deviations. When a deviation exceeds a preset threshold, it actively corrects the deviation by dynamically adjusting the transmission time of subsequent second pulses, ensuring that the two signals tend to align during continuous operation. While maintaining the parallel redundancy capability of the dual-master control system, the two time bases are transformed from sources of conflict into a reference pair for mutual verification and dynamic calibration. This completely eliminates the problem of slave nodes being unable to determine the synchronization base due to deviations between the two signals. While maintaining the reliability of the dual-master control redundancy, the two signals are gradually aligned during continuous operation. Therefore, this application, while ensuring the high reliability of the ring synchronization network, fully leverages the parallel potential of the dual-master control redundancy architecture in high-precision clock synchronization scenarios at the physical layer, ensuring the unity of seamless redundancy and dynamic high-precision maintenance of the synchronization base.

[0019] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. The same reference numerals usually represent the same components. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a structural block diagram of the synchronous ring network system of the grid-type energy storage converter provided in the embodiments of this application; Figure 2 This is a block diagram of the interface architecture of the synchronous ring network controller provided in the embodiments of this application; Figure 3 This is a block diagram of the PCS synchronous ring network master / slave control architecture provided in the embodiments of this application; Figure 4 This is a schematic diagram of the PCS synchronous ring network topology provided in the embodiments of this application; Figure 5This is a schematic diagram of the PCS synchronous ring network composite data frame slice transmission mechanism provided in the embodiments of this application; Figure 6 This is a flowchart illustrating the dual-master phase synchronization method provided in an embodiment of this application; Figure 7 This is an overview diagram of the multi-machine synchronous ring network hierarchical communication network application of the energy storage system provided in the embodiments of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. In the description of this application, it should be understood that the terms "upper," "lower," "top," "bottom," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0024] In the field of power electronics, grid-connected and grid-following converters represent two distinct control strategies. Grid-following converters use the phase and frequency of the external grid voltage as an absolute reference, passively following the grid connection via a phase-locked loop (PLL). Their output characteristics resemble a controlled current source. The synchronization accuracy and system stability of multiple converters in parallel primarily rely on the grid as a unified external reference, rather than on a clock consensus established autonomously between the converters. Therefore, grid-following converters do not have a strong inherent requirement for microsecond-level precise time synchronization between nodes. Even without global high-precision synchronization, each converter can still operate independently following the grid, typically preventing catastrophic failures characteristic of grid-connected systems, such as voltage collapse or autonomous grid disintegration. In contrast, grid-connected converters, operating in parallel, need to autonomously establish and maintain voltage and frequency stability. This necessitates extremely high-precision phase synchronization and clock alignment between multiple converters in parallel operation. Any minute synchronization deviation can lead to system instability, increased circulating current, or even equipment damage.

[0025] To improve system reliability, a dual-master redundancy architecture is introduced into the ring network synchronization scenario of a network-type energy storage converter. This involves setting up two master control devices as backups for each other. However, this inevitably introduces the following technical challenges: In this specific scenario of a ring synchronization network, if both master control devices are in operation and each independently generates a second pulse synchronization signal for transmission in the ring network, a dual time reference conflict will occur. The node will simultaneously receive two synchronization signals with time deviations, making it impossible to determine which one to use as the reference for clock calibration. Furthermore, the bidirectional transmission of the two signals within the ring network may also cause mutual interference, leading to a deterioration in synchronization accuracy.

[0026] The core approach of existing technologies to resolve dual time base conflicts typically involves selecting a single valid source from among redundant clock sources. This workaround approach fails to fully realize the parallel synchronization potential of a dual-master redundant architecture in a storage converter ring network synchronization scenario. Specifically, if this workaround is applied to a ring network synchronization scenario for a storage converter with a dual-master redundant architecture, it manifests as follows: during normal ring network operation, the system, through an election mechanism or priority setting, allows only one master control device to send a second pulse synchronization signal. The other master control device, although in hot standby mode, has its second pulse transmission function suppressed and only passively monitors the ring network status. The drawback of this solution is the lack of a continuous and direct phase calibration mechanism between the local clock of the hot standby master control device and the local clock of the active master control device. When the active master control device fails, the hot standby master control device needs to detect the fault first and then start its second pulse transmission function. There is an unpredictable jump between the second pulse phase at the moment of takeover and the second pulse phase of the active master control before the fault. This jump will cause each slave node in the ring network to experience a synchronization loss and relock process, affecting the continuity of the PWM (Pulse Width Modulation) carrier synchronization of the energy storage converter, and may even trigger a power quality event.

[0027] Furthermore, in the field of clock synchronization in distributed systems, besides master-slave synchronization schemes based on a single master clock, there exists a class of distributed synchronization schemes that do not rely on a fixed master clock. Examples include synchronization methods based on the convergence of node time averages, synchronization methods based on distributed consensus algorithms, and dynamic master-slave switching methods based on the election of the optimal master clock. The core of these schemes lies in generating a logically unified time base through a certain algorithm or rule, to which each node calibrates. However, in the ring network synchronization scenario of grid-type energy storage converters, the above scheme has the following limitations: the calculation process of the logical reference introduces an uncertain algorithm convergence time, which causes the synchronization reference itself to jitter, making it difficult to meet the microsecond or even nanosecond level synchronization accuracy requirements of grid-type energy storage converters; the logical reference relies on the collaborative calculation of multiple nodes, and when the ring network topology changes (such as the addition or removal of nodes, link failure), re-convergence is required, and the synchronization accuracy cannot be guaranteed during this period; in the dual master redundancy architecture, if the above scheme is adopted, the hot standby master controller only acts as a slave node to calibrate the logical reference during normal operation. When the active master controller fails and the hot standby master controller takes over, the mode conversion from "receiving calibration" to "sending reference" will introduce a phase jump, making it impossible to achieve true zero-latency seamless switching.

[0028] In view of this, this application provides a synchronous ring network system for a grid-type energy storage converter. Please refer to [link to relevant documentation]. Figure 1 The system includes: Multiple energy storage converters are used, each equipped with a synchronous ring network controller. The synchronous ring network controllers are connected end to end in sequence through communication interfaces to form a ring communication network.

[0029] Among them, the energy storage converter is a grid-type energy storage converter. A grid-type energy storage converter refers to a power electronic device that can actively establish and maintain the amplitude, frequency and phase of AC voltage. It has extremely high requirements for the clock synchronization accuracy of multiple machines connected in parallel.

[0030] Among them, the synchronous ring network controller is not only a communication interface, but also integrates the functions of generating, comparing, adjusting and transmitting and receiving synchronous signals. Its core can be implemented by programmable logic devices such as FPGA (Field Programmable Gate Array) to ensure the real-time and deterministic nature of the processing.

[0031] Among them, the ring communication network is the multi-machine synchronous ring network of energy storage converters. It uses a dedicated hardware communication channel to realize the superposition, transmission and distribution of control commands and 1PPS high-precision clock signals, compressing the internal command synchronization delay of multi-machine parallel connection from millisecond level to microsecond level (≤10μs), while ensuring that the time deviation of the synchronization signal does not exceed 1μs, meeting the requirements of grid-type energy storage converter clusters for high-reliability communication, accurate synchronization and intelligent operation and maintenance.

[0032] In its specific implementation, the physical layer is built on a 500Mbps LVDS or 1.25Gbps network, providing ample bandwidth of 0.5~1.25Gbps to carry high-precision clock signals, control commands, and status data. The ring network supports dual-medium transmission via fiber optic and twisted-pair cables to adapt to different scenarios. Each energy storage converter's main control board provides two communication interfaces for the synchronous ring network controller, interconnecting with adjacent devices to form a ring network. The network has redundant transmission capabilities; data can be transmitted bidirectionally within the ring. Communication and synchronization functions are unaffected by a single point of failure in any physical link, and the one-way transmission delay between adjacent devices via the ring network is ≤1μs. The synchronous ring network is compatible with mainstream communication protocols such as IEC-61850, Modbus, and IEC-60870-5-104, achieving standardized interconnection with the station control layer and protection equipment. It also supports independent operation of the data network and control network (primary and backup), ensuring long-term system stability. The system supports online firmware upgrades and reserves upgrade and debugging interfaces, allowing users to view debugging data, perform fault analysis, and export waveform files online. In debugging mode, it can also conduct data simulations, simulating various operating conditions under safe operation. Furthermore, both hardware and software retain upgrade interfaces, enabling seamless optimization and expansion without altering the existing model. This makes the system architecture forward-looking and open, providing feasibility for smooth future expansion and the integration of new technologies.

