Direct current integrated relay protection device suitable for ship direct current integrated power system

Abstract

The application relates to a direct current integrated relay protection device suitable for a direct current integrated power system of a ship, a hardware system adopts a main processor structure of embedded close coupling, a protection processor plug-in of a core is constructed by adopting an ARM+FPGA structure, and a backboard bus of the device is constructed by adopting a high-speed serial bus system structure, which is used for providing direct current differential protection, direct current line overcurrent protection, direct current bus overcurrent protection, direct current circuit breaker failure protection, direct current overvoltage protection, direct current undervoltage protection and voltage imbalance protection functions, can reliably act in milliseconds when a fault occurs in a protection area, can trip a circuit breaker, can isolate a fault and can protect a direct current integrated power system. The application can reliably act when a fault occurs in the protection area, can trip the circuit breaker by issuing an instruction, can isolate the fault and can protect the direct current integrated power system. The application solves the problem that the system cannot realize ms-level fast selective protection when a fault occurs in the direct current integrated power system.

Description

Technical Field

[0001] This invention relates to a DC integrated relay protection system, and more particularly to a ship DC integrated power system based on a permanent magnet synchronous generator + controllable rectifier technology. Background Technology

[0002] The energy crisis and increasingly stringent emission regulations have become severe challenges for the shipping industry. Faced with energy shortages and stringent emission regulations, the use of new DC integrated power systems has become an important direction for the future development of ships. Among these, DC integrated power systems based on permanent magnet synchronous generators and controllable rectifier technology are increasingly being used on various ship types, including ocean-going vessels (small and medium-sized container ships, chemical tankers, etc.), tugboats, ferries, yachts, and government vessels. Ship DC integrated power systems integrate traditional diesel engine propulsion, variable frequency drive, and ship electrical and automatic control systems into a single system. This involves numerous devices, each with different combinations of components under different operating modes, making it a highly integrated electromechanical system.

[0003] Due to the characteristics of DC integrated power systems, such as high voltage levels, large system capacity, low line impedance, and numerous energy storage components, the rate of rise and peak current of the short-circuit current will reach extremely high levels within a very short time when an inter-pole short-circuit fault occurs. According to system protection analysis, to effectively protect the system and equipment during a short-circuit fault, the time from fault detection to circuit breaker tripping should not exceed milliseconds. Existing protection devices for DC systems cannot achieve protection of the DC system within such a short time. Summary of the Invention

[0004] Based on the above problems, this invention proposes a comprehensive relay protection device suitable for shipboard DC integrated power systems. This device provides functions such as DC differential protection, DC line overcurrent protection, DC bus overcurrent protection, DC circuit breaker failure protection, DC overvoltage protection, DC undervoltage protection, and voltage imbalance protection. It can reliably operate when a fault occurs within the protected area, causing the circuit breaker to trip, isolating the fault, and protecting the DC integrated power system. This device can solve the problem that the DC integrated power system cannot achieve rapid protection when a fault occurs, improve the reliability of the DC system operation, and reduce the risk of power loss for the entire ship.

[0005] To achieve the above objectives, the technical solution of this invention is as follows: a DC integrated relay protection device suitable for a ship's DC integrated power system, comprising: a hardware system adopting an embedded tightly coupled main processor architecture, a core protection processor plug-in built using an ARM+FPGA architecture, and a backplane bus built using a high-speed serial bus system architecture, for providing DC differential protection, DC line overcurrent protection, DC bus overcurrent protection, DC circuit breaker failure protection, DC overvoltage protection, DC undervoltage protection, and voltage imbalance protection functions, capable of reliably operating within milliseconds when a fault occurs within the protection zone, causing the circuit breaker to trip, isolating the fault, and protecting the DC integrated power system.

[0006] Furthermore, various functional peripheral plug-ins are configured on the backplane bus, among which a dedicated processor module completes dedicated functions for data acquisition, measurement, and communication; the acquisition module and processing module are placed in layers, and the high and low voltage circuits are separated, making the device compact, highly reliable, and with a high protection level.

