CN113013862B - Multi-direct-current power distribution network system control method and system for automatic power distribution - Google Patents
Multi-direct-current power distribution network system control method and system for automatic power distribution Download PDFInfo
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Abstract
The invention relates to a multi-direct-current power distribution network system control method for automatic power distribution. The control method comprises the steps that a droop control strategy is adopted, and a high-voltage direct-current voltage control reference signal and a low-voltage direct-current voltage control reference signal are respectively determined and obtained according to an obtained high-voltage direct-current end electric signal and an obtained low-voltage direct-current end electric signal; then according to the two high-voltage direct-current voltage control reference signals and the low-voltage direct-current voltage control reference signal, determining a first transformer inductive current control reference signal and a second transformer inductive current control reference signal, and then determining a final transformer inductive current control reference signal according to the two transformer inductive current control reference signals; and finally, after the pulse width modulation signal is determined according to the final transformer inductive current control reference signal and the inductive current signal, power distribution is realized according to the determined pulse width modulation signal, so that the aim of stabilizing the bus voltage is fulfilled, and meanwhile, the reasonability of power distribution in the multi-direct-current power distribution network system is improved.
Description
Technical Field
The invention relates to the field of interconnection and control research application of direct-current power distribution networks, in particular to a multi-direct-current power distribution network system control method and system for automatic power distribution.
Background
With the development of society and the highlighting of environmental problems, the status of energy sources is more and more important. The distributed power generation technology converts clean energy into usable electric energy, reduces environmental pollution and becomes a hotspot of current study of scholars. The method has the advantages of high reliability, low pollution and the like, but also has the defects of volatility, intermittence and the like, and large-scale grid connection inevitably affects a power grid. The direct current distribution network not only can fully utilize the distributed power supply and exert the advantages thereof, but also can directly access the direct current loads with different voltage grades to the corresponding voltage grade direct current interfaces, thereby reducing the electric energy conversion loss in the process. After the direct current distribution network subnets are connected with each other, the direct current distribution network subnets can support voltage and power mutually, so that the reliability of the direct current distribution network is obviously improved. Because the reasonable distribution of the power distribution has close relation with the stability of the bus voltage, the power between the buses of the direct-current power distribution network is reasonably distributed, the stable operation of the system can be maintained, and the power supply reliability can be guaranteed. The existing technology for controlling power distribution among buses of a direct current distribution network is realized by utilizing a communication system and a monitoring system based on a control strategy under the condition of the communication system: various operation parameters of the direct current distribution network are obtained through real-time monitoring of the monitoring system, various operation parameters of the direct current distribution network are summarized through information communication, and the control end achieves unified coordination management of the operation parameters. Although the strategy can achieve a good control effect, the control system is complex in structural design, needs a complex communication network and an optimized control algorithm for support, and occupies a large amount of bandwidth of a power distribution network system during operation. Therefore, a multi-direct-current power distribution network system control method for automatic power distribution is needed to be applied to the research of power distribution network power control.
There are many methods for controlling the power of a direct-current power distribution network: "ecological operation and enhancement of reliability by technical control" published in volume 5 of the IEEE Transactions on Smart Grid journal, volume 5, a three-level control structure is discussed, primary droop control is used for ensuring reliable operation of a power distribution network when communication fails, and secondary control and tertiary control realize optimization and economical operation of electric energy quality based on a digital communication technology. Although global information can be obtained, the disadvantage is that if there is a single point of failure in the system, when the central controller or any one of the communication links fails, the control command cannot be transmitted, and the corresponding control target cannot be realized. "high performance control of parallel AC-DC converter interfaces for hybrid microprocessors" published in IEEE Transactions on Smart Grid, volume 5, adopts a three-level Hierarchical control system, primary control adopts droop control to realize proportional sharing of load power, secondary control aims at eliminating bus voltage error generated by droop control, and the three-level control finishes interaction with an external system, thereby realizing interaction and control between different levels of a distribution network. However, when the network size is large, the calculation load of the central controller is large, and the response speed of the system is affected.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a multi-direct-current power distribution network system control method and system for automatic power distribution.
