Substation AC / DC power system control method and device with photovoltaic energy storage

Abstract

The present invention discloses a control method and device for a substation AC / DC power supply system with photovoltaic energy storage, which relates to the technical field of power supply for substations. The method includes: connecting a photovoltaic array and a battery group to a station AC / DC bus, connecting the station AC / DC bus with a bidirectional AC / DC converter, obtaining photovoltaic power generation power and effective value of three-phase AC bus voltage, determining the system working mode, setting the station AC / DC bus voltage boundary value based on the bus voltage, and when the system works in the first or second mode, comparing the bus voltage with the corresponding voltage boundary value, switching the photovoltaic inverter and the bidirectional DC converter working mode, controlling the photovoltaic power generation power and the three-phase AC bus power supply state, and when the system works in the third mode, stopping the energy supply of the photovoltaic array and the three-phase AC bus, and providing electric energy to the load by the battery group. The present invention solves the technical problem in the related art that the electric energy obtained from the three-phase AC bus by the AC / DC power supply system cannot be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply for substations, and in particular to a control method and device for an AC / DC power supply system of a substation with photovoltaic energy storage. Background Art

[0002] The station AC and DC power supply system of the substation is an important part of the power system, and is responsible for supporting the stable operation of lighting, air conditioning, relay protection, control and communication equipment. In the daily operation of the power system, the station AC and DC system continuously supplies power to the power system according to load demand and grid conditions. In the substation, there are many free spaces that can be used for the installation of photovoltaic arrays, which can be used for photovoltaic power generation. Photovoltaic power generation is one of the most promising renewable energy sources, which has the characteristics of clean and pollution-free, abundant resources, renewable and distributed power generation.

[0003] In the related art, the existing station AC / DC system usually includes a station transformer, a high-frequency sorting module, a battery pack, and AC / DC power distribution equipment and loads, and does not include a photovoltaic power generation system. The existing station AC / DC system realizes the charge and discharge control of the battery pack and the station DC bus by directly connecting the battery pack to the station DC bus, but this strategy is not convenient for effectively controlling the charge and discharge of the battery pack. At the same time, since the existing station AC / DC system does not include a photovoltaic power generation system, there is no photovoltaic power generation energy that can be provided to the AC / DC loads. Therefore, the AC / DC loads can only consume the energy provided by the battery pack and the three-phase AC bus. This operation strategy cannot reduce the electric energy obtained by the station AC / DC system from the three-phase AC bus, which is not conducive to reducing the consumption of station electric energy.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiments of the present invention provide a control method and device for a substation AC / DC power supply system with photovoltaic energy storage, so as to at least solve the technical problem in the related art that the electric energy obtained by the AC / DC power supply system from the three-phase AC bus cannot be reduced.

[0006] According to one aspect of an embodiment of the present invention, a control method for a substation AC / DC power supply system with photovoltaic energy storage is provided, comprising: connecting a photovoltaic array to a station AC bus through a photovoltaic inverter, connecting a battery pack to the station DC bus through a bidirectional DC converter, and connecting the station AC bus and the station DC bus using a bidirectional AC / DC converter; obtaining the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, determining the working mode of the AC / DC power supply system, the working mode comprising: a first mode, a second mode and a third mode; based on the voltage of the station AC bus and the station DC bus, setting the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus, wherein the voltage upper limit is set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit. The voltage lower limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not less than the corresponding voltage setting lower limit. The setting of the voltage upper limit and the voltage lower limit is used to ensure that the relay protection device does not operate when the AC and DC power supply system of the substation is in operation; when the AC and DC power supply system is working in the first mode or the second mode, the voltage of the station AC bus and the station DC bus are compared with the corresponding voltage upper limit and voltage lower limit, and the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC and DC power supply system is switched according to the comparison result to control the power generation power of the photovoltaic array and the power supply status of the three-phase AC bus; when the AC and DC power supply system is working in the third mode, the energy supply of the photovoltaic array and the three-phase AC bus is stopped, and the battery group provides power to the AC load and the DC load in the station.

[0007] Optionally, the operation mode of the working mode includes: when the AC / DC power supply system is operating in a first mode, the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through a photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through a bidirectional DC converter; when the AC / DC power supply system is operating in a second mode, the three-phase AC bus stops supplying electric energy to the station AC bus through a station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through a photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through a bidirectional DC converter; when the AC / DC power supply system is operating in a third mode, the three-phase AC bus stops supplying electric energy to the station AC bus through a station transformer, the photovoltaic array stops supplying photovoltaic electric energy to the station AC bus through a photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through a bidirectional DC converter.

[0008] Optionally, when the AC / DC power supply system is operating in the first mode or the second mode, the operating state of the battery pack includes: when the state of charge ratio of the battery pack is less than or equal to a preset ratio, the bidirectional DC converter performs constant current charging control or constant current discharging control on the battery pack, wherein the constant current charging control or constant current discharging control refers to keeping the charging or discharging current constant during the charging or discharging process of the battery pack; or, when the state of charge ratio of the battery pack is greater than the preset ratio, the bidirectional DC converter performs constant voltage charging control or constant voltage discharging control on the battery pack, wherein the constant voltage charging control or constant voltage discharging control refers to keeping the charging or discharging voltage constant after the battery pack reaches the target voltage during the charging or discharging process of the battery pack.

[0009] Optionally, when the AC / DC power supply system is operating in a first mode, the first mode includes: in a first working state, the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, and the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, wherein the maximum power point tracking control mode refers to the photovoltaic array supplying photovoltaic electric energy to the station AC bus at maximum power; in a second working state, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, and the DC boost converter in the photovoltaic inverter operates in a limited power control mode, wherein the limited power control mode refers to the photovoltaic array supplying photovoltaic electric energy to the station AC bus at a limited power, and the limited power is less than the maximum power.

[0010] Optionally, when the AC / DC power supply system is operating in the first mode, the step of controlling the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus includes: when the AC / DC power supply system is operating in the first working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, switching the working mode of the AC / DC power supply system to the second working state to reduce the power generation power of the photovoltaic array; when the AC / DC power supply system is operating in the first working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, maintaining the AC / DC power supply system The working mode of the AC / DC power supply system is the first working state; when the AC / DC power supply system is in the second working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the first working state, the power generation power of the photovoltaic array is increased, and the three-phase AC bus supplies electric energy to the station AC bus through the station transformer again; when the AC / DC power supply system is in the second working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the working mode of the AC / DC power supply system is maintained in the second working state.

[0011] Optionally, when the AC / DC power supply system is in the second mode of operation, the second mode includes: in the third operating state, the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter operates in a stable rear-stage voltage mode, wherein the stable rear-stage voltage mode refers to that the output voltage of the DC boost converter remains stable under the control of the two-level inverter; or, in the fourth operating state, the DC boost converter in the photovoltaic inverter operates in a limited power control mode, and the two-level inverter in the photovoltaic inverter operates in a stable bus voltage mode, wherein the stable bus voltage mode refers to that the d-axis component of the station AC bus voltage remains stable under the control of the two-level inverter; in the third operating state and the fourth operating state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter both operates in a reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter both operates in a working mode for controlling the DC side voltage to remain stable, wherein the reverse buck mode refers to that electric energy flows from the station AC bus to the station DC bus under the control of the bidirectional AC / DC converter.

[0012] Optionally, when the AC / DC power supply system is operating in the second mode, the step of controlling the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus includes: when the AC / DC power supply system is operating in the third working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, switching the working mode of the AC / DC power supply system to the fourth working state to reduce the power generation power of the photovoltaic array; when the AC / DC power supply system is operating in the third working state, when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage When the voltage of the station AC bus is less than the lower voltage limit of the station AC bus or the voltage of the station DC bus is less than the lower voltage limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the third working state to increase the power generation power of the photovoltaic array; when the AC / DC power supply system is in the fourth working state, when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the working mode of the AC / DC power supply system is maintained in the fourth working state.

[0013] Optionally, when the AC / DC power supply system operates in the third mode, it includes: the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a forward boost mode, wherein the forward boost mode refers to that under the control of the bidirectional AC / DC converter, electric energy flows from the station DC bus to the station AC bus; and the bidirectional inverter in the bidirectional AC / DC converter operates in an operating mode for controlling the AC side voltage to remain stable.