[0033] In the large-scale application of energy storage, with the increasing proportion of wind and solar power generation, power system fluctuations are intensifying. Energy storage technology significantly improves the reliability of renewable energy through its balancing effect on the generation, transmission, and user sides: generation-side energy storage is mainly used for secondary frequency regulation and renewable energy grid connection; transmission-side energy storage is used to alleviate transmission congestion, delay the expansion of distribution equipment, and primary frequency regulation; and user-side energy storage is used for peak shaving, capacity cost management, improving power quality, and power supply reliability. Large-scale energy storage power stations require large single-unit capacity, high efficiency, good safety, simple coordination, and strong grid support capabilities. However, existing large-scale power stations typically use a "daisy-chain" bus connection method to connect various energy storage converters. The information transmission between each unit is limited, the delay is long, and expansion is restricted. The more parallel units, the slower the system response. When AC is connected in parallel, voltage, frequency, and phase deviations due to communication time differences can easily generate circulating currents that damage equipment. At the same time, fault location is difficult, and each unit needs to communicate with the dispatch center separately, consuming resources. The use of multi-machine synchronous ring network technology can effectively avoid the above problems: relying on dedicated hardware channels to complete the integrated transmission of instructions, key data and synchronization signals, the redundant bidirectional ring network architecture allows the system to continue operating even when a single converter fails or a line is damaged. On-site personnel only need to take the faulty equipment out of maintenance, making fault diagnosis more intuitive and faster. This ensures the safe and efficient operation of large-scale energy storage power stations and facilitates the smooth expansion of system capacity to meet the needs of large-scale energy storage projects.

[0034] like Figure 2 As shown, the synchronous ring network controller includes: The line encoding / decoding module is used to encode the fixed-length data units to be transmitted, generating encoded data units. The line encoding / decoding module, such as 8b / 10b encoding, not only achieves DC balance for clock recovery but also provides a foundation for physical layer error detection.

[0035] The forward error correction (FEC) module adds forward error correction (FEC) codes to the encoded data units, enabling the downstream synchronization ring controller receiving the encoded data units to correct errors generated during transmission based on the FEC codes. By adding redundant error correction codes at the transmitting end, the FEC module allows the receiving end to automatically correct transmission errors within a certain range, avoiding the latency overhead of retransmissions. This is crucial for maintaining the real-time performance of the synchronization signal.

[0036] The Automatic Repeat Request (ARQ) module is used to receive retransmission requests from downstream synchronous ring network controllers when the downstream controller detects uncorrectable bit errors, and retransmits the corresponding fixed-length data units according to the retransmission request. The ARQ module supplements FEC (Fault Error Correction) by initiating a feedback retransmission mechanism to ensure absolute data accuracy when bit errors exceed FEC's error correction capabilities.

[0037] In a specific implementation, the aforementioned synchronous ring network controller is built around an FPGA. Figure 2 The high-speed data transmission architecture was demonstrated: a field-programmable gate array (FPGA) integrates three layers of functional modules, from the inside out: a Digital Signal Processor (DSP) interface, a Forward Error Correction (FEC) and Automatic Repeat Request (ARQ) module, and an 8b / 10b codec module for line encoding and decoding, corresponding to line encoding / decoding, forward error correction, and automatic repeat request functions, respectively. The DSP interface serves as the hub for interaction between the energy storage converter and the external ring network. It unifies the previously conventional external interfaces of the energy storage converter by processing data through the synchronous ring network controller before external interaction, ensuring both data interface uniformity and rapid data processing capabilities. Data undergoes error correction and retransmission control via the FEC / ARQ module, and then line encoding or decoding via the 8b / 10b codec module before bidirectional transmission through the external interface. The FPGA is externally configured with two transceivers, each corresponding to an RJ45 electrical port, enabling bidirectional transmission and reception of electrical signals. Simultaneously, the system reserves two SFP (Small Form Pluggable) optical ports, allowing direct data exchange with the FPGA-side encoding / decoding module and supporting optical signal transmission. The transceivers handle encoding and decoding, and connect to other energy storage converter PCS synchronous ring network controllers via Ethernet or fiber optic interfaces through converters, forming a ring network system. The overall architecture accommodates both electrical and optical port communication requirements, adapting to high-speed data transmission requirements in various scenarios.

[0038] Specifically, FEC ensures low latency and basic reliability of synchronization signal transmission; ARQ ensures the final correct delivery of control commands and status data. This hierarchical protection strategy avoids the unacceptable delays and jitter introduced by using a single retransmission mechanism to solve all data reliability problems, thus precisely balancing the two core contradictions in synchronization networks: real-time performance and reliability.

[0039] Specifically, in this embodiment, the line encoding / decoding module provides basic error detection capabilities; the forward error correction module provides zero-latency active error correction capabilities for all data, especially synchronization signals that cannot tolerate retransmission delays, significantly reducing their error rate; and the automatic retransmission request module provides the final zero-error guarantee for control commands and status data. Synchronization signals obtain a deterministic low-latency channel because they do not need to enter the retransmission queue, while the absolute reliability of control data is thoroughly guaranteed through the retransmission mechanism. Thus, on the same physical link, the optimal solution for real-time performance and reliability is achieved by layering different functional levels within the same architecture.

[0040] The synchronous ring network controller is also configured to generate two identical copies of the same data unit of a certain length and send the two copies in two directions along the ring communication network respectively; after receiving the first arriving copy, the synchronous ring network controller at the receiving end discards the subsequent arriving duplicate copies.

[0041] Based on this hardware redundancy mechanism of dual data transmission and selective reception, the multi-PCS synchronous ring network technology possesses redundant transmission capabilities, supporting bidirectional data transmission within the ring network. This ensures that communication and synchronization functions remain unaffected even in the event of a single point of failure in the physical link, thus meeting the requirements for stable system operation. Simultaneously, this redundancy design facilitates maintenance operations by engineers, and the system maintains normal and stable operation during these operations. In terms of performance, the one-way delay of data transmission between two adjacent energy storage converters via the ring network link does not exceed 1 μs. From a multi-level protection perspective, the link layer utilizes a forward error correction module for error-resistant protection; the network layer achieves hot backup by bidirectionally sending fixed-length data unit copies along the ring network; the transmission layer ensures final reliability through an automatic retransmission request module; and the receiving end eliminates redundancy by discarding subsequently arriving duplicate copies, thereby ensuring a high degree of data transmission accuracy.

[0042] Specifically, in this embodiment, by employing an active redundancy method that simultaneously transmits two identical data copies in both directions of the ring network under normal conditions, data can still arrive from the opposite direction even when a link failure such as a fiber optic cable break occurs at a point on the ring network. The receiving end does not need to wait for topology convergence and path recalculation; it can directly select the signal from the fault-free path, eliminating fault switching time. In a ring network, even if all link segments have the same physical length, the delay of a 1PPS signal transmitted in clockwise and counterclockwise directions reaching a node may vary due to differences in repeaters and transceivers. This mechanism ensures that a node can always receive two copies from both directions, providing the receiving end with the possibility to estimate and compensate for path asymmetry by measuring the arrival time difference between the two copies, thus helping to further improve synchronization accuracy.

