A single-phase power supply device

Abstract

The present invention discloses a single-phase power supply device, which includes a Vv transformer, a TSC, a TCR, a first SVG and a second SVG. The TCR and the first SVG reduce or cancel the first reactive component of the output current in phase with the total output voltage of the Vv transformer, and the TSC and the second SVG reduce or cancel the second reactive component of the output current. When one of the first reactive component and the second reactive component is an inductive reactive component, the other is a capacitive reactive component, achieving balanced power supply, reducing or even eliminating the negative sequence current on the three-phase voltage input side of the Vv transformer, and reducing the possibility of overload and negative sequence tripping of the Vv transformer. In addition, the reactive component of the output current is relatively small compared with the active component, and the passive devices TSC and TCR cancel a part of the reactive component of the output current, and the cost of the passive devices is relatively low. Therefore, the first SVG and the second SVG with smaller capacity can be selected, reducing the cost.

Description

Technical Field

[0001] The present invention relates to the field of traction power supply, and particularly to a single-phase power supply device. Background Art

[0002] The electrified railways in China are powered by a single-phase AC traction power supply method. The transformer converts the three-phase high-voltage power of the three-phase power grid into two independent single-phase powers, and the two independent single-phase powers respectively supply power to the catenaries of two sections of electrified railways. However, since the traction load of the electrified railway is a typical fluctuating and impact load, the load difference between the two catenaries is often relatively large. Therefore, a large negative sequence current will be generated on the three-phase voltage input side of the transformer, which is likely to cause the transformer to be overloaded and negatively sequence tripped. Summary of the Invention

[0003] The object of the present invention is to provide a single-phase power supply device, which can achieve balanced power supply, reduce or even eliminate the negative sequence current on the three-phase voltage input side of the Vv transformer, reduce the possibility of the Vv transformer being overloaded and negatively sequence tripped, and reduce the economic cost.

[0004] To solve the above technical problems, the present invention provides a single-phase power supply device, including:

[0005] A Vv transformer, a TSC, a TCR, a first SVG, and a second SVG;

[0006] The input end of the Vv transformer is connected to the three-phase power grid. The first winding and the second winding at the output end of the Vv transformer are connected in series. The first winding is respectively connected in parallel with the TCR and the first SVG, and the second winding is respectively connected in parallel with the TSC and the second SVG;

[0007] The TCR is used to output a first compensation current, and the first SVG is used to output a second compensation current; the magnitude of the first current vector sum of the first compensation current and the second compensation current is not greater than the magnitude of the first reactive component of the output current in the same phase as the total output voltage of the Vv transformer, and the numerical value of the difference is less than the first preset range, and the directions are opposite;

[0008] The TSC is used to output a third compensation current, and the second SVG is used to output a fourth compensation current; the magnitude of the second current vector sum of the third compensation current and the fourth compensation current is not greater than the magnitude of the second reactive component of the output current, and the numerical value of the difference is less than the second preset range, and the directions are opposite;

[0009] When one of the first reactive component and the second reactive component is an inductive reactive component, the other is a capacitive reactive component.

[0010] Preferably, it further includes a current acquisition device for detecting the output current.

[0011] Preferably, it further includes:

[0012] A control module, configured to obtain the first current vector sum according to the magnitude of the output current and the phase angle between the total output voltage of the Vv transformer and the output voltage of the first winding, obtain the second current vector sum according to the magnitude of the output current and the phase angle between the total output voltage of the Vv transformer and the output voltage of the second winding, control the first SVG to output a second compensation current according to the first current vector sum and the first compensation current, and control the second SVG to output a fourth compensation current according to the second current vector sum and the third compensation current.

[0013] Preferably, controlling the first SVG to output a second compensation current according to the first current vector sum and the first compensation current includes:

[0014] Controlling the first SVG to output a second compensation current in a closed-loop manner according to the first current vector sum and the first compensation current;

[0015] Controlling the second SVG to output a fourth compensation current according to the second current vector sum and the third compensation current includes:

[0016] Controlling the second SVG to output a fourth compensation current in a closed-loop manner according to the second current vector sum and the third compensation current.

[0017] Preferably, it further includes an alarm module, and the control module is further configured to control the alarm module to alarm when detecting that the magnitude of the output current is greater than a first preset threshold.

[0018] Preferably, the alarm module includes a sound alarm module and / or a display alarm module.

[0019] Preferably, the control module is a full digital control system based on DSP.

