WO2024001674A1

WO2024001674A1 - Photovoltaic storage flexible grid-connected system and method

Info

Publication number: WO2024001674A1
Application number: PCT/CN2023/098111
Authority: WO
Inventors: 王绍民; 林松青; 薛晓峰; 潘喜良; 曾垂栋; 杜武荣; 徐挺进; 姜滨; 梁晓斌; 张宗祯; 葛传军; 常云潇; 杨沛豪; 兀鹏越; 寇水潮; 王小辉; 燕云飞; 郭昊; 殷悦; 李志鹏
Original assignee: 华能罗源发电有限责任公司; 西安热工研究院有限公司
Priority date: 2022-06-29
Filing date: 2023-06-02
Publication date: 2024-01-04
Also published as: CN114825450A; CN114825450B

Abstract

Disclosed is a photovoltaic storage flexible grid-connected system, comprising a thermal power plant service unit, a power electronic transformation SOP unit and a photovoltaic storage microgrid unit. The thermal power plant service unit comprises a 6kV plant service bus and is used for transferring power to a power grid system. The photovoltaic storage microgrid unit comprises a 400V comprehensive energy bus and is used for transferring power to the thermal power plant service unit by means of the power electronic transformation SOP unit. A high-voltage side of the power electronic transformation SOP unit is connected to the 6kV plant service bus, and a low-voltage side of the power electronic transformation SOP unit is connected to the 400V comprehensive energy bus, the power electronic transformation SOP unit being used for providing a power transfer channel when the thermal power plant service unit and the photovoltaic storage microgrid unit transfer power.

Description

Optical storage flexible grid connection system and method

Cross-references to related applications

This application claims priority from Chinese Patent Application No. 2022107478625 filed in China on June 29, 2022, the entire content of which is incorporated herein by reference.

Technical field

The present disclosure relates to the field of power transmission technology, and specifically to an optical storage flexible grid connection system and method.

Background technique

With the development of science and technology, thermal power plants are transforming and upgrading into comprehensive energy load source supply enterprises. In related technologies, when a photovoltaic system is incorporated into a high-voltage bus system for thermal power plants as a load source, a corresponding access solution needs to be selected based on the access capacity. These solutions have one thing in common, that is, both the power supply and the load are connected to the high-voltage bus system used in thermal power plants. However, this will exceed the original design capacity of the busbar, which will require expansion of the interval. In addition, the short-circuit current exceeds the limit after large-capacity loads are connected, which requires large-scale transformation of the equipment in the high-voltage busbar system for thermal power plants. Secondly, the increase in equipment in the high-voltage busbar system for thermal power plants will lead to an increase in fault points, which will in turn lead to an increase in the probability of busbar failure.

Contents of the invention

Embodiments of the present disclosure provide a flexible optical storage grid-connected system and method. The main purpose is to provide an optical storage grid-connected factory system with low equipment failure rate, flexible control method and high power supply reliability.

According to an embodiment of the present disclosure, a flexible grid-connected system for photovoltaic and storage is provided, including: a thermal power plant unit, a power electronics transformer SOP unit and a photovoltaic and storage microgrid unit;

The thermal power plant unit includes a 6kV factory busbar, which is used for power transmission to the power grid system;

The photovoltaic storage microgrid unit includes a 400V integrated energy bus for power transmission to the thermal power plant unit through a power electronics transformer SOP unit;

The high-voltage side of the power electronic transformation SOP unit is connected to the 6kV factory bus, and the low-voltage side of the power electronic transformation SOP unit is connected to the 400V comprehensive energy bus for use in the thermal power plant. When the unit and the optical storage microgrid unit perform power transmission, a power transmission channel is provided;

The 6kV factory busbar includes: 6kV factory A-section busbar and 6kV factory B-section busbar. The power electronic transformation SOP unit includes: power transmission switch, SOP·DC/AC converter, SOP high-voltage side filter capacitor , Power electronic transformer isolation DC-DC converter, SOP low-voltage side filter capacitor, SOP·AC/DC converter;

Wherein, the AC side of the SOP·DC/AC converter is connected to the 6kV factory through the power transmission switch. Section B busbar, the DC side of the SOP DC/AC converter is connected to the high voltage side of the power electronic transformer isolation type DC-DC converter through the SOP high voltage side filter capacitor. The power electronic transformer isolation type The low-voltage side of the DC-DC converter is connected to the DC side of the SOP·AC/DC converter through the SOP low-voltage side filter capacitor, and the AC side of the SOP·AC/DC converter is connected to the 400V Integrated energy bus;

The photovoltaic storage microgrid unit also includes: photovoltaic power generation system grid-connected switch, photovoltaic inverter, photovoltaic panel, energy storage system grid-connected switch, energy storage system PCS, energy storage components, integrated energy load grid-connected switch and integrated energy load;

Wherein, the photovoltaic panel is connected to the 400V comprehensive energy bus through the photovoltaic inverter and the photovoltaic power generation system grid connection switch, and the energy storage element is connected through the energy storage system PCS and the energy storage system. The grid switch is connected to the 400V integrated energy bus, and the integrated energy load is connected to the 400V integrated energy bus through the integrated energy load grid-connected switch.