[0043] Forward Error Correction (FEC) and Automatic Repeat Request (ARQ) modules constitute a hierarchical data protection system. Their division of labor and cooperation are key to achieving a balance between real-time performance and reliability. Specifically, for fixed-length data units carrying second-pulse synchronization signals, transmission is extremely sensitive to delay and jitter; therefore, only FEC is used for protection. The receiver's FEC module can correct most random errors generated during transmission in real time without requesting retransmission, thus providing a deterministic, low-error transmission channel with zero additional delay for the synchronization signal. For fixed-length data units carrying control commands or status data, the absolute integrity of the data is more critical, but they are relatively insensitive to microsecond-level delays. Therefore, while these data units benefit from the baseline protection provided by FEC, if the receiver detects uncorrectable error blocks after FEC correction, the ARQ module will immediately initiate a retransmission request to the transmitter. The transmitter's ARQ module will retrieve the corresponding data unit from a dedicated retransmission buffer and retransmit it until the receiver confirms error-free reception. This hierarchical design ensures that the latency and jitter of the synchronization signal are completely unaffected by the waiting delays and transmission scheduling uncertainties that may be introduced by the ARQ retransmission mechanism. Meanwhile, the absolute correctness of control and status data is fully guaranteed by the ARQ mechanism, achieving differentiated service quality satisfaction for different types of data within the same physical link and communication protocol framework. Furthermore, the redundant transmission mechanism, which sends copies of the same data unit bidirectionally along the ring network, further ensures that the protection functions of FEC and ARQ are unaffected in the event of a single point of failure. For example, if a link in one direction experiences a high bit error rate, causing FEC to operate continuously at full capacity for error correction, or if ARQ repeatedly requests retransmissions, the receiver can seamlessly select a valid data copy received from the other direction, ensuring the overall robustness of the system.

[0044] Each energy storage converter's synchronous ring network controller includes an analog signal acquisition interface and a digital signal acquisition interface. The analog signal acquisition interface is used to receive analog electrical signals from the main circuit of the energy storage converter or external sensors. The analog electrical signals represent the operating parameters of the energy storage converter. The digital signal acquisition interface is used to receive switch status signals from the main circuit of the energy storage converter or external devices. Under the trigger of the second pulse synchronization signal, the synchronous ring network controller synchronously acquires analog electrical signals and switch status signals through the analog signal acquisition interface and the digital signal acquisition interface, and associates and stores the acquired analog electrical signals and switch status signals with the corresponding timestamp information.

[0045] The analog signal acquisition interface serves as the physical connection channel between the synchronous ring network controller and the main circuit of the energy storage converter, as well as external sensors. It receives analog electrical signals characterizing operating parameters. Specifically, these operating parameters encompass various electrical and non-electrical physical quantities reflecting the real-time operating status and health of the energy storage converter. In practice, these operating parameters include, but are not limited to: DC-side voltage, DC-side current, AC-side phase voltage, AC-side phase current, power module temperature, internal ambient temperature, power device switching frequency, DC bus insulation resistance to ground, and cooling system flow rate or pressure. These parameters include both electrical quantities directly acquired from the main circuit and standardized electrical signals obtained from external sensors, converted by signal conditioning circuitry to conform to the input range of the analog signal acquisition interface (e.g., 0–10V or 4–20mA). The analog-to-digital converter inside the synchronous ring network controller performs synchronous sampling, holding, and conversion of each analog input channel at the arrival time of the trigger edge of the second pulse synchronization signal. This ensures that the acquisition moments of all channels are precisely aligned on the time axis, so that each frame of acquired data carries the instantaneous operating condition information of the same absolute moment, providing a multi-dimensional data foundation with time consistency for subsequent real-time control, state estimation, and fault analysis.

[0046] The switch quantity acquisition interface is used to receive discrete switch status signals, such as circuit breaker opening and closing status, contactor status, and protection action signals.

[0047] Among them, the acquisition signal triggered by the second pulse synchronization signal refers to using the globally unified time reference after high-precision synchronization through the entire ring communication network as the acquisition trigger beat.

[0048] The timestamp information is an absolute time stamp bound to each frame of acquired data, originating from a high-precision clock calibrated by dual master controllers within the system.

[0049] Specifically, by introducing a second-pulse-triggered synchronous acquisition mechanism at the synchronous ring network controller level, a globally synchronized data acquisition system is established. This ensures that each energy storage converter on the ring network initiates analog-to-digital conversion and switch quantity recording at the same absolute moment, thus naturally ensuring the time consistency of the data acquired by each device. This provides a unified time-dimensional data foundation for subsequent fault analysis and coordinated control. In multi-device systems, when transient events occur, engineers can accurately compare the current flow direction, voltage drop depth, and protection action sequence of different converters at the same microsecond moment, achieving true system-level fault playback and root cause localization.

[0050] The analog signal acquisition interface includes multiple analog signal input channels, and the digital signal acquisition interface includes multiple digital signal input channels. The synchronous ring network controller is configured to synchronously acquire analog signal data through multiple analog signal input channels at a preset sampling rate, and synchronously record digital signal status through multiple digital signal input channels at a preset time resolution.

[0051] The multiple analog input channels enable a single synchronous ring network controller to simultaneously acquire multiple analog signals in parallel. In a practical implementation, it can support up to 32 analog channels.

[0052] The preset sampling rate is the time density parameter for analog signal acquisition. For example, it is set to no less than 10kHz, which means that a synchronous acquisition of each analog signal channel is completed every 100 microseconds, which is sufficient to capture the waveform details of the fundamental wave and harmonic waves of the power grid.

[0053] Among them, multiple digital input channels enable a single synchronous ring network controller to have the ability to monitor multiple discrete signals in parallel.

[0054] The preset time resolution is the time precision of recording the switch state change, for example, it can reach the level of 1 microsecond, so that any moment of switch state change can be accurately captured and marked.

[0055] Specifically, the main circuit of an energy storage converter contains a large number of analog and switching signals that need to be monitored. If the number of acquisition channels is insufficient or the sampling rate is too low, comprehensive and detailed operating data cannot be obtained, resulting in insufficient information input for the control algorithm and difficulty in covering all key signals in fault recording. By clearly defining the configuration requirements of multiple channels and high sampling rate / high time resolution, the integrity and precision of data acquisition are ensured, providing sufficient information sources for the control system and fault analysis. Under the second pulse triggering mechanism, each controller synchronously acquires complete electrical waveforms at a high sampling rate through dozens of analog channels, while simultaneously capturing the precise moment of switching events at high time resolution. Integrating high-precision synchronous acquisition and communication functions on the same hardware platform makes each synchronous ring network controller a powerful integrated data acquisition terminal, reducing the number of system components, lowering wiring complexity, and ensuring the synchronization between multi-channel data, laying the foundation for refined control and panoramic status awareness of network-type energy storage converters.

[0056] When a fault event is detected, the synchronous ring network controller reads analog data and switch status within a preset time period before and after the fault event based on the timestamp information, and generates a fault recording file.

[0057] Among them, fault events refer to abnormal states that occur during system operation, such as overcurrent, overvoltage, short circuit, communication interruption, and protection actions.

[0058] The preset time period is the time window covered by the fault recording, such as several cycles before and after the fault triggering time (e.g., no less than 6 cycles).

[0059] Among them, the fault recording file is a data file containing all analog waveforms and switch status sequences within the time period. Its storage format facilitates on-site viewing, remote access, and analysis by third-party software.

[0060] Specifically, building upon the technology of synchronous data acquisition and timestamp-associated storage, the synchronous ring network controller is further endowed with the ability to automatically generate fault waveform files. When a fault event is detected, the synchronous ring network controller uses the fault time as an anchor point to extract data from its local storage that is precisely located by timestamps and covers the complete time period before and after the fault, packaging it into a file that can be analyzed offline. The generated fault waveform file covers complete data for at least several cycles before, during, and after the fault, and shares the same time base with the waveform files of other converters in the ring network. As a result, maintenance personnel can precisely align the waveform files of each unit on the timeline, achieving a leap from single-unit fault waveform recording to system-level panoramic fault waveform recording; it can intuitively determine the fault source, propagation path, and protection action sequence, significantly shortening fault analysis time and improving the operational reliability and maintainability of the energy storage power station.