[0020] Preferably, it further includes:

[0021] A power supply module, configured to supply power to the first SVG and the second SVG.

[0022] Preferably, it further includes:

[0023] A switch module, which is connected in series between the output end of the Vv transformer and the load, and is configured to disconnect when the magnitude of the output current is greater than a second preset threshold.

[0024] The present invention provides a single-phase power supply device, including a Vv transformer, a TSC, a TCR, a first SVG, and a second SVG. The TCR and the first SVG reduce or cancel the first reactive component of the output current in phase with the total output voltage of the Vv transformer, and the TSC and the second SVG reduce or cancel the second reactive component of the output current. When one of the first reactive component and the second reactive component is an inductive reactive component, the other is a capacitive reactive component, achieving balanced power supply, reducing or even eliminating the negative sequence current on the three-phase voltage input side of the Vv transformer, and reducing the possibility of overload and negative sequence tripping of the Vv transformer. In addition, the reactive component of the output current is relatively small compared with the active component, and the passive devices TSC and TCR cancel a part of the reactive component of the output current, and the cost of the passive devices is relatively low. Therefore, the first SVG and the second SVG with smaller capacities can be selected, reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 is a schematic structural diagram of a single-phase power supply device provided by the present invention;

[0027] Figure 2 is a three-phase input voltage vector diagram of a single-phase power supply device provided by the present invention;

[0028] Figure 3 is a vector diagram of voltage and current of a single-phase power supply device provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The core of the present invention is to provide a single-phase power supply device, which can achieve balanced power supply, reduce or even eliminate the negative sequence current on the three-phase voltage input side of the Vv transformer, reduce the possibility of overload and negative sequence tripping of the Vv transformer, and reduce the economic cost.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0031] Please refer to Figure 1 ,Figure 1 The structural schematic diagram of a single-phase power supply device provided by the present invention, the single-phase power supply device includes:

[0032] Vv transformer 1, TCR (Thyristor Controlled Reactor) 2, TSC (Thyristor Switched Capacitor) 3, first SVG (Static Var Generation) 4 and second SVG 5;

[0033] The input end of the Vv transformer 1 is connected to a three-phase power grid. The first winding and the second winding at the output end of the Vv transformer 1 are connected in series. The first winding is respectively connected in parallel with the TCR 2 and the first SVG 4. The second winding is respectively connected in parallel with the TSC 3 and the second SVG 5;

[0034] The TCR 2 is used to output a first compensation current, and the first SVG 4 is used to output a second compensation current; the first current vector sum I c1 of the first compensation current and the second compensation current is not greater than the magnitude of the first reactive component of the output current I o in the same phase as the total output voltage U o of the Vv transformer 1, and the numerical value of the difference is less than the first preset range, and the directions are opposite;

[0035] The TSC 3 is used to output a third compensation current, and the second SVG 5 is used to output a fourth compensation current; the second current vector sum I c2 of the third compensation current and the fourth compensation current is not greater than the magnitude of the second reactive component of the output current I o and the numerical value of the difference is less than the second preset range, and the directions are opposite;

[0036] When one of the first reactive component and the second reactive component is an inductive reactive component, the other is a capacitive reactive component.

[0037] Considering that the traction load of an electrified railway is a typical fluctuating and impact load, when the transformer supplies power to it, a large negative sequence current may be generated on the three-phase voltage input side of the transformer, resulting in transformer overload and negative sequence tripping.

[0038] To solve the above technical problems, the present invention provides a single-phase power supply device, which includes a Vv transformer 1, a TSC 3, a TCR 2, a first SVG 4 and a second SVG 5. Figure 1 The three-phase input voltages of the Vv transformer 1 in it are U A 、U B and U C ,U A 、U Band U C Please refer to Figure 2 for the relationship between the magnitude and phase of Figure 2 Figure Figure 2 is the three-phase input voltage vector diagram of a single-phase power supply device provided by the present invention. It can be seen from the figure that the magnitudes of U A , U B and U C are equal, and the phase difference between any two of them is 120°. The output voltage of the first winding at the output end of the Vv transformer 1 is U1, the output voltage of the second winding at the output end of the Vv transformer 1 is U2, and the total output voltage of the Vv transformer 1 is U o , and U o is the vector sum of U1 and U2. For example, when U o = 27.5 KV, The input end of the Vv transformer 1 is connected to a three-phase power grid. The first winding and the second winding at the output end of the Vv transformer 1 are connected in series, so that the three-phase voltage can be transformed into a single-phase voltage output, and only supply power to the catenary of a section of electrified railway.

