CN113394758B - Short-circuit current engineering calculation method for ship power system based on DC/DC converter power supply - Google Patents

Short-circuit current engineering calculation method for ship power system based on DC/DC converter power supply Download PDF

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CN113394758B
CN113394758B CN202110946119.8A CN202110946119A CN113394758B CN 113394758 B CN113394758 B CN 113394758B CN 202110946119 A CN202110946119 A CN 202110946119A CN 113394758 B CN113394758 B CN 113394758B
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CN113394758A (en
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纪锋
马伟明
马凡
付立军
梅丹
张彦
胡祺
陶涛
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Hubei Donghu Laboratory
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0092—Details of emergency protective circuit arrangements concerning the data processing means, e.g. expert systems, neural networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/006—Calibration or setting of parameters
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/04—Power grid distribution networks

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Abstract

The invention belongs to the technical field of safe operation of an electric power system, and discloses a short-circuit current engineering calculation method for a ship electric power system based on DC/DC converter power supply, which comprises 7 steps of single-machine short-circuit current initial steady-state component calculation, short-circuit discharge mode judgment, single-machine short-circuit current transient component peak value calculation, single-machine short-circuit current peak value calculation, single-machine short-circuit tail end steady-state current calculation, summary short-circuit current peak value calculation and summary short-circuit steady-state current calculation. The invention estimates the peak value and the peak value moment of the short-circuit current of the ship power system powered by the DC/DC converter by adopting an analytical calculation mode, has the advantages of better calculation simplicity and calculation speed than a simulation calculation method, has the error between the calculation result and the simulation result not exceeding 10 percent, belongs to the allowable range of engineering calculation, can effectively support the overall efficient design and safe operation analysis of the ship power system, and can be applied to other direct current for ships, new energy for land use and the like and accessed to a power supply type power grid by using the converter.

Description

Short-circuit current engineering calculation method for ship power system based on DC/DC converter power supply
Technical Field
The invention relates to the technical field of safe operation of independent power systems, in particular to a short-circuit current engineering calculation method for a ship power system based on power supply of a DC/DC converter, which can be used for carrying out short-circuit current engineering analysis calculation on a direct-current power grid supplied by the DC/DC converter and is suitable for a ship power system and a land-based new energy independent power grid.
Background
With the development of new energy technology and the maturity of power electronic conversion technology, in order to achieve the goals of emission reduction and efficiency improvement, ship power is gradually converted from traditional chemical energy to electric energy for driving, but the existing mature large-capacity power and electric energy storage adopts a direct current system, and the problems that output voltage fluctuates along with discharge intensity, attenuation along with discharge depth, output power is uncontrollable, and power equalization of parallel power supplies is difficult to achieve effectively exist, so that power needs to be supplied to a ship direct current load through a DC/DC converter.
The short-circuit tolerant capability of the power supply system of the power generator is different from that of a power supply system of the power generator, the over-current tolerant capability of a power electronic device is very limited, when the short-circuit fault occurs in the power supply system of the DC/DC converter, the output current of the DC/DC converter is generally limited to 1.5-3 times of rated current due to the self safety consideration of power transformation equipment, and if the short circuit occurs in a power grid, the output current of the DC/DC converter enters a constant current state after transient impact overshoot caused by an output filter and waits for the protection action of a switch. Therefore, the short-circuit characteristic of the DC/DC converter is completely different from the short-circuit output mechanism of the generator, the difference of the short-circuit characteristic is obvious, the conventional short-circuit current calculation method aiming at the conventional three-phase generator or multi-phase rectifier generator cannot be applied to the power supply system of the DC/DC converter, and the difficulty is brought to the protection and setting of the power grid. Therefore, a short-circuit current calculation method suitable for a DC/DC converter power supply type power system needs to be provided, and the protection setting requirements of the power grid are met.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a DC/DC converter-based power supply ship power system short-circuit current engineering calculation method, and solves the problems that engineering analysis calculation of the converter-based power supply ship power system short-circuit current is difficult to perform and system protection setting design cannot be effectively supported due to large difference between the converter short-circuit current characteristic and a generator.
