Energy-saving regulation and control device based on whole-station centralized control of photovoltaic power station

Abstract

According to the energy-saving regulation and control device based on the whole-station centralized control of the photovoltaic power station, the boosting transformers are arranged and connected to the current collection lines, after the photovoltaic power station stops generating power, the control cabinet controls the second contactors to disconnect the current collection lines from the power grid, so that the photovoltaic power station is off the grid, and the situation that the inverter is no-load and wastes the energy of the power grid is avoided; before the photovoltaic power station recovers power generation, the first contactors can be controlled to be closed, so that starting voltage can be provided for the current collection lines through the boosting transformers, pre-starting excitation can be provided for the inverters, and after the inverters are pre-started, the corresponding second contactors are controlled to be closed, so that excitation inrush current generated when the photovoltaic power station recovers power generation and recovers grid connection can be effectively reduced, and the power generation efficiency of the photovoltaic power station is improved. And the grid-connected safety is ensured. According to the energy-saving regulation and control device based on the whole-station centralized control of the photovoltaic power station, convenience is provided for safe implementation of grid disconnection at night and grid connection recovery in daytime of the photovoltaic power station, and power grid energy loss of the photovoltaic power station at night can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic grid-connected technology, and in particular to an energy-saving control device based on the centralized control of the entire photovoltaic power station. Background Art

[0002] Photovoltaic power stations convert solar energy into electrical energy, and the output is direct current, which is generally connected to the high-voltage AC power grid through an inverter. Among them, when the photovoltaic power station is connected to the grid, it will generate an excitation inrush current, which will affect the life of the transformer. In the existing technology, even if the photovoltaic power station has no output at night, it will remain connected to the grid, which will cause the transformer to be in a no-load state at night. The existence of the excitation inrush current will cause energy loss in the no-load transformer, resulting in the problem of energy waste in the photovoltaic power station at night.

[0003] In order to reduce no-load losses at night, in the existing technology, a current-limiting resistor or inductor is generally connected in series on the collector line from the photovoltaic power station to the power grid to limit the excitation inrush current under no-load conditions, thereby reducing no-load losses. However, this does not eliminate the losses and will continue to waste grid energy. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide an energy-saving control device based on the centralized control of the entire photovoltaic power station to solve the problem in the prior art that photovoltaic power stations have no-load losses at night and waste grid energy.

[0005] The present invention provides an energy-saving control device based on the centralized control of the entire photovoltaic power station, the energy-saving control device comprises a control cabinet, a first contactor and a step-up transformer, wherein:

[0006] A step-down transformer is connected between the control cabinet and the busbar to obtain working power from the busbar through the step-down transformer;

[0007] One side of the step-up transformer is connected to the control cabinet through the first contactor so as to draw power from the busbar through the control cabinet and the step-down transformer when the first contactor is closed, and the other side of the step-up transformer is connected to a collector;

[0008] The step-up transformer and the first contactor are provided in plurality, and the number is consistent with the number of the collecting wires, and the step-up transformers are connected to the collecting wires in a one-to-one correspondence;

[0009] One end of each of the collectors is connected to the busbars one by one through a second contactor, and the other end is connected to the corresponding photovoltaic unit through an inverter;

[0010] The control cabinet is used to control the second contactor to open after the photovoltaic power station stops generating electricity, and to control the first contactor to close before the photovoltaic power station resumes generating electricity, so as to provide a starting voltage to the collector through the step-up transformer, provide pre-start excitation to the inverter, and control the corresponding second contactor to close after each inverter is pre-started.

[0011] Optionally, the control cabinet is further used to control the first contactors to close in sequence according to a first preset sequence, so as to control the inverters to pre-start in sequence.

[0012] Optionally, the control cabinet is further used to control each of the first contactors to disconnect after each of the inverters completes pre-startup and the photovoltaic power station resumes power generation.

[0013] Optionally, a third contactor is connected between the step-down transformer and the busbar.