[0039] Preferably, to make the load of the transformer operate at a unity power factor, taking the traction condition as an example, the output current I o of the Vv transformer 1 is in the same phase as the total output voltage U o , and the active component magnitudes of the output current I o on the two output windings of the Vv transformer 1 are the same, while the reactive component magnitudes are equal, and one is an inductive reactive component and the other is a capacitive reactive component. To achieve the above purpose, the first winding is respectively connected in parallel with the TCR2 and the first SVG4, and the second winding is respectively connected in parallel with the TSC3 and the second SVG5. The TCR2 and the first SVG4 cancel the first reactive component of the output current I o that is in the same phase as the total output voltage U o of the Vv transformer 1, and the TSC3 and the second SVG5 cancel the second reactive component of the output current I o .

[0040] When one of the first reactive component and the second reactive component is an inductive reactive component, the other is a capacitive reactive component. Specifically, both the TCR2 and the first SVG4 can output inductive reactive current to cancel the capacitive reactive component in the output current I o , and the magnitude of this inductive reactive current is equal to and in the opposite phase of the capacitive reactive component magnitude of the output current I o ; at this time, both the TSC3 and the second SVG5 will output capacitive reactive current to cancel the output current I oThe capacitive reactive component in it, the magnitude of the capacitive reactive current is equal to that of the inductive reactive component and the phases are opposite. Of course, vice versa, both TCR2 and the first SVG4 can output capacitive reactive current to cancel the output current I o The inductive reactive component in it, the magnitude of the capacitive reactive current is equal to that of the inductive reactive component and the phases are opposite; at this time, both TSC3 and the second SVG5 can output inductive reactive current to cancel the output current I o The capacitive reactive component in it, the magnitude of the inductive reactive current is equal to that of the capacitive reactive component and the phases are opposite. Which specific method to adopt can be determined according to the load of the Vv transformer 1, and this application does not make special limitations here.

[0041] Please refer to Figure 3 , Figure 3 is the vector diagram of the voltage and current of a single-phase power supply device provided by the present invention. The reactive component of the output current I o on the first winding is I op , the reactive component of the output current I o on the second winding is I oq . TCR2 is used to output the first compensation current, the first SVG4 is used to output the second compensation current, and the first current vector sum I c1 of the first compensation current and the second compensation current is equal in magnitude and opposite in direction to I op ; TSC3 is used to output the third compensation current, and the second SVG5 is used to output the fourth compensation current; the second current vector sum I c2 of the third compensation current and the fourth compensation current is equal in magnitude and opposite in direction to I oq . Through the above method, the currents on the first winding and the second winding of the Vv transformer 1 are equal in magnitude and in phase with the voltages on the two windings respectively, realizing balanced power supply in the way of reactive power compensation, reducing or even eliminating the negative sequence current on the three-phase voltage input side of the Vv transformer 1, and reducing the possibility of overload and negative sequence tripping of the Vv transformer 1.

[0042] In practical applications, considering that the transformer can withstand a certain negative sequence current, and in order to further select the first SVG and the second SVG with smaller capacities, it is allowed that the magnitude of the first current vector sum is slightly smaller than that of the first reactive component, and the magnitude of the second current vector sum is slightly smaller than that of the second reactive component. The values of the first preset range and the second preset range are set according to the requirements for unbalance degree in actual applications such as grid parameters, load parameters, and standard requirements. Among them, the unbalance degree is the magnitude of the negative sequence component of the current in the three-phase power grid / the magnitude of the positive sequence component of the current in the three-phase power grid. For example, the unbalance degree can be 2% or 1.3%.

[0043] In addition, the reactive component of the output current I o in the same phase as the total output voltage U of the Vv transformer 1 o is relatively small compared to the active component, and the reactive component of the output current is offset by using the passive devices TSC3 and TCR2. Moreover, the cost of the passive devices is relatively low. Therefore, the relatively small-capacity first SVG4 and second SVG5 can be selected, reducing the cost.

[0044] Based on the above embodiments,

[0045] As a preferred embodiment, it further includes a current acquisition device for detecting the output current.

[0046] In the present invention, by setting a current acquisition device to detect the output current, based on this, the magnitude of the first current I c1 for offsetting the reactive component of the output current and the magnitude of the second current I c2 can be determined first, so as to further obtain the magnitude of the second compensation current output by the first SVG4 and the magnitude of the fourth compensation current output by the second SVG5, and finally reduce or eliminate the negative sequence current generated on the three-phase voltage input side of the transformer, achieving balanced power supply, and the method is simple.

