Low-voltage power distribution energy storage system

Abstract

The application provides a low-voltage power distribution energy storage system, which is characterized in that: a tap is arranged on a low-voltage winding of a filter-type power distribution transformer, a power converter is connected to the tap of the low-voltage winding after AC filtering, so that an isolation transformer is not needed between the power distribution transformer and the power converter for voltage conversion; a filter reactance winding is wound in a filter-type power distribution transformer in a special structure, which is compact, has high integration, and does not affect the high-voltage winding and the low-voltage winding of the power distribution transformer, has no magnetic saturation characteristics, has good inductance linearity, and replaces a core filter reactance device with large heat generation and working noise and inductance nonlinearity; the technical problems of heat generation and electromagnetic interference caused by the isolation transformer and the core reactance device are solved, the power loss is significantly reduced, the space occupied by the equipment in the energy storage container is reduced, and the working noise is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage systems, in particular to a low-voltage power distribution energy storage system. BACKGROUND

[0002] The power supply reliability and power supply quality of the low-voltage power distribution network directly affect the daily power consumption of power users, so the power company has always focused on upgrading and reconstruction of the low-voltage power distribution network, and the application of electrochemical energy storage system in the low-voltage power distribution network has technical advantages such as power support, improvement of power supply reliability and power quality, and realization of peak load shifting. For the electrochemical energy storage system, the modular and small-sized distributed installation method is very suitable for application in the user side of the low-voltage power distribution system.

[0003] In practical application, the distributed electrochemical energy storage system is usually composed of electrochemical battery group, power unit, control and protection system, isolation transformer, AC filter, auxiliary system and the like, and is usually integrated in a container. For the energy storage converter system, the converter power unit, control unit, isolation transformer, core reactor, filter capacitor and the like are usually integrated in an energy storage converter cabinet.

[0004] However, in actual operation, the isolation transformer and the core reactor are the main heat sources and electromagnetic interference sources in the energy storage converter cabinet, so the energy storage converter cabinet needs to be specially designed for heat dissipation channels and forced heat dissipation measures, in addition, the isolation transformer and the core reactor also occupy a large space of the converter cabinet, and for the core reactor, it also has the disadvantages of high working noise, large heat generation and large heat loss, which has a negative impact on the promotion and application of the modular and small-sized low-voltage user side distributed energy storage system. SUMMARY

[0005] The purpose of the present application is to provide a low-voltage power distribution energy storage system, which solves the technical problems of large space of energy storage system equipment, large electromagnetic equipment heat and large electromagnetic interference in the existing low-voltage power distribution network.

[0006] Therefore, the present application provides a low-voltage power distribution energy storage system, which comprises an energy storage battery group, a power converter, a filter reactor, a filter type power distribution transformer, a DC side capacitor and a filter capacitor.

[0007] The filter type power distribution transformer comprises a low-voltage winding and a high-voltage winding, the low-voltage winding, the high-voltage winding and the winding of the filter reactor are wound on one core column, and the low-voltage winding is provided with a tap.

[0008] One end of the winding of the filter reactor and one end of the filter capacitor are connected with the tap.

[0009] Another end of the filter capacitor is connected with a low-voltage side of the filter distribution transformer.

[0010] Another end of the filter reactor winding is connected with an AC side of the power converter.

[0011] The power converter is connected with two ends of the DC side capacitor respectively.

[0012] Two ends of the DC side capacitor are connected with a positive electrode and a negative electrode of the energy storage battery pack respectively.

[0013] Preferably, the filter distribution transformer is a three-phase transformer.

[0014] Further, each low-voltage winding and high-voltage winding of the three-phase transformer is jointly wound on a core column with a winding of the filter reactor respectively.

[0015] Preferably, the filter reactor winding is composed of two sub-windings in reverse series.

[0016] Further, the two sub-windings are arranged in an up-down manner in the vertical direction of the core column.

[0017] Preferably, the number of turns, height and inner and outer radii of the two sub-windings are equal respectively.