In order to achieve the purpose, the invention provides the following scheme:
a multi-direct current distribution network system control method for automatic power distribution comprises the following steps:
acquiring a high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal in a multi-direct-current distribution network system; the high-voltage direct current end electric signal comprises: a high voltage direct current terminal voltage signal and a high voltage direct current terminal current signal; the low voltage DC terminal electric signal comprises: a low voltage DC terminal voltage signal and a low voltage DC terminal current signal;
determining a high-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the high-voltage direct-current end electric signal;
determining a first transformer inductive current control reference signal according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal;
determining a low-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the low-voltage direct-current end electric signal;
determining a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal;
determining a final transformer inductive current control reference signal according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal;
obtaining an inductive current signal in a multi-direct-current power distribution network system;
determining a pulse width modulation signal according to the final transformer inductive current control reference signal and the inductive current signal;
and distributing power in the multi-direct-current power distribution network system according to the pulse width modulation signals.
Preferably, the determining a first transformer inductive current control reference signal according to the high-voltage dc voltage control reference signal and the high-voltage dc voltage signal specifically includes:
determining a first voltage difference value according to the high-voltage direct-current voltage control reference signal and the high-voltage direct-current terminal voltage signal by using a comparator;
and obtaining a first transformer inductive current control reference signal according to the first voltage difference value by using a proportional integrator.
Preferably, the determining a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current terminal voltage signal specifically includes:
determining a second voltage difference value according to the low-voltage direct-current voltage control reference signal and a low-voltage direct-current end voltage signal by using a comparator;
and obtaining a second transformer inductive current control reference signal according to the second voltage difference value by using a proportional integrator.
Preferably, the determining a final transformer inductive current control reference signal according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal specifically includes:
obtaining a first current difference value according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal by using a comparator; and the first current difference value is the final transformer inductance current control reference signal.
Preferably, the determining a pulse width modulation signal according to the final transformer inductor current control reference signal and the inductor current signal specifically includes:
obtaining a second current difference value according to the final transformer inductive current control reference signal and the inductive current signal by using a comparator;
and determining a pulse width modulation signal according to the second current difference value by using a proportional integrator.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a multi-direct-current power distribution network system control method for automatic power distribution, which comprises the steps of respectively determining and obtaining a high-voltage direct-current voltage control reference signal and a low-voltage direct-current voltage control reference signal according to an obtained high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal by adopting a droop control strategy, determining a first transformer inductive current control reference signal and a second transformer inductive current control reference signal according to the two high-voltage direct-current voltage control reference signals and the low-voltage direct-current voltage control reference signal, determining a final transformer inductive current control reference signal according to the two transformer inductive current control reference signals, and finally realizing power distribution according to the determined pulse width modulation signal after determining a pulse width modulation signal according to the final transformer inductive current control reference signal and the inductive current signal so as to achieve the purpose of stabilizing bus voltage and simultaneously improve the rationality of power distribution in the multi-direct-current power distribution network system.
The invention also provides a multi-direct-current power distribution network system control system for automatic power distribution, which corresponds to the multi-direct-current power distribution network system control method for automatic power distribution. The system specifically comprises:
the first signal acquisition module is used for acquiring a high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal in the multi-direct-current power distribution network system; the high-voltage direct current end electric signal comprises: a high voltage direct current terminal voltage signal and a high voltage direct current terminal current signal; the low voltage DC terminal electrical signal comprises: a low voltage DC terminal voltage signal and a low voltage DC terminal current signal;
the high-voltage direct current voltage control reference signal determining module is used for determining a high-voltage direct current voltage control reference signal by adopting a droop control strategy according to the high-voltage direct current end electric signal;
the first transformer inductive current control reference signal determining module is used for determining a first transformer inductive current control reference signal according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal;
the low-voltage direct-current voltage control reference signal determining module is used for determining a low-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the low-voltage direct-current end electric signal;
the second transformer inductive current control reference signal determining module is used for determining a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal;
a third transformer inductive current control reference signal determination module, configured to determine a final transformer inductive current control reference signal according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal;
the second signal acquisition module is used for acquiring an inductive current signal in the multi-direct-current power distribution network system;
the pulse width modulation signal determining module is used for determining a pulse width modulation signal according to the final transformer inductive current control reference signal and the inductive current signal;
and the power distribution module is used for distributing the power in the multi-direct-current power distribution network system according to the pulse width modulation signal.
Preferably, the first transformer inductive current control reference signal determining module specifically includes:
a first voltage difference value determination unit for determining a first voltage difference value according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal by using a comparator;
and the first transformer inductive current control reference signal determining unit is used for obtaining a first transformer inductive current control reference signal according to the first voltage difference value by using a proportional integrator.