[0007] Furthermore, the protection functions and measurement interfaces of the DC integrated relay protection device are implemented using a single device. When the protection starts and the protection trips, the DC integrated relay protection device sends the corresponding trip signal to the DC circuit breaker to clear the fault or abnormal operating conditions in the area and ensure the safe operation of the system.

[0008] Furthermore, to meet the requirements of DC systems for rapid protection, the communication between the DC integrated relay protection device and the current transformer and circuit breaker mainly adopts optical fiber and FT3 protocol, and other communication interfaces besides optical fiber and FT3 protocol are reserved as backups. The DC integrated relay protection device obtains sampling data from the optical CT through serial optical fiber and sends trip command to the DC circuit breaker through serial optical fiber. The encoding format adopts FT3 protocol to ensure that the whole link time from the acquisition of fault signal to the completion of DC circuit breaker trip is controlled within 800us.

[0009] Furthermore, the DC integrated relay protection device provides a DC analog input channel, supporting two input modes: 4-20mA current or -10V-10V voltage. It adopts an electromagnetic compatibility design, with each channel isolated from the device and from each other, effectively suppressing electromagnetic interference in the process loop. The converted output voltage signal is connected to the analog signal processing module via the backplane for acquisition.

[0010] Furthermore, the DC integrated relay protection device interacts with current transformers, voltage transformers, DC circuit breakers, and other protection devices via signals.

[0011] Furthermore, the system software used in the DC integrated relay protection device is divided into a driver layer, a runtime system layer, a function block library, and a visual programming tool ViGET. It provides two task modes: 8 interrupts and 5 cycle tasks, with a minimum task interval of 100u. The function block library includes 6 basic categories: DC control and protection, arithmetic logic operations, I / O functions, network communication, service diagnosis, and special applications.

[0012] Furthermore, in order to achieve high-precision capture of DC fault current and realize DC system protection, a hybrid measurement method of Rogowski coil + magneto-optical effect is adopted. The Rogowski coil has a fast response and accurate capture of the AC component of the current and the pulse current, and the magneto-optical effect has the ability to accurately measure the DC component of the current to realize DC fault protection.

[0013] The present invention has the following beneficial effects:

[0014] 1. The DC integrated relay protection device of the present invention can provide functions such as DC differential protection, DC line overcurrent protection, DC bus overcurrent protection, DC circuit breaker failure protection, DC overvoltage protection, DC undervoltage protection and voltage imbalance protection. It can reliably operate within milliseconds when a fault occurs in the protection zone, causing the circuit breaker to trip, isolating the fault, protecting the DC integrated power system, and greatly improving the safety, stability and reliability of DC system operation.

[0015] 2. The DC integrated relay protection device in this invention is small in size and has a high protection level, making it particularly suitable for application environments with relatively poor environmental conditions and high space requirements, such as offshore platforms and ships;

[0016] 3. The analog signal module in the DC integrated relay protection device of this invention provides 14 DC analog input channels, supporting both 0-20mA current and 0-10V voltage modes. These two modes are set via internal DIP switches. Each channel is isolated from the internal components of the device and from each other, effectively suppressing electromagnetic interference from process loops, etc., giving this device strong anti-electromagnetic interference capabilities.

[0017] 4. The DC integrated relay protection device system software in this invention is divided into a driver layer, a runtime system layer, a function block library, and a visual programming tool. It provides two task modes: 8 interrupts and 5 cycles, with a minimum task interval of 100µs. Nearly 500 mature algorithm modules can run in both task modes, strongly guaranteeing the correctness and reliability of the control and protection system application program.

[0018] 5. The DC integrated relay protection device in this invention adopts an LCD display panel, which has functions such as electrical wiring status display, parameter setting, control and reset, making it convenient for users to quickly locate faults.

