An ac side dynamic voltage regulator for single phase systems

Abstract

This invention discloses a dynamic voltage regulator for the AC side of a single-phase system. The DC side of an H-bridge inverter unit is connected to both the positive and negative terminals. The midpoint of the second arm of the AC side of the H-bridge inverter unit is connected to the series input terminal, and the midpoint of the first arm of the AC side is connected to the series output terminal via a series coupling inductor. The series input and series output terminals are connected in series to the power grid as two main terminals. The control and detection module includes a voltage detection unit and a dynamic logic control unit. The primary side of the voltage detection unit is connected to the series input terminal, and the secondary side is connected to the dynamic logic control unit. The output terminal of the dynamic logic control unit is connected to the drive circuit of the H-bridge inverter unit. This regulator can achieve dynamic voltage suppression, effectively improving the grid-connected power and power generation efficiency of the photovoltaic system.

Description

Technical Field

[0001] This invention belongs to the field of power electronic equipment technology and relates to a dynamic voltage regulator for the AC side of a single-phase system. Background Technology

[0002] At the end of the distribution network where distributed photovoltaic (PV) power has a high penetration rate, backfeeding of PV power causing voltage rise at the grid connection point is a common problem. When the voltage exceeds the national standard limit (usually 110% of the rated voltage), the PV inverter will implement derating or grid disconnection protection, resulting in "curtailment" losses.

[0003] Existing solutions either focus on system-level modifications (such as grid upgrades or the installation of centralized energy storage), which are costly; or rely on the inverter's own reactive power regulation capabilities, which have limited effectiveness and affect active power output. In recent years, the concept of series voltage compensation has been proposed, but most of the publicly available technical solutions are principle-based system architectures, describing and connecting inverters, transformers, controllers, etc., as separate components. This distributed design has disadvantages such as complex on-site installation, cumbersome wiring, large space occupation, and reliability affected by on-site construction quality. It is not convenient for rapid and standardized deployment in existing photovoltaic projects, especially in the narrow distribution environments of residential or commercial rooftop photovoltaic systems.

[0004] Therefore, there is an urgent need for a highly integrated, modular, plug-and-play dedicated device that can be easily connected in series with existing lines in the form of a standardized product, and intelligently achieve dynamic voltage suppression, thereby effectively improving the grid-connected power and power generation efficiency of photovoltaic systems. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dynamic voltage regulator for the AC side of a single-phase system. This regulator can achieve dynamic voltage suppression and effectively improve the grid-connected power and power generation efficiency of the photovoltaic system.

[0006] To achieve the above objectives, the present invention discloses an AC side dynamic voltage regulator for a single-phase system, comprising a series voltage injection module, a power grid, and a control and detection module; The series voltage injection module includes an H-bridge inverter unit, a positive terminal, and a negative terminal; the DC side of the H-bridge inverter unit is connected to the positive terminal and the negative terminal; the midpoint of the second bridge arm on the AC side of the H-bridge inverter unit is connected to the series input terminal, and the midpoint of the first bridge arm on the AC side of the H-bridge inverter unit is connected to the series output terminal through a series coupling inductor; the series input terminal and the series output terminal are connected in series to the power grid as two main terminals. The control and detection module includes a voltage detection unit and a dynamic logic control unit. The primary side of the voltage detection unit is connected to the series input terminal, the secondary side of the voltage detection unit is connected to the dynamic logic control unit, and the output terminal of the dynamic logic control unit is connected to the drive circuit of the H-bridge inverter unit.

[0007] Furthermore, the voltage detection unit employs a Hall voltage sensor.

[0008] Furthermore, it also includes a chassis, a series voltage injection module, and a control and detection module housed within the chassis.

[0009] Furthermore, wall-mounting holes are provided on both sides of the chassis.

[0010] Furthermore, guide rail mounting slots are provided on both sides of the chassis.

[0011] Furthermore, a human-machine interface panel is provided on the front of the chassis, which is connected to the dynamic logic control unit.

[0012] Furthermore, the H-bridge inverter unit consists of four IGBTs.

[0013] Furthermore, a buffer energy storage unit is connected between the positive and negative terminals.

[0014] Furthermore, the buffer energy storage unit is formed by connecting several thin-film capacitors in parallel.