Preferably, the second transformer inductive current control reference signal determining module specifically includes:
the second voltage difference value determining unit is used for determining a second voltage difference value according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal by using the comparator;
and the second transformer inductive current control reference signal determining unit is used for obtaining a second transformer inductive current control reference signal according to the second voltage difference value by using a proportional integrator.
Preferably, the third transformer inductive current control reference signal determining module specifically includes:
a first current difference determining unit, configured to obtain, by using a comparator, a first current difference according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal; and the first current difference value is the final transformer inductance current control reference signal.
Preferably, the pulse width modulation signal determining module specifically includes:
a second current difference determination unit, configured to obtain, by using a comparator, a second current difference according to the final transformer inductive current control reference signal and the inductive current signal;
and the pulse width modulation signal determining unit is used for determining a pulse width modulation signal according to the second current difference value by using a proportional integrator.
The technical problems solved by the multi-direct-current power distribution network system control system for automatic power distribution provided by the invention are the same as the technical effects of the multi-direct-current power distribution network system control method for automatic power distribution provided by the invention, and the detailed description is omitted.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a multi-DC distribution network system control method for automatic power distribution provided by the present invention;
FIG. 2 is a schematic diagram of a circuit structure of a bidirectional DC/DC converter used in the embodiment of the present invention;
fig. 3 is a model schematic diagram of a multi-dc distribution network system control method for automatic power distribution according to an embodiment of the present invention;
FIG. 4 is a waveform diagram illustrating voltage characteristics of a high voltage DC bus and a low voltage DC bus under load variation conditions, according to an embodiment of the present invention; wherein, fig. 4 (a) is a voltage characteristic waveform diagram of the high voltage DC bus under the condition of load change; FIG. 4 (b) is a waveform diagram of the voltage characteristic of the low voltage DC bus under load variation;
FIG. 5 is a waveform diagram illustrating characteristics of inductor current of a bidirectional DC/DC converter under a load variation condition according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a multi-dc distribution network system control system for automatic power distribution according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a multi-direct-current power distribution network system control method and system for automatic power distribution so as to improve the reasonability of power distribution among buses.
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description thereof.
As shown in fig. 1, the method for controlling a multi-dc distribution network system with automatic power distribution provided by the present invention includes:
step 100: and acquiring a high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal in the multi-direct-current distribution network system. The high-voltage direct current end electric signal includes: a high voltage direct current terminal voltage signal and a high voltage direct current terminal current signal. The low voltage DC terminal electrical signal comprises: the low-voltage direct-current terminal voltage signal and the low-voltage direct-current terminal current signal.
Step 101: and determining a high-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the high-voltage direct-current end electric signal.
Step 102: and determining a first transformer inductive current control reference signal according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal. Specifically, the method comprises the following steps:
a first voltage difference is determined from the high voltage dc voltage control reference signal and the high voltage dc voltage signal using a comparator.
And obtaining a first transformer inductive current control reference signal according to the first voltage difference value by using a proportional integrator.
Step 103: and determining a low-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the low-voltage direct-current end electric signal.
Step 104: and determining a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal. Specifically, the method comprises the following steps:
and determining a second voltage difference value according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal by using the comparator.
And obtaining a second transformer inductive current control reference signal according to the second voltage difference value by using a proportional integrator.
Step 105: and determining a final transformer inductive current control reference signal according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal. In particular, the method comprises the following steps of,
and obtaining a first current difference value according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal by using a comparator. The first current difference is the final transformer inductance current control reference signal.
Step 106: and acquiring an inductive current signal in the multi-direct-current power distribution network system.
Step 107: and determining a pulse width modulation signal according to the final transformer inductive current control reference signal and the inductive current signal. In particular, the method comprises the following steps of,
and obtaining a second current difference value according to the final transformer inductive current control reference signal and the inductive current signal by using the comparator.
And determining the pulse width modulation signal according to the second current difference value by using a proportional integrator.
Step 108: power in the multiple DC distribution grid system is distributed according to the pulse width modulation signal.
The present invention will be described in detail below by taking as an example the case where the power of the bidirectional DC/DC converter circuit shown in fig. 2 is controlled by the multi-DC distribution network system control method of automatic power distribution described above. In the specific application process, the following formula has applicability, and numerical value replacement can be carried out according to different system structures.
