A method for preventing the collapse of the DC bus in a ship electrical system and a ship electrical system

Abstract

Embodiments of the present disclosure relate to the technical field of ship electrical systems, and provide a method for preventing the collapse of the DC bus in a ship electrical system and a ship electrical system, which can at least solve the problem that the existing ship electrical system cannot quickly respond to the bus collapse caused by the unit failure shutdown. The method includes: detecting whether the DC networked driver is in an overloaded state at a sampling moment; if so, obtaining the rated current of the DC networked driver and the output current of the DC networked driver at the sampling moment; obtaining the overload coefficient of the DC networked driver according to the rated current of the DC networked driver and the output current of the DC networked driver at the sampling moment; obtaining the cumulative overload of the DC networked driver according to the overload coefficient of the DC networked driver and the overload time of the DC networked driver; and adjusting the output current limit of the DC networked driver at the moment according to the cumulative overload of the DC networked driver and the load derating coefficient.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the technical field of ship power systems, and in particular, to a ship power system and a method for preventing bus collapse in a ship power system. Background Art

[0002] In the prior art, a ship power system includes a main controller, a plurality of DC networking drivers, a plurality of load drivers, and a bus. The plurality of DC networking drivers and the plurality of load drivers are connected through the bus. Among them, each DC networking driver includes a battery charge and discharge DC source and a generator AC-DC converter, and each load driver includes an inverter power supply, a frequency converter driver, etc. The stability of the plurality of DC networking drivers determines the stability of the entire ship power system. The failure shutdown of a certain unit or multiple units among them will cause the output capabilities of the plurality of DC networking drivers to decrease, and the decrease in the output capabilities of the plurality of DC networking drivers will cause violent fluctuations in the current and voltage on the bus, resulting in bus collapse. To solve the above problems, in the prior art, the main controller is usually used to collect the working states of each unit in real time and implement energy scheduling according to the working states of each unit. However, this scheduling method is slow and cannot quickly respond to the bus collapse problem caused by the failure shutdown of the unit. Summary of the Invention

[0003] Embodiments of the present disclosure provide a method for preventing bus collapse in a ship power system, which is at least beneficial to solving the problem that the ship power system in the prior art cannot quickly respond to the bus collapse problem caused by the failure shutdown of the unit.

[0004] On the one hand, embodiments of the present disclosure provide a method for preventing bus collapse in a ship power system, including:

[0005] Detecting whether the DC networking driver is in an overload state at the sampling time ti.

[0006] If so, obtaining the rated current I of the DC networking driver e and the sampling time t i the output current I(t of the DC networking driver i ).

[0007] According to the rated current I of the DC networking driver e and the sampling time t i the output current I(t of the DC networking driver i ), obtaining the overload coefficient K(t of the DC networking driver i ).

[0008] According to the overload coefficient K(t of the DC networking driver i ) and the overload time t of the DC networking driver n, obtain the cumulative overload amount P of the DC networked driver sum .

[0009] According to the cumulative overload amount P of the DC networked driver sum and the overload derating factor P th , adjust t I at the output current limit I(t I ) of the DC networked driver at that moment.

[0010] where i = 0, 1, 2,..., I, and I is a positive integer.

[0011] According to some embodiments of the present disclosure, the obtaining of the overload factor of the DC networked driver according to the rated current of the DC networked driver and the output current of the DC networked driver at the sampling moment specifically includes:

[0012] According to the sampling moment t i the output current I(t i ) corresponding to the DC networked driver and the rated current I e , calculate the overload factor K(t i ) of the DC driver, K(t i ) = I(t i ) - I e .

[0013] According to some embodiments of the present disclosure, the cumulative overload amount of the DC networked driver is calculated by the following formula:

[0014]

[0015] According to some embodiments of the present disclosure, characterized in that the output current limit I(t I ) of the DC networked driver at that moment is calculated by the following formula: I

[0016]

[0017] According to some embodiments of the present disclosure, t i+1 - t i = 1 ms.

[0018] According to some embodiments of the present disclosure, after adjusting the output current of the DC networked driver, the method further includes:

[0019] Obtain the DC bus voltage V(t I ) of the load driver, and compare the DC bus voltage V(t I ) of the load driver with the normal minimum DC bus voltage V min of the load driver.