[0014] According to another aspect of an embodiment of the present invention, a control device for an AC / DC power supply system of a substation with photovoltaic energy storage is provided, comprising: a connection unit, used to connect a photovoltaic array to a station AC bus through a photovoltaic inverter, connect a battery pack to the station DC bus through a bidirectional DC converter, and connect the station AC bus and the station DC bus using a bidirectional AC / DC converter; a determination unit, used to obtain the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and determine the working mode of the AC / DC power supply system, the working modes including: a first mode, a second mode and a third mode; a setting unit, based on the voltage of the station AC bus and the station DC bus, sets the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus, wherein the voltage upper limit is to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit. The variable to be set, the voltage lower limit is the variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not less than the corresponding voltage setting lower limit, the setting of the voltage upper limit and the voltage lower limit is used to ensure that the relay protection device does not operate when the AC and DC power supply systems of the substation are in operation; the first control unit is used to compare the voltages of the station AC bus and the station DC bus with the corresponding voltage upper limit and voltage lower limit when the AC and DC power supply system is working in the first mode or the second mode, and switch the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC and DC power supply system according to the comparison result, and control the power generation power of the photovoltaic array and the power supply status of the three-phase AC bus; the second control unit is used to stop the energy supply of the photovoltaic array and the three-phase AC bus when the AC and DC power supply system is working in the third mode, and the battery group provides power to the AC load and the DC load in the station.

[0015] Optionally, the operation mode of the working mode in the determination unit includes: a first power supply module, which is used when the AC / DC power supply system is working in the first mode, the three-phase AC bus supplies electric energy to the station AC bus through the station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter; a second power supply module, which is used when the AC / DC power supply system is working in the second mode, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter; a third power supply module, which is used when the AC / DC power supply system is working in the third mode, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, the photovoltaic array stops supplying photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter.

[0016] Optionally, when the AC / DC power supply system is operating in the first mode or the second mode, the first control unit, the operating state of the battery pack includes: a first charging and discharging module, which is used for the bidirectional DC converter to perform constant current charging control or constant current discharging control on the battery pack when the state of charge ratio of the battery pack is less than or equal to a preset ratio, wherein the constant current charging control or constant current discharging control refers to keeping the charging or discharging current constant during the charging or discharging process of the battery pack; a second charging and discharging module, which is used for the bidirectional DC converter to perform constant voltage charging control or constant voltage discharging control on the battery pack when the state of charge ratio of the battery pack is greater than a preset ratio, wherein the constant voltage charging control or constant voltage discharging control refers to keeping the charging or discharging voltage constant after the battery pack reaches a target voltage during the charging or discharging process of the battery pack.

[0017] Optionally, when the AC / DC power supply system is operating in a first mode, the first control unit includes: a first working module, which is used to operate in a first working state, in which the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, and the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, wherein the maximum power point tracking control mode refers to the photovoltaic array supplying photovoltaic electric energy to the station AC bus at maximum power; a second working module, which is used to operate in a second working state, in which the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, and the DC boost converter in the photovoltaic inverter operates in a limited power control mode, wherein the limited power control mode refers to the photovoltaic array supplying photovoltaic electric energy to the station AC bus at a limited power, and the limited power is less than the maximum power.

[0018] Optionally, the first control unit controls the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus when the AC / DC power supply system is operating in the first mode, including: a first control module, which is used to switch the working mode of the AC / DC power supply system to the second working state to reduce the power generation power of the photovoltaic array when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus when the AC / DC power supply system is operating in the first working state; and a second control module, which is used to maintain the AC / DC power supply system in the first working state when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit. The working mode of the power source system is the first working state; the third control module is used to switch the working mode of the AC / DC power supply system to the first working state when the AC / DC power supply system is working in the second working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, increase the power generation power of the photovoltaic array, and the three-phase AC bus re-supply electric energy to the station AC bus through the station transformer; the fourth control module is used to keep the working mode of the AC / DC power supply system in the second working state when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit.

[0019] Optionally, when the first control unit is in the second mode of the AC / DC power supply system working state, the second mode includes: a third working module, which is used to operate the third working state, the DC boost converter in the photovoltaic inverter operates in the maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter operates in the stable rear-stage voltage mode, wherein the stable rear-stage voltage mode means that the output voltage of the DC boost converter remains stable under the control of the two-level inverter; a fourth working module, which is used to operate the fourth working state, the DC boost converter in the photovoltaic inverter operates in the limited power control mode, and the photovoltaic inverter The two-level inverter in the embodiment operates in a stable bus voltage mode, wherein the stable bus voltage mode refers to that the d-axis component of the station AC bus voltage remains in a stable state under the control of the two-level inverter; the fifth working module is used for, in the third working state and the fourth working state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter operates in a working mode for controlling the DC side voltage to remain stable, wherein the reverse buck mode refers to that under the control of the bidirectional AC / DC converter, electric energy flows from the station AC bus to the station DC bus.

[0020] Optionally, the first control unit controls the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus when the AC / DC power supply system is operating in the second mode, including: a fifth control module, which is used to switch the working mode of the AC / DC power supply system to a fourth working state to reduce the power generation power of the photovoltaic array when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus when the AC / DC power supply system is operating in the third working state; and a sixth control module, which is used to switch the working mode of the AC / DC power supply system to a fourth working state to reduce the power generation power of the photovoltaic array when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than the corresponding voltage upper limit when the AC / DC power supply system is operating in the third working state. When the voltage is at the lower limit, the working mode of the AC / DC power supply system is maintained in the third working state; the seventh control module is used to switch the working mode of the AC / DC power supply system to the third working state when the AC / DC power supply system is working in the fourth working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, so as to increase the power generation power of the photovoltaic array; the eighth control module is used to maintain the working mode of the AC / DC power supply system in the fourth working state when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit.

[0021] Optionally, when the AC / DC power supply system is operating in the third mode, the second control unit includes: a ninth control module, which is used for the bidirectional DC boost isolation converter in the bidirectional AC / DC converter to operate in a forward boost mode, wherein the forward boost mode refers to the flow of electric energy from the station DC bus to the station AC bus under the control of the bidirectional AC / DC converter; and a tenth control module, which is used for the bidirectional inverter in the bidirectional AC / DC converter to operate in an operating mode of controlling the AC side voltage to remain stable.

[0022] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is further provided, the computer-readable storage medium including a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the above-mentioned methods for controlling an AC / DC power supply system of a substation with photovoltaic energy storage.

[0023] According to another aspect of an embodiment of the present invention, there is also provided an electronic device, comprising one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by one or more processors, the one or more processors implement any one of the above-mentioned methods for controlling an AC / DC power supply system of a substation with photovoltaic energy storage.

[0024] According to another aspect of an embodiment of the present invention, a computer program product is also provided, including a computer program, which, when executed by a processor, implements the steps of any one of the above-mentioned methods for controlling an AC / DC power supply system of a substation with photovoltaic energy storage.

[0025] In the present disclosure, a photovoltaic array is connected to a station AC bus through a photovoltaic inverter, a battery group is connected to the station DC bus through a bidirectional DC converter, a bidirectional AC / DC converter is used to connect the station AC bus and the station DC bus, and then the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus are obtained to determine the working mode of the AC / DC power supply system. Then, based on the voltage of the station AC bus and the station DC bus, the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus are set. Then, when the AC / DC power supply system is working in the first mode or the second mode, the voltage of the station AC bus and the station DC bus are compared with the corresponding voltage upper limit and voltage lower limit. According to the comparison result, the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system is switched to control the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus. Finally, when the AC / DC power supply system is working in the third mode, the energy supply of the photovoltaic array and the three-phase AC bus is stopped, and the battery group provides power to the AC load and the DC load in the station, thereby realizing effective control of power and energy in the AC / DC power supply system.