As shown in figure 2, the high-voltage DC bus and the low-voltage DC bus of the direct-current distribution network are connected through a bidirectional DC/DC converter, and the high-voltage direct-current side circuit comprises an impedance R 1 ，R 1 Resulting in a voltage loss of Δ U 1 . The low-voltage DC side circuit comprises an inductor L, a capacitor C and an impedance R 2 ，R 2 Resulting in a voltage loss of Δ U 2 . High voltage DC bus voltage of U dcH Low voltage DC bus voltage of U dcL . The voltage of the high-voltage direct current end of the bidirectional DC/DC converter is U dc1 Current is I dc1 . The voltage of the low-voltage direct current of the bidirectional DC/DC converter is U dc2 With a current of I dc2 . An inductive current of I L 。
Obtaining the rated voltage U of the low-voltage DC bus in FIG. 2 dc2rated 0.75kV, the maximum limit value U of the low-voltage DC bus voltage dc2max 0.7875kV, minimum limit of low voltage DC bus voltage U dc2min 0.7125kV, low voltage sag factor K dc2 Is 0.0375.
As shown in fig. 3, according to the low-voltage dc terminal electrical signal, the droop control strategy is adopted to determine the low-voltage dc voltage control reference signal U thereof dc2ref . Low-voltage DC voltage control reference signal U dc2ref The expression of (a) is as follows:
U dc2ref ＝U dc2rated -K dc2 ·I dc2
wherein, I dc2 Is a low-voltage direct-current end current signal of the DC/DC converter.
The obtained low-voltage direct-current end reference voltage U of the bidirectional DC/DC converter dc2ref With the voltage U at the low-voltage DC terminal dc2 After being compared by the comparator, the signal is passed throughA proportional-integral element (PI in FIG. 3) is obtained, and then a second bidirectional DC/DC converter inductive current control reference signal I is obtained Lref2 (i.e., the second transformer inductor current control reference signal).
And introducing a high-voltage direct-current terminal voltage and a current signal of the bidirectional DC/DC converter into the outer loop control of the direct current droop control strategy. Rated voltage U of high-voltage DC bus dc1rated 1.5kV, the maximum limit value U of the high-voltage DC bus voltage dc1max 1.575kV, the minimum limit value U of the high-voltage DC bus voltage dc1min 1.425kV, high voltage sag factor K dc1 Is 0.075. After introducing the voltage and current signals of the high-voltage DC bus to the outer ring control of the AC droop control, the high-voltage DC controls the reference signal U dc1ref The expression is as follows:
U dc1ref ＝U dc1rated -K dc1 ·I dc1
in the formula I dc1 Is a high-voltage direct-current end current signal of the bidirectional DC/DC converter.
High voltage DC control reference signal U dc1ref And a high voltage direct current terminal voltage signal U dc1 After comparison by the comparator, a first bidirectional DC/DC converter inductive current control reference signal I is obtained through a proportional-integral link Lref1 (i.e., the first transformer inductor current control reference signal).
First bidirectional DC/DC converter inductive current control reference signal I Lref1 And a second bidirectional DC/DC converter inductor current control reference signal I Lref2 Obtaining a reference signal I for controlling inductive current of the bidirectional DC/DC converter after comparison by a comparator Lref (i.e. the final converter inductor current control reference signal).
In the formula, K ps1 Is the proportionality constant of the high-voltage side, K is1 Is the integral constant of the high-voltage side, K ps2 Is a proportionality constant of the low-voltage side, K is2 And s is a differential operator, namely an integral constant of the low-voltage end.
Inductive current control reference signal I of bidirectional DC/DC converter Lref And the inductive current I L After comparison, a modulation signal of PWM (pulse width modulation) can be obtained through a PI (proportional integral) link.
The advantages of the solution provided by the present invention are explained below based on actual parameters.
As shown in fig. 4, at time 5 seconds, the low voltage DC bus has 0.1MW load put in, at time 10 seconds, the high voltage DC bus has 0.2MW load put in, at time 15 seconds, the low voltage DC bus has 0.1MW load removed, and at time 20 seconds, the high voltage DC bus has 0.2MW load removed. During this period, the high voltage DC bus voltage U dcH The amplitude is stabilized in a normal range (1.575 kV-1.425 kV), and the low-voltage DC bus voltage U dcL The amplitude is stable in the normal range (0.7875 kV-0.7125 kV).