[0020] If the DC bus voltage V(t I ) of the load driver is less than the normal minimum DC bus voltage V min of the load driver, then according to the DC bus voltage V(t I ) of the load driver, the normal minimum DC bus voltage V min of the load driver, and the rated output voltage V e of the load driver, adjust the output voltage of the load driver.

[0021] According to some embodiments of the present disclosure, adjusting the output voltage of the load driver includes:

[0022] The output voltage of the load driver after adjustment is calculated by the following formula:

[0023]

[0024] where V out represents the output voltage of the load driver after adjustment, V min represents the normal minimum DC bus voltage of the load driver, V e represents the rated output voltage of the load driver, and K is the output derating factor.

[0025] According to some embodiments of the present disclosure, the method further includes:

[0026] When V out is adjusted to 1 / 2V e , detect whether the load driver is still in the overload state. If so, the load driver fails and stops.

[0027] On the other hand, embodiments of the present disclosure provide a ship electrical system, including a plurality of DC networked drivers, a bus, and a plurality of load drivers. The plurality of DC networked drivers and the plurality of load drivers are connected through the bus;

[0028] The DC networked driver is configured to:

[0029] Detect whether the DC networked driver is in the overload state at the sampling time ti;

[0030] If so, obtain the rated current I e of the DC networked driver and the sampling time t i the output current I(t i ) of the DC networked driver;

[0031] According to the rated current I e of the DC networked driver and the sampling time ti The output current I(t of the DC networked driver i ) is used to obtain the overload factor K(t of the DC networked driver i );

[0032] Based on the overload factor K(t of the DC networked driver i ) and the overload time t of the DC networked driver n , the cumulative overload amount P of the DC networked driver is obtained sum ;

[0033] Based on the cumulative overload amount P of the DC networked driver sum and the overload derating factor P th , the output current limit I(t of the DC networked driver at time t I ) is adjusted I ;

[0034] where i = 0, 1, 2,..., I, and I is a positive integer

[0035] According to some embodiments of the present disclosure, the load driver is configured to

[0036] obtain the DC bus voltage V(t of the load driver I ), and compare the DC bus voltage V(t of the load driver I ) with the normal minimum DC bus voltage V of the load driver min ;

[0037] If the DC bus voltage V(t of the load driver I ) is less than the normal minimum DC bus voltage V of the load driver min , then based on the DC bus voltage V(t of the load driver I ), the normal minimum DC bus voltage V of the load driver min and the rated output voltage V of the load driver e , the output voltage of the load driver is adjusted

[0038] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has at least the following advantages. When one or more of the N DC networked drivers fail and stop operating or their output capabilities weaken, in order to maintain the stability of the current and voltage on the bus connected to the N DC networked drivers, one or more of the remaining DC networked drivers need to increase their output current. At the sampling time ti, if the output current I(t of the DC networked driver i ) is greater than the rated current I of the DC networked driver e, the DC networked driver operates in the overload state. On this basis, the DC networked driver operating in the overload state smoothly reduces the output current limit I(t I ), to reduce the output current of the DC networked driver, so that the output current I(t i ) of the DC networked driver is within the rated current I e . In this way, it can not only avoid the DC networked driver operating in the overload state for too long, but also avoid the bus collapse problem caused by the excessive rapid drop of the current and voltage on the bus. Description of the Drawings

[0039] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a scale limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following-described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a schematic flowchart of a method for preventing bus collapse in a ship electrical system provided by an embodiment of the present disclosure;

[0041] Figure 2 It is a schematic flowchart of another method for preventing bus collapse in a ship electrical system provided by an embodiment of the present disclosure;

[0042] Figure 3 It is a schematic structural diagram of a ship electrical system provided by an embodiment of the present disclosure. Detailed Embodiments

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will elaborate on each embodiment of the present application in conjunction with the drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present application, many technical details are proposed to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation manner of the present application. The various embodiments can be combined and cross-referenced with each other on the premise of not being contradictory.