[0026] In the present disclosure, photovoltaic energy supply of the AC / DC power supply system is realized by connecting the photovoltaic array to the station AC bus. The station AC bus and the station DC bus are connected by a bidirectional AC / DC converter, so that the station AC bus and the station DC bus can supply power to each other, so that the surplus photovoltaic power generation energy can be stored in the battery pack, and when necessary, the stored photovoltaic power can be discharged by the battery pack to supply the AC load and the DC load in the station at the same time. The working mode of the AC / DC power supply system is determined according to the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system is switched under different modes, the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus are controlled, and the balanced flow of power and energy in the AC / DC power supply system is realized, so that the voltage of the station AC bus and the station DC bus remains stable, thereby solving the technical problem in the related art that the electric energy obtained by the AC / DC power supply system from the three-phase AC bus cannot be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1It is a flow chart of an optional control method of a substation AC / DC power supply system with photovoltaic energy storage according to an embodiment of the present invention;

[0029] Figure 2 is a structural diagram of an existing AC / DC power supply system of a substation according to an embodiment of the present invention;

[0030] Figure 3 is a structural diagram of an optional substation AC / DC power supply system with photovoltaic energy storage added according to an embodiment of the present invention;

[0031] Figure 4 is a structural diagram of an optional photovoltaic inverter according to an embodiment of the present invention;

[0032] Figure 5 is a structural diagram of an optional bidirectional AC / DC converter according to an embodiment of the present invention;

[0033] Figure 6 It is a structural diagram of a bidirectional inverter in an optional bidirectional AC / DC converter according to an embodiment of the present invention, which works in a state of controlling AC voltage stability;

[0034] Figure 7 It is a structural diagram of a bidirectional inverter in an optional bidirectional AC / DC converter according to an embodiment of the present invention, which works in a state of controlling the DC voltage to be stable;

[0035] Figure 8 is a structural diagram of a DC boost converter in an optional photovoltaic inverter operating in a maximum power point tracking control mode according to an embodiment of the present invention;

[0036] Fig. 9 is a structural diagram of a DC boost converter in an optional photovoltaic inverter operating in a limited power control mode according to an embodiment of the present invention;

[0037] Fig.10 is a structural diagram of a two-level inverter in an optional photovoltaic inverter according to an embodiment of the present invention operating in a stable rear-stage voltage mode;

[0038] Fig.11 is a structural diagram of a two-level inverter in an optional photovoltaic inverter according to an embodiment of the present invention operating in a stable bus voltage mode;

[0039] Fig.12 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant current charging according to an embodiment of the present invention;

[0040] Fig.13 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant voltage charging according to an embodiment of the present invention;

[0041] Fig.14 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant current discharge according to an embodiment of the present invention;

[0042] Fig.15 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant voltage discharge according to an embodiment of the present invention;

[0043] Fig.16 is a schematic diagram of switching between different working states in an optional first mode according to an embodiment of the present invention;

[0044] Fig.17 is a schematic diagram of switching between different working states in an optional second mode according to an embodiment of the present invention;

[0045] Fig.18 is a schematic diagram of an optional control device for a substation AC / DC power supply system with photovoltaic energy storage added according to an embodiment of the present invention;

[0046] Fig.19 The hardware structure block diagram of an electronic device (or mobile device) for a control method of an AC / DC power supply system of a substation with photovoltaic energy storage added according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0049] It should be noted that the control method and device for the AC / DC power supply system of a substation with photovoltaic energy storage in the present disclosure can be used in the field of power supply technology of substations. When controlling the AC / DC power supply system of a substation with photovoltaic energy storage, it can also be used in any field except the field of power supply technology of substations. When controlling the AC / DC power supply system of a substation with photovoltaic energy storage, the present disclosure does not limit the application field of the control method and device for the AC / DC power supply system of a substation with photovoltaic energy storage.

[0050] The following embodiments of the present invention may be applied to various systems / applications / devices for controlling AC / DC power supply systems of substations with photovoltaic energy storage. The present invention connects the photovoltaic array to the station AC bus through a photovoltaic inverter, connects the station AC bus with the station DC bus by using a bidirectional AC / DC converter, obtains the power generation of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, determines the working mode of the AC / DC power supply system, and then sets the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus based on the voltage of the station AC bus and the station DC bus. Then, when the AC / DC power supply system is working in the first mode or the second mode, the voltage of the station AC bus and the station DC bus is compared with the corresponding voltage upper limit and voltage lower limit, and the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system is switched according to the comparison result, the power generation of the photovoltaic array and the power supply state of the three-phase AC bus are controlled, and finally, when the AC / DC power supply system is working in the third mode, the energy supply of the photovoltaic array and the three-phase AC bus is stopped, and the battery group provides electric energy to the AC load and the DC load in the station, so as to realize the balanced flow of power and energy in the AC / DC power supply system, thereby making the voltage of the station AC bus and the station DC bus stable.

[0051] The present invention is described in detail below in conjunction with various embodiments.

[0052] Embodiment 1

[0053] According to an embodiment of the present invention, an embodiment of a method for controlling an AC / DC power supply system of a substation with photovoltaic energy storage is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in an order different from that shown here.

[0054] Figure 1 is a flow chart of an optional control method for a substation AC / DC power supply system with photovoltaic energy storage according to an embodiment of the present invention, such as Figure 1 As shown, the method comprises the following steps:

[0055] Step S101, connect the photovoltaic array to the station AC bus through the photovoltaic inverter, connect the battery pack to the station DC bus through the bidirectional DC converter, and use the bidirectional AC / DC converter to connect the station AC bus and the station DC bus.

[0056] In the existing substation AC and DC power supply system, the station AC bus adopts the 380V AC voltage standard, the station DC bus adopts the 110V DC voltage standard, and the three-phase AC bus is a 10KV AC bus. Figure 2 is a structural diagram of an existing substation AC / DC power supply system according to an embodiment of the present invention. Figure 2 middle, The electric energy output from the 10KV AC bus to the station AC bus. is the power of the AC load in the station, is the power of the DC load in the station, is the electric energy flowing between the station AC bus and the station DC bus, It is the power of charging and discharging the battery pack. When the battery pack is in the charging state, Greater than zero, when the battery pack is in a discharging state, Less than zero. Figure 3 is a structural diagram of an optional substation AC / DC power supply system with photovoltaic energy storage according to an embodiment of the present invention. Figure 3 middle, is the power generated by the photovoltaic array, The electric energy output from the 10KV AC bus to the station AC bus. is the electric energy flowing between the station AC bus and the station DC bus, The power of charging and discharging the battery pack, is the power of the AC load in the station, The embodiment of the present invention connects the photovoltaic array to the substation AC / DC power supply system, and proposes a control strategy for the AC / DC power supply system to maintain the stability of the station AC bus voltage and the station DC bus voltage.

[0057] Step S102, obtaining the power generation of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and determining the working mode of the AC / DC power supply system, the working modes including: a first mode, a second mode and a third mode.

[0058] In the embodiment of the present invention, the operating mode of the AC / DC power supply system is determined by acquiring the power generation of the photovoltaic array and the effective value of the voltage of the three-phase AC bus (i.e., the 10KV AC bus), and the operating modes of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system are switched under different modes to control the power generation of the photovoltaic array and the power supply state of the three-phase AC bus, thereby achieving a balanced flow of power and energy in the AC / DC power supply system.

[0059] Optionally, the operation mode of the working mode includes: when the AC / DC power supply system is operating in a first mode, the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through a photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through a bidirectional DC converter; when the AC / DC power supply system is operating in a second mode, the three-phase AC bus stops supplying electric energy to the station AC bus through a station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through a photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through a bidirectional DC converter; when the AC / DC power supply system is operating in a third mode, the three-phase AC bus stops supplying electric energy to the station AC bus through a station transformer, the photovoltaic array stops supplying photovoltaic electric energy to the station AC bus through a photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through a bidirectional DC converter.

[0060] In the embodiment of the present invention, the working modes include a first mode, a second mode and a third mode, which are respectively:

[0061] ;

[0062] in, is the effective value of the voltage of the three-phase AC bus, is the critical value of the three-phase AC bus voltage undervoltage. is the power generated by the photovoltaic array.

[0063] When the AC / DC power supply system operates in the first mode, the 10kV three-phase AC busbar operates normally, that is, The station transformer also operates normally, and the 10kV three-phase AC bus supplies power to the station AC bus through the station transformer; the photovoltaic array participates in power generation, that is, the power generation The photovoltaic array supplies photovoltaic power to the station AC bus through the photovoltaic inverter; the battery group works normally and supplies power to the station DC bus through the bidirectional DC converter. At this time, energy flows from the station AC bus to the station DC bus.

[0064] When the AC / DC power supply system is operating in the second mode, a fault occurs on the 10kV three-phase AC busbar and the voltage drops. , the 10kV three-phase AC busbar exits the power supply system, and no longer supplies energy to the station AC busbar through the station transformer; the photovoltaic array participates in power generation, that is, the electric power The photovoltaic array integrates the photovoltaic power generation energy into the station AC bus through the photovoltaic inverter; the battery group works normally and supplies power to the station DC bus through the bidirectional DC converter. At this time, the energy flows from the station AC bus to the station DC bus.

[0065] When the AC / DC power supply system is operating in the third mode, a fault occurs on the 10kV three-phase AC busbar and the voltage drops. , the 10kV three-phase AC busbar exits the power supply system, and no longer supplies energy to the station AC busbar through the station transformer; the photovoltaic array does not participate in power generation, that is, , the PV array no longer supplies PV power to the station AC bus through the PV inverter; the battery pack works normally, supplies power to the station DC bus through the bidirectional DC converter, and maintains the stability of the station AC bus voltage and the station DC bus voltage.