[0018] Preferably, the high-voltage winding adopts a delta connection.

[0019] Preferably, another end of the filter capacitor is connected with a neutral line of the low-voltage side of the filter distribution transformer.

[0020] Further, the low-voltage winding adopts a star connection leading to the neutral line.

[0021] Preferably, the winding of the filter reactor is connected with the filter capacitor to form an AC filter.

[0022] Compared with the prior art, the embodiment of the present application has the following advantages:

[0023] In the embodiment of the present application, a low-voltage power distribution energy storage system is provided, comprising: an energy storage battery pack, a power converter, a filter reactor, a filter type power distribution transformer, a DC side capacitor and a filter capacitor; the filter type power distribution transformer comprises a low-voltage winding and a high-voltage winding, the low-voltage winding, the high-voltage winding and the winding of the filter reactor are wound on one core column, the low-voltage winding is provided with a tap; one end of the winding of the filter reactor and one end of the filter capacitor are connected with the tap; the other end of the filter capacitor is connected with the low-voltage side of the filter type power distribution transformer; the other end of the winding of the filter reactor is connected with the AC side of the power converter; the power converter is connected with both ends of the DC side capacitor respectively; both ends of the DC side capacitor are connected with the positive electrode and the negative electrode of the energy storage battery pack respectively.

[0024] The present application provides a low-voltage power distribution energy storage system, by setting a tap in the low-voltage winding of the filter type power distribution transformer, the power converter is connected with the tap of the low-voltage winding after AC filtering, so that the isolation transformer is not needed between the power distribution transformer and the power converter for voltage conversion; the filter reactor winding is wound in the filter type power distribution transformer with a special structure, which is compact, high integration, and does not affect the high-voltage and low-voltage windings of the power distribution transformer, and has no magnetic saturation characteristics, good inductance linearity, and replaces the iron core filter reactor with large heat and working noise and inductance nonlinearity; the technical problems of heat and electromagnetic interference caused by the isolation transformer and the iron core reactor are solved, the effect of significantly reducing the power loss is achieved, and the equipment space and working noise in the energy storage container are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 A low-voltage power distribution energy storage system provided by the present application is shown in the topological structure diagram.

[0027] Figure 2 A filter type power distribution transformer with a low-voltage winding tap of a low-voltage power distribution energy storage system provided by the present application is shown in the single-phase diagram.

[0028] In the drawings, the reference signs are as follows:

[0029] C f , filter capacitor; L f , filter reactor; C dcDC capacitor. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0032] Unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] Please refer to Figure 1 and Figure 2 , Figure 1 a low-voltage power distribution energy storage system provided by the present application, Figure 2 a single-phase schematic diagram of a filter type power distribution transformer with low-voltage winding taps of a low-voltage power distribution energy storage system provided by the present application.

[0034] An embodiment of a low-voltage power distribution energy storage system provided by the present application comprises: an energy storage battery pack, a power converter, a filter reactor L f , a filter type power distribution transformer, a DC capacitor C dc and a filter capacitor C f .

[0035] The filter type power distribution transformer comprises a low-voltage winding and a high-voltage winding, and the low-voltage winding, the high-voltage winding and the winding of the filter reactor L f are wound on one core column, and the low-voltage winding is provided with a tap;

[0036] One end of the winding of the filter reactor L f and one end of the filter capacitor C f are connected to the tap.

[0037] It should be noted that the low-voltage winding of the filter type distribution transformer is provided with a tap, and the power converter is connected to the tap of the low-voltage winding through the filter reactor and the filter capacitor. No isolation transformer is needed to be additionally configured between the filter type distribution transformer and the power converter for voltage conversion, thereby saving the cost of configuring the isolation transformer and reducing the space occupied by the isolation transformer.

[0038] The filter capacitor C f is connected to the low-voltage side of the filter type distribution transformer at the other end.