In one embodiment of the present disclosure, the 6kV factory busbar includes: a 6kV factory A-section busbar and a 6kV factory B-section busbar; the thermal power plant unit also includes: a thermal power generator, a thermal power unit main transformer, High power plant transformer for thermal power units, 6kV plant section A busbar grid-connected switch, 6kV plant section B busbar grid-connected switch, 6kV plant section A load grid-connected switch, 6kV plant section B load grid-connected switch, 6kV plant section A load grid-connected switch Section load and 6kV factory B section load;

Wherein, the thermal power generator is connected to the main transformer of the thermal power unit and the high-voltage side of the high-voltage transformer of the thermal power unit. The low-voltage side A branch of the high-voltage transformer of the thermal power unit is connected to the grid through the 6kV factory A-section busbar. The switch is connected to the 6kV factory A-section bus, and the low-voltage side B branch of the high-power transformer of the thermal power unit is connected to the 6kV factory B-section bus through the 6kV factory B-section bus grid connection switch. The 6kV The factory A-section load is connected to the 6kV factory A-section busbar through the 6kV factory A-section load grid-connected switch, and the 6kV factory B-section load is connected to the 6kV factory B-section load grid-connected switch. The 6kV factory B section busbar.

In one embodiment of the present disclosure, the power electronic transformer isolated DC-DC converter includes a high frequency transformer;

The high-frequency transformer is used to control the output voltage of the high-frequency transformer by controlling the frequency of the high-frequency transformer.

In one embodiment of the present disclosure, the SOP·DC/AC converter, the power electronic transformer isolated DC-DC converter and the SOP·AC/DC converter are all fully controlled by back-to-back voltage sources. type power electronic device.

In one embodiment of the present disclosure, the SOP·DC/AC converter and the SOP·AC/DC converter are equipped with a four-quadrant power control function, and the power response time corresponding to the four-quadrant power control function is millisecond level;

When the thermal power plant unit and the optical storage microgrid unit perform power transmission through the power electronic transformation SOP unit, the power transmission is performed through the power four-quadrant operation mode.

In one embodiment of the present disclosure, the SOP·DC/AC converter adopts a reactive power control method and a constant DC voltage control method, and the SOP·AC/DC converter adopts a reactive power control method and a constant DC voltage control method. AC side voltage control method.

In one embodiment of the present disclosure, when the SOP·DC/AC converter, the power electronic transformer isolated DC-DC converter and the SOP·AC/DC converter operate, the Real-time power adjustment requirements, operating according to the preset power factor.

In one embodiment of the present disclosure, it also includes a light storage microgrid control center;

The optical storage microgrid control center is used to control the power transmission size, power transmission form and power transmission direction of the power electronic transformer SOP unit.

In summary, the flexible grid-connected optical and storage system proposed in one aspect of the present disclosure includes: a thermal power plant unit, a power electronics transformation SOP unit and an optical storage microgrid unit; the thermal power plant unit includes a 6kV factory busbar , used for power transmission to the power grid system; the photovoltaic storage microgrid unit includes a 400V integrated energy bus, used for power transmission to the unit of the thermal power plant through a power electronics transformation SOP unit; the power electronics transformation The high-voltage side of the SOP unit is connected to the 6kV factory bus, and the low-voltage side of the power electronic transformation SOP unit is connected to the 400V comprehensive energy bus for use in the thermal power plant unit and the optical storage unit. When the microgrid unit performs power transmission, a power transmission channel is provided; the 6kV factory bus includes: 6kV factory A-section bus and 6kV factory B-section bus; the power electronic transformation SOP unit includes: power transmission switch, SOP ·DC/AC converter, SOP high-voltage side filter capacitor, power electronic transformer isolated DC-DC converter, SOP low-voltage side filter capacitor, SOP·AC/DC converter;

Wherein, the AC side of the SOP·DC/AC converter is connected to the 6kV factory B section busbar through the power transmission switch, and the DC side of the SOP·DC/AC converter is connected to the SOP high voltage The side filter capacitor is connected to the high-voltage side of the power electronic transformer isolated DC-DC converter, and the low-voltage side of the power electronic transformer isolated DC-DC converter is connected to the SOP through the SOP low-voltage side filter capacitor. The DC side of the AC/DC converter, the AC side of the SOP·AC/DC converter is connected to the 400V comprehensive energy bus;