In order to achieve the purpose, the invention provides a short-circuit current engineering calculation method of a ship power system based on DC/DC converter power supply, which is characterized by comprising the following steps:
the method is applied to a ship power system, and the power system is on a ship through a DC/DC converterThe direct current load is supplied with power, and the short-circuit path of the power system is provided withmDC/DC converter and 1 unidirectional conduction type loadmThe number set of the DC/DC converters is { M }, thiRated output voltage of the DC/DC converter isU idcRated output current ofI idcSteady state output power before short circuit isP i0After short circuit, the output current is limited toK idcDouble rated current, output filter capacitorC fi The method comprises the following steps:
1) calculating initial steady-state component of single-machine short-circuit currentI iss；
2) Damping ratio delta i Judging a short-circuit discharge mode as a short-circuit discharge mode criterion;
3) calculating transient component peak value of short-circuit current according to different short-circuit discharge modesI ist；
4) Calculating single machine short circuit current peak valueI isdcp=I iss+I ist；
5) Calculating the steady-state current of the short-circuit end of a single machineI isdcs=K dci ·I idc；
6) Calculating and summarizing short-circuit current peak valueI sdcp；
7) Calculating summary short-circuit steady-state currentI sdcs。
Preferably, the initial steady-state component of the short-circuit current of the single machine in the step 1)I issThe calculation method comprises the following steps:
Figure 843243DEST_PATH_IMAGE001
。
preferably, said step 2) damping ratio Δ i The calculation method comprises the following steps:
Figure 863151DEST_PATH_IMAGE002
in the formula (I), the compound is shown in the specification,R i in order to short-circuit the total resistance of the loop,L i is the total inductance of the short circuit loop.
Preferably, when Δ i <1 time, short circuit current transient component peakI istThe calculation method comprises the following steps:
Figure 6688DEST_PATH_IMAGE003
in the formula (I), the compound is shown in the specification,ω ithe angular velocity is represented by the angular velocity,L i the total inductance of the short-circuit loop is shown,t irepresenting the time of the peak of the transient component of the short-circuit current,eis a natural constant.
Preferably, when Δ i >1 time, short circuit current transient component peakI istThe calculation method comprises the following steps:
Figure 795652DEST_PATH_IMAGE004
in the formula (I), the compound is shown in the specification,L i the total inductance of the short-circuit loop is shown,t irepresenting the time of the peak of the transient component of the short-circuit current,p 1、p 2the root of the feature is represented,eis a natural constant.
Preferably, when Δ i Peak value of transient component of short-circuit current when =1I istThe calculation method comprises the following steps:
Figure 491076DEST_PATH_IMAGE005
in the formula (I), the compound is shown in the specification,L i the total inductance of the short-circuit loop is shown,t irepresenting the time of the peak of the transient component of the short-circuit current,eis a natural constant.
Preferably, the step 6) of calculating the summed short-circuit current peak valueI sdcpThe calculation method comprises the following steps:
Figure 355870DEST_PATH_IMAGE006
。
preferably, the short-circuit steady-state current is summarized in the step 7)I sdcsThe calculation method comprises the following steps:
Figure 162152DEST_PATH_IMAGE007
。
preferably, the ship power system adopts a flat power supply mode, the load is directly connected with the busbar, and the impedance of a cable from the load to the busbar is far smaller than the equivalent series impedance of an output filter of the DC/DC converter.
Preferably, the DC/DC converter output employs LC filtering.