As shown in fig. 5, at the time of 5 seconds, the low voltage DC bus is loaded with 0.1MW, and the direction of the change increment of the inductor current IL flowing through the bidirectional DC/DC converter is from the high voltage DC bus to the low voltage D C bus, that is, the high voltage DC bus distributes a part of the load added on the low voltage DC bus.
At the time of 10 seconds, 0.2MW load is put on the high-voltage DC bus, and the direction of the change increment of the inductive current IL flowing through the bidirectional DC/DC converter is from the low-voltage DC bus to the high-voltage DC bus, namely, the low-voltage DC bus distributes a part of the load added on the high-voltage DC bus.
At the moment of 15 seconds, 0.1MW load on the low-voltage DC bus is cut off, and the direction of the change increment of the inductive current IL flowing through the bidirectional DC/DC converter is from the low-voltage DC bus to the high-voltage DC bus, namely, the high-voltage DC bus also reduces a part of power output due to the reduction of the load on the low-voltage DC bus.
At 20 seconds, 0.2MW of load on the high voltage DC bus is removed, and the incremental change in the inductor current IL flowing through the bidirectional DC/DC converter is in the direction from the high voltage DC bus to the low voltage DC bus, i.e., the low voltage DC bus also reduces a portion of the power output due to the reduced load on the high voltage DC bus.
The invention also provides a multi-direct-current power distribution network system control system for automatic power distribution, which corresponds to the multi-direct-current power distribution network system control method for automatic power distribution. As shown in fig. 6, the system specifically includes: the device comprises a first signal acquisition module 1, a high-voltage direct-current voltage control reference signal determination module 2, a first transformer inductive current control reference signal determination module 3, a low-voltage direct-current voltage control reference signal determination module 4, a second transformer inductive current control reference signal determination module 5, a third transformer inductive current control reference signal determination module 6, a second signal acquisition module 7, a pulse width modulation signal determination module 8 and a power distribution module 9.
The first signal acquisition module 1 is used for acquiring a high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal in the multi-direct-current distribution network system. The high-voltage direct current end electric signal includes: a high voltage direct current terminal voltage signal and a high voltage direct current terminal current signal. The low voltage DC terminal electrical signal comprises: a low voltage dc terminal voltage signal and a low voltage dc terminal current signal.
The high-voltage direct current voltage control reference signal determining module 2 is used for determining a high-voltage direct current voltage control reference signal by adopting a droop control strategy according to the high-voltage direct current end electric signal.
The first transformer inductive current control reference signal determination module 3 is configured to determine a first transformer inductive current control reference signal according to the high-voltage dc voltage control reference signal and the high-voltage dc terminal voltage signal.
The low-voltage direct-current voltage control reference signal determining module 4 is used for determining the low-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the low-voltage direct-current end electric signal.
The second transformer inductive current control reference signal determining module 5 is configured to determine a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current terminal voltage signal.
The third transformer inductive current control reference signal determining module 6 is configured to determine a final transformer inductive current control reference signal according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal.
The second signal acquisition module 7 is used for acquiring an inductive current signal in the multi-dc power distribution network system.
The pulse width modulation signal determining module 8 is configured to determine a pulse width modulation signal according to the final transformer inductor current control reference signal and the inductor current signal.
The power distribution module 9 is used for distributing power in the multi-direct current power distribution network system according to the pulse width modulation signals.
As a preferred embodiment of the present invention, the first transformer inductive current control reference signal determining module 3 specifically includes: the device comprises a first voltage difference value determining unit and a first transformer inductive current control reference signal determining unit.
The first voltage difference value determining unit is used for determining a first voltage difference value according to the high-voltage direct current voltage control reference signal and the high-voltage direct current voltage signal by using the comparator.
The first transformer inductive current control reference signal determining unit is used for obtaining a first transformer inductive current control reference signal according to the first voltage difference value by using a proportional integrator.
As another preferred embodiment of the present invention, the second transformer inductor current control reference signal determining module 5 specifically includes: the second voltage difference value determining unit and the second transformer inductive current control reference signal determining unit.
The second voltage difference value determining unit is used for determining a second voltage difference value according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal by using the comparator.
The second transformer inductive current control reference signal determination unit is used for obtaining a second transformer inductive current control reference signal according to the second voltage difference value by using the proportional integrator.
As another preferred embodiment of the present invention, the third transformer inductor current control reference signal determining module 6 specifically includes: a first current difference determination unit.