Wherein, the photovoltaic panel is connected to the 400V comprehensive energy bus through the photovoltaic inverter and the photovoltaic power generation system grid connection switch, and the energy storage element is connected through the energy storage system PCS and the energy storage system. The grid switch is connected to the 400V integrated energy bus, and the integrated energy load is connected to the 400V integrated energy bus through the integrated energy load grid-connected switch. This disclosure integrates the photovoltaic storage microgrid unit and the power electronic transformer SOP unit as part of the flexible distribution network into the high-voltage bus system for thermal power plants, which will not exceed the original design capacity of the original bus bar for thermal power units, and therefore does not require extended interval. In addition, the power electronics transformer SOP unit is used to connect the optical storage microgrid unit to the thermal power plant unit, which can reduce the increase in the thermal power plant high-voltage bus system when the optical storage microgrid unit is integrated into the thermal power plant high-voltage bus system. equipment, thereby reducing equipment failure rates. In addition, the power electronics transformer SOP unit is used to connect the photovoltaic storage microgrid unit to the thermal power plant unit, which can also reduce the short-circuit current after connecting to a large-capacity load, thereby enabling In order to reduce the degree of modification of equipment in the high-voltage busbar system of thermal power plants. Moreover, the optical storage flexible grid-connected system has flexible control methods and high power supply reliability.

Additional aspects and advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.

Description of drawings

The above and/or additional aspects and advantages of the present disclosure will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic structural diagram of an optical storage flexible grid-connected system provided by an embodiment of the present disclosure;

Figure 2 is a schematic structural diagram of a unit for a thermal power plant provided by an embodiment of the present disclosure;

Figure 3 is a schematic structural diagram of a power electronic transformer SOP unit provided by an embodiment of the present disclosure;

Figure 4 is a schematic structural diagram of an optical storage flexible grid-connected system provided by an embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of a light-storage microgrid unit provided by an embodiment of the present disclosure.

Explanation of reference symbols: 1—unit for thermal power plant; 2—power electronics transformer SOP unit; 3—solar and storage microgrid unit; 4—solar and storage microgrid control center;

1-1—Thermal power generator; 1-2—Thermal power unit main transformer; 1-3—Thermal power unit high plant transformer; 1-4—6kV plant section A busbar grid connection switch; 1-5—6kV plant section B Busbar grid-connected switch; 1-6-6kV factory use section A busbar; 1-7-6kV factory use section B busbar; 1-8-6kV factory use section A load grid-connected switch; 1-9-6kV factory use section B Load grid-connected switch; 1-10-6kV factory A-section load; 1-11-6kV factory B-section load;

2-1—Power transmission switch; 2-2—SOP·DC/AC converter; 2-3—SOP high-voltage side filter capacitor; 2-4—Power electronic transformer isolated DC-DC converter; 2-5— SOP low-voltage side filter capacitor; 2-6—SOP·AC/DC converter;

3-1—400V comprehensive energy bus; 3-2—Photovoltaic power generation system grid connection switch; 3-3—Photovoltaic inverter; 3-4—Photovoltaic panels; 3-5—Energy storage system grid connection switch; 3-6 —Energy storage system PCS; 3-7—Energy storage components; 3-8—Comprehensive energy load grid connection switch; 3-9—Comprehensive energy load.

Detailed ways

Embodiments of the present disclosure are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present disclosure and are not to be construed as limitations of the present disclosure. On the contrary, the disclosed embodiments include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

The present disclosure will be described in detail below with reference to specific embodiments.

Figure 1 is a schematic structural diagram of an optical storage flexible grid-connected system provided by an embodiment of the present disclosure.

As shown in Figure 1, an embodiment of the present disclosure provides a flexible grid-connected system for light and storage, including: a thermal power plant unit 1, a power electronics transformation SOP unit 2, and a light and storage microgrid unit 3;

The thermal power plant unit 1 includes a 6kV factory busbar, which is used for power transmission to the power grid system;

The photovoltaic storage microgrid unit 3 includes a 400V integrated energy bus 3-1, which is used to transmit power to the thermal power plant unit 1 through the power electronic transformation SOP unit 2;

The high-voltage side of the power electronic transformation SOP unit 2 is connected to the 6kV factory bus, and the low-voltage side of the power electronic transformation SOP unit 2 is connected to the 400V integrated energy bus 3-1, which is used for unit 1 in thermal power plants and optical storage microgrids. When unit 3 performs power transmission, it provides a power transmission channel.

According to some embodiments, distribution networks transformed using flexible power electronics technology are an important trend and can effectively solve some bottleneck problems in the development of traditional distribution networks. Advanced power electronics technology can build a flexible, reliable, and efficient distribution network, which can not only improve the power quality, reliability, and operating efficiency of the distribution system, but also cope with the volatility of traditional loads and proportional renewable energy.

In some embodiments, the embodiments of the present disclosure can not only improve the reliability of the plant system by integrating the photovoltaic storage microgrid unit 3 and the power electronic transformation SOP unit 2 into the thermal power plant as part of the flexible distribution network, It can also improve the economics and scalability of photovoltaic and integrated energy load access, and separate traditional power generation from diversified operations. In addition, integrating the photovoltaic storage microgrid unit 3 and the power electronic transformer SOP unit 2 as part of the flexible distribution network into the high-voltage bus system of the thermal power plant will not exceed the original design capacity of the thermal power unit's original bus bar and does not require expansion. interval.