[0066] Step S103, based on the voltages of the station AC bus and the station DC bus, set the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus, wherein the voltage upper limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit, and the voltage lower limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not less than the corresponding voltage setting lower limit. The setting of the voltage upper limit and the voltage lower limit is used to ensure that the relay protection device does not operate when the AC and DC power supply systems of the substation are in operation.

[0067] The embodiment of the present invention proposes to control the power and energy in the AC / DC power supply system under different working modes of the AC / DC power supply system. During the control process, the voltages of the station AC bus and the station DC bus are compared with the corresponding voltage upper limit and voltage lower limit, and different working states are switched under different working modes according to the comparison results, so as to change the working modes of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system, realize the balanced flow of power and energy, and finally maintain the stability of the station DC bus voltage and the station AC bus voltage.

[0068] It should be noted that the voltage upper and lower limits of the station AC and DC busbars are set according to the requirements of the power system relay protection. In the power system relay protection requirements, the 110V station DC busbar voltage cannot exceed the upper limit of the set value, that is: ,in, is the effective value of the station DC bus voltage, The fixed value can be set to: ,in, To provide a reference value for the stable operation of the station DC bus voltage, in the embodiment of the present invention For 110V, is a constant value, The size can be set by yourself. When the station DC bus voltage exceeds the upper limit of the fixed value, the power system will take relay protection action. At the same time, the 110V station DC bus voltage cannot exceed the lower limit of the fixed value, that is: ,in, is the effective value of the station DC bus voltage, The fixed value can be set to: ,in, To provide a reference value for the stable operation of the station DC bus voltage, in the embodiment of the present invention For 110V, is a constant value, When the station DC bus voltage is lower than the lower limit of the set value, the power system will take relay protection action.

[0069] In the embodiment of the present invention, in order to make the station DC bus voltage meet the power system relay protection requirements, the voltage upper limit and voltage lower limit of the station DC bus are set as follows:

[0070] ;

[0071] in, is the voltage upper limit of the station DC bus, is the lower voltage limit of the station DC bus, is the effective value of the station DC bus voltage, , is a constant value, , The size is set by yourself.

[0072] Similarly, in the power system relay protection requirements, the 380V station AC bus voltage cannot exceed the upper limit of the set value, that is: ,in, is the effective value of the voltage of the station AC bus, The fixed value can be set to: ,in, To provide a reference value for the stable operation of the station AC bus voltage, in the embodiment of the present invention 380V, is a constant value, The size can be set by yourself. When the station AC bus voltage exceeds the upper limit of the fixed value, the power system will take relay protection action. At the same time, the 380V station AC bus voltage cannot exceed the lower limit of the fixed value, that is: ,in, is the effective value of the voltage of the station AC bus, The fixed value can be set to: ,in, To provide a reference value for the stable operation of the station AC bus voltage, in the embodiment of the present invention 380V, is a constant value, When the station AC bus voltage is lower than the lower limit of the set value, the power system will take relay protection action.

[0073] In the embodiment of the present invention, in order to make the station AC bus voltage meet the power system relay protection requirements, the voltage upper limit and voltage lower limit of the station AC bus are set as follows:

[0074] ;

[0075] in, is the voltage upper limit of the station AC bus, is the lower voltage limit of the station AC busbar, is the effective value of the voltage of the station AC bus, , is a constant value, , The voltage upper and lower limits of the station DC bus are the basis for switching different working states when the AC and DC power supply system is working in the first mode or the second mode. By setting the voltage upper and lower limits of the station AC bus and the station DC bus, it can be ensured that the station AC bus voltage and the station DC bus voltage are not greater than the corresponding voltage setting upper limit and not less than the corresponding voltage setting lower limit, so as not to trigger the relay protection action of the substation AC and DC power supply system.

[0076] Step S104, when the AC / DC power supply system is operating in the first mode or the second mode, the voltages of the station AC bus and the station DC bus are compared with the corresponding voltage upper limit and voltage lower limit, and the working modes of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system are switched according to the comparison result to control the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus.

[0077] In the embodiment of the present invention, when the AC / DC power supply system is operating in the first or second mode, the station AC / DC bus voltage is compared with the corresponding voltage upper limit and voltage lower limit, and the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system is switched according to the comparison result to control the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus. The photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system have many working modes. Figure 4is a structural diagram of an optional photovoltaic inverter according to an embodiment of the present invention. The photovoltaic inverter includes a DC boost converter (the embodiment of the present invention adopts a Boost converter) and a bidirectional inverter (the embodiment of the present invention adopts a two-level inverter). Figure 4 middle, is the output voltage of the photovoltaic array, is the output voltage of the DC boost converter, It is the effective value of the voltage of the station AC bus. Figure 5 : is a structural diagram of an optional bidirectional AC / DC converter according to an embodiment of the present invention. The bidirectional AC / DC converter includes a bidirectional DC boost isolation converter and a bidirectional inverter. The output voltage of the station DC bus is first boosted by the bidirectional DC boost isolation converter, and then converted into AC power by the bidirectional inverter (the embodiment of the present invention adopts a two-level inverter) and fed into the station AC bus. Figure 5 middle, is the effective value of the station DC bus voltage, is the DC side voltage of the bidirectional inverter, It is the effective value of the voltage of the station AC bus. It should be noted that the working modes of the bidirectional DC boost isolation converter in the bidirectional AC / DC converter include a positive voltage boost mode and a reverse voltage buck mode. In the positive voltage boost mode, energy flows from the station DC bus to the station AC bus, and in the reverse voltage buck mode, energy flows from the station AC bus to the station DC bus.

[0078] The working modes of the bidirectional inverter in the bidirectional AC / DC converter include a control mode for stabilizing the AC voltage and a control mode for stabilizing the DC voltage. Figure 6 is a structural diagram of a bidirectional inverter in an optional bidirectional AC / DC converter according to an embodiment of the present invention, working in a state of controlling AC voltage stability. Figure 7 is a structural diagram of a bidirectional inverter in an optional bidirectional AC / DC converter according to an embodiment of the present invention, working in a state of controlling the DC voltage to be stable. Figure 6 and Figure 7 middle, represents the integral proportional controller, represents inductance, is the d-axis component of the station AC bus voltage, for Given a reference value, is the DC side voltage of the bidirectional inverter, for Given a reference value, , are the d-axis component and q-axis component of the output voltage of the bidirectional inverter, , are the d-axis component and q-axis component of the station AC bus voltage respectively, , They are the d-axis component and q-axis component of the three-phase current of the bidirectional inverter, , for , The given reference values ​​are all the expected values ​​of the AC / DC power supply system in the embodiment of the present invention when it is in a stable working state, and can be adjusted and set by oneself. Figure 6 The bidirectional inverter in the bidirectional AC / DC converter can control the AC voltage to maintain a stable state. Figure 7 The bidirectional inverter can control the DC side voltage to maintain a stable state by using the control strategy.

[0079] The operating modes of the DC boost converter in the photovoltaic inverter include a maximum power point tracking control mode (i.e., MPPT control mode) and a power limiting control mode. Figure 8 is a structural diagram of a DC boost converter in an optional photovoltaic inverter operating in a maximum power point tracking control mode according to an embodiment of the present invention, Fig. 9 is a structural diagram of a DC boost converter in an optional photovoltaic inverter according to an embodiment of the present invention working in a limited power control mode, Figure 8 and Fig. 9 middle, represents the proportional-integral controller, Represents the zero-order holder, which is used to sample the voltage and current of the photovoltaic array. is the duty cycle of the DC boost converter, is the output voltage of the DC boost converter, for Given a reference value, is the inductor current of the DC boost converter, for The given reference value of Figure 8 The control strategy of the DC boost converter can enable the photovoltaic array to supply photovoltaic power to the station AC bus at maximum power. Fig. 9 The control strategy of the DC boost converter can enable the photovoltaic array to supply photovoltaic power to the station AC bus at a limited power. The limited power can be set according to the grid demand.

