A solar storage and charging control system and method

Abstract

The application belongs to the technical field of power electronics, and particularly relates to a kind of light storage charging control system and method. Including grid-connected point E and main control module, grid-connected point E is connected with node D through first air circuit breaker QF1;Node D is connected with node B through third AC contactor KM3;Node B is connected with energy storage converter;Energy storage converter is connected with photovoltaic energy storage module;Grid-connected point E is connected with node C through second air circuit breaker QF2 and first AC contactor KM1 in turn;Node C is connected with node B through second AC contactor KM2;Node C is connected with load through third air circuit breaker QF3;First AC contactor KM1 and second AC contactor KM2 are interlocked, second AC contactor KM2 and third AC contactor KM3 are interlocked;Main control module is used to obtain forward active power data of grid-connected point E, and thereby control output power of energy storage converter. The application avoids power supply short circuit caused by sudden power of power grid through interlocking relationship between AC contactors.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics, and in particular relates to a photovoltaic storage and charging control system and method. Background Art

[0002] In recent years, photovoltaic (PV)-plus-energy storage products have experienced rapid growth. Current tiered electricity pricing and power restrictions, as well as policies requiring a certain percentage of energy storage to be installed alongside PV installations, have encouraged the installation of both PV and energy storage systems in some large and medium-sized industrial parks. These systems can offer diverse benefits to owners, such as the ability to generate PV for their own use and to capitalize on peak and valley voltage arbitrage through energy storage. PV-plus-energy storage systems can also serve as a backup power source, utilizing PV generation and energy storage to power park equipment during grid outages. This ensures the operation of critical equipment and mitigates economic losses caused by power outages or curtailments.

[0003] The current popular solar-to-storage system application model in the industry is to charge energy at a low price and discharge it at a high price to achieve peak-valley arbitrage, and prioritize self-use of photovoltaic power generation (load + energy storage consumption), with excess power then being connected to the grid. This application model fully utilizes solar resources and avoids waste. However, park photovoltaic power generation is different from photovoltaic power stations. The photovoltaic installation area limits the installed power and the efficiency of photovoltaic power generation. The possibility of excess power being connected to the grid is extremely small. Even then, customers must apply for grid connection approval according to relevant national grid connection policies, which is a cumbersome process and wastes funds and resources. Summary of the Invention

[0004] The purpose of the present invention is to provide a photovoltaic storage and charging control system and method to solve the technical problem that the existing photovoltaic storage system control and grid connection are complicated and cumbersome, resulting in waste of manpower and material resources.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] In a first aspect, a solar storage and charging control system includes a grid connection point E and a main control module, wherein the grid connection point E is connected to a node D via a first air circuit breaker QF1;

[0007] The node D is connected to the node B via the third AC contactor KM3;

[0008] The node B is connected to the energy storage converter;

[0009] The energy storage converter is connected to the photovoltaic energy storage module;

[0010] The grid connection point E is connected to the node C via the second air circuit breaker QF2 and the first AC contactor KM1 connected in series;

[0011] The node C is connected to the node B via the second AC contactor KM2;

[0012] The node C is connected to the load via a third air circuit breaker QF3;

[0013] The first AC contactor KM1 is interlocked with the second AC contactor KM2, and the second AC contactor KM2 is interlocked with the third AC contactor KM3;

[0014] The main control module is used to obtain the forward active power data of the grid connection point E and control the output power of the energy storage converter according to the forward active power data of the grid connection point E.

[0015] A further improvement of the present invention is that: the photovoltaic energy storage module includes an energy storage battery, a DC-DC module and a photovoltaic string, the photovoltaic string is connected to the DC-DC module, the DC-DC module is connected to node A through a first DC contactor KZ1, the node A is connected to KZ2 through a second DC contactor, and the node A is connected to the energy storage converter.

[0016] A further improvement of the present invention is that the node D is connected to a charging module, and the charging module is used to charge the electric vehicle.

[0017] A further improvement of the present invention is that: a bidirectional meter is provided at the grid connection point E, and a signal output end of the bidirectional meter is connected to a signal input end of the main control module.

[0018] A further improvement of the present invention is that: the main control module and the energy storage converter communicate via CAN; the main control module and the charging module also communicate via CAN.

[0019] A further improvement of the present invention is that the main control module communicates with the bidirectional meter via RS485.