[0061] Specifically, by unifying the trigger source for data acquisition to a highly synchronized second pulse signal, it is ensured that all converters in the entire power station acquire their analog and digital signals at the same absolute moment, and each frame of data is timestamped from the same clock reference. When a transient event (such as a short circuit or resonance) occurs, the fault recording files of each converter are not only complete in content (preset time periods before and after the fault), but more importantly, their timelines are strictly aligned. When engineers compare and analyze these recording files, it is like viewing data recorded by an oscilloscope with dozens of channels but completely synchronized in time. They can accurately reconstruct the circulating current path of the fault current, the sequence of protection actions, and other key information, making the originally difficult multi-machine collaborative fault analysis intuitive and accurate, greatly improving operation and maintenance efficiency and fault root cause analysis capabilities.

[0062] As a specific implementation, the aforementioned multi-channel synchronous acquisition capability can be further defined as follows: supporting synchronous acquisition of 32 analog channels at a sampling rate of ≥10 kHz, and supporting synchronous recording of 32 digital channels at a time resolution of ≤1 μs. When the synchronous ring network controller detects a fault event, it reads the analog data and digital status within a preset time period before and after the fault event based on the timestamp information, generating a fault waveform file. In this embodiment, each fault waveform record can cover complete data for no less than 6 cycles before and after the fault, and is stored in the device's local non-volatile memory, supporting on-site viewing, remote access, and export, thereby providing continuous and complete data support for fault analysis and troubleshooting. This synchronous acquisition and waveform recording mechanism based on second pulse synchronous triggering significantly facilitates data comparison, analysis, and simulation experiments between multiple PCS units.

[0063] Specifically, in this embodiment, the second pulse signal calibrated across the entire network is used as the trigger source, ensuring that the analog and digital input / output actions of all converters are synchronized at the same nanosecond-level absolute time point, and each frame of data is timestamped based on this unified clock. After a fault occurs, extracting the fault waveform files of any one or more devices yields a data set that is strictly aligned on the timeline, as if it originated from a precision waveform recorder with hundreds of channels. This provides maintenance personnel with information to reconstruct the fault current circulation path, the causal timing of protection actions, the resonance propagation process, and other complex transient phenomena across devices, enabling the deduction of multi-machine system faults based on accurate data, thereby quickly locating the root cause of the energy storage power station fault.

[0064] like Figure 1 , Figure 3 As shown, two of the multiple energy storage converters operate as master control devices in a ring communication network. Each of the two master control devices' synchronization ring controllers generates a 1 Pulse Per Second (1PPS) synchronization signal, which is simultaneously transmitted within the ring communication network. The 1 Pulse Per Second (1PPS) synchronization signal is a clock reference signal that generates one pulse per second, with its rising or falling edge representing a precise absolute time point.

[0065] As one specific implementation method, Figure 3The topology of a PCS synchronous ring network system with a dual-master architecture is demonstrated. PCS 1 serves as the master control device (Master 1), PCS 2 as the master control device (Master 2), and the remaining PCSs within the ring network act as slave devices. Each PCS employs a hierarchical structure, consisting of a PCS control system and a synchronous ring network system. The two systems interact bidirectionally via two links, M1 and M2. Each PCS's synchronous ring network system connects to the ring communication network via two independent second-pulse synchronization signals, M1 1PPS and M2 1PPS. Ring network data flows along the ring path, thereby achieving synchronous coordination and data exchange among multiple PCs.

[0066] In terms of system operation mechanism, the two main control devices serve as hot backups for each other, acting as decision nodes for fault information aggregation and power allocation within the ring network, and performing real-time transmission and reception monitoring. All other PCS within the ring network transmit their control commands, status commands, and network fault information to the main control devices, which then collect, package, and send them to backend systems such as remote monitoring systems or energy management systems. When a main control device fails or goes out of service, the backup main control device automatically takes over the main control functions. This dual-main redundancy architecture effectively ensures system redundancy reliability and improves overall operational stability.

[0067] In practical applications, since the two second pulse synchronization signals are transmitted simultaneously in the ring communication network, the error range and accuracy of the time difference are guaranteed to reach a one-way delay of ≤1 μs; in a typical scenario of 12 PCS networked and connected, the total end-to-end delay from the main control device issuing the command to the farthest slave device receiving it is ≤10 μs.

[0068] refer to Figure 4 The ring communication network, consisting of interconnected synchronous ring network controllers, supports bidirectional data transmission and reception, enabling efficient interaction of the second pulse synchronization signal, control commands, and data.

[0069] like Figure 5 As shown, the synchronous ring network controller of each energy storage converter is configured to divide the second pulse synchronization signal, control command and status data to be transmitted in the ring communication network into fixed-length data units, and encapsulate the fixed-length data units in the same slice period into a composite data frame, and transmit the composite data frame serially through the ring communication network in units of fixed-length data units.

[0070] Among them, the fixed-length data unit is the smallest processing unit of the communication link layer. Its length is fixed, which is conducive to the hardware to perform pipelined high-speed, low-latency processing.

[0071] The slice period is a time window during which all messages generated and ready to be sent are grouped together.

[0072] Among them, the composite data frame is a single data transmission structure formed by uniformly encapsulating different types of business data (synchronization, control, status) within the same period, realizing the converged transmission of multiple services on the same physical link.

[0073] Serial transmission refers to the sequential use of physical channels by each data unit in order to introduce a priority preemption mechanism.

[0074] Figure 5 This paper presents a specific implementation of slice transmission based on a synchronous ring network communication architecture: The synchronous ring network system integrated within a single energy storage converter encapsulates and multiplexes three types of data—second pulse synchronization signals, control commands, and status data—into a unified data stream. This stream then enables bidirectional data interaction with other PCS devices via the ring network link. Multiple PCS devices within the ring network are connected in series to form a closed ring communication topology. Each device can send and receive composite data frames that integrate second pulse synchronization signals, control commands, and status data, achieving synchronization and control communication between multiple nodes. During the encapsulation and encoding / decoding process, the synchronous ring network controller divides the second pulse synchronization signals, control commands, and status data into fixed-length data units, packages them for overall transmission and reception, and sends the processed message to the ring network or to the energy storage converter PCS main control DSP via an external interface. During transmission, the synchronous ring network controller verifies the received data in real time. If an anomaly or corruption is detected, the affected data is discarded, and the sending end is notified to retransmit, thus ensuring data reliability.

[0075] Specifically, by forcibly slicing and recombining asynchronously arriving service flows of different priorities into homogeneous fixed-length data unit sequences on the time axis, the conflict problem of mixed transmission of heterogeneous data is avoided. This allows the synchronization signal, which has the most stringent requirements for transmission delay and jitter, to obtain channel occupancy within the shortest possible time slice, avoiding being blocked by long message data. From the transmission mechanism, the jitter of the synchronization signal is suppressed, ensuring its deterministic and predictable transmission delay.

[0076] In practice, the length of a fixed-length data unit can be optimized according to the bandwidth of the physical link and the requirements of the synchronization signal period. For example, with a bandwidth of 500Mbps, if the 1PPS period is 1 second, the length of the data unit can be designed to be 64 bytes or 128 bytes to balance transmission efficiency and preemption granularity.

[0077] The synchronous ring network controller is also configured to assign a higher transmission priority to the data unit representing the second pulse synchronization signal than to the data unit representing the control command and the data unit representing the status data.

[0078] Specifically, the data unit representing the second pulse synchronization signal enjoys the highest transmission priority. From the root of the communication scheduling mechanism, it ensures that the transmission delay and jitter of clock synchronization information are not affected by the instantaneous fluctuations of any other network service load, providing deterministic quality of service guarantee for high-precision clock synchronization at the microsecond or even nanosecond level.

[0079] Specifically, the transmission order between control commands and status data can be set separately by the system according to their respective real-time requirements, or processed according to the first-in-first-out principle. This does not affect the absolute priority of the second pulse synchronization signal as the highest priority service.