The short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply effectively solves the problem that the protection calculation is not based on the reason that the short-circuit output characteristics of the DC/DC converter and a generator are different, realizes the analysis calculation of the whole network short-circuit current, and provides technical support for the selective protection design and the protection equipment selection of the DC/DC converter power supply type direct current power grid. The invention estimates the peak value and the peak value moment of the short-circuit current of the ship power system powered by the DC/DC converter by adopting an analytical calculation mode, has the advantages of better calculation simplicity and calculation speed than a simulation calculation method, has the error between the calculation result and the simulation result not exceeding 10 percent, belongs to the allowable range of engineering calculation, can effectively support the overall efficient design and safe operation analysis of the ship power system, and can be applied to other direct current for ships, new energy for land use and the like and accessed to a power supply type power grid by using the converter.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a diagram of a typical topology of a marine vessel power system powered by a DC/DC converter;
FIG. 3 is a simulated waveform diagram of the short-circuit current at the outlet F1 of the inverter Q1 in FIG. 2 when an inter-pole short circuit occurs;
fig. 4 is a simulated waveform diagram of a short-circuit current when an inter-pole short circuit occurs at the outlet F2 of the load breaker BKZ in fig. 2;
FIG. 5 is a simulated waveform of short circuit current when an inter-pole short circuit occurs at the load inlet F3 of FIG. 2;
fig. 6 is a comparison of results of simulation and engineering calculation of the peak value and the peak arrival time of the short-circuit current when the inter-electrode short circuit occurs at three short-circuit points in the embodiment.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
In order to make the technical solution of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. In addition, the technical features mentioned in the embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, the short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply provided by the present invention includes: calculating the initial steady state component of the single-machine short-circuit current, judging the short-circuit discharge mode, calculating the transient component peak value of the single-machine short-circuit current, calculating the steady state current at the tail end of the single-machine short circuit, calculating the peak value of the summary short-circuit current, and calculating the summary short-circuit steady state current by 7 steps. The calculation method provided by the invention is not only suitable for a ship power system, but also suitable for other marine direct current, land new energy and other power grids which are connected with a power supply by using the converter.
The ship power system converts electric energy output by direct current power supplies such as lithium batteries and the like into direct current with adjustable voltage amplitude, controllable discharge rate and power supply quality meeting system requirements through the DC/DC converter, supplies power to a whole ship load, supplies power to the load in a one-way conduction mode, and does not feed back the electric energy to the system in the operation process. The ship power system adopts a flat power supply mode, a load is directly connected with a busbar, and the impedance of a cable from the load to the busbar is far smaller than the equivalent series impedance of an output filter of the DC/DC converter. And LC filtering is adopted for the output of the DC/DC converter.
The following illustrates the implementation of the process of the invention:
DC/DC converter single machine short circuit current calculation
1.1 Single machine short-circuit Current calculation
Suppose there is a short circuit pathmA DC/DC converter and 1 unidirectional conducting load, the secondiRated output voltage of the DC/DC converter isU idcRated output current ofI idcSteady state output power before short circuit isP i0After short circuit, the output current is limited toK idcDouble rated current, output filter capacitorC fi Filter capacitor associated resistorR Cfi Output filter inductorL fi Filter inductor associated resistorR Lfi Filtering current-limiting resistorR fi The resistance of the cable from the outlet of the converter to the DC bus isR li The cable inductance isL li The load supporting capacitor isC z The resistance of the cable from the load inlet to the DC bus isR lz The cable inductance isL lz Short-circuit resistance ofR s 。
1.1.1 initial steady-state component of short-circuit Current
Let us rememberiThe initial steady-state component of the short-circuit current of the DC/DC converter isI issThen, then
Figure 71202DEST_PATH_IMAGE008
（1）
1.1.2 short-circuit discharge mode determination
Short circuit loop total resistance
Figure 671948DEST_PATH_IMAGE009
（2）
Short circuit loop total inductance
Figure 541815DEST_PATH_IMAGE010
（3）
Short circuit discharge mode criterion
Figure 886209DEST_PATH_IMAGE011
（4）
If Δ i <1, jumping to 1.1.3;
if Δ i >1, jumping to 1.1.4;
if Δ i If not, jumping to 1.1.5;
in the formula (I), the compound is shown in the specification,L fi 、L fk are respectively the firstiPlatform, firstkThe output filter inductance of the corresponding branch of the DC/DC converter,L li 、L lk are respectively the firstiPlatform, firstkThe cable inductance from the outlet of the corresponding branch of the DC/DC converter to the DC bus,kare subscript numbers.