The first current difference determining unit is used for obtaining a first current difference according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal by using the comparator. The first current difference is the final transformer inductance current control reference signal.
As another preferred embodiment of the present invention, the pulse width modulation signal determining module 8 specifically includes: a second current difference determination unit and a pulse width modulation signal determination unit.
The second current difference determining unit is used for obtaining a second current difference according to the final transformer inductive current control reference signal and the inductive current signal by using the comparator.
The pulse width modulation signal determining unit is used for determining a pulse width modulation signal according to the second current difference value by using a proportional integrator.
In summary, the method and system for controlling a multi-DC distribution network system with automatic power distribution provided by the present invention consider that DC droop control can achieve good control of bus voltage under a no-communication condition, so that two DC buses with different voltage levels are connected to each other through a bidirectional DC/DC converter, a DC droop control strategy is applied to power control, low-voltage bus voltage is stabilized through DC droop control, and voltage and current signals at a high-voltage DC end of the bidirectional DC/DC converter are introduced into outer loop control of the DC droop control strategy.
The method controls the voltage of the low-voltage bus by applying the direct current droop control strategy to the power control of the direct current distribution network, and introduces the voltage and current signals of the high-voltage direct current end of the bidirectional DC/DC converter into the specific operation process in the outer loop control of the direct current droop control strategy to control the power in real time.
The overall control principle is as follows: when the load of the low-voltage DC bus changes, the voltage of the low-voltage DC bus changes, and the application of the direct current droop control strategy controls and stabilizes the voltage of the low-voltage DC bus, so that the bidirectional DC/DC converter can act correspondingly. Wherein one action is removed as a load, the low voltage DC bus voltage rises and the DC bus power demand decreases. At this time, the power flowing from the high voltage DC bus to the low voltage DC bus through the bidirectional DC/DC converter will decrease. The other is put into service as a load, the DC bus voltage drops and the DC bus power demand rises. At this time, the power flowing from the high-voltage DC bus to the low-voltage DC bus through the bidirectional DC/DC converter increases.
When the load of the high-voltage DC bus changes, the voltage of the high-voltage DC bus also changes, and because the voltage and current signals of the high-voltage direct-current end of the bidirectional DC/DC converter are introduced into the outer loop control of the direct-current droop control strategy, the bidirectional DC/DC converter can make corresponding actions. In which one of the actions is removed as a load, the high voltage DC bus voltage rises and the high voltage DC bus power demand decreases, so that the power flowing from the low voltage DC bus through the bidirectional DC/DC converter to the high voltage DC bus will decrease. The other action is put into the load, the voltage of the high-voltage DC bus decreases, and the power demand of the high-voltage DC bus increases, so that the power flowing from the low-voltage DC bus to the high-voltage DC bus through the bidirectional DC/DC converter increases.
Therefore, no matter the load of the high-voltage DC bus or the low-voltage DC bus changes, the corresponding DC bus voltage changes. At this time, the bidirectional DC/DC converter adopts the multi-DC distribution network system control method for automatic power distribution, which is provided by the invention, and can automatically balance and distribute the power of the high-voltage DC bus and the low-voltage DC bus under the condition of no communication, so that the voltage of the high-voltage DC bus and the low-voltage DC bus is more stable, and the power distribution among the buses is more reasonable.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.
Claims (8)
1. A multi-direct current distribution network system control method for automatic power distribution is characterized by comprising the following steps:
acquiring a high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal in a multi-direct-current distribution network system; the high-voltage direct current end electric signal comprises: a high voltage direct current terminal voltage signal and a high voltage direct current terminal current signal; the low voltage DC terminal electrical signal comprises: a low voltage DC terminal voltage signal and a low voltage DC terminal current signal;
determining a high-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the high-voltage direct-current end electric signal;
determining a first transformer inductive current control reference signal according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal;
determining a low-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the low-voltage direct-current end electric signal;
determining a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal;
obtaining a first current difference value according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal by using a comparator; the first current difference value is a final transformer inductance current control reference signal;
obtaining an inductive current signal in a multi-direct-current power distribution network system;
determining a pulse width modulation signal according to the final transformer inductive current control reference signal and the inductive current signal;
and distributing power in the multi-direct-current power distribution network system according to the pulse width modulation signals.