[0080] Furthermore, this highest priority of the synchronization signal is exclusive and universal: if any other type of data other than control commands and status data exists during the operation of the ring network, such as firmware upgrade packages, debugging and diagnostic information, background batch configuration data, or waveform file export streams, the transmission priority of these data units is lower than that of the data units representing the second pulse synchronization signal.

[0081] The synchronization ring network controller is also configured to: when a target data unit representing a second pulse synchronization signal is to be transmitted, if a data unit is currently being transmitted, terminate the transmission of the current data unit, replace it with the target data unit at the current transmission position, and resume transmission of the terminated data unit from the terminated position after the target data unit has been transmitted. This allows synchronization signal units to interrupt the transmission of any asynchronous data at the microsecond or even nanosecond level, gaining immediate channel access rights. After transmission is complete, the terminated data unit can be accurately resumed from the termination point, ensuring the integrity of other service data. This achieves perfect coexistence of high-priority time-sensitive data and low-priority high-volume data, providing key technical support for achieving low-jitter parallel operation of dual clock sources within the ring network.

[0082] This essentially involves adding a priority insertion function to the synchronous ring network controller, implementing a dual-clock-source slice-based preemptive transmission mechanism. Specifically, the synchronous ring network system segments the second pulse synchronization signal, control commands, and status data into fixed-length data units and inserts them into the transmission channel. When important information representing the second pulse synchronization signal needs to be transmitted, even if a data stream is currently being transmitted, the target data unit can be inserted into the transmission queue at any time, completing its transmission with priority. After transmission is complete, normal data segmentation and transmission resume, thus ensuring the priority delivery of high-priority data. This mechanism enables low-jitter time synchronization of the second pulse synchronization signal, and supports parallel transmission of two second pulse synchronization signals within the ring network, further ensuring that time synchronization errors meet requirements. This dual-clock-source slice-based preemptive transmission method allows the energy storage converter synchronous ring network controller to quickly insert important information into the interactive data at any time, enabling efficient and timely communication with other synchronous ring network controllers.

[0083] Specifically, traditional priority queuing mechanisms cannot solve the uncontrollable waiting delay introduced by the channel being occupied by a long data packet when a high-priority data unit arrives. This delay is unacceptable for microsecond-level synchronization signals. In this embodiment, this problem is solved through three synergistic effects: First, various types of data are divided into uniform fixed-length units, eliminating the uncertainty in transmission time caused by differences in data packet length; second, the second pulse synchronization signal unit is given absolute transmission priority; finally, hardware-level preemption logic for termination, replacement, and recovery is introduced, allowing the second pulse signal unit to interrupt the transmission of currently asynchronous data and immediately occupy the channel at any time, and then precisely recover from the breakpoint afterwards. This compresses the transmission jitter of the synchronization signal to below the transmission time of a fixed-length data unit, ensuring a high degree of predictability of its end-to-end delay at the protocol level; at the same time, the preempted low-priority data will not be discarded or require retransmission of the entire frame due to interruption, introducing only a very small increase in transmission delay, ensuring the integrity of control and status information and throughput efficiency. On a unified physical link, deterministic low-latency transmission of time-sensitive signals and integrity assurance for high-throughput data are achieved simultaneously.

[0084] Each master control device's synchronous ring network controller is configured to receive and compare two second pulse synchronization signals in real time via a ring communication network. When the deviation between the two second pulse synchronization signals exceeds a preset threshold, the transmission time of subsequent second pulse synchronization signals is adjusted to correct the deviation. The specific value of the preset threshold depends on the system's synchronization accuracy requirements. For example, in a scenario where the phase deviation of the PWM carrier synchronization of each converter is required to be less than 1 microsecond, this threshold can be set to the tens to hundreds of nanoseconds range.

[0085] In practical implementation, this mainly involves measuring link delay and monitoring and calibrating the deviation of the two second-pulse synchronization signals. The reference nodes for both second-pulse synchronization signals are derived from the master control energy storage converter. The master control equipment, which acts as a hot backup, performs real-time calibration and deviation adjustment for the two second-pulse synchronization signals. When a time offset or synchronization error exceeds the acceptable range, the master control equipment continuously adjusts the slice transmission time of the fixed-length data unit to ensure the stability of the second-pulse reference signal. Other slave devices within the ring network receive and follow the second-pulse clock synchronization calibration provided by the master and backup units, thereby ensuring the accurate and unified clock throughout the entire ring communication network.

[0086] In a specific embodiment, each master control device's synchronous ring network controller can integrate a high-precision time-to-digital converter (TDC) and a digital phase-locked loop (DPLL) circuit. The TDC uses a local high-stability clock as a reference and compares in real-time the effective edges of the received second pulse signal generated by another master control device with the effective edges of the second pulse signal generated locally, thereby obtaining phase difference data with sub-nanosecond resolution. This phase difference data is then fed into the DPLL's loop filter to filter out high-frequency random deviations introduced by transmission jitter, physical link transient noise, etc., and extracts the slowly varying components reflecting the true frequency difference and phase offset between the two master control clock sources. The numerically controlled oscillator (NCO) module in the DPLL dynamically adjusts the count value of the next second pulse cycle at this end according to the slowly varying component. By implementing small, smooth step-phase adjustments within one or more signal cycles, the phase difference gradually converges towards the preset target value, thereby achieving precise alignment of the two parallel second pulse signals during continuous dynamic correction.

[0087] Specifically, the two master control devices perform mutual verification, dynamic calibration, and parallel collaboration. Each master control device is not only responsible for signal transmission but also for real-time monitoring of the other signal and proactive adjustment of its own signal. When the two signals deviate due to differences in crystal oscillators, asymmetrical transmission paths, or other reasons, the master control device actively eliminates the deviation by dynamically adjusting its own transmission timing. This ensures that the two clock sources approach alignment during continuous operation, thereby achieving high-precision clock synchronization while maintaining high reliability.

[0088] like Figure 6 As shown, the steps for adjusting the transmission time of the subsequent second pulse synchronization signal include: S601 uses the second pulse synchronization signal generated by the synchronous ring network controller of another master control device as the reference signal and the second pulse synchronization signal generated at this end as the feedback signal.

[0089] The reference signal specifically refers to the second pulse synchronization signal generated by the synchronization ring network controller of another master control device and received through the physical medium of the ring communication network.

[0090] The feedback signal refers to the second pulse synchronization signal generated by the local synchronous ring network controller at the current moment and about to be sent to the ring network.

[0091] In practical FPGA logic design, the output of the local second pulse generation circuit is typically used to drive the physical transceiver, while an internal loop feed is sent to a phase detector or time-to-digital converter as feedback. Meanwhile, the second pulse signal received from another master device is parsed and recovered at the physical layer and then sent to the same phase detector as a reference. This ensures that the physical path and circuit delay experienced by the reference and feedback signals when entering the measurement stage are calibrable and compensable, laying the foundation for subsequent high-precision phase difference measurements.

[0092] S603 measures the phase difference between the feedback signal and the reference signal.

[0093] The phase difference refers to the deviation of the effective edge (usually the rising edge) of the feedback signal from the reference signal on the time axis. Its unit of measurement is a time interval on the order of picoseconds or nanoseconds.

[0094] Specifically, phase difference measurement needs to be able to distinguish differences much smaller than the clock cycle. For example, inside the core chip of a synchronous ring network controller (such as an FPGA), phase interpolation technology using a dedicated high-speed serial transceiver or a dedicated carry chain delay line can be used to achieve TDC with femtosecond or even picosecond resolution, thereby accurately obtaining the tiny time difference between the edges of two asynchronous signals.

[0095] In practice, step S603 also includes a preprocessing step for the measured values. The directly measured raw phase difference may contain high-frequency jitter caused by signal transmission path asymmetry, physical link delay differences, and measurement noise. Therefore, after the measurement stage, a digital filter, such as a moving average or Kalman filter, is usually applied to preprocess the raw phase difference data to filter out high-frequency noise and extract the slowly varying component reflecting the true deviation between the two master control clock references. This filtered and shaped phase difference is the physical quantity that proceeds to step S605 for control.