[0020] A further improvement of the present invention is that: DI1, DI2, DI3, DI4 and DI5 of the main control module are respectively connected to the feedback contact of the first AC contactor KM1, the feedback contact of the second AC contactor KM2, the feedback contact of the third AC contactor KM3, the feedback contact of the first DC contactor KZ1 and the feedback contact of the second DC contactor KZ2;

[0021] DO1, DO2, DO3, DO4 and DO5 of the main control module correspond to the coil control state of the first AC contactor KM1, the coil control state of the second AC contactor KM2, the coil control state of the third AC contactor KM3, the coil control state of the first DC contactor KZ1 and the coil control state of the second DC contactor KZ2 respectively.

[0022] In a second aspect, a method for controlling solar storage and charging includes the following steps:

[0023] Obtain the forward active power data of the grid connection point E and transmit it to the main control module;

[0024] The photovoltaic energy storage module is connected to the grid or absorbed through the energy storage converter. The main control module controls the inverter output power of the energy storage converter according to the forward active power data.

[0025] When the grid is out of power, the photovoltaic energy storage module supplies power to the load through the off-grid inversion of the energy storage converter;

[0026] When the power grid switches from energized to de-energized, the first AC contactor KM1 and the third AC contactor KM3 are disconnected first, and then the second AC contactor KM2 is closed, and the energy storage converter is started synchronously to perform off-grid inverter output;

[0027] When the grid is powered on again from a power outage, the second AC contactor KM2 is disconnected first, the off-grid inverter output of the energy storage converter is stopped synchronously, and then the first AC contactor KM1 and the third AC contactor KM3 are closed.

[0028] A further improvement of the present invention is that when controlling the inverter output power of the energy storage converter according to the forward active power data, the method specifically includes:

[0029] If the forward active power is greater than the rated output power of the energy storage converter + the judgment threshold, the main control module controls the energy storage converter to output full power inverter;

[0030] If the judgment threshold < forward active power < rated output power of the energy storage converter, the main control module controls the inverter output of the energy storage converter to be: forward active power - judgment threshold;

[0031] If the forward active power is less than the judgment threshold, the energy storage converter stops the inverter output.

[0032] A further improvement of the present invention is that the judgment threshold is 3kW.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] The present invention controls whether the energy storage converter is connected to the grid and the grid output power and switches in and out of the off-grid inverter of the energy storage converter by obtaining the forward active power of the grid connection point. This ensures reliable operation without the need for a cumbersome grid connection application process, thus avoiding waste of manpower and material resources.

[0035] The present invention realizes the AC output of the energy storage converter and the power supply of the grid through the interlocking of the first AC contactor KM1 and the second AC contactor KM2; the second AC contactor KM2 and the third AC contactor KM3, thereby avoiding a power short circuit caused by a sudden power supply from the grid.

[0036] The present invention avoids violations caused by surplus power being connected to the grid due to load power being less than the output power of the energy storage converter by setting a judgment threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 A topological diagram of a solar storage and charging control system according to the present invention;

[0039] Figure 2 This is a schematic diagram of a main control unit in a solar storage and charging control system of the present invention.

[0040] In the figure: 1. Bidirectional meter; 2. Energy storage converter; 3. Charging module; 4. Load; 5. Energy storage battery; 6. DC-DC module; 7. Photovoltaic string. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0042] The following detailed description is an exemplary description and is intended to provide further detailed description of the present invention. Unless otherwise indicated, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0043] Example 1

[0044] like Figure 1-2 As shown, a solar storage and charging control system includes a grid connection point E and a main control module. The grid connection point E is connected to the node D through the first air circuit breaker QF1;

[0045] Node D is connected to charging module 3, and node D is connected to node B via a third AC contactor KM3;

[0046] Node B is connected to energy storage converter 2;

[0047] Energy storage converter 2 is connected to node A;

[0048] Node A is connected to the DC-DC module 6 via the first DC contactor KZ1, and the DC-DC module 6 is connected to the photovoltaic string 7;

[0049] Node A is connected to the energy storage battery 5 via the second DC contactor KZ2;

[0050] The grid connection point E is connected to the node C via the second air circuit breaker QF2 and the first AC contactor KM1 connected in series;

[0051] Node C is connected to node B via the second AC contactor KM2;

[0052] Node C is connected to load 4 via the third air circuit breaker QF3;

[0053] The first AC contactor KM1 is interlocked with the second AC contactor KM2, and the second AC contactor KM2 is interlocked with the third AC contactor KM3;

[0054] A bidirectional meter 1 is provided at the grid connection point E;

[0055] The signal input end of the main control module is connected to the bidirectional meter 1 , and the signal output end of the main control module is connected to the energy storage converter 2 .