It is easy to understand that when coal power companies use the idle land and roofs in the factory to build affordable grid-connected photovoltaic power generation projects, since the power supply and load are connected to the high-voltage bus system of the thermal power plant, the original design capacity of the bus will be exceeded. This in turn requires extending the interval. In addition, the short-circuit current exceeds the limit after large-capacity loads are connected, which requires large-scale transformation of the equipment in the high-voltage busbar system for thermal power plants. Secondly, the increase in equipment in the high-voltage busbar system for thermal power plants will lead to an increase in fault points, which will in turn lead to an increase in the probability of busbar failure. By using the flexible grid-connected photovoltaic storage system provided by the embodiments of the present disclosure, the built photovoltaic power generation device can be directly connected to the factory power system. Therefore, when the photovoltaic storage microgrid unit 3 is incorporated into the high-voltage bus system for thermal power plants, the equipment added to the high-voltage bus system for thermal power plants can be reduced, thereby reducing the equipment failure rate, thereby improving the economic benefits of thermal power units and coal-fired power enterprises. .

In the embodiment of the present disclosure, FIG. 2 is a schematic structural diagram of a unit for a thermal power plant provided by the embodiment of the present disclosure. As shown in Figure 2, the 6kV factory busbar includes: 6kV factory A-section busbar 1-6 and 6kV factory B-section busbar 1-7. The thermal power plant unit 1 also includes: thermal power generator 1-1, thermal power unit Main transformer 1-2, thermal power unit high plant transformer 1-3, 6kV plant section A bus grid-connected switch 1-4, 6kV plant section B busbar grid-connected switch 1-5, 6kV plant section A load grid-connected switch 1-8, 6kV factory B section load grid connection switch 1-9, 6kV factory A section load 1-10 and 6kV factory B section load 1-11;

Among them, the thermal power generator 1-1 is connected to the high-voltage side of the thermal power unit main transformer 1-2 and the thermal power unit high-voltage transformer 1-3. The low-voltage side A branch of the thermal power unit high-voltage transformer 1-3 passes through the 6kV factory A-section busbar. The grid-connected switch 1-4 is connected to the 6kV factory A-section busbar 1-6. The low-voltage side B branch of the thermal power unit high-voltage transformer 1-3 is connected to the 6kV factory B-side through the 6kV factory B-section busbar grid-connected switch 1-5. Section buses 1-7, 6kV factory A section loads 1-10 are connected to the 6kV factory A section busbars 1-6 through the 6kV factory A section load grid connection switch 1-8, and 6kV factory B section loads 1-11 pass through The 6kV factory B section load grid-connected switch 1-9 is connected to the 6kV factory B section busbar 1-7.

According to some embodiments, the thermal power generator 1-1 is connected to the power grid system through the thermal power unit main transformer 1-2. Furthermore, the thermal power generator 1-1 can transmit power to the power grid system through the thermal power unit main transformer 1-2.

According to some embodiments, the high-voltage factory transformer 1-3 of the thermal power unit refers to a high-voltage factory transformer connected to the outlet of the thermal power generator 1-1 and used to step down the voltage and supply power to the thermal power plant itself. For example, the high-voltage transformer 1-3 of the thermal power unit can reduce the 20kV voltage output by the thermal power generator 1-1 to 6kV.

In some embodiments, by closing the 6kV factory A-section load grid connection switch 1-8, the 6kV factory A-section busbar 1-6 can supply power to the 6kV factory A-section load 1-10. By closing the 6kV factory B section load grid connection switch 1-9, the 6kV factory B section busbar 1-7 can supply power to the 6kV factory B section load 1-11.

In the embodiment of the present disclosure, the 6kV factory busbar includes: 6kV factory A-section busbar 1-6 and 6kV factory B-section busbar 1-7. FIG. 3 is a schematic structural diagram of a power electronic transformer SOP unit provided by an embodiment of the present disclosure. As shown in Figure 3, the power electronic transformer SOP unit 2 includes: power transmission switch 2-1, SOP·DC/AC converter 2-2, SOP high-voltage side filter capacitor 2-3, power electronic transformer isolation type DC- DC converter 2-4, SOP low-voltage side filter capacitor 2-5, SOP·AC/DC converter 2-6;

Among them, the AC side of the SOP·DC/AC converter 2-2 is connected to the 6kV factory B section bus 1-7 through the power transmission switch 2-1, and the DC side of the SOP·DC/AC converter 2-2 passes through The SOP high-voltage side filter capacitor 2-3 is connected to the high-voltage side of the power electronic transformer isolated DC-DC converter 2-4, and the low-voltage side of the power electronic transformer isolated DC-DC converter 2-4 passes through the SOP low-voltage side filter capacitor 2 -5 is connected to the DC side of the SOP·AC/DC converter 2-6, and the AC side of the SOP·AC/DC converter 2-6 is connected to the 400V integrated energy bus 3-1.