[0096] S605, based on the phase difference, adjusts the transmission phase of the subsequent second pulse synchronization signal at this end so that the phase difference converges towards the preset target value.

[0097] The physical essence of adjusting the transmission phase of the subsequent second pulse synchronization signal at this end is to dynamically and minutely increase or decrease the counting period of the internal clock counter used to generate the second pulse at this end. For example, if the signal at this end lags behind the reference signal, the second-to-last counting period of the counter is temporarily shortened by a few picoseconds, causing the edge of the next pulse to arrive earlier, thereby achieving phase catching up.

[0098] The preset target value is not necessarily zero; it can also be a fixed phase offset set manually to compensate for the fixed delay introduced by the different physical location of the main control device or the difference in signal processing path.

[0099] The purpose of convergence is to avoid introducing new, drastic phase steps during the adjustment process, ensuring a smooth transition of the synchronization reference seen from the node. This convergence process is typically implemented using a proportional-integral (PI) controller. The proportional element responds quickly to the magnitude of the current phase difference, while the integral element continuously accumulates small steady-state errors and eventually eliminates them, enabling the feedback signal's phase to accurately track and lock onto the reference signal's phase minus a preset target value. By adjusting the coefficients of the PPI controller, a balance can be struck between convergence speed and stability, ensuring that even with slight frequency differences between the crystal oscillators of the two master controllers, the two second pulse signals maintain dynamic and precise phase alignment throughout their entire lifecycle.

[0100] For example, this can be implemented using digital circuitry within an FPGA. Specifically, a high-speed counter is used to count local clock cycles, and when a valid edge of the reference signal is detected, the current count value R is recorded. ref When a valid edge of the feedback signal (local loopback signal) is detected, the count value R is recorded. fb The difference between the two (R) fb - R ref This is the original phase difference. After smoothing by a digital filter (such as a proportional-integral controller), a phase adjustment step value is generated. This step value is used to dynamically increase or decrease the count value at the transmission time in the next signal cycle until the phase difference converges to a preset target value range. To avoid static errors introduced by transmission path asymmetry, a ring network path delay can be measured and calibrated during system initialization, and this fixed offset can be included in the calculation of the preset target value.

[0101] In implementation, the main control equipment can use a digital phase-locked loop (PLL) or a similar feedback control mechanism to achieve deviation correction. For example, main control equipment one uses the 1PPS signal received from main control equipment two as a reference input and the 1PPS signal generated at its own end as a feedback input, measuring the time difference between the two signals through a phase detector. This time difference, after being processed by a loop filter, is used to dynamically adjust the phase of a digitally controlled oscillator, thereby adjusting the transmission time of the next 1PPS pulse at its own end, forming a closed-loop negative feedback system that continuously converges the phase difference between the two signals towards zero (or a preset fixed compensation value).

[0102] When the controller of the local master control device executes the phase adjustment step, it essentially tracks and locks its own second pulse phase to the second pulse phase of the other master control device. Under this mechanism, the two master control devices are coupled and serve as references to each other. Because the local clocks of each master control device participate in the closed-loop tracking and calibration process throughout, the phases of each master control device remain locked with high precision in real time. If either master control device fails to operate, the synchronous ring network controller of the other master control device, whose output second pulse signal has already been precisely aligned with the peer signal at the physical layer, does not need to undergo a switch from monitoring calibration mode to autonomous transmission mode when it takes over the master control function, and will not introduce unpredictable phase steps. For each slave node on the ring network, the dual-path synchronization reference they continuously receive and lock onto remains uninterrupted or unchanged. This truly achieves zero-delay, seamless redundancy switching from the physical clock source to the system control decision level, fundamentally ensuring the continuity of pulse width modulation carrier synchronization of the energy storage converter.

[0103] Specifically, in this embodiment, each master control device uses its own output second pulse as a feedback signal and the real-time received second pulse from the other party as a dynamically changing reference input. This ensures that the phase change of the local signal is always dynamically constrained by the feedback signal, and that a single instantaneous fluctuation of the reference signal does not easily cause a jump of the same magnitude in the local signal. The phase adjustment process exhibits a gradual convergence towards a preset target value, and the synchronization reference output by the system demonstrates continuous smoothness and robustness. This provides a highly stable and abrupt global clock reference for the slave nodes within the ring network.

[0104] Each energy storage converter's synchronous ring network controller is configured to: upon detecting a communication interruption with its adjacent synchronous ring network controller on one side, generate fault data information. This fault data information includes the synchronous ring network controller's own node information, the communication interface identifier where the communication interruption was detected, and the fault type, which may include link disconnection or adjacent synchronous ring network controller exit. The fault data information is then forwarded to the master control device via its other adjacent synchronous ring network controller. Upon receiving the fault data information, the master control device is configured to send a forwarding path update command to each synchronous ring network controller within the ring communication network. This command instructs each synchronous ring network controller to redirect data units originally sent to the side experiencing the communication interruption to the other side.

[0105] Among them, the detection of communication interruption can be based on a combination of multiple criteria such as physical layer signal loss, link layer continuous verification failure, or heartbeat message timeout.

[0106] The fault data information includes three key elements: the node's own information, used to identify the source of the fault report; the communication interface identifier that detected the communication interruption, used to precisely pinpoint which port on that node the fault occurred on; and the fault type, distinguished from link disconnection and neighbor node exit by analyzing interruption characteristics (such as complete signal loss or signal quality degradation, no response from neighbors or a neighbor actively sending a termination statement). Fault data information may also include: a timestamp field recording the time of the fault occurrence, and a link quality parameter field recording the signal-to-noise ratio or bit error rate at the last moment before the fault. This provides the master control equipment with a basis for determining whether the fault is a gradual degradation.

[0107] Among them, the forwarding path update instruction is a new one-to-one or one-to-many forwarding rule actively calculated and generated by the master control device based on the network topology view and fault location results, which guides each node to switch the data unit sent to the faulty direction to the intact direction.

[0108] Specifically, fault detection capabilities are decentralized to each ring network node, with nodes on both sides of the breakpoint performing detection simultaneously and independently. The generated fault data includes node, interface, and type information, enabling the master control device to receive two complementary reports from both sides of the breakpoint. Through cross-comparison, it accurately distinguishes between a broken link and a completely lost node. When communication is interrupted on one side, the node automatically selects the adjacent node on the other side as the forwarding path, eliminating the need for pre-configured backup routes. This fully utilizes the bidirectional nature of the ring topology, ensuring that the fault report itself is unaffected by the fault and can be reliably delivered to the master control device. Upon receiving fault information, the master control device issues a forwarding path update command. During path switching, due to the bidirectional redundant transmission mechanism, the receiver can seamlessly select signals from intact paths, ensuring uninterrupted synchronization.

[0109] The aforementioned fault reporting and path update mechanism relies on the coordinated implementation of the ring network routing protocol and ring network fault detection function integrated into the synchronous ring network controller. In a specific implementation, the ring network routing protocol is primarily responsible for network topology discovery, role election, and the establishment of forwarding paths: when the ring network is established, the master control device sends a link detection packet to the next device. The link detection packet is transmitted hop-by-hop along the ring network, carrying the self-information added by each node, until it finally returns to the master control device, thus completing the ring network topology detection process. Based on this, the master control device learns the entire network topology and generates a forwarding path, which is then distributed to each synchronous ring network controller within the ring network. The ring network fault detection function is responsible for real-time monitoring of link and device faults. Each synchronous ring network controller continuously monitors the transmit and receive status of its bidirectional links and feeds back the link status to adjacent nodes in real time. Once an adjacent link is detected to be disconnected or a device exits, the synchronous ring network controller immediately generates fault data information containing its own node information, fault interface identifier, and fault type, and reports it to the master control device through the intact side link. After receiving fault data, the main control device determines the link break location based on the fault node information, dynamically recalculates the forwarding path, and sends forwarding path update commands to each synchronous ring network controller within the ring network. Each node then reverses the data units originally sent to the faulty side until the fault disappears, at which point normal ring network message transmission mode is restored. Furthermore, the ring network clock synchronization module monitors and calibrates the deviation between the two second pulse synchronization signals, together forming a complete ring network operation assurance system. When the number of fault points exceeds one unit or one node, or when both main control devices are out of operation, the fault detection module will notify each node to shut down to ensure system safety.