[0014] Optionally, the control cabinet is further used to control the second contactors to disconnect in sequence according to a second preset sequence after the photovoltaic power station stops generating electricity.

[0015] The energy-saving control device based on the centralized control of the entire photovoltaic power station provided by the present invention includes a control cabinet, a first contactor and a step-up transformer, wherein a step-down transformer is connected between the control cabinet and the substation bus to obtain working power from the bus through the step-down transformer; one side of the step-up transformer is connected to the control cabinet through the first contactor to obtain power from the bus through the control cabinet and the step-down transformer when the first contactor is closed, and the other side of the step-up transformer is connected to the collector line; one end of each collector line is connected to the bus one by one through a second contactor, and the other end is connected to the corresponding photovoltaic unit through an inverter; there are multiple step-up transformers and contactors, and the number is consistent with the number of collector lines, and the step-up transformers are connected to the collector lines one by one. The energy-saving control device based on the centralized control of the photovoltaic power station provided by the present invention can control the second contactor to be disconnected through the control cabinet after the photovoltaic power station stops generating electricity, so as to disconnect the photovoltaic power station from the grid, thereby avoiding the inverter from being idle and wasting grid energy. Before the photovoltaic power station resumes generating electricity, the first contactor can be controlled to be closed, so that the starting voltage can be provided to the collector through the step-up transformer, and the pre-start excitation can be provided to the inverter. After each inverter is pre-started, the corresponding second contactor can be controlled to be closed, which can effectively reduce the excitation surge current when the photovoltaic power station resumes generating electricity and restoring grid connection, ensure the safety of grid connection, provide convenience for the safe realization of the photovoltaic power station being disconnected from the grid at night and restoring grid connection during the day, and can effectively avoid the loss of grid energy by the photovoltaic power station at night. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of an energy-saving control device based on the centralized control of the entire photovoltaic power station in an embodiment of the present invention.

[0017] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0019] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0021] To solve the problem that photovoltaic power stations in the prior art have no-load losses at night, which will waste a lot of grid energy. The present invention provides an energy-saving control device based on the centralized control of the entire photovoltaic power station, including a control cabinet, a first contactor and a step-up transformer, wherein a step-down transformer is connected between the control cabinet and the substation bus to obtain working power from the bus through the step-down transformer; one side of the step-up transformer is connected to the control cabinet through the first contactor to obtain power from the bus through the control cabinet and the step-down transformer when the first contactor is closed, and the other side of the step-up transformer is connected to the collector line; one end of each collector line is connected to the bus one by one through a second contactor, and the other end is connected to the corresponding photovoltaic unit through an inverter; there are multiple step-up transformers and contactors, and the number is consistent with the number of collector lines, and the step-up transformer The contactor is connected to the collector line one by one. After the photovoltaic power station stops generating electricity, the control cabinet can be used to control the second contactor to disconnect, so that the photovoltaic power station is disconnected from the grid, avoiding the inverter from wasting grid energy when it is unloaded. Before the photovoltaic power station resumes generating electricity, the first contactor can be controlled to close, so that the step-up transformer can provide a starting voltage to the collector line and pre-start excitation to the inverter. After each inverter is pre-started, the corresponding second contactor can be controlled to close, which can effectively reduce the excitation inrush current when the photovoltaic power station resumes generating electricity and restoring grid connection, ensuring the safety of grid connection, providing convenience for the safe realization of photovoltaic power station disconnecting from the grid at night and restoring grid connection during the day, and effectively avoiding the loss of grid energy by photovoltaic power station at night.

[0022] Specifically, Figure 1 As shown, the energy-saving control device based on the centralized control of the photovoltaic power station in this embodiment mainly includes a control cabinet 11, a first contactor K1 and a step-up transformer T1, wherein a step-down transformer T2 is connected between the control cabinet 11 and the bus 20 to obtain the working power from the bus 20 through the step-down transformer T2, wherein the bus 20 is, for example, a 35KV high-voltage bus, and the step-down transformer T2 is a 35KV to 220V step-down transformer, which provides 220V AC power for the control cabinet 11 and the rear-end step-up transformer T1.