[0080] The working modes of the two-level inverter in the photovoltaic inverter include a rear-stage voltage stabilization mode and a bus voltage stabilization mode. Fig.10 is a structural diagram of a two-level inverter in an optional photovoltaic inverter according to an embodiment of the present invention, operating in a stable rear-stage voltage mode, Fig.11 is a structural diagram of a two-level inverter in an optional photovoltaic inverter according to an embodiment of the present invention working in a stable bus voltage mode, Fig.10 and Fig.11 middle, represents the integral proportional controller, represents inductance, is the d-axis component of the station AC bus voltage, for Given a reference value, is the output voltage of the DC boost converter, for Given a reference value, , are the d-axis component and q-axis component of the output voltage of the bidirectional inverter, , are the d-axis component and q-axis component of the station AC bus voltage respectively, , They are the d-axis component and q-axis component of the three-phase current of the bidirectional inverter, , for , The given reference value of Fig.10 Under the control strategy of the two-level inverter, the output voltage of the DC boost converter can be kept stable. Fig.11 Under the control strategy, the two-level inverter can keep the d-axis component of the station AC bus voltage in a stable state.

[0081] Optionally, when the AC / DC power supply system is operating in the first mode or the second mode, the operating state of the battery pack includes: when the state of charge ratio of the battery pack is less than or equal to a preset ratio, the bidirectional DC converter performs constant current charging control or constant current discharging control on the battery pack, wherein the constant current charging control or constant current discharging control refers to keeping the charging or discharging current constant during the charging or discharging process of the battery pack; or, when the state of charge ratio of the battery pack is greater than the preset ratio, the bidirectional DC converter performs constant voltage charging control or constant voltage discharging control on the battery pack, wherein the constant voltage charging control or constant voltage discharging control refers to keeping the charging or discharging voltage constant after the battery pack reaches the target voltage during the charging or discharging process of the battery pack.

[0082] The bidirectional DC converter can control the charging and discharging of the battery pack at constant current and constant voltage through a proportional-integral controller. Fig.12 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant current charging according to an embodiment of the present invention, Fig.13 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant voltage charging according to an embodiment of the present invention, Fig.14is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant current discharge according to an embodiment of the present invention, Fig.15 is a structural diagram of an optional bidirectional DC converter controlling a battery pack to perform constant voltage discharge according to an embodiment of the present invention. Figure 12-15 middle, represents the proportional-integral controller, is the duty cycle of the bidirectional DC converter, is the current flowing into the battery pack, for Given a reference value, is the voltage of the battery pack, for The reference value of is the current flowing into the battery pack, for Given a reference value, is the effective value of the station DC bus voltage, for Reference value. Fig.12 Under the control strategy, the bidirectional DC converter performs constant current charging control on the battery pack, so that the charging current of the battery pack remains constant during the charging process; Fig.13 Under the control strategy, the bidirectional DC converter performs constant voltage charging control on the battery pack, so that during the charging process of the battery pack, when the battery pack reaches the target voltage, the charging voltage is kept constant; Fig.14 Under the control strategy, the bidirectional DC converter performs constant current discharge control on the battery pack, so that the discharge current of the battery pack remains constant during the discharge process; Fig.15 Under the control strategy, the bidirectional DC converter performs constant voltage discharge control on the battery pack, so that during the discharge process of the battery pack, when the battery pack discharges to the target voltage, the discharge voltage is kept constant.

[0083] In the embodiment of the present invention, when the AC / DC power supply system is operating in the first mode or the second mode, when the state of charge ratio value of the battery pack is less than or equal to the preset ratio value, the bidirectional DC converter performs constant current charging control or constant current discharging control on the battery pack, and when the state of charge ratio value of the battery pack is greater than the preset ratio value, the bidirectional DC converter performs constant voltage charging control or constant voltage discharging control on the battery pack, and the preset ratio value is set automatically. It should be noted that during the charging and discharging process of the battery pack, the charging and discharging current must be less than or equal to the rated charging and discharging current.

[0084] Optionally, when the AC / DC power supply system is operating in a first mode, the first mode includes: in a first working state, the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, and the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, wherein the maximum power point tracking control mode refers to the photovoltaic array supplying photovoltaic electric energy to the station AC bus at maximum power; in a second working state, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, and the DC boost converter in the photovoltaic inverter operates in a limited power control mode, wherein the limited power control mode refers to the photovoltaic array supplying photovoltaic electric energy to the station AC bus at a limited power, and the limited power is less than the maximum power.

[0085] In an embodiment of the present invention, when the AC / DC power supply system operates in a first mode, the first mode includes a first working state and a second working state. In the first working state, the three-phase AC bus supplies power to the station AC bus through the station transformer, and the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode; in the second working state, the station transformer stops running, the three-phase AC bus no longer supplies power to the station AC bus through the station transformer, the DC boost converter in the photovoltaic inverter operates in a power limiting control mode, and the bidirectional inverter in the bidirectional AC / DC converter operates in a working mode of controlling the DC voltage stability.

[0086] Optionally, when the AC / DC power supply system is operating in the first mode, the step of controlling the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus includes: when the AC / DC power supply system is operating in the first working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, switching the working mode of the AC / DC power supply system to the second working state to reduce the power generation power of the photovoltaic array; when the AC / DC power supply system is operating in the first working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, maintaining the AC / DC power supply system The working mode of the AC / DC power supply system is the first working state; when the AC / DC power supply system is in the second working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the first working state, the power generation power of the photovoltaic array is increased, and the three-phase AC bus supplies electric energy to the station AC bus through the station transformer again; when the AC / DC power supply system is in the second working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the working mode of the AC / DC power supply system is maintained in the second working state.

[0087] In an embodiment of the present invention, when the AC / DC power supply system is operating in the first mode, controlling the power generation of the photovoltaic array and the power supply state of the three-phase AC bus requires switching between the first working state and the second working state. Fig.16 is a schematic diagram of switching between different working states in an optional first mode according to an embodiment of the present invention, Fig.16 middle, is the voltage of the station DC bus, is the voltage upper limit of the station DC bus, is the lower voltage limit of the station DC bus, is the voltage of the station AC bus, is the voltage upper limit of the station AC bus, is the lower voltage limit of the station AC busbar, Fig.16 Mode 1 in corresponds to the first mode, case 1 corresponds to the first working state, and case 2 corresponds to the second working state. When the AC / DC power supply system is in the first working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, it indicates that the power generation of the photovoltaic array is too large, and the battery group and AC / DC loads cannot absorb the power generation of the photovoltaic array, that is, Therefore, the excess energy is gathered on the station AC / DC bus, causing the station AC / DC bus voltage to gradually increase. In order to keep the station AC / DC bus voltage stable, it is necessary to switch the working state of the AC / DC power supply system from the first state to the second state to reduce the power generation of the photovoltaic array. It should be noted that is the power generated by the photovoltaic array, is the power generation power of the station AC bus, is the charge and discharge power of the battery pack, is the AC load power in the station, is the DC load power in the station.

[0088] When the AC / DC power supply system is in the second working state, when the voltage of the station AC bus is less than the lower voltage limit of the station AC bus or the voltage of the station DC bus is less than the lower voltage limit of the station DC bus, , indicating that the AC and DC loads are too large, and the total supply of the power generation of the photovoltaic array and the discharge power of the battery group is less than the AC and DC loads. Therefore, the energy gathered on the station AC and DC bus is too little, resulting in a gradual decrease in the voltage of the station AC and DC bus. In order to keep the voltage of the station AC and DC bus stable, the working state of the AC and DC power supply system is switched from the second state to the first state at this time to increase the power generation of the photovoltaic array, and the three-phase AC bus supplies power to the station AC bus through the station transformer again. When the AC and DC power supply system is working in the first or second state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the existing state remains unchanged.

[0089] Optionally, when the AC / DC power supply system is in the second mode of operation, the second mode includes: in the third operating state, the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter operates in a stable rear-stage voltage mode, wherein the stable rear-stage voltage mode refers to that the output voltage of the DC boost converter remains stable under the control of the two-level inverter; or, in the fourth operating state, the DC boost converter in the photovoltaic inverter operates in a limited power control mode, and the two-level inverter in the photovoltaic inverter operates in a stable bus voltage mode, wherein the stable bus voltage mode refers to that the d-axis component of the station AC bus voltage remains stable under the control of the two-level inverter; in the third operating state and the fourth operating state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter both operates in a reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter both operates in a working mode for controlling the DC side voltage to remain stable, wherein the reverse buck mode refers to that electric energy flows from the station AC bus to the station DC bus under the control of the bidirectional AC / DC converter.

[0090] In an embodiment of the present invention, when the AC / DC power supply system operates in the second mode, the second mode includes two working states, namely the third working state and the fourth working state. In the third working state, the DC boost converter in the photovoltaic inverter operates in the maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter operates in the stable rear stage voltage mode; in the fourth working state, the DC boost converter in the photovoltaic inverter operates in the power limiting control mode, and the two-level inverter in the photovoltaic inverter operates in the stable bus voltage mode. In the third working state and the fourth working state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in the reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter operates in the working mode of controlling the DC side voltage to remain stable.