[0044] In the related art, a ship electrical system usually collects the working states of various units (such as a DC network drive or a load drive) in the ship power system in real time through a main controller, and realizes energy scheduling according to the working states of the various units. For example, in the case where one of multiple DC network drives fails and shuts down, the main controller detects the failure or invalidation of the DC network drive by detecting the working states of the various units, and then realizes energy scheduling by controlling other DC network drives or load drives. However, this method of realizing energy scheduling through the main controller is usually slow and cannot quickly cope with the bus collapse problem caused by the unit failure and shutdown.

[0045] To solve the above problems, referring to Figure 1 , an embodiment of the present disclosure provides a method for preventing bus collapse in a ship electrical system, including the following steps:

[0046] S100. At sampling time t i detect whether the DC network drive is in an overload state, i = 0, 1, 2,..., I, where I is a positive integer.

[0047] It should be noted that any one of the N DC network drives can detect whether the corresponding DC network drive is in an overload state at sampling time ti. Among them, the overload state refers to a working state in which the output power of the DC network drive is greater than the rated power. When one or more of the N DC network drives fail and shut down or the output capacity decreases, in order to maintain the normal operation of the load drive, one or more of the remaining DC network drives need to increase the output power as much as possible to ensure the current and voltage on the bus. At this time, the output power provided by the DC network drive is greater than the rated power, and it is in an overload state.

[0048] S200. If so, obtain the rated current I e of the DC network drive and the output current I(t i ) of the DC network drive at sampling time t i .

[0049] The rated current I e refers to the current when the DC network drive operates at the rated power under the rated voltage, which is usually determined when designing the DC network drive, while the output current I(t i ) is obtained at sampling time t i .

[0050] S300. According to the rated current I e of the DC network drive and sampling time t i the output current I(t i) to obtain the overload factor K(t of the DC networked drive i ).

[0051] The overload factor K(t i ) is used to represent the overload degree of the DC networked drive at the sampling time t i .

[0052] S400. According to the overload factor K(t i ) of the DC networked drive and the overload time t I of the DC networked drive, the cumulative overload amount P sum of the DC networked drive is obtained.

[0053] When the DC networked drive is working in an overloaded state, the DC networked drive will heat up due to overload. The cumulative overload amount P sum is used for the heat accumulated by the DC networked drive due to overload within the overload time t I .

[0054] S500. According to the cumulative overload amount P sum of the DC networked drive and the overload derating factor P th , the output current limit I(t I ) of the DC networked drive at time t is adjusted. I )

[0055] On this basis, when one or more of the N DC networked drives fail and stop or their output capabilities weaken, in order to maintain the stability of the current and voltage on the bus connected to the N DC networked drives, one or more of the remaining DC networked drives need to increase their output current. At the sampling time t i , if the output current I(t i ) of the DC networked drive is greater than the rated current I e of the DC networked drive, then the DC networked drive is working in an overloaded state. On this basis, the DC networked drive working in an overloaded state smoothly reduces the output current limit I(t I ) to reduce the output current of the DC networked drive, so that the output current I(t i ) of the DC networked drive is within the rated current I e . In this way, it can avoid the DC networked drive working in an overloaded state for too long and also avoid the problem of bus collapse caused by too rapid voltage drop of the current and voltage on the bus.

[0056] In some embodiments, obtaining the overload factor of the DC networked drive according to the rated current of the DC networked drive and the output current of the DC networked drive at the sampling time specifically includes:

[0057] According to the sampling moment t i the output current I(t i ) of the corresponding DC networked driver and the rated current I e , calculate the overload factor K(t i ) of the DC driver, K(t i ) = I(t i ) - I e .

[0058] In some embodiments, the cumulative overload of the DC networked driver is calculated by the following formula:

[0059]

[0060] In some embodiments, t i+1 - t i = 1ms.

[0061] It should be noted that t i+1 - t i = 1ms means that the adjustment period of the DC networked driver is 1ms, that is, the current of the DC networked driver is sampled every 1ms.

[0062] In some embodiments, the output current limit I(t I ) of the DC networked driver at the moment t is calculated by the following formula: I ) is calculated by the following formula:

[0063]

[0064] It should be noted that I max represents the maximum output current of the DC networked driver, which limits the output capacity of the DC networked driver. In the normal working state, the output current limit of the DC networked driver is equal to I max . When the DC networked driver is working in the overload state, the current of the DC networked driver is greater than the rated current. At this time, it is necessary to gradually adjust the output current limit to the rated current, so as to gradually adjust the output current of the DC networked driver to the rated current and make the DC networked driver work gradually return to the normal working state.