[0023] One side of the step-up transformer T1 is connected to the control cabinet 10 through the first contactor K1 to draw power from the bus through the control cabinet 10 and the step-down transformer T2 when the first contactor K1 is closed. The other side of the step-up transformer T1 is connected to the collector 30 to obtain the starting voltage according to the obtained 220V AC power conversion.

[0024] There are multiple step-up transformers T1 and first contactors K1, and the number is consistent with the number of collectors 30, so that each step-up transformer T1 can be connected one-to-one with each collector 30, and one end of each collector 30 is connected to the bus 20 one by one through a second contactor K2, and the other end is connected to the corresponding photovoltaic unit (not shown in the figure) through an inverter (not shown in the figure).

[0025] The control cabinet 10 is used to control the second contactor K2 to disconnect after the photovoltaic power station stops generating electricity, so as to avoid the inverter connected to the collector 30 being connected to the bus 20. After the photovoltaic power station stops generating electricity, no-load excitation is generated according to the current on the bus 20, thereby wasting the energy of the bus grid.

[0026] The control cabinet 10 is also used to control the closing of the first contactor K1 before the photovoltaic power station resumes power generation, so as to provide a starting voltage to the collector 30 through the step-up transformer T1, provide pre-start excitation to the inverter, and control the corresponding second contactor K2 to close after each inverter is pre-started, and the starting voltage is lower than the bus voltage on the bus 20, so that the pre-start excitation is between the normal operating excitation and the zero excitation, so that after the photovoltaic power source resumes power generation, the pre-start excitation is increased to the normal operating excitation, thereby reducing the excitation surge current when the photovoltaic grid is connected, and ensuring the safety of the grid connection.

[0027] In order to further reduce the excitation inrush current and improve the service life of the system, in the present embodiment, the control cabinet 10 is also used to control the closing of each first contactor K1 in sequence according to the first preset sequence, so as to control the pre-start of each inverter in sequence, which can reduce the load change rate of the step-down side of the step-down transformer K2, thereby reducing the excitation inrush current on the step-down side of the step-down transformer K2, and improving the service life and working safety of the step-down transformer T2.

[0028] In order to reduce the working loss of the energy-saving control device, in this embodiment, the control cabinet 10 is also used to control the first contactors K1 to disconnect and stop the operation of the step-up transformer T1 after each inverter has completed pre-start and the photovoltaic power station has resumed power generation and completed grid connection, thereby reducing the operating consumption of the step-up transformer T1.

[0029] In an optional embodiment, contactors are provided on both sides of the step-up transformer T1. After the photovoltaic power station resumes power generation and is connected to the grid, the contactors on both sides can be controlled to disconnect, disconnecting the step-up transformer T1 from the control cabinet 10 and the collector 30, and completely disconnecting it from the grid, thereby avoiding no-load losses caused by the step-up transformer T1 being connected to the grid on one side.

[0030] In order to further reduce the system loss, in the present invention, a third contactor K3 is connected between the step-down transformer T2 and the busbar 20. When the control cabinet 10 is enabled, the third contactor K3 can be disconnected to disconnect the step-down transformer T2 from the power grid, thereby reducing the no-load loss of the step-down transformer T2.

[0031] Specifically, for example, after the photovoltaic power station stops generating electricity, the control cabinet 10 controls the second contactor K2 to disconnect, and the photovoltaic power station is disconnected from the grid. At this time, the third contactor K3 can be disconnected; or after the photovoltaic power station resumes generating electricity and completes the grid connection, the control cabinet 10 no longer needs to enable the output, and the third contactor K3 can be disconnected.