[0091] Optionally, when the AC / DC power supply system is operating in the second mode, the step of controlling the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus includes: when the AC / DC power supply system is operating in the third working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, switching the working mode of the AC / DC power supply system to the fourth working state to reduce the power generation power of the photovoltaic array; when the AC / DC power supply system is operating in the third working state, when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage When the voltage of the station AC bus is less than the lower voltage limit of the station AC bus or the voltage of the station DC bus is less than the lower voltage limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the third working state to increase the power generation power of the photovoltaic array; when the AC / DC power supply system is in the fourth working state, when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the working mode of the AC / DC power supply system is maintained in the fourth working state.

[0092] In the embodiment of the present invention, when the AC / DC power supply system is operating in the second mode, the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus need to be switched between the third working state and the fourth working state. Fig.17 is a schematic diagram of switching between different working states under an optional second mode according to an embodiment of the present invention, Fig.17 middle, is the voltage of the station DC bus, is the voltage upper limit of the station DC bus, is the lower voltage limit of the station DC bus, is the voltage of the station AC bus, is the voltage upper limit of the station AC bus, is the lower voltage limit of the station AC busbar, Fig.17Mode 2 in corresponds to the second mode, case 1 corresponds to the third working state, and case 2 corresponds to the fourth working state. When the AC / DC power supply system is in the third working state, when the voltage of the station AC bus is greater than the upper voltage limit of the station AC bus or the voltage of the station DC bus is greater than the upper voltage limit of the station DC bus, it indicates that the power generation of the photovoltaic array is too large, and the battery group and the AC / DC load cannot absorb the power generation of the photovoltaic array. The excess energy increases the voltage of the station AC / DC bus. At this time, it is necessary to switch the working state to the fourth working state. When the AC / DC power supply system is in the fourth working state, when the voltage of the station AC bus is less than the lower voltage limit of the station AC bus or the voltage of the station DC bus is less than the lower voltage limit of the station DC bus, since the station AC bus does not participate in the power supply at this time, it indicates that the AC / DC load is too large, and the total supply of the power generation of the photovoltaic array and the discharge power of the battery group is less than the AC / DC load, resulting in a decrease in the voltage of the station AC / DC bus. At this time, it is necessary to switch the working state to the third working state. When the AC / DC power supply system is operating in the third or fourth state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the existing state remains unchanged.

[0093] Step S105, when the AC / DC power supply system is operating in the third mode, the photovoltaic array and the three-phase AC busbar are stopped from supplying energy, and the battery group provides power to the AC load and the DC load in the station.

[0094] In an embodiment of the present invention, when the AC / DC power supply system is operating in the third mode, the 10KV three-phase AC bus is in a fault and voltage-loss state, the station transformer stops running, the 10KV three-phase AC bus no longer supplies power to the station AC bus, and the photovoltaic array stops generating electricity. The battery group simultaneously provides power to the AC load and the DC load in the station and maintains the stability of the station DC bus voltage.

[0095] Optionally, when the AC / DC power supply system operates in the third mode, it includes: the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a forward boost mode, wherein the forward boost mode refers to that under the control of the bidirectional AC / DC converter, electric energy flows from the station DC bus to the station AC bus; and the bidirectional inverter in the bidirectional AC / DC converter operates in an operating mode for controlling the AC side voltage to remain stable.

[0096] In an embodiment of the present invention, when the AC / DC power supply system operates in the third mode, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a forward boost mode, and the bidirectional inverter in the bidirectional AC / DC converter operates in an operating mode for controlling the AC side voltage to remain stable. In the third mode, power and energy flow from the station DC bus to the station AC bus.

[0097] The steps provided by the control method of the AC / DC power supply system of the substation with photovoltaic energy storage are realized by connecting the photovoltaic array to the station AC bus, and by using a bidirectional AC / DC converter to connect the station AC bus and the station DC bus, so that the station AC bus and the station DC bus can supply power to each other, so that the surplus photovoltaic power generation energy can be stored in the battery pack, and when necessary, the stored photovoltaic power can be discharged by the battery pack to supply the AC load and the DC load in the station at the same time, and the working mode of the AC / DC power supply system is determined according to the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system is switched under different modes, and the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus are controlled, so as to realize the balanced flow of power and energy in the AC / DC power supply system, thereby solving the technical problem in the related art that the power obtained by the AC / DC power supply system from the three-phase AC bus cannot be reduced.

[0098] The following is a detailed description in conjunction with another embodiment.

[0099] Embodiment 2

[0100] A control device for a substation AC / DC power supply system with photovoltaic energy storage provided in this embodiment includes multiple implementation units, each of which corresponds to each implementation step in the above-mentioned embodiment 1.

[0101] Fig.18 is a schematic diagram of an optional control device for a substation AC / DC power supply system with photovoltaic energy storage according to an embodiment of the present invention, such as Fig.18As shown, the control device for the AC / DC power supply system of the substation with photovoltaic energy storage may include: a connection unit 180, a determination unit 181, a setting unit 182, a first control unit 183, and a second control unit 184. The connection unit 180 is used to connect the photovoltaic array to the station AC bus through a photovoltaic inverter, connect the battery pack to the station DC bus through a bidirectional DC converter, and use a bidirectional AC / DC converter to connect the station AC bus and the station DC bus; the determination unit 181 is used to obtain the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and determine the working mode of the AC / DC power supply system, and the working mode includes: a first mode, a second mode, and a third mode; the setting unit 182 sets the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus based on the voltage of the station AC bus and the station DC bus, wherein the voltage upper limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit, and the voltage lower limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit, and the voltage lower limit is a variable set to ensure that the voltage of the station AC bus The voltage of the station AC bus and the voltage of the station DC bus are not less than the variable set by the corresponding voltage setting lower limit. The setting of the voltage upper limit and the voltage lower limit is used to ensure that the relay protection device does not operate when the AC and DC power supply system of the substation is in operation; the first control unit 183 is used to compare the voltage of the station AC bus and the station DC bus with the corresponding voltage upper limit and voltage lower limit when the AC and DC power supply system is working in the first mode or the second mode, and switch the working mode of the photovoltaic inverter and the bidirectional DC converter in the AC and DC power supply system according to the comparison result to control the power generation power of the photovoltaic array and the power supply status of the three-phase AC bus; the second control unit 184 is used to stop the energy supply of the photovoltaic array and the three-phase AC bus when the AC and DC power supply system is working in the third mode, and the battery group provides power to the AC load and the DC load in the station.

[0102] The above-mentioned substation AC / DC power supply system control device with photovoltaic energy storage can connect the photovoltaic array to the station AC bus through the photovoltaic inverter through the connection unit 180, connect the battery pack to the station DC bus through the bidirectional DC converter, and use the bidirectional AC / DC converter to connect the station AC bus and the station DC bus, so as to realize the photovoltaic energy supply of the AC / DC power supply system, and enable the station AC and DC buses to supply power to each other, so that the surplus photovoltaic power generation energy can be stored in the battery pack, and when necessary, the stored photovoltaic power can be discharged by the battery pack to supply the AC load and the DC load in the station at the same time, and then obtain the power generation power of the photovoltaic array and the effective value of the voltage of the three-phase AC bus through the determination unit 181, determine the working mode of the AC / DC power supply system, and then set the voltage of the station AC bus and the station DC bus based on the voltage of the station AC bus and the station DC bus through the setting unit 182. The voltage upper limit and the voltage lower limit of the DC bus are determined, and then the first control unit 183 compares the voltages of the station AC bus and the station DC bus with the corresponding voltage upper limit and voltage lower limit when the AC / DC power supply system is operating in the first mode or the second mode, and switches the operating mode of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system according to the comparison result to control the power generation power of the photovoltaic array and the power supply status of the three-phase AC bus. Finally, the second control unit 184 stops the energy supply of the photovoltaic array and the three-phase AC bus when the AC / DC power supply system is operating in the third mode, and the battery pack provides electrical energy to the AC load and the DC load in the station, thereby achieving a balanced flow of power and energy in the AC / DC power supply system, so that the voltages of the station AC and DC buses remain stable, thereby solving the technical problem in the related art that the electrical energy obtained from the three-phase AC bus by the AC / DC power supply system cannot be reduced.

[0103] Optionally, the operation mode of the working mode in the determination unit 181 includes: a first power supply module, which is used when the AC / DC power supply system is working in the first mode, the three-phase AC bus supplies electric energy to the station AC bus through the station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter; a second power supply module, which is used when the AC / DC power supply system is working in the second mode, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter; a third power supply module, which is used when the AC / DC power supply system is working in the third mode, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, the photovoltaic array stops supplying photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter.