[0047] In addition, protection measures can also be taken according to the magnitude of the output current detected by the current acquisition device, such as setting an alarm device, etc., to improve the safety and reliability of the single-phase power supply device.

[0048] As a preferred embodiment, it further includes:

[0049] a control module for obtaining the first current vector sum I o according to the magnitude of the output current and the phase angle between the total output voltage U of the Vv transformer 1 and the output voltage U1 of the first winding, obtaining the second current vector sum I c1 according to the magnitude of the output current I o and the phase angle between the total output voltage U of the Vv transformer 1 and the output voltage U2 of the second winding, controlling the first SVG4 to output the second compensation current according to the first current vector sum I o and the first compensation current, and controlling the second SVG5 to output the fourth compensation current according to the second current vector sum I c2 and the third compensation current. c2 c2

[0050] Please refer to Figure 3 Figure 3 which is the vector diagram of the voltage and current of a single-phase power supply device provided by the present invention. In this embodiment, the control module obtains the magnitude of the output current I o detected by the current acquisition device, and the first current vector sum Ic1 is equal to the output current I o multiplied by the total output voltage U of the Vv transformer 1 o the sine value of the phase angle between the output voltage U1 of the first winding and the second current vector sum I c2 is equal to the output current I o multiplied by the total output voltage U of the Vv transformer 1 o the sine value of the phase angle between the output voltage U2 of the second winding and the first SVG4 outputs the second compensation current with the magnitude of the first current vector sum I c1 the difference between the magnitude of the second current vector sum I and the magnitude of the first compensation current, and the second SVG5 outputs the fourth compensation current with the magnitude of the second current vector sum I c2 the difference between the magnitude of the second current vector sum I and the magnitude of the second compensation current.

[0051] For different types of loads, the control order of the output currents of the TCR2, TSC3, the first SVG4, and the second SVG5 is different. It is also possible to control the time and magnitude of the first compensation current output by the TSC3 and the third compensation current output by the TCR2 through the control module. This application does not make specific limitations on this.

[0052] In summary, the present invention realizes the automatic control of the second compensation current output by the first SVG4 and the fourth compensation current output by the second SVG5 by setting a control module, realizes balanced power supply, and reduces or even eliminates the negative sequence current on the three-phase voltage input side of the Vv transformer 1.

[0053] As a preferred embodiment, controlling the first SVG4 to output the second compensation current according to the first current vector sum and the first compensation current includes:

[0054] Controlling the first SVG4 to output the second compensation current in a closed-loop manner according to the first current vector sum and the first compensation current;

[0055] Controlling the second SVG5 to output the fourth compensation current according to the second current vector sum and the third compensation current includes:

[0056] Controlling the second SVG5 to output the fourth compensation current in a closed-loop manner according to the second current vector sum and the third compensation current.

[0057] Closed-loop control is a control method that corrects according to the output feedback of the first SVG4 / second SVG5. When the deviation between the actual and the planned is measured, it is corrected according to the preset standard. In this embodiment, the negative feedback form in closed-loop control is adopted. The first SVG4 is controlled according to the difference between the second compensation current collected in real time / preset period and the first preset compensation current value, and the second SVG5 is controlled according to the difference between the fourth compensation current collected in real time / preset period and the second preset compensation current value. In this embodiment, the single-phase power supply device can maintain the preset state through self-regulation, improving the anti-interference ability and reliability.

[0058] As a preferred embodiment, it further includes an alarm module, and the control module is further configured to control the alarm module to alarm when detecting that the magnitude of the output current is greater than the first preset threshold.

[0059] In this embodiment, when the control module detects that the magnitude of the output current is greater than the first preset threshold, it controls the alarm module to alarm, which is convenient for users to perform maintenance in time, improving the reliability and safety of the operation of the single-phase power supply device.

[0060] As a preferred embodiment, the alarm module includes a sound alarm module and / or a display alarm module.

[0061] In this embodiment, when the control module detects that the magnitude of the output current is greater than the first preset threshold, it can control the alarm module to emit an alarm prompt sound and / or display an alarm message, which is convenient for users to perform maintenance in time. Specifically, the sound alarm module can be a buzzer, and the display alarm module can be an LED display screen, which is not particularly limited herein.

[0062] As a preferred embodiment, the control module is a full digital control system based on DSP.