[0110] For example, in a ring network containing PCS 1 to PCS 8, assume a fiber optic cable break occurs in the link between PCS 3 and PCS 4. At this time, PCS 3 detects a communication interruption on its right port, generates fault information {Node=PCS 3, Interface=Right Port, Type=Link Disconnected}, and forwards it to the master device via its left port through PCS 2 and PCS 1. PCS 4 detects a communication interruption on its left port, generates fault information {Node=PCS 4, Interface=Left Port, Type=Link Disconnected}, and forwards it to the master device via its right port through PCS 5, PCS 6, PCS 7, and PCS 8. The master device receives both reports and determines the fault to be a unidirectional / bidirectional link break between PCS 3 and PCS 4. Subsequently, the master control device sends forwarding path update commands to each synchronous ring network controller within the ring network. The specific actions performed by each node are as follows: data units originally destined for the right port in PCS 3 are now sent to the left port; data units originally destined for the left port in PCS 4 are now sent to the right port; data units originally destined for the right port in PCS 2 (via PCS 3→PCS 4) are now sent to the left port (via PCS 1); data units originally destined for the left port in PCS 5 (via PCS 4→PCS 3) are now sent to the right port (via PCS 6→PCS 7→PCS 8); and so on. Each node changes its original data destined for the faulty segment to the direction furthest from the faulty segment. When the link is repaired, the nodes detect the restoration of communication and report it. The master control device then issues another command to restore the original forwarding path.

[0111] In practical implementation, the embodiments of this application are applicable to multiple fault scenarios. For example, when two link faults occur in a ring network, as long as the two master control devices are located in different network segments, each segment can still receive at least one second pulse synchronization signal and maintain basic operation.

[0112] In practice, for faults caused by adjacent nodes exiting the network, the main control device can send a node offline alarm to the network management system at the same time as sending the forwarding path update command, triggering the operation and maintenance response process.

[0113] Specifically, in this embodiment, fault perception capability is extended to every ring network node. Nodes on both sides of the fault point simultaneously generate structured fault vectors containing node, interface, and type information, and immediately report from intact paths using the bidirectional characteristics of the ring network. The dual-source complementary fault vectors provide the main control device with precise, first-hand diagnostic information down to specific link segments or nodes, completely eliminating the ambiguity of single-source alarms and ensuring decisions are based on solid cross-validation data. The forwarding path update command issued by the main control device based on the network topology view is a one-time, deterministic optimal path calculation and distribution. Its recovery speed is orders of magnitude faster than the multiple handshakes and gradual convergence of distributed protocols, minimizing the network bandwidth degradation time caused by faults. This mechanism, combined with redundant transmission, ensures that the second pulse synchronization signal relying on the ring network transmission itself remains uninterrupted or unchanged throughout the entire cycle of fault perception, reporting, decision-making, and updating, achieving truly seamless synchronization recovery.

[0114] Furthermore, the system boasts excellent scalability, reserving upgrade interfaces for future project expansion and the integration of new equipment, thus supporting the future integration and upgrade of devices such as solid-state transformers. For example, it supports the expansion of multiple protocol specifications (such as IEC-61850, Modbus, etc.), facilitating standardized interaction with EMS or other dispatching systems, and meeting future integration needs with different systems through its scalability; the system also supports online firmware upgrades, which is beneficial for continuous optimization and functional evolution.

[0115] In practical implementation, the system can support more than two master control devices, such as three master control devices forming a parallel operation architecture with higher redundancy. When N master control devices are running in parallel, each master control device uses the other N-1 physical second pulse signals received on the ring network as an independent reference source. It measures the physical phase difference between its own signal and each reference signal in parallel through a high-speed hardware phase detection circuit, and fuses these phase differences in real time into a composite error signal for calibration. For example, a weighted synthesis method is used. This signal directly acts on the local numerically controlled oscillator to adjust the transmission time of subsequent second pulses in a closed loop. When any master control device exits, the control loops inside the remaining devices only show a reduction in the number of input channels and an instantaneous automatic redistribution of the weights of the remaining channels. This is a continuous transition without interruption at the physical signal tracking level. As a result, a distributed physical clock array is formed within the ring network, consisting of all master control clocks pulling each other closer and converging. This achieves seamless synchronization with inherent redundancy that does not depend on any single node and does not require switching time.

[0116] Specifically, in this embodiment, a dual-master parallel collaborative clock synchronization architecture is constructed, fundamentally reconciling the contradiction between high reliability redundancy and high-precision synchronization in a ring synchronization network. Specifically, by assigning each master control device the dual role of signal sender and deviation corrector, the two originally conflicting second pulse signals are transformed into a pair of mutually verifying and dynamically calibrated references. In terms of reliability, a single point of failure in any master control device or link will not cause the synchronization reference to disappear, achieving seamless redundancy throughout the entire path from the physical link to the clock source. In terms of accuracy, the continuous mutual calibration of the two high-precision clock sources forms an effective closed-loop negative feedback, actively suppressing long-term frequency drift caused by aging, temperature drift, and other factors from a single clock source. This allows the synchronization accuracy maintained by the system under normal operating conditions to even exceed the limits achievable by relying on any single master control clock.

[0117] Please see Figure 7 , Figure 7 This paper demonstrates an exemplary hierarchical communication architecture for a power storage converter PCS system. The lowest layer consists of multiple PCS units connected in series via bidirectional links to form a closed synchronous ring network. Within this ring network, second pulse synchronization signals (1PPS), control commands, and various status data are transmitted, enabling multi-unit synchronous coordination and data interaction. Each PCS unit establishes bidirectional communication with its corresponding battery management system (BMS) via an RS485 / CAN interface, collecting battery status data and issuing control commands to achieve coordinated control between the PCS and the battery system. The system constructs a three-layer hierarchical communication network: MMS A / B network, GOOSE A / B network, and RS485 / CAN bus. Each PCS unit connects to these three networks, possessing bidirectional data interaction capabilities with the GOOSE A / B network, MMS A / B network, and RS485 / CAN bus. The Energy Management System (EMS) in the diagram communicates bidirectionally with the entire PCS system via both the MMS A / B network and the GOOSE A / B network: non-real-time monitoring, configuration, and maintenance data are transmitted via the MMS A / B network, while real-time control commands are issued and status information is collected via the GOOSE A / B network. This forms bidirectional links between PCS-GOOSE A / B network-EMS and PCS-MMS A / B network-EMS, as well as a local data interaction link between BMS-PCS-RS485 / CAN bus, constituting a complete communication and control system from BMS and PCS units to EMS.

[0118] In practical implementation, multiple energy storage converters (PCS) are connected via a synchronous ring network, with PCS 1 and PCS 2 designated as the master control devices by default, serving as hot standby for each other. The master control device acts as the centralized communication node for the ring network, engaging in bidirectional data exchange with the EMS via both the MMS A / B and GOOSE A / B networks. Simultaneously, each PCS connects to local devices such as the BMS. The remaining PCS within the ring network collect their control commands, status information, and network fault data via the ring network to the master control device, which then packages and uploads them to the EMS. The master control device also receives control commands from the EMS and distributes them within the ring network. When the master PCS 1 fails, the standby PCS 2 automatically takes over the master's function and interacts with the EMS. Once the master PCS 1 recovers, the standby PCS 2 returns to standby status. This centralized master-standby wiring method simplifies fault analysis, facilitates rapid fault location, and enables timely handling. In addition, the main control equipment in the synchronous ring network is connected to the RS485 / CAN bus. Some local devices with low real-time requirements can be directly connected to this bus without having to connect each PCS separately, which facilitates flexible wiring and debugging on site. The data collected by the connected local devices can be processed and distributed uniformly within the synchronous ring network, further improving the convenience of system integration and operation and maintenance.