[0104] Optionally, when the AC / DC power supply system of the first control unit 183 is operating in the first mode or the second mode, the operating state of the battery pack includes: a first charging and discharging module, which is used for the bidirectional DC converter to perform constant current charging control or constant current discharging control on the battery pack when the state of charge ratio of the battery pack is less than or equal to a preset ratio, wherein the constant current charging control or constant current discharging control refers to keeping the charging or discharging current constant during the charging or discharging process of the battery pack; a second charging and discharging module, which is used for the bidirectional DC converter to perform constant voltage charging control or constant voltage discharging control on the battery pack when the state of charge ratio of the battery pack is greater than a preset ratio, wherein the constant voltage charging control or constant voltage discharging control refers to keeping the charging or discharging voltage constant after the battery pack reaches the target voltage during the charging or discharging process of the battery pack.

[0105] Optionally, when the AC / DC power supply system is operating in a first mode, the first control unit 183 includes: a first working module, which is used to operate in a first working state, in which the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, and the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, wherein the maximum power point tracking control mode refers to the photovoltaic array supplying photovoltaic power to the station AC bus at maximum power; a second working module, which is used to operate in a second working state, in which the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, and the DC boost converter in the photovoltaic inverter operates in a limited power control mode, wherein the limited power control mode refers to the photovoltaic array supplying photovoltaic power to the station AC bus at a limited power, and the limited power is less than the maximum power.

[0106] Optionally, the first control unit 183 controls the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus when the AC / DC power supply system is operating in the first mode, including: a first control module, which is used to switch the working mode of the AC / DC power supply system to the second working state when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus when the AC / DC power supply system is operating in the first working state, so as to reduce the power generation power of the photovoltaic array; a second control module, which is used to maintain the AC / DC power supply system in the first working state when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit. The working mode of the power supply system is the first working state; the third control module is used to switch the working mode of the AC / DC power supply system to the first working state when the AC / DC power supply system is working in the second working state, when the voltage of the station AC bus is less than the lower voltage limit of the station AC bus or the voltage of the station DC bus is less than the lower voltage limit of the station DC bus, increase the power generation power of the photovoltaic array, and the three-phase AC bus re-supply electric energy to the station AC bus through the station transformer; the fourth control module is used to maintain the working mode of the AC / DC power supply system in the second working state when the AC / DC power supply system is working in the second working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding upper voltage limit and greater than or equal to the lower voltage limit.

[0107] Optionally, when the first control unit 183 is in the second mode of the AC / DC power supply system working state, the second mode includes: a third working module, which is used to operate the third working state, the DC boost converter in the photovoltaic inverter operates in the maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter operates in the stable rear-stage voltage mode, wherein the stable rear-stage voltage mode refers to that the output voltage of the DC boost converter remains stable under the control of the two-level inverter; a fourth working module, which is used to operate the fourth working state, the DC boost converter in the photovoltaic inverter operates in the limited power control mode, and the photovoltaic inverter The two-level inverter in the converter operates in a stable bus voltage mode, wherein the stable bus voltage mode refers to that the d-axis component of the station AC bus voltage is kept in a stable state under the control of the two-level inverter; the fifth working module is used for, in the third working state and the fourth working state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter operates in a working mode for controlling the DC side voltage to remain stable, wherein the reverse buck mode refers to that under the control of the bidirectional AC / DC converter, electric energy flows from the station AC bus to the station DC bus.

[0108] Optionally, the first control unit 183 controls the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus when the AC / DC power supply system is operating in the second mode, including: a fifth control module, which is used to switch the working mode of the AC / DC power supply system to a fourth working state when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus when the AC / DC power supply system is operating in the third working state, thereby reducing the power generation power of the photovoltaic array; a sixth control module, which is used to switch the working mode of the AC / DC power supply system to a fourth working state when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than the voltage upper limit of the station DC bus when the AC / DC power supply system is operating in the third working state. The seventh control module is used for, when the AC / DC power supply system is in the fourth working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, switching the working mode of the AC / DC power supply system to the third working state to increase the power generation power of the photovoltaic array; the eighth control module is used for, when the AC / DC power supply system is in the fourth working state, when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, maintaining the working mode of the AC / DC power supply system in the fourth working state.

[0109] Optionally, when the AC / DC power supply system is operating in the third mode, the second control unit 184 includes: a ninth control module, which is used for the bidirectional DC boost isolation converter in the bidirectional AC / DC converter to operate in a forward boost mode, wherein the forward boost mode refers to the flow of electric energy from the station DC bus to the station AC bus under the control of the bidirectional AC / DC converter; and a tenth control module, which is used for the bidirectional inverter in the bidirectional AC / DC converter to operate in a working mode of controlling the AC side voltage to remain stable.

[0110] The above-mentioned substation AC / DC power supply system control device with photovoltaic energy storage can also include a processor and a memory. The above-mentioned connection unit 180, determination unit 181, setting unit 182, first control unit 183, second control unit 184, etc. are all stored in the memory as program units, and the processor executes the above-mentioned program units stored in the memory to realize corresponding functions.

[0111] The above processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the AC and DC power supply system of the substation with photovoltaic energy storage can be controlled by adjusting the kernel parameters.

[0112] The above-mentioned memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one storage chip.

[0113] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is further provided, the computer-readable storage medium including a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the method for controlling the AC / DC power supply system of a substation with photovoltaic energy storage added according to any one of the above-mentioned embodiments one.

[0114] According to another aspect of an embodiment of the present invention, there is also provided an electronic device, comprising one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by one or more processors, the one or more processors implement the method for controlling an AC / DC power supply system of a substation with photovoltaic energy storage added according to any one of the above-mentioned embodiments one.

[0115] The present application also provides a computer program product, including a computer program, which, when executed by a processor, implements the steps of the method for controlling a substation AC / DC power supply system with photovoltaic energy storage described in each embodiment of the present application.

[0116] The present application also provides a computer program product, including a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for controlling the AC / DC power supply system of a substation with photovoltaic energy storage added described in each embodiment of the present application are implemented.

[0117] Fig.19 1 is a hardware structure block diagram of an electronic device (or mobile device) for a control method of a substation AC / DC power system with photovoltaic energy storage according to an embodiment of the present invention. Fig.19 As shown, the electronic device may include one or more ( Fig.19 1902a, 1902b, ..., 1902n are used to illustrate) processor (the processor may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 1904 for storing data. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of the I / O interface), a network interface, a keyboard, a power supply and / or a camera. A person skilled in the art can understand that Fig.19 The structure shown is only for illustration and does not limit the structure of the above electronic device. Fig.19More or fewer components as shown, or with Fig.19 Different configurations are shown.

[0118] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0119] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0120] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0121] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0122] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0123] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc. Various media that can store program codes.

[0124] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A control method for a substation AC / DC power supply system with photovoltaic energy storage, characterized in that: include: Connecting the photovoltaic array to the station AC bus through a photovoltaic inverter, connecting the battery pack to the station DC bus through a bidirectional DC converter, and connecting the station AC bus with the station DC bus using a bidirectional AC / DC converter; Obtaining the power generation of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and determining the working mode of the AC / DC power supply system, wherein the working mode includes: a first mode, a second mode, and a third mode; Based on the voltages of the station AC bus and the station DC bus, the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus are set, wherein the voltage upper limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit, and the voltage lower limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not less than the corresponding voltage setting lower limit. The setting of the voltage upper limit and the voltage lower limit is used to ensure that the relay protection device does not operate when the AC and DC power supply systems of the substation are in operation; When the AC / DC power supply system is operating in the first mode or the second mode, the voltages of the station AC bus and the station DC bus are compared with the corresponding voltage upper limit and voltage lower limit, and the working modes of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system are switched according to the comparison result to control the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus; When the AC / DC power supply system is in the second mode, the second mode includes: a third working state, the DC boost converter in the photovoltaic inverter works in a maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter works in a stable rear-stage voltage mode, wherein the stable rear-stage voltage mode means that the output voltage of the DC boost converter remains stable under the control of the two-level inverter; or a fourth working state, the DC boost converter in the photovoltaic inverter works in a limited power control mode, and the two-level inverter in the photovoltaic inverter works in a stable rear-stage voltage mode. In a stable bus voltage mode, wherein the stable bus voltage mode refers to that the d-axis component of the station AC bus voltage is kept stable under the control of the two-level inverter; in the third working state and the fourth working state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter is operated in a reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter is operated in a working mode for controlling the DC side voltage to remain stable, wherein the reverse buck mode refers to that electric energy flows from the station AC bus to the station DC bus under the control of the bidirectional AC / DC converter; When the AC / DC power supply system is operating in the second mode, the step of controlling the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus includes: when the AC / DC power supply system is operating in the third working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, switching the working mode of the AC / DC power supply system to the fourth working state to reduce the power generation power of the photovoltaic array; when the AC / DC power supply system is operating in the third working state, when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit When the AC / DC power supply system is in the third working state, the working mode of the AC / DC power supply system is maintained in the third working state; when the AC / DC power supply system is in the fourth working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the third working state to increase the power generation power of the photovoltaic array; when the AC / DC power supply system is in the fourth working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the working mode of the AC / DC power supply system is maintained in the fourth working state; When the AC / DC power supply system operates in the third mode, the energy supply of the photovoltaic array and the three-phase AC bus is stopped, and the battery group provides power to the AC load and the DC load in the station.