[0065] Exemplarily, the working process of the above method is described. The shipboard power system includes two DC networked drivers, and the rated current I e of each of the two DC networked drivers is 100A, the maximum output current I max = 200A, and the two DC networked drivers work at the rated current I eWhen powering the load driver below, the output current in the two DC networked drivers is 200A. At the sampling moment t0, one of the DC networked drivers shuts down due to a fault. To ensure that the current and voltage on the bus do not drop rapidly, the other DC networked driver provides the corresponding maximum output current of 200A.

[0066] Next, to gradually reduce the operating current of the other DC networked driver to the corresponding rated current of 100A, the corresponding output current limit needs to be adjusted. At this time, the output current I(t0) = 200A.

[0067] Calculate the overload derating factor K(t0) = I(t0) - I e = 100A.

[0068] Calculate the cumulative overload of the DC networked driver, P sum = ∑ i＝0 K(t0) = 100.

[0069] Next, adjust the output current limit of the DC networked driver. The adjustment period is 1ms. The output current limit I(t1) of the DC networked driver at time t1 is calculated by the following formula:

[0070] Among them, P th = 1000.

[0071] On this basis, the DC networked driver needs to adjust the output current limit to 100A at time t I . According to the calculation, when the output current limit is reduced to 100A, P = 500. sum = 500.

[0072] According to and the adjustment period of 1ms, it can be calculated that at about I = 30, that is, after 30ms, the DC networked driver can adjust the output current limit to 100A.

[0073] Based on this, the DC networked driver can smoothly adjust the output current, thereby effectively reducing the fluctuation of the bus voltage.

[0074] See Figure 2 , in some embodiments, after adjusting the output current of the DC networked driver, the method for preventing the bus from collapsing in the ship power system further includes:

[0075] S600. Obtain the DC bus voltage V(t I ) of the load driver, and compare the DC bus voltage V(t I ) of the load driver with the normal minimum DC bus voltage V of the load drivermin Comparison

[0076] S700. If the DC bus voltage V(t I ) of the load driver is less than the normal minimum DC bus voltage V min of the load driver, then according to the DC bus voltage V(t I ) of the load driver, the minimum output voltage V min of the load driver, and the rated output voltage V e of the load driver, adjust the output voltage of the load driver.

[0077] It should be noted that when it is detected that the DC networked driver is in an overloaded state, the DC networked driver adjusts the output current. At this time, the current and voltage on the bus fluctuate slightly. The load driver receives the fluctuation signal and makes corresponding adjustments to the output of the load driver, thereby reducing the power of the load driver and making the output power of the DC networked driver better meet the requirements of the load driver.

[0078] In some embodiments, adjusting the output voltage of the load driver includes:

[0079] The output voltage of the adjusted load driver is calculated by the following formula:

[0080]

[0081] where, V out represents the output voltage of the adjusted load driver, V min represents the normal minimum DC bus voltage of the load driver, V e represents the rated output voltage of the load driver, and K is the output derating factor.

[0082] In some embodiments, the method for preventing the bus from collapsing in the ship electrical system further includes:

[0083] When V out is adjusted to 1 / 2Ve, detect whether the DC networked driver is still in an overloaded state. If so, the load driver fails and stops.

[0084] On the other hand, referring to Figure 3 , an embodiment of the present disclosure provides a ship electrical system, including M DC networked drivers, a bus, and N load drivers. The M DC networked drivers and the N load drivers are connected through the bus.

[0085] The DC networked driver is used for:

[0086] At the sampling time t i detect whether the DC networked driver is in an overloaded state.

[0087] If so, obtain the rated current I of the DC network drive e and the sampling time t i The output current I(t of the DC network drive i ).

[0088] According to the rated current I of the DC network drive e and the sampling time t i The output current I(t of the DC network drive i ), obtain the overload factor K(t of the DC network drive i ).

[0089] According to the overload factor K(t of the DC network drive i ) and the overload time t of the DC network drive I , obtain the cumulative overload amount P of the DC network drive sum .