1.1.3 Δ i <Transient component of 1 hour short circuit current
Note the book
Figure 649765DEST_PATH_IMAGE012
Short circuit current transient component
Figure 421412DEST_PATH_IMAGE013
（5）
Transient component peak moment of short circuit current
Figure 27843DEST_PATH_IMAGE014
Peak value of transient component of short-circuit current
Figure 175928DEST_PATH_IMAGE015
（6）
In the formula (I), the compound is shown in the specification,R i in order to short-circuit the total resistance of the loop,ω ithe angular velocity is represented by the angular velocity,β ithe phase angle is represented as a function of,L i the total inductance of the short-circuit loop is shown,t iindicating the time of the peak of the short-circuit current,δ iwhich represents the attenuation coefficient of the light beam,eis a natural constant.
1.1.4 Δ i >Transient component of 1 hour short circuit current
Note the book
Figure 793991DEST_PATH_IMAGE016
p i1、p i2Representing a feature root;
short circuit current transient component
Figure 2118DEST_PATH_IMAGE017
（7）
Transient component peak moment of short circuit current
Figure 846577DEST_PATH_IMAGE018
Peak value of transient component of short-circuit current
Figure 532774DEST_PATH_IMAGE019
（8）
1.1.5 Δ i Transient component of short-circuit current at time of =1
Note the book
Figure 270923DEST_PATH_IMAGE020
Short circuit current transient component
Figure 10471DEST_PATH_IMAGE021
（9）
Transient component peak moment of short circuit current
Figure 201281DEST_PATH_IMAGE022
Peak value of transient component of short-circuit current
Figure 691168DEST_PATH_IMAGE023
（10）
The invention is based on the mathematical completeness of the column and the delta i State of =1, in fact, it is almost impossible for Δ to exist in a real physical system due to the dispersion of line parameters and the time shift characteristic i State of =1.
1.1.6 short-circuit peak current
First, theiSingle-machine peak short-circuit current of DC/DC converter
Figure 283823DEST_PATH_IMAGE024
（11）
1.2 Single machine short-circuit terminal steady state current calculation
First, theiSingle-machine end steady-state short-circuit current of DC/DC converter
Figure 709119DEST_PATH_IMAGE025
（12）
Second, short circuit current summary calculation
Common on the short-circuit pathmAnd the DC/DC converter is connected to the grid, and the serial number set of the DC/DC converter is { M }.
Short circuit peak current summary calculation
The total peak current of the short circuit on the path is
Figure 387225DEST_PATH_IMAGE026
（13）
Wherein the content of the first and second substances,I sti calculated by the formulas (5) - (10).
Short-circuit steady-state current summary calculation
The total steady state current of the short circuit on the path is
Figure 415224DEST_PATH_IMAGE027
（14）
Specific examples of the present application are given below.
As shown in FIG. 2, Q1 and Q2 are 2 DC/DC converters for providing DC power supply to the whole network and having unidirectional output conduction characteristicC f1、C f2In order to output the filter capacitance,R Cf1、R Cf2in order to filter the associated resistance of the capacitor,R f1、R f2in order to filter the current-limiting resistor,L f1、L f2in order to output the filter inductance,R Lf1、R Lf2the filter inductor is associated with a resistor;
RZin order to be an equivalent load,C Z supporting a capacitor for a load;
BKQ1 and BKQ2 are DC/DC converters Q1 and Q2 output filter outlet direct current breakers respectively, and BKZ is a load inlet direct current breaker;
R l 1、R l2is the cable resistance from the outlet of the converter to the dc bus,L l1、L l2is the cable inductance from the converter outlet to the dc bus,R lZfor the resistance of the cable from the load inlet to the dc bus,L lZis the cable inductance from the load inlet to the dc bus.