[0119] In summary, the synchronous ring network system of the grid-type energy storage converter proposed in this application fundamentally reconstructs the logical relationship between redundancy and synchronization. It transforms the dual time references, which are considered conflicting in existing technologies, into resources for achieving higher levels of system reliability and accuracy. At the clock reference generation level, it fundamentally abandons the inherent technical bias that dual clock sources are conflicting sources and must be used only once. By endowing each of the two master control devices with the ability to receive, compare, and actively adjust the two parallel second pulse signals in the ring network in real time, a bidirectional calibration mechanism is constructed, making the two master control devices two clock sources operating in parallel, mutually verifying, and dynamically calibrating. Thus, the two signals converge towards the preset target value under continuous closed-loop calibration. From the node perspective, what is always seen is a unified and stable clock reference after dual-source mutual calibration. Since the local clocks of each master control device participate in the above closed-loop calibration throughout, their phases maintain precise real-time tracking. Once either master control device fails and exits operation, the other master control device takes over instantly, eliminating unpredictable phase jumps and achieving true seamless redundancy. At the signal transmission bearer level, by forcibly slicing heterogeneous data into fixed-length data units and assigning absolute preemption priority to the second pulse synchronization signal, the coupling of uncontrollable waiting delays introduced by long data packet transmission to synchronization signal jitter is eliminated at the protocol level. Through a hierarchical reliability design of forward error correction and automatic retransmission requests, the synchronization signal achieves high reliability without entering the retransmission queue, avoiding the disruption of real-time performance caused by retransmission delays. Through bidirectional active concurrent redundancy and a first-come-first-served strategy for data units, the self-healing time during link failures is compressed to near zero, ensuring that any single-point physical damage does not evolve into interruption or phase disturbance of the synchronization signal. This provides a deterministic foundation for the parallel, interference-free transmission of dual synchronization signals at the physical and link layers, forming a deep synergy with the upper-layer calibration mechanism. When a physical link or node fails, the structured fault vector generated by the nodes on both sides of the breakpoint is reported to the master control through intact path redundancy. The master control, based on the network topology view... Figure 1 The optimal forwarding path update command is determined and issued in one go, compressing the fault recovery time to the level of a single transmission delay in the communication loop. In conjunction with the aforementioned redundant transmission mechanism, the synchronization function is uninterrupted and does not degrade throughout the entire self-healing cycle.

[0120] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the connection within two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0121] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, while this specification describes specific embodiments, other embodiments are also within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in the order shown in different embodiments and still achieve the desired results. Additionally, the processes depicted in the drawings do not necessarily require a specific order or sequence of connections to achieve the desired results; in some implementations, parallel processing of multiple tasks is possible or may be advantageous.

[0122] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. The focus of each embodiment is to describe the differences from other embodiments.

[0123] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A synchronous ring network system for a grid-type energy storage converter, characterized in that, include: Multiple energy storage converters, each equipped with a synchronous ring network controller, are connected end to end in sequence through a communication interface to form a ring communication network; Two of the multiple energy storage converters operate as main control devices in the ring communication network; the synchronous ring network controllers of the two main control devices each generate a second pulse synchronization signal, and the two second pulse synchronization signals are transmitted simultaneously in the ring communication network. The synchronous ring network controller of each of the master control devices is configured to receive and compare the two second pulse synchronization signals in real time through the ring communication network. When the deviation between the two second pulse synchronization signals exceeds a preset threshold, the transmission time of the subsequent second pulse synchronization signal is adjusted to correct the deviation. The adjustment of the transmission time of the subsequent second pulse synchronization signal includes: using the second pulse synchronization signal generated by the synchronization ring network controller of another master control device as a reference signal, and using the second pulse synchronization signal currently generated at this end as a feedback signal; measuring the phase difference between the feedback signal and the reference signal; and adjusting the transmission phase of the subsequent second pulse synchronization signal at this end according to the phase difference, so that the phase difference converges towards a preset target value. The synchronous ring network controller of each energy storage converter is configured to divide the second pulse synchronization signal, control command and status data to be transmitted in the ring communication network into fixed-length data units, and encapsulate the fixed-length data units in the same slice period into a composite data frame, and transmit the composite data frame serially through the ring communication network in units of fixed-length data units.

2. The system according to claim 1, characterized in that, The synchronous ring network controller is also configured to assign a higher transmission priority to the data unit representing the second pulse synchronization signal than to the data unit representing the control command and the data unit representing the status data.

3. The system according to claim 2, characterized in that, The synchronization ring network controller is further configured to: when there is a target data unit representing the second pulse synchronization signal to be transmitted, if there is a data unit currently being transmitted, terminate the transmission of the current data unit, replace the target data unit with the current transmission position for transmission, and resume the transmission of the terminated data unit from the terminated position after the target data unit has been transmitted.

4. The system according to claim 1, characterized in that, The synchronous ring network controller includes: The line encoding / decoding module is used to perform line encoding on the fixed-length data unit to be transmitted, and generate encoded data units; A forward error correction module is used to add a forward error correction check code to the encoded data unit so that the downstream synchronous ring network controller receiving the encoded data unit can correct the bit errors generated during transmission based on the forward error correction check code. The automatic retransmission request module is used to receive a retransmission request from the downstream synchronous ring network controller when the downstream synchronous ring network controller detects a bit error that cannot be completely corrected, and to retransmit the corresponding fixed-length data unit according to the retransmission request.

5. The system according to claim 4, characterized in that, The synchronous ring network controller is also configured to generate two identical copies of the same fixed-length data unit and transmit the two copies in two directions of the ring communication network respectively; after receiving the first arriving copy, the synchronous ring network controller at the receiving end discards the subsequent arriving duplicate copies.

6. The system according to claim 1, characterized in that, Each of the energy storage converters' synchronous ring network controllers includes an analog signal acquisition interface and a digital signal acquisition interface; The analog signal acquisition interface is used to receive analog electrical signals from the main circuit of the energy storage converter or external sensors; the analog electrical signals represent the operating parameters of the energy storage converter. The switch quantity acquisition interface is used to receive switch status signals from the main circuit of the energy storage converter or external devices. The synchronous ring network controller, triggered by the second pulse synchronization signal, synchronously acquires the analog electrical signal and the switch status signal through the analog quantity acquisition interface and the switch quantity acquisition interface, and associates and stores the acquired analog electrical signal, the switch status signal and the corresponding timestamp information.

7. The system according to claim 6, characterized in that, The analog signal acquisition interface includes multiple analog signal input channels, and the digital signal acquisition interface includes multiple digital signal input channels. The synchronous ring network controller is configured to synchronously acquire analog data at a preset sampling rate through the multiple analog input channels; The status of the switching signals is recorded synchronously through the multiple switching input channels at a preset time resolution.

8. The system according to claim 6 or 7, characterized in that, When the synchronous ring network controller detects a fault event, it reads analog data and switch status within a preset time period before and after the fault event based on the timestamp information, and generates a fault recording file.

9. The system according to claim 1, characterized in that, Each of the energy storage converters' synchronous ring network controllers is configured to: when a communication interruption is detected in a neighboring synchronous ring network controller on one side, generate fault data information, the fault data information including the node information of the synchronous ring network controller itself, the communication interface identifier of the detected communication interruption, and the fault type, the fault type including link disconnection or the neighboring synchronous ring network controller exiting; and forward the fault data information to the main control device through the neighboring synchronous ring network controller on the other side. The master control device is configured to send a forwarding path update instruction to each synchronous ring network controller in the ring communication network after receiving the fault data information. The forwarding path update instruction is used to instruct each synchronous ring network controller to change the data unit originally sent from the side of the communication interruption to be sent to the other side.

Images