[0019] 6. The DC integrated relay protection device in this invention operates at a speed in the hundreds of microseconds, enabling rapid detection of DC system faults. Using relays to output switching signals requires milliseconds, which is insufficient for short-circuit fault protection in medium-voltage DC systems. Furthermore, optical level tripping would fail to determine if a break in the tripping circuit has occurred. Therefore, the protection device sends a tripping command to the DC circuit breaker via serial optical fiber, using the FT3 encoding format. Under this signal transmission configuration, the acquisition and output of the fiber optic current transformer totals no more than 50 μs; the FT3 reception of the protection device is synchronous, with a minimum protection main processing cycle of 100 μs and a protection delay of no more than 5 cycles, totaling 500 μs; the tripping output uses FT3 encoding with an 8 μs delay, and the DC circuit breaker receives the signal synchronously, completing the tripping in 100 μs. Therefore, the theoretical end-to-end delay from fault signal acquisition to DC circuit breaker tripping completion is 758 microseconds. Attached Figure Description

[0020] Figure 1 This is a hardware schematic diagram of the DC integrated relay protection device of the present invention;

[0021] Figure 2 This is a schematic diagram of the architecture of the DC integrated relay protection device of the present invention;

[0022] Figure 3 This is a schematic diagram of the differential protection configuration of the DC integrated relay protection device of the present invention;

[0023] Figure 4 This is a schematic diagram of the composition of the DC integrated relay protection device of the present invention;

[0024] Figure 5 This is a functional flowchart of the DC integrated relay protection device of the present invention;

[0025] Figure 6 This is a functional flowchart of the DC integrated relay protection device of the present invention;

[0026] Figure 7 This is a front view of the DC integrated relay protection device of the present invention;

[0027] Figure 8 This is a rear view of the DC integrated relay protection device of the present invention. Detailed Implementation

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0029] In a DC integrated power system based on permanent magnet synchronous generator + controlled rectifier technology, due to the system's characteristics of high voltage level, large system capacity, low line impedance, and numerous energy storage components, the short-circuit current rise rate and peak current will reach extremely high levels when an inter-pole short-circuit fault occurs. According to system protection analysis, to effectively protect system equipment during a short-circuit fault, the time from fault detection to circuit breaker tripping should not exceed milliseconds. To address the challenges of rapid and selective fault protection in DC systems, this invention proposes a DC integrated relay protection device suitable for shipboard DC integrated power systems, such as... Figures 1 to 8 As shown, this DC integrated relay protection device includes: a hardware system employing an embedded, tightly coupled main processor architecture; a core protection processor module built using an ARM+FPGA architecture to meet the specific application requirements of marine protection devices; and a high-speed serial bus system architecture for the device's backplane bus, allowing for flexible configuration of various functional peripherals on the backplane bus. The device boasts good scalability and maintainability, supporting microsecond-level computation intervals. A dedicated processor module performs specialized functions such as data acquisition, measurement, and communication. The acquisition and processing modules are layered, separating high-voltage and low-voltage circuits. The device is compact, highly reliable, and offers a high protection level, suitable for compact applications on offshore platforms and ships. The DC integrated relay protection device system software features 5 levels of cyclic tasks and 8 levels of interrupt tasks. Users can set the execution cycle of each cyclic task according to actual application requirements and flexibly select the interrupt source for each interrupt task, serving as a general-purpose system to meet the task design needs of different applications.

[0030] Protection range of DC integrated relay protection device: The protection area of ​​DC integrated relay protection device is the DC system.

[0031] Configuration of DC integrated relay protection device: The protection functions and measurement interfaces of the DC integrated relay protection device are implemented using a single device. When protection is initiated and tripped, the integrated relay protection device sends the corresponding trip signal to the DC circuit breaker to clear faults or abnormal operating conditions within the area, ensuring the safe operation of the system. All protection devices possess all required protection functions and can independently provide comprehensive and accurate protection for the protected equipment.

[0032] The functional characteristics of a DC integrated relay protection device include at least the following: the protection design comprehensively considers all aspects of AC and DC system operation and equipment stress, and has the function of preventing protection maloperation caused by inconsistent transient characteristics of instrument transformers; the protection distinguishes different fault states and performs actions in stages according to the different degrees and development trends of the faults.