The parameters of the DC/DC converter are: rated output voltageU dc1=U dc2=1000V and rated output current ofI dc1=I dc2=1080A, output current amplitude limit after short circuitK dc1=K dc2=2, converter output filter capacitanceC f1=C f2=3000 μ F, filter capacitance associated resistanceR Cf1=R Cf2Filter current limiting resistance of =0.4m omegaR f1=R f2=0.14 Ω, output filter inductanceL f1=L f2=9 muH, filter inductance associated resistanceR Lf1=R Lf2=0.184mΩ；
The circuit impedance of the system is calculated as follows: cable resistance from outlet of converter Q1 to direct current busR l1=74 μ Ω, cable inductanceL l1=1.995 muH, cable resistance of converter Q2 outlet to DC busR l2 =148 mu Ω cable inductanceL l2=4 muh, cable resistance from load inlet to dc busR lZ =125 μ Ω, cable inductanceL Z =2.6 muH, short-circuit resistanceRs=5μΩ；
The stable state output power before the short circuit of the calculation system is asP 01=P 02=1MW。
EXAMPLE 1 DC/DC CONVERTER Q1 SHORT-CIRCUIT BETWEEN THE OUTLET F1
Under the working condition, the short-circuit currents of the circuit breakers BKQ1 and BKQ2 are provided by the current transformer Q2, the circuit breaker BKZ has no short-circuit current, and the short-circuit current of the current transformer Q1 does not pass through the circuit breaker and is only used for triggering the self short-circuit protection of the Q1 equipment, so the short-circuit protection is not calculated in the embodiment.
1. Calculating initial steady-state component of single-machine short-circuit current
Figure 862386DEST_PATH_IMAGE028
2. Determining short circuit discharge mode
Short circuit loop total resistance
Figure 707851DEST_PATH_IMAGE029
Short circuit loop total inductance
Figure 873253DEST_PATH_IMAGE030
Short circuit discharge mode criterion
Figure 704943DEST_PATH_IMAGE031
3. Δ i >1-hour short circuit current transient component calculation
Figure 147557DEST_PATH_IMAGE032
Figure 39290DEST_PATH_IMAGE033
Then the formula is calculated from the transient component of the short-circuit current
Figure 426409DEST_PATH_IMAGE034
The time of the transient component peak of the short-circuit current can be obtained
Figure 796210DEST_PATH_IMAGE035
Peak value of transient component of short-circuit current
Figure 217964DEST_PATH_IMAGE036
4. Single machine short circuit current peak calculation
Figure 169346DEST_PATH_IMAGE037
5. Single machine short circuit end steady state current calculation
Figure 43761DEST_PATH_IMAGE038
6. Short circuit current summary peak calculation
There are only 1 DC/DC converter Q2 in the short circuit path, so the total peak current of the short circuit in the path is
Figure 482833DEST_PATH_IMAGE039
7. Short circuit current summary steady state value calculation
The total steady state current of the short circuit on the path is
Figure 634460DEST_PATH_IMAGE040
。
Example 2 load breaker BKZ outlet F2 interelectrode short circuit
Under the working condition, short-circuit currents of the circuit breakers BKQ1 and BKQ2 are respectively provided by current transformers Q1 and Q2, and short-circuit current of the circuit breaker BKZ is jointly provided by Q1 and Q2.