According to some embodiments, in response to the thermal power plant unit 1 and the photovoltaic storage microgrid unit 3 performing power transmission through the power electronic transformation SOP unit 2, the photovoltaic storage microgrid unit 3 may transmit power to the thermal power plant through the power electronic transformation SOP unit 2. The thermal power plant unit 1 can also transmit power to the optical storage microgrid unit 3 through the power electronic transformation SOP unit 2.

In some embodiments, in response to the light-storage microgrid unit 3 transmitting power to the thermal power plant unit 1 through the power electronic transformation SOP unit 2, the low-voltage AC power output by the light-storage microgrid unit 3 is converted through the SOP·AC/DC. Current converter 2-6 converts it into low voltage direct current. Then, the low-voltage direct current is filtered by the SOP low-voltage side filter capacitor 2-5 and then transmitted to Power electronic transformer isolated DC-DC converter 2-4. Furthermore, the filtered low-voltage direct current is converted into high-voltage direct current through the power electronic transformer isolation DC-DC converter 2-4. Secondly, the high-voltage direct current is filtered by the SOP high-voltage side filter capacitor 2-3 and then transmitted to the SOP·DC/AC converter 2-2. Then, the filtered high-voltage direct current is inverted into high-voltage alternating current through the SOP·DC/AC converter 2-2. Finally, the high-voltage alternating current is transmitted to the 6kV factory B section busbar 1-7 through the power transmission switch 2-1.

In some embodiments, in response to the thermal power plant unit 1 transmitting power to the optical storage microgrid unit 3 through the power electronic transformation SOP unit 2, the high-voltage alternating current output by the thermal power plant unit 1 passes through the power transmission switch 2-1 Transmit to SOP·DC/AC converter 2-2. Next, the high-voltage alternating current is rectified into high-voltage direct current by the SOP·DC/AC converter 2-2. Furthermore, the high-voltage direct current is filtered by the SOP high-voltage side filter capacitor 2-3 and then transmitted to the power electronic transformer isolation DC-DC converter 2-4. Secondly, the filtered high-voltage direct current is converted into low-voltage direct current through the power electronic transformer isolation DC-DC converter 2-4. Then, the low-voltage direct current is filtered by the SOP low-voltage side filter capacitor 2-5 and then transmitted to the SOP·AC/DC converter 2-6. Finally, the filtered low-voltage direct current is converted into low-voltage alternating current through the SOP·AC/DC converter 2-6 and then transmitted to the 400V integrated energy bus 3-1.

According to some embodiments, in the related technology, each light-storage microgrid unit 3 needs to be configured with a separate PCS, and then incorporated into the thermal power 6kV factory system through a step-up transformer. However, the equipment failure rate of this grid-connected method is high and flexible regulation cannot be achieved. Moreover, due to the huge size of the step-up transformer, a single photovoltaic storage microgrid unit 3 requires a large volume when integrated into a thermal power 6kV factory system.

In some embodiments, the embodiment of the present disclosure connects each of the at least one photovoltaic and storage microgrid units 3 to the 6kV in the thermal power plant unit 1 through the corresponding power electronic transformation SOP unit 2 The factory busbar eliminates the need for a step-up transformer, thereby reducing the volume required when a single photovoltaic storage microgrid unit 3 is integrated into a thermal power 6kV factory system, reducing equipment failure rates, and enabling flexible regulation.

In some embodiments, the traditional SOP unit only includes the SOP·DC/AC converter 2-2 and the SOP·AC/DC converter 2-6. The power electronic transformation SOP unit 2 provided by the embodiment of the present disclosure adopts A power electronic transformer isolation DC-DC converter 2-4 is added between the SOP·DC/AC converter 2-2 and the SOP·AC/DC converter 2-6 to achieve high-frequency voltage transformation without the need for Step-up transformer, flexible control method and reliable power supply. In addition, compared with the step-up transformer, the power electronic transformer isolation DC-DC converter 2-4 is smaller and more convenient to maintain.

In some embodiments, the power electronic transformation SOP unit 2 provided by the embodiment of the present disclosure has certain advantages in power quality adjustment and harmonic suppression when realizing high-frequency transformation, and has the functions of voltage level conversion, electrical isolation, A series of functional advantages such as power adjustment and control.

In the embodiment of the present disclosure, the power electronic transformer isolated DC-DC converter 2-4 includes a high-frequency transformer;

A high-frequency transformer is used to control the output voltage of the high-frequency transformer by controlling the frequency of the high-frequency transformer.

According to some embodiments, the high-frequency transformer is used to control the frequency of the high-frequency transformer by controlling the frequency of the high-frequency transformer. When outputting voltage, the output voltage of the high-frequency transformer can be reduced by reducing the frequency of the high-frequency transformer. The output voltage of the high-frequency transformer can also be increased by increasing the frequency of the high-frequency transformer.

In some embodiments, the high frequency transformer is rated at 10 kHz.

In the embodiment of the present disclosure, the SOP·DC/AC converter 2-2, the power electronic transformer isolated DC-DC converter 2-4 and the SOP·AC/DC converter 2-6 are all back-to-back voltage source full-circuit converters. Controlled power electronic devices.