[0090] According to the cumulative overload amount P of the DC network drive sum and the overload derating factor P th , adjust the output current limit amount I(t of the DC network drive at time t I ). I )

[0091] where i = 0, 1, 2,..., I, and I is a positive integer

[0092] In some embodiments, the load drive is used to

[0093] Obtain the DC bus voltage V(t of the load drive I ), and compare the DC bus voltage V(t of the load drive I ) with the normal minimum DC bus voltage V of the load drive min .

[0094] If the DC voltage V(t of the load drive I ) is less than the normal minimum DC bus voltage V of the load drive min , then according to the DC bus voltage V(t of the load drive I ), the normal minimum DC bus voltage V of the load drive min and the rated output voltage V of the load drive e , adjust the output voltage of the load drive

[0095] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made to them in form and details without departing from the spirit and scope of the present disclosure. Any person skilled in the art can make their respective changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A method for preventing busbar collapse in a ship electrical system, characterized in that, Including: The ship electrical system includes M DC networked drivers, and at sampling time t i detect whether the DC networked driver is in an overload state; If so, obtain the rated current I of the DC networking driver e and the sampling time t i The output current I(t) of the DC networking driver i ); According to the rated current I of the DC networking driver e and the sampling time t i the output current I(t i ) of the DC networking driver, the overload factor K(t i ) of the DC networking driver is obtained, where K(t i ) = I(t i ) - I e ; According to the overload factor K(t i ) of the DC networked driver and the overload time of the DC networked driver, the cumulative overload amount P sum of the DC networked driver is obtained, where According to the cumulative overload amount P of the DC networking driver sum and the overload derating factor , adjust the output current limit of the DC networking driver at the moment , where where \(i = 0, 1, 2, \ldots, I\), is a positive integer.

2. The method according to claim 1, wherein 。 3. The method according to claim 1, characterized in that, After adjusting the output current of the DC networked driver, the method further includes: Obtain the DC bus voltage of the load driver , and compare the DC bus voltage of the load driver with the normal minimum DC bus voltage of the load driver ; If the DC bus voltage of the load driver is less than the normal minimum DC bus voltage of the load driver , then, based on the DC bus voltage of the load driver , the normal minimum DC bus voltage of the load driver , and the rated output voltage of the load driver , adjust the output voltage of the load driver.

4. The method according to claim 3, characterized in that, Adjusting the output voltage of the load driver includes: The adjusted output voltage of the load driver is calculated by the following formula: ； Among them, represents the output voltage of the load driver after adjustment, represents the normal minimum DC bus voltage of the load driver, represents the rated output voltage of the load driver, and K is the output derating factor.

5. The method according to claim 4, wherein The method further includes: When is adjusted to 1 / 2V e , it is detected whether the load driver is still in the overload state. If so, the load driver fails and stops operating.

6. A ship electrical system, characterized in that, Including M DC networked drivers, a bus, and N load drivers, the M DC networked drivers and the N load drivers are connected through the bus; The DC networked driver is used for: At sampling time t i Detect whether the DC networked driver is in an overload state; If so, obtain the rated current I of the DC networking driver e and the sampling time t i The output current I(t) of the DC networking driver i ); According to the rated current I of the DC networking driver e and the sampling time t i the output current I(t i ) of the DC networking driver, the overload factor K(t i ) of the DC networking driver is obtained, where K(t i ) = I(t i ) - I e ; According to the overload coefficient K(t i ) of the DC networked driver and the overload time of the DC networked driver, the cumulative overload amount P sum of the DC networked driver is obtained, where ; Based on the cumulative overload P of the DC network drive sum and the overload derating factor , adjust the output current limit of the DC network drive at the moment , where where \(i = 0, 1, 2, \ldots, I\), which are positive integers, and \(M\) and \(N\) are positive integers.

7. The marine electrical system according to claim 6, characterized in that, The load driver is used for: Obtain the DC bus voltage of the load driver , and compare the DC bus voltage of the load driver with the normal minimum DC bus voltage of the load driver ; If the DC bus voltage of the load driver is less than the normal minimum DC bus voltage of the load driver , then according to the DC bus voltage of the load driver , the normal minimum DC bus voltage of the load driver and the rated output voltage of the load driver , adjust the output voltage of the load driver.

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