1. Single machine short circuit current initial steady state component calculation
Figure 867995DEST_PATH_IMAGE041
Figure 229706DEST_PATH_IMAGE042
2. Short circuit discharge mode determination
Short circuit loop total resistance
Figure 941310DEST_PATH_IMAGE043
Figure 462290DEST_PATH_IMAGE044
Short circuit loop total inductance
Figure 866727DEST_PATH_IMAGE045
Figure 715734DEST_PATH_IMAGE046
Short circuit discharge mode criterion
Figure 371974DEST_PATH_IMAGE047
Figure 357248DEST_PATH_IMAGE048
3. Δ i >Transient component of 1 hour short circuit current
Figure 932586DEST_PATH_IMAGE049
，
Figure 268889DEST_PATH_IMAGE050
，
Figure 587875DEST_PATH_IMAGE051
，
Figure 584912DEST_PATH_IMAGE052
Then the formula is calculated from the transient component of the short-circuit current
Figure 331151DEST_PATH_IMAGE053
The time of the transient component peak of the short-circuit current can be obtained
Figure 889172DEST_PATH_IMAGE054
Figure 887215DEST_PATH_IMAGE055
Peak of transient component of short circuit peak current
Figure 847080DEST_PATH_IMAGE056
Figure 764221DEST_PATH_IMAGE057
4. Single machine short circuit current peak calculation
Figure 75116DEST_PATH_IMAGE058
5. Single machine short circuit end steady state current calculation
Figure 860539DEST_PATH_IMAGE059
6. Short circuit current summary peak calculation
2 DC/DC converters Q1 and Q2 are arranged on the short-circuit path, so that the total peak current of the short-circuit on the path is
Figure 674911DEST_PATH_IMAGE060
7. Short circuit current summary steady state value calculation
The total steady state current of the short circuit on the path is
Figure 28532DEST_PATH_IMAGE061
EXAMPLE 3 interelectrode short-circuiting at the load inlet F3
The working condition is similar to that of embodiment 2, except that the impedance of the cable of the load branch is connected in series in the short circuit loop, and the influence of the impedance on the distribution of the short-circuit current between the two converter branches needs to be considered.
1. Initial steady-state component of single-machine short-circuit current
Figure 561144DEST_PATH_IMAGE062
2. Short circuit discharge mode determination
Short circuit loop total resistance
Figure 635411DEST_PATH_IMAGE063
Short circuit loop total inductance
Figure 835448DEST_PATH_IMAGE064
Figure 359970DEST_PATH_IMAGE065
Short circuit discharge mode criterion
Figure 3048DEST_PATH_IMAGE066
3. Δ i <Transient component of 1 hour short circuit current
Figure 271218DEST_PATH_IMAGE067
Then the formula is calculated from the transient component of the short-circuit current
Figure 60183DEST_PATH_IMAGE068
The time of the transient component peak of the short-circuit current can be obtained
Figure 365393DEST_PATH_IMAGE069
Peak value of transient component of short-circuit current
Figure 138177DEST_PATH_IMAGE070
4. Single machine short circuit current peak calculation
Figure 944459DEST_PATH_IMAGE071
5. Single machine short circuit end steady state current calculation
Figure 712564DEST_PATH_IMAGE072
6. Short circuit current summary peak calculation
2 DC/DC converters Q1 and Q2 are arranged on the short-circuit path, so that the total peak current of the short-circuit on the path is
Figure 578889DEST_PATH_IMAGE073
3-5 show the simulation waveforms of the short-circuit current (based on PSCAD simulation software) when the three embodiments of the DC/DC converter 1 are short-circuited at the outlet F1, the load breaker outlet F2 and the load inlet F3, respectively; fig. 6 shows the simulation and calculation comparison results. It can be seen that the deviation between the short-circuit current calculation method and the simulation calculation is not more than 10%, and the method belongs to the error range allowed by engineering calculation and can effectively support engineering design.
Those not described in detail in this specification are within the skill of the art.
Finally, it should be noted that the above detailed description is only for illustrating the technical solution of the patent and not for limiting, although the patent is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the patent can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the patent, which should be covered by the claims of the patent.