[0039] It should be noted that the high-voltage winding and the low-voltage winding of each phase of the filter type distribution transformer are commonly wound on one core column with the winding of one filter reactor L f . The low-voltage winding is provided with a tap for connection with the filter capacitor and the filter reactor.

[0040] The filter reactor L f is connected to the alternating current side of the power converter at the other end of the winding.

[0041] The power converter is connected to both ends of the direct current side capacitor.

[0042] The direct current side capacitor C dc is connected to the positive electrode and the negative electrode of the energy storage battery pack at both ends.

[0043] It can be understood that one side of the power converter is connected to the energy storage battery pack through the direct current side capacitor, and the other side of the power converter is connected to the tap of the low-voltage winding of the filter type distribution transformer through the filter reactor and the filter capacitor.

[0044] The low-voltage distribution energy storage system provided by the embodiment of the present application is configured by setting a tap in the low-voltage winding of the filter type distribution transformer, and the power converter is connected to the tap of the low-voltage winding through the filter reactor and the filter capacitor, so that no isolation transformer is needed to be configured between the distribution transformer and the power converter for voltage conversion. The filter reactor winding is wound in the filter type distribution transformer in a special structure, which is compact and has high integration, and does not affect the high-voltage winding and the low-voltage winding of the distribution transformer. The filter reactor has no magnetic saturation characteristic and good inductance linearity, and replaces the iron core filter reactor with large heat and noise and inductance nonlinearity. The technical problems of heat and electromagnetic interference caused by the isolation transformer and the iron core reactor are solved, thereby significantly reducing the power loss, reducing the space occupied by the energy storage container device, and reducing the working noise.

[0045] The above is one embodiment of the low-voltage distribution energy storage system provided by the embodiment of the present application, and the following is another embodiment of the low-voltage distribution energy storage system provided by the embodiment of the present application.

[0046] Please refer to Figure 1 and Figure 2 On the basis of the previous embodiment, the present embodiment provides another embodiment of the low-voltage power distribution energy storage system, comprising:

[0047] Preferably, the filter-type power distribution transformer is a three-phase transformer.

[0048] Further, the low-voltage winding and the high-voltage winding of each phase of the three-phase transformer are respectively co-wound with a winding of a filter reactor L f on a core column.

[0049] It should be noted that each phase of the three-phase filter-type power distribution transformer has a set of high-voltage winding and low-voltage winding, and the high-voltage winding and the low-voltage winding of each phase are respectively co-wound with a winding of a filter reactor on a core column.

[0050] Preferably, the winding of the filter reactor L f is composed of two sub-windings in reverse series.

[0051] Further, the two sub-windings are arranged in an up-down manner in the vertical direction of the core column.

[0052] Preferably, the number of turns, height and inner and outer radii of the two sub-windings are respectively equal.

[0053] It should be noted that the winding of the filter reactor L f is composed of two sub-windings in reverse series arranged in an up-down manner in the vertical direction, and the number of turns, height and inner and outer radii of the two sub-windings are respectively equal.

[0054] The magnetic flux of the winding of the filter reactor is composed of two sub-windings. Due to the special winding structure of the two sub-windings, the main magnetic flux generated by the two sub-windings in the core is equal in size and opposite in polarity and cancels out each other. Overall, the main magnetic flux generated by the winding of the filter reactor in the core of the transformer is zero, and there is no main magnetic flux interlinking between the high-voltage winding and the low-voltage winding of the transformer. Therefore, the winding of the filter reactor and the winding of the transformer do not affect each other due to electromagnetic induction. In addition, since the main magnetic flux in the core is zero, the inductance of the winding of the filter reactor is completely determined by the leakage magnetic flux interlinking with the air. Due to the characteristics of the leakage magnetic flux, the winding of the filter reactor does not have the magnetic saturation characteristics, and its inductance value is constant, the inductance linearity is good, the heat generation is low, and the working noise is low.