[0015] Furthermore, during operation, the upstream end of the output circuit breaker of the photovoltaic power generation unit is connected to the series input terminal, and the downstream end is connected to the series output terminal.

[0016] The present invention has the following beneficial effects: In specific operation, the AC-side dynamic voltage regulator for single-phase systems described in this invention uses a dynamic logic control unit to monitor the voltage at the series input terminal in real time through a voltage detection unit, and uses this to determine whether dynamic compensation is needed. When compensation is needed, the H-bridge inverter unit is controlled to perform voltage regulation, thereby achieving dynamic voltage suppression, avoiding malfunctions and frequent actions, and effectively improving the grid-connected power and power generation efficiency of the photovoltaic system.

[0017] Furthermore, this invention employs an H-bridge topology with coupled inductors, eliminating the need for bulky power frequency isolation transformers. Combined with thin-film capacitor buffering, this achieves miniaturization and low cost of the device while ensuring functionality.

[0018] Furthermore, the chassis is equipped with wall-mounting holes and rail mounting slots on both sides, allowing it to be directly installed in the user's existing distribution box. This reduces the space requirements on site and makes it particularly suitable for the retrofitting of existing photovoltaic projects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an external view of the present invention; Figure 2 This is the internal electrical schematic diagram of the present invention.

[0021] In this diagram, 1 represents the chassis, 101 represents the wall-mounted mounting hole, 201 represents the H-bridge inverter unit, 202 represents the series coupled inductor, L1_in represents the series input terminal, L1_out represents the series output terminal, 301 represents the voltage detection unit, 302 represents the dynamic logic control unit, 4 represents the human-machine interface panel, 5 represents the buffer energy storage unit, PV represents the photovoltaic power generation unit, and Grid represents the power grid. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0024] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0026] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0027] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] refer to Figure 1 and Figure 2 The AC-side dynamic voltage regulator for a single-phase system described in this invention includes a chassis 1. The chassis 1 is made of metal and has protective and heat dissipation functions. Both sides of the chassis 1 are designed with standard 35mm guide rail mounting slots or wall-mounting mounting holes 101, allowing for flexible selection of the installation method according to the conditions of the on-site distribution box. The chassis 1 houses a series voltage injection module and a control and detection module. A human-machine interface panel 4 is located on the front of the chassis 1.

[0031] The series voltage injection module includes an H-bridge inverter unit 201, a positive terminal DC+, and a negative terminal DC-. The DC side of the H-bridge inverter unit 201 is connected to the positive terminal DC+ and the negative terminal DC-. The H-bridge inverter unit 201 consists of four IGBTs. The midpoint of the second bridge arm on the AC side of the H-bridge inverter unit 201 is connected to the series input terminal L1_in. The midpoint of the first bridge arm on the AC side of the H-bridge inverter unit 201 is connected to the series output terminal L1_out through a series coupling inductor 202. A buffer energy storage unit 5 is connected between the positive terminal DC+ and the negative terminal DC-. The series input terminal L1_in and the series output terminal L1_out are connected in series to the power grid as two main terminals.

[0032] The control and detection module includes a voltage detection unit 301 and a dynamic logic control unit 302. The voltage detection unit 301 uses a Hall effect voltage sensor. Its primary side (high voltage side) is connected to the series input terminal L1_in, and its secondary side (low voltage side) outputs an isolated signal proportional to the grid connection point voltage to the dynamic logic control unit 302. The dynamic logic control unit 302 is based on a high-performance MCU, which internally presets action thresholds (e.g., 235V) and warning thresholds (e.g., 230V). The output PWM port of the dynamic logic control unit 302 is connected to the drive circuit of the H-bridge inverter unit 201. The human-machine interface panel 4 is mounted on the front of the chassis 1 and connected to the control and detection module via a ribbon cable.

[0033] The working process of this invention is as follows: This device is applied to a single-phase residential photovoltaic system. During installation, the phase line at the lower end of the output circuit breaker of the photovoltaic power generation unit PV (i.e., the grid connection point) is disconnected. The upstream end of the original line is connected to the series input terminal L1_in, and the downstream end is connected to the series output terminal L1_out. The neutral line remains unchanged. After the device is powered on, the voltage detection unit 301 monitors the voltage at the series input terminal L1_in (i.e., the grid connection point voltage U_pcc) in real time.