2. The method for controlling a multi-dc distribution grid system for automatic power distribution according to claim 1, wherein the determining a first transformer inductor current control reference signal based on the high-voltage dc voltage control reference signal and the high-voltage dc terminal voltage signal comprises:
determining a first voltage difference value according to the high-voltage direct-current voltage control reference signal and the high-voltage direct-current terminal voltage signal by using a comparator;
and obtaining a first transformer inductive current control reference signal according to the first voltage difference value by using a proportional integrator.
3. The method for controlling a multi-dc distribution network system for automatic power distribution according to claim 1, wherein the determining a second transformer inductive current control reference signal according to the low-voltage dc voltage control reference signal and the low-voltage dc terminal voltage signal specifically comprises:
determining a second voltage difference value according to the low-voltage direct-current voltage control reference signal and a low-voltage direct-current end voltage signal by using a comparator;
and obtaining a second transformer inductive current control reference signal according to the second voltage difference value by using a proportional integrator.
4. The method for controlling a multiple dc power distribution grid system for automatic power distribution according to claim 1, wherein the determining a pwm signal according to the final transformer inductor current control reference signal and the inductor current signal comprises:
obtaining a second current difference value according to the final transformer inductive current control reference signal and the inductive current signal by using a comparator;
and determining a pulse width modulation signal according to the second current difference value by using a proportional integrator.
5. A multi-dc distribution network system control system with automatic power distribution, comprising:
the first signal acquisition module is used for acquiring a high-voltage direct-current end electric signal and a low-voltage direct-current end electric signal in the multi-direct-current power distribution network system; the high-voltage direct current end electric signal comprises: a high voltage direct current terminal voltage signal and a high voltage direct current terminal current signal; the low voltage DC terminal electrical signal comprises: a low voltage DC terminal voltage signal and a low voltage DC terminal current signal;
the high-voltage direct-current voltage control reference signal determining module is used for determining a high-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the high-voltage direct-current end electric signal;
the first transformer inductive current control reference signal determining module is used for determining a first transformer inductive current control reference signal according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal;
the low-voltage direct-current voltage control reference signal determining module is used for determining a low-voltage direct-current voltage control reference signal by adopting a droop control strategy according to the low-voltage direct-current end electric signal;
the second transformer inductive current control reference signal determining module is used for determining a second transformer inductive current control reference signal according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal;
a third transformer inductive current control reference signal determination module, configured to determine a final transformer inductive current control reference signal according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal;
the second signal acquisition module is used for acquiring inductive current signals in the multi-direct-current power distribution network system;
the pulse width modulation signal determining module is used for determining a pulse width modulation signal according to the final transformer inductive current control reference signal and the inductive current signal;
the power distribution module is used for distributing power in the multi-direct-current power distribution network system according to the pulse width modulation signals;
the third transformer inductive current control reference signal determination module specifically includes:
a first current difference determining unit, configured to obtain, by using a comparator, a first current difference according to the first transformer inductive current control reference signal and the second transformer inductive current control reference signal; and the first current difference value is the final transformer inductance current control reference signal.
6. The system for controlling a multi-dc distribution network system for automatic power distribution according to claim 5, wherein the first transformer inductor current control reference signal determining module specifically comprises:
a first voltage difference value determination unit for determining a first voltage difference value according to the high-voltage direct current voltage control reference signal and the high-voltage direct current terminal voltage signal by using a comparator;
and the first transformer inductive current control reference signal determining unit is used for obtaining a first transformer inductive current control reference signal according to the first voltage difference value by using a proportional integrator.
7. The system for controlling a multi-dc distribution network system for automatic power distribution according to claim 5, wherein the second transformer inductor current control reference signal determining module specifically comprises:
the second voltage difference value determining unit is used for determining a second voltage difference value according to the low-voltage direct-current voltage control reference signal and the low-voltage direct-current end voltage signal by using the comparator;
and the second transformer inductive current control reference signal determining unit is used for obtaining a second transformer inductive current control reference signal according to the second voltage difference value by using a proportional integrator.
8. The system for controlling a system of multiple direct current power distribution networks with automatic power distribution according to claim 5, wherein the pulse width modulation signal determining module specifically comprises:
a second current difference determination unit, configured to obtain, by using a comparator, a second current difference according to the final transformer inductive current control reference signal and the inductive current signal;
and the pulse width modulation signal determining unit is used for determining a pulse width modulation signal according to the second current difference value by using a proportional integrator.
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