[0055] It can be understood that the filter reactor winding is integrated into the filter distribution transformer, and to realize the electromagnetic decoupling of the filter reactor and the filter distribution transformer, the filter reactor winding needs to adopt the special winding structure described above, so as to ensure that the filter reactor and the filter distribution transformer have no influence on each other in normal operation. Through the above winding method, the filter reactor winding wound on the distribution transformer core replaces the core reactor with large heat dissipation and working noise, and nonlinear inductance.

[0056] Preferably, the high-voltage winding adopts a delta connection.

[0057] It should be noted that the delta connection is to connect each phase power supply or load in sequence, and the point connected at each end is led out as the three phase lines of three-phase power. Because the connection shape is similar to a triangle, this connection is called delta connection.

[0058] Preferably, one end of the filter capacitor C f is connected to the high-voltage side of the filter distribution transformer.

[0059] Further, the low-voltage winding adopts a star connection with a neutral line.

[0060] Preferably, the winding of the filter reactor L f is connected to the filter capacitor C f to form an AC filter.

[0061] It should be noted that the winding of the filter reactor is connected to the filter capacitor, which is equivalent to an AC filter. The AC filter is an important part of the AC-DC power conversion system, which can compensate for the reactive power consumed by the converter, and at the same time filter and reduce the harmonics generated in the conversion process to avoid harm to the AC system.

[0062] The low-voltage power distribution energy storage system provided by the embodiments of the present application is configured by setting a tap on the low-voltage winding of a three-phase transformer, and the power converter is connected to the tap of the low-voltage winding after AC filtering, so that the power distribution transformer and the power converter do not need to be configured with an isolation transformer for voltage conversion; meanwhile, the high-voltage winding of each phase of the three-phase transformer adopts a delta connection, and the low-voltage winding adopts a star connection with a neutral line; and the filter reactance winding is wound in the three-phase transformer in a special structure, which is compact and has high integration, and does not affect the high-voltage and low-voltage windings of the power distribution transformer, and has no magnetic saturation characteristics, good inductance linearity, and replaces the iron core filter reactor which has large heat generation and working noise and inductance nonlinearity; the winding of the filter reactor is connected to the filter capacitor on the AC side to form an AC filter, which can effectively filter the harmonics generated on the AC side of the converter. The technical problems of heat generation and electromagnetic interference caused by the isolation transformer and the iron core reactor are solved, the power loss is significantly reduced, and the space occupied by the energy storage container device and the working noise are reduced.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A low-voltage power distribution and energy storage system, characterized in that, include: Energy storage battery packs, power converters, filter reactors, filter-type distribution transformers, DC-side capacitors, and filter capacitors; The filtered distribution transformer includes a low-voltage winding and a high-voltage winding. The low-voltage winding, the high-voltage winding, and the winding of the filter reactor are all wound on a single iron core column. The low-voltage winding is provided with a tap. One end of the filter reactor winding and one end of the filter capacitor are both connected to the tap; The other end of the filter capacitor is connected to the low-voltage side of the filter distribution transformer; The other end of the filter reactor winding is connected to the AC side of the power converter; The power converter is connected to both ends of the DC-side capacitor; The two ends of the DC-side capacitor are connected to the positive and negative terminals of the energy storage battery pack, respectively. The filter reactor winding consists of two winding segments connected in reverse series. The two winding segments are arranged vertically on the iron core column, and the number of turns, height, and inner and outer radii of the two winding segments are equal. The filtered distribution transformer is a three-phase transformer, and the other ends of the three filtered capacitors are all connected to the neutral line on the low-voltage side of the filtered distribution transformer.

2. The low-voltage power distribution and energy storage system according to claim 1, characterized in that, The high-voltage winding adopts a delta connection.

3. The low-voltage power distribution and energy storage system according to claim 1, characterized in that, The low-voltage winding adopts a star connection with the neutral line leading out.

4. The low-voltage power distribution and energy storage system according to claim 1, characterized in that, The windings of the filter reactor and the filter capacitor are connected to form an AC filter.

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