[0032] In order to reduce the inrush current of the grid-connected bus 20, in this embodiment, the control cabinet 10 is also used to control the second contactor K2 to disconnect in sequence according to a second preset sequence after the photovoltaic power station stops generating electricity, which can reduce the excitation inrush current on other transformers connected to the bus 20 and improve system reliability.

[0033] Among them, the first preset order is used to regulate the excitation when connected to the grid, and the second preset order is used to regulate the excitation when disconnected from the grid, and the contactors that act are the first contactor K1 and the second contactor K2 respectively. The specifications of the transformer and inverter that act are basically the same, and the specific order can be flexibly set respectively. Among them, if the specifications of the transformer and inverter that act are quite different, they can be specifically selected according to the degree of excitation influence when connected to the grid or disconnected from the grid and the linear modulation requirements of the excitation surge current. This application does not make any special restrictions on this.

[0034] The energy-saving control device based on the centralized control of the entire photovoltaic power station provided by the present invention is provided with multiple step-up transformers connected to each collecting line. After the photovoltaic power station stops generating electricity, the control cabinet can be used to control the second contactor to disconnect the connection between the collecting line and the power grid, so that the photovoltaic power station is disconnected from the grid, thereby avoiding the inverter from wasting power grid energy when it is idle. Before the photovoltaic power station resumes power generation, the first contactor can be controlled to close, so that the starting voltage can be provided to the collecting line through the step-up transformer, and the pre-start excitation can be provided to the inverter. After each inverter is pre-started, the corresponding second contactor can be controlled to close, which can effectively reduce the excitation surge current when the photovoltaic power station resumes power generation and grid connection, ensure the safety of grid connection, and provide convenience for the safe realization of photovoltaic power station being disconnected from the grid at night and restoring grid connection during the day. It can effectively avoid the loss of grid energy by the photovoltaic power station at night and improve the power supply capacity of the grid system.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0036] The above-mentioned embodiments only express several specific implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An energy-saving control device based on the centralized control of the entire photovoltaic power station, characterized in that: The energy-saving control device includes a control cabinet, a first contactor and a step-up transformer, wherein: A step-down transformer is connected between the control cabinet and the busbar to obtain working power from the busbar through the step-down transformer; One side of the step-up transformer is connected to the control cabinet through the first contactor so as to draw power from the busbar through the control cabinet and the step-down transformer when the first contactor is closed, and the other side of the step-up transformer is connected to a collector; The step-up transformer and the first contactor are provided in plurality, and the number is consistent with the number of the collecting wires, and the step-up transformers are connected to the collecting wires in a one-to-one correspondence; One end of each of the collectors is connected to the busbars one by one through a second contactor, and the other end is connected to the corresponding photovoltaic unit through an inverter; The control cabinet is used to control the second contactor to open after the photovoltaic power station stops generating electricity, and to control the first contactor to close before the photovoltaic power station resumes generating electricity, so as to provide a starting voltage to the collector through the step-up transformer, provide pre-start excitation to the inverter, and control the corresponding second contactor to close after each inverter is pre-started.

2. The energy-saving control device based on the centralized control of the photovoltaic power station according to claim 1 is characterized in that: The control cabinet is also used to control the first contactors to close in sequence according to a first preset sequence, so as to control the inverters to pre-start in sequence.

3. The energy-saving control device based on the centralized control of the photovoltaic power station according to claim 1 is characterized in that: The control cabinet is also used to control each of the first contactors to disconnect after each of the inverters completes pre-startup and the photovoltaic power station resumes power generation.

4. The energy-saving control device based on the centralized control of the photovoltaic power station according to claim 1 is characterized in that: A third contactor is connected between the step-down transformer and the busbar.

5. The energy-saving control device based on the centralized control of the photovoltaic power station according to claim 1 is characterized in that: The control cabinet is also used to control the second contactors to disconnect in sequence according to a second preset sequence after the photovoltaic power station stops generating electricity.

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