[0033] The DC protection system based on the DC integrated relay protection device has a three-layer structure: integrated monitoring by operators, protection layer, and field layer. The integrated monitoring layer mainly deploys the integrated monitoring system, which communicates with the protection devices and the monitoring system to achieve functions such as event sequence recording and event alarms. The control and protection layer mainly includes the DC line protection system and the DC bus protection system, primarily implementing the protection functions within each protection area. The field layer mainly implements the analog quantity (optical signal, electrical signal) acquisition functions required by the protection system. To ensure the speed of trip command transmission, the DC circuit breaker is connected to the protection device via a fiber optic network or directly uses optical level triggering. The protection devices are networked via fiber optic switches to achieve data exchange. The protection system is equipped with a self-test function; when the protection host or board fails, the program exits the protection prematurely to prevent malfunction. Station engineers can optimize and correct the protection parameters during system operation; the protection system has a built-in fault recording function, recording input analog quantities, switch quantities, and protection calculation digital quantities.

[0034] DC integrated relay protection device for monitoring and determining DC short-circuit faults:

[0035] The current signals at both ends of the DC line are collected and differentially analyzed. If a ground fault or short circuit occurs, the differential current will exceed the protection setting, triggering the protection operation. The differential operation logic is as follows:

[0036] |IEDX_1+IEDX_2+IEDX_3+…+IEDX_N|>I_set+k_set*I_RES

[0037] Where: I_RES is the braking value, I_RES=|IEDX_1+IEDX_2+IEDX_3+…+IEDX_N|; k_set is the ratio coefficient; I_set is the threshold value; IDX_1, IDX_2, IDX_3, …, IDX_N are the DC currents flowing into the DC line or bus X, respectively. The differential protection's operating time must be coordinated with the converter's overcurrent withstand time and the system instability time under low voltage. The consequence of this protection operation is that all DC circuit breakers within the protection area will trip; and the DC circuit breaker failure protection will be activated.

[0038] DC integrated relay protection device for monitoring and diagnosing overcurrent faults in DC lines:

[0039] Directional DC overcurrent protection, with the direction of current flow towards the DC bus as the square (this function can be enabled or disabled as needed). The operating logic of the line overcurrent protection is as follows:

[0040] The protection action output is IEDX_1 < 0 and |IEDX_1| > I_set (reverse overcurrent protection action output), where: I_set is the threshold value; IEDX_1 is the DC current at the beginning and end of DC line X. The protection action time must be coordinated with the converter overcurrent withstand time and the system instability time under low voltage. The consequence of this protection action is to trip the DC circuit breaker of DC line X; and to activate the DC circuit breaker failure protection.

[0041] DC integrated relay protection device for monitoring and diagnosing DC bus overcurrent faults:

[0042] Configure directional DC bus overcurrent protection. The positive direction of current at the bus tie is defined as the flow from bus 2 to bus 1, and from the bus to the line. The protection criteria are based on the status values ​​of the overcurrent elements in each branch within the protection area to identify the fault region. The line overcurrent protection operation logic is as follows:

[0043] When the overcurrent protection of each branch does not operate or is deactivated, SN = 0; when the overcurrent protection of each branch operates in the reverse direction, SN = 1; when the overcurrent protection of each branch operates in the forward direction, SN = -1; Ssum = |S1 + S2 + ... + Sn|, using the state value of the current branch within the protection zone that can provide short-circuit energy as the protection setting Sset. If Ssum ≥ Sset, it is a fault within the zone, and the protection trips. The protection action time must be coordinated with the converter overcurrent withstand time and the system instability time under low voltage. The consequence of this protection action is that the DC circuit breakers at both ends of DC line X are tripped, and the DC circuit breaker failure protection is activated.

[0044] DC integrated relay protection device for monitoring and diagnosing DC circuit breaker failures:

[0045] DC circuit breakers connected to the DC bus must be equipped with DC circuit breaker failure protection. When a trip command for a DC circuit breaker is received, DC circuit breaker failure detection is initiated. If the circuit breaker is determined to be faulty, all adjacent circuit breakers will trip. The principle of circuit breaker failure detection is as follows: 1) A trip signal for a DC circuit breaker is received; 2) if di / dt > Δ, it indicates that the fault current is still rising, and the DC circuit breaker has failed. The tripping delay should be coordinated with the circuit breaker opening time, allowing sufficient time for the circuit breaker current to be interrupted. The consequence of this protection action is that all DC circuit breakers adjacent to the failed circuit breaker will trip.