2. The control method according to claim 1, characterized in that: The operation mode of the working mode includes: When the AC / DC power supply system operates in the first mode, the three-phase AC bus supplies electric energy to the station AC bus through the station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery group supplies electric energy to the station DC bus through the bidirectional DC converter; When the AC / DC power supply system operates in the second mode, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, the photovoltaic array supplies photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery pack supplies electric energy to the station DC bus through the bidirectional DC converter; When the AC / DC power supply system operates in the third mode, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, the photovoltaic array stops supplying photovoltaic electric energy to the station AC bus through the photovoltaic inverter, and the battery pack supplies electric energy to the station DC bus through the bidirectional DC converter.

3. The control method according to claim 1, characterized in that: When the AC / DC power supply system operates in the first mode or the second mode, the operating state of the battery pack includes: When the state of charge ratio value of the battery pack is less than or equal to a preset ratio value, the bidirectional DC converter performs constant current charging control or constant current discharging control on the battery pack, wherein the constant current charging control or the constant current discharging control means that during the charging or discharging process of the battery pack, the charging or discharging current is kept constant; or, When the state of charge ratio value of the battery pack is greater than a preset ratio value, the bidirectional DC converter performs constant voltage charging control or constant voltage discharging control on the battery pack, wherein the constant voltage charging control or the constant voltage discharging control means that during the charging or discharging process of the battery pack, when the charging or discharging of the battery pack reaches a target voltage, the charging or discharging voltage is kept constant.

4. The control method according to claim 1, characterized in that: When the AC / DC power supply system operates in the first mode, the first mode includes: In a first working state, the three-phase AC bus supplies electric energy to the station AC bus through a station transformer, and the DC boost converter in the photovoltaic inverter operates in a maximum power point tracking control mode, wherein the maximum power point tracking control mode means that the photovoltaic array supplies photovoltaic electric energy to the station AC bus at maximum power; In the second working state, the three-phase AC bus stops supplying electric energy to the station AC bus through the station transformer, and the DC boost converter in the photovoltaic inverter operates in a limited power control mode, wherein the limited power control mode means that the photovoltaic array supplies photovoltaic electric energy to the station AC bus with a limited power, and the limited power is less than the maximum power.

5. The control method according to claim 4, characterized in that: When the AC / DC power supply system operates in the first mode, the step of controlling the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus comprises: When the AC / DC power supply system is operating in the first working state, when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the second working state to reduce the power generation power of the photovoltaic array; When the AC / DC power supply system is operating in the first working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, maintaining the working mode of the AC / DC power supply system in the first working state; When the AC / DC power supply system is operating in the second working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, the working mode of the AC / DC power supply system is switched to the first working state, the power generation power of the photovoltaic array is increased, and the three-phase AC bus supplies electric energy to the station AC bus again through the station transformer; When the AC / DC power supply system is operating in the second working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, the working mode of the AC / DC power supply system is maintained in the second working state.

6. The control method according to claim 1, characterized in that: When the AC / DC power supply system operates in the third mode, the method includes: The bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a forward boost mode, wherein the forward boost mode means that electric energy flows from the station DC bus to the station AC bus under the control of the bidirectional AC / DC converter; The bidirectional inverter in the bidirectional AC / DC converter operates in a working mode for controlling the AC side voltage to remain stable.

7. A substation AC / DC power system control device with photovoltaic energy storage, characterized in that: include: A connection unit, used to connect the photovoltaic array to the station AC bus through a photovoltaic inverter, connect the battery pack to the station DC bus through a bidirectional DC converter, and connect the station AC bus with the station DC bus using a bidirectional AC / DC converter; A determination unit, used to obtain the power generation of the photovoltaic array and the effective value of the voltage of the three-phase AC bus, and determine the working mode of the AC / DC power supply system, wherein the working mode includes: a first mode, a second mode and a third mode; A setting unit, based on the voltages of the station AC bus and the station DC bus, sets the voltage upper limit and voltage lower limit of the station AC bus and the station DC bus, wherein the voltage upper limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not greater than the corresponding voltage setting upper limit, and the voltage lower limit is a variable set to ensure that the voltage of the station AC bus and the voltage of the station DC bus are not less than the corresponding voltage setting lower limit, and the setting of the voltage upper limit and the voltage lower limit is used to ensure that the relay protection device does not operate when the AC and DC power supply systems of the substation are in operation; a first control unit, configured to compare the voltages of the station AC bus and the station DC bus with the corresponding voltage upper limit and voltage lower limit when the AC / DC power supply system is operating in the first mode or the second mode, and switch the working modes of the photovoltaic inverter and the bidirectional DC converter in the AC / DC power supply system according to the comparison result, so as to control the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus; When the AC / DC power supply system is in the second mode, the first control unit comprises: a third working module for operating the third working state, the DC boost converter in the photovoltaic inverter operates in the maximum power point tracking control mode, and the two-level inverter in the photovoltaic inverter operates in the stable rear-stage voltage mode, wherein the stable rear-stage voltage mode means that the output voltage of the DC boost converter remains stable under the control of the two-level inverter; and a fourth working module for operating the fourth working state, the DC boost converter in the photovoltaic inverter operates in the limited power control mode, and the two-level inverter in the photovoltaic inverter operates in the stable rear-stage voltage mode. The two-level inverter operates in a stable bus voltage mode, wherein the stable bus voltage mode refers to that the d-axis component of the station AC bus voltage is kept stable under the control of the two-level inverter; a fifth working module, used for, in the third working state and the fourth working state, the bidirectional DC boost isolation converter in the bidirectional AC / DC converter operates in a reverse buck mode, and the bidirectional inverter in the bidirectional AC / DC converter operates in a working mode of controlling the DC side voltage to remain stable, wherein the reverse buck mode refers to that under the control of the bidirectional AC / DC converter, electric energy flows from the station AC bus to the station DC bus; The first control unit controls the power generation power of the photovoltaic array and the power supply state of the three-phase AC bus when the AC / DC power supply system is operating in the second mode, including: a fifth control module, which is used to switch the working mode of the AC / DC power supply system to the fourth working state to reduce the power generation power of the photovoltaic array when the voltage of the station AC bus is greater than the voltage upper limit of the station AC bus or the voltage of the station DC bus is greater than the voltage upper limit of the station DC bus when the AC / DC power supply system is operating in the third working state; and a sixth control module, which is used to switch the working mode of the AC / DC power supply system to the fourth working state to reduce the power generation power of the photovoltaic array when the voltage of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the corresponding voltage upper limit when the AC / DC power supply system is operating in the third working state. a seventh control module, for, when the AC / DC power supply system is operating in the fourth working state, when the voltage of the station AC bus is less than the voltage lower limit of the station AC bus or the voltage of the station DC bus is less than the voltage lower limit of the station DC bus, switching the operating mode of the AC / DC power supply system to the third working state to increase the power generation power of the photovoltaic array; an eighth control module, for, when the AC / DC power supply system is operating in the fourth working state, when the voltages of the station AC bus and the station DC bus are both less than or equal to the corresponding voltage upper limit and greater than or equal to the voltage lower limit, maintaining the operating mode of the AC / DC power supply system in the fourth working state; The second control unit is used to stop the power supply of the photovoltaic array and the three-phase AC bus when the AC / DC power supply system is operating in the third mode, and the battery group provides power to the AC load and the DC load in the station.

8. An electronic device, characterized in that: It includes one or more processors and a memory, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the control method of the substation AC / DC power supply system with photovoltaic energy storage as described in any one of claims 1 to 6.

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