[0034] When U_pcc is lower than the warning threshold, the dynamic logic control unit 302 judges that the voltage is normal and does not issue a compensation command, and the H-bridge inverter unit 201 does not work.

[0035] When U_pcc rises and exceeds the action threshold, the dynamic logic control unit 302 immediately starts and calculates the amplitude and phase of the compensation voltage to be injected (requiring it to be in opposite phase to the current) based on the magnitude of U_pcc exceeding the threshold. It then generates a PWM wave to drive the H-bridge inverter unit 201 to operate, thereby supplementing the amplitude and phase of the voltage.

[0036] The H-bridge inverter unit 201 converts the energy of the DC-side capacitor into an AC voltage that is synchronized with the grid but has a controllable direction. After being smoothed and current-limited by the series coupling inductor 202, this voltage is superimposed on the main line. Since the injected voltage is opposite to the current direction, it manifests as a voltage drop on the line, thereby pulling down the voltage U_pcc at the series input terminal L1_i (grid connection point).

[0037] When U_pcc is pulled down to below the action threshold minus the hysteresis width, the device stops compensation. This hysteresis control effectively prevents switching oscillations near the threshold point.

[0038] Throughout the process, the human-computer interaction panel 4 can be used to observe in real time, and parameters such as action thresholds can be modified on-site by pressing buttons.

[0039] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0040] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0041] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A dynamic voltage regulator for the AC side of a single-phase system, characterized in that, Includes a series voltage injection module, a grid, and a control and detection module; The series voltage injection module includes an H-bridge inverter unit (201), a positive terminal (DC+), and a negative terminal (DC-); the DC side of the H-bridge inverter unit (201) is connected to the positive terminal (DC+) and the negative terminal (DC-); the midpoint of the second bridge arm on the AC side of the H-bridge inverter unit (201) is connected to the series input terminal (L1_in), and the midpoint of the first bridge arm on the AC side of the H-bridge inverter unit (201) is connected to the series output terminal (L1_out) through a series coupling inductor (202). The series input terminal (L1_in) and the series output terminal (L1_out) are connected in series to the power grid as two main terminals. The control and detection module includes a voltage detection unit (301) and a dynamic logic control unit (302). The primary side of the voltage detection unit (301) is connected to the series input terminal (L1_in), the secondary side of the voltage detection unit (301) is connected to the dynamic logic control unit (302), and the output terminal of the dynamic logic control unit (302) is connected to the drive circuit of the H-bridge inverter unit (201).

2. The AC-side dynamic voltage regulator for a single-phase system according to claim 1, characterized in that, The voltage detection unit (301) uses a Hall voltage sensor.

3. The AC-side dynamic voltage regulator for a single-phase system according to claim 1, characterized in that, It also includes a chassis (1), a series voltage injection module and a control and detection module are disposed in the chassis (1).

4. The AC-side dynamic voltage regulator for a single-phase system according to claim 3, characterized in that, The chassis (1) has wall mounting holes (101) on both sides.

5. The AC-side dynamic voltage regulator for a single-phase system according to claim 3, characterized in that, The chassis (1) has guide rail mounting slots on both sides.

6. The AC-side dynamic voltage regulator for a single-phase system according to claim 3, characterized in that, The front of the chassis (1) is provided with a human-machine interface panel (4), which is connected to the dynamic logic control unit (302).

7. The AC-side dynamic voltage regulator for a single-phase system according to claim 1, characterized in that, The H-bridge inverter unit (201) consists of four IGBTs.

8. The AC-side dynamic voltage regulator for a single-phase system according to claim 1, characterized in that, A buffer energy storage unit (5) is connected between the positive terminal (DC+) and the negative terminal (DC-).

9. The AC-side dynamic voltage regulator for a single-phase system according to claim 8, characterized in that, The buffer energy storage unit (5) is formed by connecting several thin film capacitors in parallel.

10. The AC-side dynamic voltage regulator for a single-phase system according to claim 1, characterized in that, During operation, the upstream end of the output circuit breaker of the photovoltaic power generation unit (PV) is connected to the series input terminal (L1_in), and the downstream end is connected to the series output terminal (L1_out).

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