According to some embodiments, back-to-back refers to a control method. The characteristic of back-to-back is that among two associated devices (or two parts of one device), the control purpose of one device is to adapt to the input, and the control purpose of the other device is to adapt to the output.

According to some embodiments, a fully controlled power electronic device refers to a power electronic device that can be controlled to be turned on and turned off through a control signal. Devices used in fully controlled power electronic devices include, but are not limited to, gate turn-off thyristors, power field effect transistors, insulated gate bipolar transistors (IGBT), etc.

In some embodiments, in response to the SOP·DC/AC converter 2-2, the power electronic transformer isolated DC-DC converter 2-4, and the SOP·AC/DC converter 2-6, the back-to-back voltage source full The devices used in controlled power electronic devices, SOP·DC/AC converter 2-2, power electronic transformer isolated DC-DC converter 2-4 and SOP·AC/DC converter 2-6 can be High power and high frequency IGBT components. Since the maximum short-circuit current that high-power high-frequency IGBT components can increase does not exceed 1.5 times its rated current, the protection judgment logic is simple and efficient. Therefore, the transmission efficiency and transmission effect when the thermal power plant unit 1 and the photovoltaic storage microgrid unit 3 transmit power through the power electronic transformation SOP unit 2 can be improved.

In the embodiment of the present disclosure, the SOP·DC/AC converter 2-2 and the SOP·AC/DC converter 2-6 have a four-quadrant power control function, and the power response time corresponding to the four-quadrant power control function is milliseconds. ;

When the thermal power plant unit 1 and the photovoltaic storage microgrid unit 3 transmit power through the power electronic transformer SOP unit 2, the power is transmitted through the power four-quadrant operation mode.

According to some embodiments, the four-quadrant power control function refers to having the ability to control positive voltage and current (first quadrant), negative voltage and current (second quadrant), negative voltage and negative current (third quadrant), and positive voltage and negative current ( The fourth quadrant) is the function of controlling the power of these four quadrants.

In some embodiments, the power four-quadrant operation mode refers to the mode of power transmission through the four-quadrant power control function of the SOP·DC/AC converter 2-2 and the SOP·AC/DC converter 2-6. .

In the embodiment of the present disclosure, the SOP·DC/AC converter 2-2 adopts a reactive power control method and a constant DC voltage control method, and the SOP·AC/DC converter 2-6 adopts a reactive power control method and a constant DC voltage control method. AC side voltage control method.

In the embodiment of the present disclosure, when the SOP·DC/AC converter 2-2, the power electronic transformer isolated DC-DC converter 2-4 and the SOP·AC/DC converter 2-6 are working, according to the power consumption Load real-time power adjustment requirements, according to the preset power factor Count runs.

According to some embodiments, the fixed AC side voltage control method refers to a control method that only controls the AC side voltage.

According to some embodiments, the constant DC voltage control method refers to a control method that only controls the DC side voltage.

According to some embodiments, the reactive power control method refers to the control of reactive power exchanged between the converter or high-voltage DC converter station and the AC grid connected thereto.

According to some embodiments, power factor (PF), also known as power factor, is a unique physical quantity in AC power systems. It is the ratio of the effective power consumed by a load to its apparent power. It is an infinite value between 0 and 1. Dimension quantity.

In some embodiments, when the SOP·DC/AC converter 2-2, the power electronic transformer isolated DC-DC converter 2-4 and the SOP·AC/DC converter 2-6 are working, unit Power factor operation.

In some embodiments, unity power factor refers to the power factor when the power factor is equal to 1.

In this embodiment of the present disclosure, FIG. 4 is a schematic structural diagram of an optical storage flexible grid-connected system provided by this embodiment of the present disclosure. As shown in Figure 4, the light-storage flexible grid-connected system also includes a light-storage microgrid control center 4;

The optical storage microgrid control center 4 is used to control the power transmission size, power transmission form and power transmission direction of the power electronic transformer SOP unit 2.

In the embodiment of the present disclosure, FIG. 5 is a schematic structural diagram of a light-storage microgrid unit provided by the embodiment of the present disclosure. As shown in Figure 5, the photovoltaic storage microgrid unit 3 also includes: photovoltaic power generation system grid-connected switch 3-2, photovoltaic inverter 3-3, photovoltaic panel 3-4, energy storage system grid-connected switch 3-5, storage Energy system PCS3-6, energy storage components 3-7, comprehensive energy load grid connection switch 3-8 and comprehensive energy load 3-9;

Among them, the photovoltaic panel 3-4 is connected to the 400V comprehensive energy bus 3-1 through the photovoltaic inverter 3-3 and the photovoltaic power generation system grid-connected switch 3-2, and the energy storage element 3-7 is connected through the energy storage system PCS3-6 and the energy storage system PCS3-6. The energy system grid-connected switch 3-5 is connected to the 400V integrated energy bus 3-1, and the integrated energy load 3-9 is connected to the 400V integrated energy bus 3-1 through the integrated energy load grid-connected switch 3-8.