Claims (8)

1. The short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply is characterized in that the method is applied to the ship power system, the power system supplies power to a ship direct current load through the DC/DC converter, and a short-circuit path of the power system is provided with a short-circuit currentmDC/DC converter and 1 unidirectional conduction type loadmThe number set of the DC/DC converters is { M }, thiRated output voltage of the DC/DC converter isU idcRated output current ofI idcSteady state output power before short circuit isP i0After short circuit, the output current is limited toK idcDouble rated current, output filter capacitorC fi The method comprises the following steps:
1) calculating initial steady-state component of single-machine short-circuit currentI iss；
2) Damping ratio delta i Judging a short-circuit discharge mode as a short-circuit discharge mode criterion;
3) calculating transient component peak value of short-circuit current according to different short-circuit discharge modesI ist；
4) Calculating single machine short circuit current peak valueI isdcp=I iss+I ist；
5) Calculating the steady-state current of the short-circuit end of a single machineI isdcs=K dci ·I idc；
6) Calculating and summarizing short-circuit current peak valueI sdcp；
7) Calculating summary short-circuit steady-state currentI sdcs；
Damping ratio Delta in the step 2) i The calculation method comprises the following steps:
Figure 267245DEST_PATH_IMAGE001
in the formula (I), the compound is shown in the specification,R i in order to short-circuit the total resistance of the loop,L i is the total inductance of the short circuit loop;
total resistance of short circuit loop:
Figure 80480DEST_PATH_IMAGE002
（2）
short circuit loop total inductance:
Figure 375195DEST_PATH_IMAGE003
（3）
in the formula, a filter current-limiting resistorR fi Filter capacitor associated resistorR Cfi Filter inductor associated resistorR Lfi The resistance of the cable from the outlet of the converter to the DC bus isR li The resistance of the cable from the load inlet to the DC bus isR lz Short-circuit resistance ofR s Output filter inductorL fi The inductance of the cable from the converter outlet to the DC bus isL li The inductance of the cable from the load inlet to the DC bus isL lz 。
2. The short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply of claim 1, wherein the short-circuit current engineering calculation method comprises the following steps: initial steady-state component of short-circuit current of single machine in the step 1)I issThe calculation method comprises the following steps:
Figure 553367DEST_PATH_IMAGE004
。
3. the short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply of claim 1, wherein the short-circuit current engineering calculation method comprises the following steps: when delta i <1 time, short circuit current transient component peakI istThe calculation method comprises the following steps:
Figure 238426DEST_PATH_IMAGE005
in the formula (I), the compound is shown in the specification,ω ithe angular velocity is represented by the angular velocity,L i the total inductance of the short-circuit loop is shown,t irepresenting the time of the peak of the transient component of the short-circuit current,δ iwhich represents the attenuation coefficient of the light beam,eis a natural constant.
4. The short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply of claim 1, wherein the short-circuit current engineering calculation method comprises the following steps: when delta i >1 time, short circuit current transient component peakI istThe calculation method comprises the following steps:
Figure 917669DEST_PATH_IMAGE006
in the formula (I), the compound is shown in the specification,L i the total inductance of the short-circuit loop is shown,t iindicating the time of the peak of the short-circuit current,p i1、p i2the root of the feature is represented,δ iwhich represents the attenuation coefficient of the light beam,eis a natural constant.
5. The method for calculating short-circuit current engineering of ship power system supplied with power based on DC/DC converter as claimed in claim 1, wherein the delta is i Peak value of transient component of short-circuit current when =1I istThe calculation method comprises the following steps:
Figure 4574DEST_PATH_IMAGE007
in the formula (I), the compound is shown in the specification,L i the total inductance of the short-circuit loop is shown,t iindicating the time of the peak of the short-circuit current,δ iwhich represents the attenuation coefficient of the light beam,eis a natural constant.
6. The short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply of claim 1, wherein the short-circuit current engineering calculation method comprises the following steps: calculating the summary short-circuit current peak value in the step 6)I sdcpThe calculation method comprises the following steps:
Figure 619226DEST_PATH_IMAGE008
。
7. the short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply of claim 1, wherein the short-circuit current engineering calculation method comprises the following steps: summarizing short-circuit steady-state current in the step 7)I sdcsThe calculation method comprises the following steps:
Figure 791581DEST_PATH_IMAGE009
。
8. the short-circuit current engineering calculation method for the ship power system based on the DC/DC converter power supply of claim 1, wherein the short-circuit current engineering calculation method comprises the following steps: the ship power system adopts a flat power supply mode, a load is directly connected with a busbar, and the impedance of a cable from the load to the busbar is far smaller than the equivalent series impedance of an output filter of the DC/DC converter.
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