[0063] In this embodiment, a full digital control system based on DSP is adopted as the control module. It is a control system suitable for performing digital signal processing operations. Its main application is to implement various digital signal processing algorithms in real time and quickly and perform control, with simple operation and high reliability.

[0064] In addition, other devices that can meet the control requirements can also be used, which are not particularly limited in this application.

[0065] As a preferred embodiment, it further includes:

[0066] A power supply module for supplying power to the first SVG4 and the second SVG5.

[0067] In this embodiment, a power supply module is provided to supply power to the first SVG4 and the second SVG5. Specifically, by respectively controlling the switching tubes of the first SVG4 and the second SVG5, the second compensation current output by the first SVG4 and the fourth compensation current output by the second SVG5 are respectively controlled. For example, the power supply module may include a power supply switch and a power supply. The power supply supplies power to the first SVG4 and the second SVG5 when the power supply switch is closed, with a simple structure and easy to implement.

[0068] As a preferred embodiment, it further includes:

[0069] A switch module, which is connected in series between the output terminal of the Vv transformer 1 and the load, and is used to disconnect when the magnitude of the output current is greater than a second preset threshold.

[0070] In this embodiment, a switch module is provided to disconnect when the magnitude of the output current is greater than a second preset threshold, improving the working reliability and safety of the single-phase power supply device. Specifically, the control module can be used to control the switch module, or it can be other control methods, and the present application does not make special limitations on this.

[0071] It should be noted that in this specification, the term "including", "comprising" or any other variant thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0072] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A single-phase power supply device, characterized in that, It includes a Vv transformer, a TCR, a TSC, a first SVG, and a second SVG; The input end of the Vv transformer is connected to a three-phase power grid. The first winding and the second winding at the output end of the Vv transformer are connected in series. The first winding is respectively connected in parallel with the TCR and the first SVG, and the second winding is respectively connected in parallel with the TSC and the second SVG; The TCR is used to output a first compensation current, and the first SVG is used to output a second compensation current; the magnitude of the first current vector sum of the first compensation current and the second compensation current is not greater than the magnitude of the first reactive component of the output current in phase with the total output voltage of the Vv transformer, and the numerical value of the difference is less than a first preset range, and the directions are opposite; The TSC is used to output a third compensation current, and the second SVG is used to output a fourth compensation current; the magnitude of the second current vector sum of the third compensation current and the fourth compensation current is not greater than the magnitude of the second reactive component of the output current, and the numerical value of the difference is less than a second preset range, and the directions are opposite; When one of the first reactive component and the second reactive component is an inductive reactive component, the other is a capacitive reactive component; A control module, which is used to obtain the first current vector sum according to the magnitude of the output current and the phase angle between the total output voltage of the Vv transformer and the output voltage of the first winding, obtain the second current vector sum according to the magnitude of the output current and the phase angle between the total output voltage of the Vv transformer and the output voltage of the second winding, control the first SVG to output the second compensation current according to the first current vector sum and the first compensation current, and control the second SVG to output the fourth compensation current according to the second current vector sum and the third compensation current.

2. The single-phase power supply device according to claim 1, characterized in that It also includes a current acquisition device, which is used to detect the output current.

3. The single-phase power supply device according to claim 1, characterized in that, Controlling the first SVG to output the second compensation current according to the first current vector sum and the first compensation current includes: Controlling the first SVG to output the second compensation current in a closed-loop manner according to the first current vector sum and the first compensation current; Controlling the second SVG to output the fourth compensation current according to the second current vector sum and the third compensation current includes: Controlling the second SVG to output the fourth compensation current in a closed-loop manner according to the second current vector sum and the third compensation current.

4. The single-phase power supply device according to claim 1, characterized in that, It also includes an alarm module. The control module is also used to control the alarm module to give an alarm when it detects that the magnitude of the output current is greater than a first preset threshold.

5. The single-phase power supply device according to claim 4, characterized in that, The alarm module includes a sound alarm module and / or a display alarm module.

6. The single-phase power supply device according to claim 1, wherein, The control module is a full digital control system based on DSP.

7. The single-phase power supply device according to claim 1, characterized in that It also includes: A power supply module, which is used to supply power to the first SVG and the second SVG.

8. The single-phase power supply device according to any one of claims 1 to 7, characterized in that It also includes: A switch module, which is connected in series between the output end of the Vv transformer and the load, and is used to disconnect when the magnitude of the output current is greater than a second preset threshold.

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