According to some embodiments, when the photovoltaic storage microgrid unit 3 is operating normally, the light energy can be converted into electrical energy through the photovoltaic panels 3-4, thereby realizing the photovoltaic reverse transmission of electricity to the thermal power plant unit 1, which can reduce the power consumption rate of the plant. In turn, the economic benefits of thermal power units can be improved.

In some embodiments, when there is insufficient light or at night, the energy storage element 3-7 can be discharged and supply power to the comprehensive energy load 3-9. In response to the insufficient electric energy of the energy storage element 3-7, the thermal power plant unit 1 can supply power to the comprehensive energy load 3-9 through the power electronic transformation SOP unit 2.

According to some embodiments, the energy storage element 3-7 refers to a power source that can be flexibly charged and discharged. Energy storage components 3-7 can dynamically absorb and release energy in the light-storage microgrid unit 3, and because of their fast response and flexible control, they are irreplaceable in maintaining grid-side frequency stability of the light-storage microgrid unit 3. Advantage.

In some embodiments, when installing the energy storage element 3-7, the energy storage element 3-7 can be connected to the grid of the distributed power point. The DC side of the inverter serves as the basis for regulating the load.

In summary, the flexible solar and storage grid-connected system proposed in the embodiment of the present disclosure includes: a thermal power plant unit 1, a power electronics transformation SOP unit 2 and a solar storage microgrid unit 3; the thermal power plant unit 1 includes a 6kV factory busbar , used for power transmission to the power grid system; the photovoltaic storage microgrid unit 3 includes a 400V comprehensive energy bus 3-1, used for power transmission to the thermal power plant unit 1 through the power electronic transformation SOP unit 2; power electronics The high-voltage side of the transformer SOP unit 2 is connected to the 6kV factory bus, and the low-voltage side of the power electronic transformer SOP unit 2 is connected to the 400V integrated energy bus 3-1, which is used in the thermal power plant unit 1 and the optical storage microgrid unit 3. When performing power transmission, a power transmission channel is provided. This disclosure integrates the photovoltaic storage microgrid unit 3 and the power electronic transformation SOP unit 2 as part of the flexible distribution network into the high-voltage busbar system for thermal power plants, which will not exceed the original design capacity of the original busbar for thermal power units. Therefore, There is no need to extend the interval. In addition, the photovoltaic storage microgrid unit 3 is connected to the thermal power plant unit 1 through the power electronic transformer SOP unit 2, which can reduce the time required to integrate the photovoltaic storage microgrid unit 3 into the thermal power plant high-voltage bus system. The additional equipment in the system can, in turn, reduce the equipment failure rate. In addition, by connecting the photovoltaic storage microgrid unit 3 to the thermal power plant unit 1 through the power electronic transformation SOP unit 2, the short-circuit current after connecting a large-capacity load can be reduced, thereby reducing the impact on the high-voltage bus system of the thermal power plant. The extent to which the equipment has been modified. Moreover, the optical storage flexible grid-connected system has flexible control methods and high power supply reliability.

It should be noted that in the description of the present disclosure, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Furthermore, in the description of the present disclosure, "plurality" means two or more unless otherwise specified.

Any process or method descriptions in flowcharts or otherwise described herein may be understood to represent modules, segments, or portions of code that include one or more executable instructions for implementing the specified logical functions or steps of the process. , and the scope of the preferred embodiments of the present disclosure includes additional implementations in which functions may be performed out of the order shown or discussed, including in a substantially simultaneous manner or in the reverse order, depending on the functionality involved, which shall It should be understood by those skilled in the art to which embodiments of the present disclosure belong.

It should be understood that various parts of the present disclosure may be implemented in hardware, software, firmware, or combinations thereof. In the above embodiments, various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if it is implemented in hardware, as in another embodiment, it can be implemented by any one or a combination of the following technologies known in the art: a logic gate circuit with a logic gate circuit for implementing a logic function on a data signal. Discrete logic circuits, application specific integrated circuits with suitable combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), etc.

Those of ordinary skill in the art can understand that all or part of the steps involved in implementing the methods of the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When executed, the program includes one of the steps of the method embodiment or a combination thereof.

In addition, each functional unit in various embodiments of the present disclosure may be integrated into one processing module, each unit may exist physically alone, or two or more units may be integrated into one module. The above integrated modules can be implemented in the form of hardware or software function modules. If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

The storage media mentioned above can be read-only memory, magnetic disks or optical disks, etc.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "an example," "specific examples," or "some examples" or the like means that specific features are described in connection with the embodiment or example. , structures, materials, or features are included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present disclosure have been shown and described above, it can be understood that the above-mentioned embodiments are illustrative and should not be construed as limitations of the present disclosure. Those of ordinary skill in the art can make modifications to the above-mentioned embodiments within the scope of the present disclosure. The embodiments are subject to changes, modifications, substitutions and variations.