[0046] DC integrated relay protection device for monitoring and diagnosing DC overvoltage faults:

[0047] DC overvoltage protection is configured based on the withstand voltage capability of the primary equipment, and is divided into inter-pole voltage criteria and pole-to-ground voltage criteria. The inter-pole voltage criterion mainly reflects the equipment's withstand voltage capability, while the pole-to-ground voltage criterion mainly reflects the equipment's insulation withstand voltage capability to ground. The protection criteria are as follows:

[0048] |UdP-UdN|>U_set(pole-to-ground) or (|UdP| or |UdN|)>U_set(pole-to-ground).

[0049] Where UdP and UdN are the positive and negative DC voltages, respectively; and IdP and IdN are the positive and negative DC currents, respectively. The protection settings and delay need to be determined based on the overvoltage withstand capability of the primary equipment. The consequence of this protection action is the tripping of the DC circuit breaker.

[0050] DC integrated relay protection device for monitoring and diagnosing DC low-voltage faults:

[0051] The system monitors the DC positive and negative voltage and current. Upon the occurrence of a short circuit fault between the positive and negative terminals, it will exhibit characteristics of low voltage and overcurrent. Once the protection settings are met, the protection system will activate. The protection function can be enabled or disabled as needed.

[0052] The protection criterion is:

[0053] |UdP-UdN|>U_set&(|IdP|>I_setor|IdN|>I_set)

[0054] Where UdP and UdN are the positive and negative DC voltages, respectively; and IdP and IdN are the positive and negative DC currents, respectively. The protection settings and delays need to be coordinated with the withstand capability of the primary equipment and the operating time of the main protection. The consequence of this protection action is the tripping of the DC circuit breaker.

[0055] DC integrated relay protection device for voltage imbalance fault monitoring and fault diagnosis:

[0056] A single-pole fault will cause the voltage of the faulted pole to drop to zero, while the voltage of the non-faulted pole will double. This voltage imbalance, once the protection settings are met, will trigger the protection system (the protection function can be enabled or disabled as needed). The positive line voltage UdP and the negative line voltage UdN are used as the protection criteria.

[0057] |UdP+UdN|>Δ

[0058] The consequence of this protection action is the closure of the grounding resistance bypass switch (if applicable).

[0059] like Figure 2 This is a schematic diagram of the architecture of the DC integrated relay protection device in an embodiment of the present invention. The device collects information such as voltage and current of the DC system through optical signals and electrical signals, and issues commands to the opening and closing status of the DC circuit breaker and performs fault protection based on the collected data.

[0060] This invention has the following characteristics:

[0061] 1. The hardware system of the DC integrated relay protection device in this invention adopts an embedded tightly coupled main processor architecture. In view of the special application requirements of ship protection devices, the core protection processor plug-in is built with ARM+FPGA+ASIC architecture. The backplane bus of the device is built with a high-speed serial bus system architecture. Various functional peripheral plug-ins can be flexibly configured on the backplane bus. The device has good scalability and maintainability.

[0062] 2. The DC integrated relay protection device in this invention supports microsecond-level operation intervals as low as 1000 microseconds; it uses a dedicated processor module to complete dedicated functions such as data acquisition, measurement, and communication; the data acquisition module and the processing module are placed in layers, and the strong and weak currents are separated, which has a strong anti-electromagnetic interference capability. The device is compact, highly reliable, and has a high protection level, making it suitable for compact space applications on offshore platforms and ships.

[0063] 3. The DC integrated relay protection device in this invention adopts mature networks such as Ethernet and fieldbus, which are internationally recognized and mature networks with open protocols, facilitating system expansion and communication with other systems and devices. The network has a good fault diagnosis and recovery mechanism and can recover quickly when the network is blocked.