Claims

A flexible grid-connected light and storage system, characterized by including: a thermal power plant unit, a power electronics transformer SOP unit and a light and storage microgrid unit;

The thermal power plant unit includes a 6kV factory busbar, which is used for power transmission to the power grid system;

The photovoltaic storage microgrid unit includes a 400V integrated energy bus for power transmission to the thermal power plant unit through a power electronics transformer SOP unit;

The high-voltage side of the power electronic transformation SOP unit is connected to the 6kV factory bus, and the low-voltage side of the power electronic transformation SOP unit is connected to the 400V comprehensive energy bus for use in the thermal power plant unit. When performing power transmission with the optical storage microgrid unit, provide a power transmission channel;

The 6kV factory busbar includes: 6kV factory A-section busbar and 6kV factory B-section busbar. The power electronic transformation SOP unit includes: power transmission switch, SOP·DC/AC converter, SOP high-voltage side filter capacitor , Power electronic transformer isolation DC-DC converter, SOP low-voltage side filter capacitor, SOP·AC/DC converter;

Wherein, the AC side of the SOP·DC/AC converter is connected to the 6kV factory B section busbar through the power transmission switch, and the DC side of the SOP·DC/AC converter is connected to the SOP high voltage The side filter capacitor is connected to the high-voltage side of the power electronic transformer isolated DC-DC converter, and the low-voltage side of the power electronic transformer isolated DC-DC converter is connected to the SOP through the SOP low-voltage side filter capacitor. The DC side of the AC/DC converter, the AC side of the SOP·AC/DC converter is connected to the 400V comprehensive energy bus;

The photovoltaic storage microgrid unit also includes: photovoltaic power generation system grid-connected switch, photovoltaic inverter, photovoltaic panel, energy storage system grid-connected switch, energy storage system PCS, energy storage components, integrated energy load grid-connected switch and integrated energy load;

Wherein, the photovoltaic panel is connected to the 400V comprehensive energy bus through the photovoltaic inverter and the photovoltaic power generation system grid connection switch, and the energy storage element is connected through the energy storage system PCS and the energy storage system. The grid switch is connected to the 400V integrated energy bus, and the integrated energy load is connected to the 400V integrated energy bus through the integrated energy load grid-connected switch.
The optical storage flexible grid-connected system according to claim 1, wherein the 6kV factory busbar includes: a 6kV factory A-section busbar and a 6kV factory B-section busbar, and the thermal power plant unit further includes: Thermal power generator, thermal power unit main transformer, thermal power unit high power transformer, 6kV factory A-section busbar grid-connected switch, 6kV factory B-section busbar grid-connected switch, 6kV factory A-section load grid-connected switch, 6kV factory B-section busbar grid-connected switch Load grid-connected switch, 6kV factory A-section load and 6kV factory B-section load;

Wherein, the thermal power generator is connected to the main transformer of the thermal power unit and the high-voltage side of the high-voltage transformer of the thermal power unit, and the low-voltage side A branch of the high-voltage transformer of the thermal power unit is connected to the grid through the 6kV factory A-section busbar. The switch is connected to the 6kV factory A-section bus, and the low-voltage side B branch of the high-power transformer of the thermal power unit is connected to the grid through the 6kV factory B-section bus. The switch is connected to the 6kV factory B section busbar. The 6kV factory A section load is connected to the 6kV factory A section busbar through the 6kV factory A section load grid connection switch. The 6kV factory B section load The load is connected to the 6kV factory B-section busbar through the 6kV factory B-section load grid connection switch.
The flexible grid-connected optical storage system of claim 1, wherein the power electronic transformer isolation DC-DC converter includes a high-frequency transformer;

The high-frequency transformer is used to control the output voltage of the high-frequency transformer by controlling the frequency of the high-frequency transformer.
The flexible grid-connected optical storage system of claim 1, wherein the SOP·DC/AC converter, the power electronic transformer isolation DC-DC converter and the SOP·AC/DC converter are The current converters are all back-to-back voltage source fully controlled power electronic devices.
The flexible grid-connected optical storage system of claim 1, wherein the SOP·DC/AC converter and the SOP·AC/DC converter have a four-quadrant power control function, and the four-quadrant power control function is The power response time corresponding to the power control function is milliseconds;

When the thermal power plant unit and the optical storage microgrid unit perform power transmission through the power electronic transformation SOP unit, the power transmission is performed through the power four-quadrant operation mode.
The flexible grid-connected optical storage system of claim 1, wherein the SOP·DC/AC converter adopts a reactive power control method and a constant DC voltage control method, and the SOP·AC/DC converter adopts a reactive power control method and a constant DC voltage control method. The device adopts reactive power control method and constant AC side voltage control method.
The flexible grid-connected optical storage system of claim 1, wherein the SOP·DC/AC converter, the power electronic transformer isolation DC-DC converter and the SOP·AC/DC converter are When the inverter is working, it operates according to the preset power factor according to the real-time power adjustment demand of the electrical load.
The flexible grid-connected system for light and storage as claimed in claim 1, further comprising a light and storage microgrid control center;

The optical storage microgrid control center is used to control the power transmission size, power transmission form and power transmission direction of the power electronic transformer SOP unit.