[0064] 4. The DC integrated relay protection device in this invention has fully considered the convenience of maintenance in its design. All components, such as the controller module, digital signal acquisition module, and analog signal acquisition module, are installed in a unified plug-in form. All interfaces are led out through aviation plug terminals, which avoids the situation of leading out multiple wires from the same wiring port. It can also minimize the situation of loose joints, short circuits, and open circuits caused by disconnection during the test and debugging process, and facilitate wiring inspection and maintenance.

[0065] 5. The rear wiring socket of the DC integrated relay protection device in this invention is of the aviation plug type and adopts a design to prevent mis-plugging. Each socket and plug corresponds one-to-one, which can prevent the plug from being mistakenly connected to other sockets on the panel.

[0066] The above examples are merely illustrative of the principles and specific steps of the present invention and are not intended to limit the invention. Any person skilled in the art can make corresponding modifications and optimizations to the above examples without departing from the principles of the invention, and these modifications and optimizations shall fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A DC integrated relay protection device suitable for a ship's DC integrated power system, characterized in that, include: The hardware system adopts an embedded, tightly coupled main processor architecture, using an ARM+FPGA architecture to build the core protection processor module, and a high-speed serial bus system architecture to build the device's backplane bus. It provides DC differential protection, DC line overcurrent protection, DC bus overcurrent protection, DC circuit breaker failure protection, DC overvoltage protection, DC undervoltage protection, and voltage imbalance protection functions. It can reliably operate within milliseconds when a fault occurs within the protected area, tripping the circuit breaker, isolating the fault, and protecting the DC integrated power system. To meet the requirements of the DC system for fast protection, the communication between the DC integrated relay protection device and the current transformer and circuit breaker mainly uses fiber optic and FT3 protocols, with interfaces for other communication methods as backups. The DC integrated relay protection device acquires sampling data from the optical CT via serial fiber and sends trip commands to the DC circuit breaker via serial fiber. The encoding format uses the FT3 protocol to ensure that the entire link time from fault signal acquisition to DC circuit breaker tripping is controlled within 800µs. The DC integrated relay protection device provides DC analog input channels, supporting both 4~20mA current and -10V~10V voltage input methods. It employs an electromagnetic compatibility design, with each channel isolated from the device's internal components and from each other, effectively suppressing electromagnetic interference in the process loop. The converted output voltage signal is connected to the analog signal processing module via the backplane for acquisition. The system software of the DC integrated relay protection device is divided into a driver layer, a runtime system layer, a function block library, and the visual programming tool ViGET. It provides two task modes: 8 interrupts and 5 cycle tasks, with a minimum task interval of 100µs. The function block library includes six basic categories: DC control and protection, arithmetic logic operations, I / O functions, network communication, service diagnostics, and special applications. To achieve high-precision capture of DC fault current and realize DC system protection, a Rogowski coil + magneto-optical effect hybrid measurement method is adopted. This method utilizes the Rogowski coil's fast response and accurate capture of the AC component and pulse current, and the magneto-optical effect's accurate measurement capability of the DC component of the current for DC fault protection.

2. The DC integrated relay protection device for ship DC integrated power systems according to claim 1, characterized in that: Various functional peripheral plug-ins are configured on the backplane bus. Among them, the dedicated processor module completes the dedicated functions of data acquisition, measurement and communication. The acquisition module and the processing module are placed in layers, and the strong and weak currents are separated, making the device compact, highly reliable and with a high protection level.

3. The DC integrated relay protection device for ship DC integrated power systems according to claim 1, characterized in that: The protection functions and measurement interfaces of the DC integrated relay protection device are implemented using a single device. When the protection starts and the protection trips, the DC integrated relay protection device sends the corresponding trip signal to the DC circuit breaker to clear the fault or abnormal operating condition in the area and ensure the safe operation of the system.

4. The DC integrated relay protection device for ship DC integrated power systems according to claim 1, characterized in that: The DC integrated relay protection device interacts with current transformers, voltage transformers, DC circuit breakers, and other protection devices via signals.

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