[0056] DI1, DI2, DI3, DI4 and DI5 of the main control module are respectively connected to the feedback contact of the first AC contactor KM1, the feedback contact of the second AC contactor KM2, the feedback contact of the third AC contactor KM3, the feedback contact of the first DC contactor KZ1 and the feedback contact of the second DC contactor KZ2;

[0057] DO1, DO2, DO3, DO4 and DO5 of the main control module correspond to the coil control state of the first AC contactor KM1, the coil control state of the second AC contactor KM2, the coil control state of the third AC contactor KM3, the coil control state of the first DC contactor KZ1 and the coil control state of the second DC contactor KZ2 respectively;

[0058] Whether the control of the first AC contactor KM1 , the second AC contactor KM2 , the third AC contactor KM3 , the first DC contactor KZ1 and the second DC contactor KZ2 is effective is detected through DI and DO of the main control module.

[0059] The main control module and the two-wire meter use RS85 interface for communication;

[0060] The main control module and the energy storage converter 2 communicate via CAN;

[0061] The main control module and the charging module 3 also communicate via CAN.

[0062] This system can control the opening and closing of the contactor to achieve the following functions:

[0063] The grid supplies power to load 4;

[0064] The power grid charges the electric vehicle through the charging module 3 or the energy storage converter 2;

[0065] The power grid charges the energy storage battery 5 through the energy storage converter 2;

[0066] The photovoltaic string 7 charges the energy storage battery 5 through the DC-DC module 6;

[0067] The photovoltaic string 7 charges the electric vehicle through the DC-DC module 6;

[0068] The photovoltaic string 7 supplies power to the load 4 through the DC-DC module 6 and the energy storage converter 2;

[0069] The energy storage battery 5 supplies power to the load 4 through the energy storage converter 2;

[0070] The energy storage battery 5 charges the electric vehicle through the energy storage converter 2 and the charging module 3 .

[0071] Example 2

[0072] A method for controlling solar storage and charging, comprising the following steps:

[0073] The forward active power data obtained from the power grid is detected by a two-wire meter and transmitted to the main control module;

[0074] When the grid has electricity, the energy storage battery 5 and the photovoltaic string 7 are connected to the grid or absorbed through the energy storage converter 2. The main control module controls the inverter output power of the energy storage converter 2 according to the forward active power data;

[0075] When the grid is out of power, the energy storage battery 5 and the photovoltaic string 7 provide power to the load 4 through the off-grid inversion of the energy storage converter 2;

[0076] When the grid switches from energized to de-energized, the first AC contactor KM1 and the third AC contactor KM3 are disconnected first, and 2S later the second AC contactor KM2 is closed, and the energy storage converter 2 is started synchronously for off-grid inverter output;

[0077] When the grid is powered on again from a power outage, the second AC contactor KM2 is disconnected first, and the off-grid inverter output of the energy storage converter is stopped synchronously. After 2S, the first AC contactor KM1 and the third AC contactor KM3 are closed.

[0078] When controlling the inverter output power of the energy storage converter 2 according to the forward active power data, in order to avoid violations caused by the surplus power being connected to the grid due to the load 4 power being less than the output power of the energy storage converter 2, the power obtained from the grid, i.e., the forward active power, can be monitored by the bidirectional meter 1. At the same time, a judgment threshold is set. When the forward active power is less than the judgment threshold, the grid-connected inverter output of the energy storage converter 2 is stopped. The judgment threshold is less than the rated output power of the energy storage converter. Specifically, the following steps are included:

[0079] If the forward active power is greater than the rated output power of the energy storage converter + the judgment threshold, the main control module controls the energy storage converter 2 to output full power inverter power;

[0080] If the judgment threshold < forward active power < rated output power of the energy storage converter, the main control module controls the inverter output of the energy storage converter 2 to be: forward active power - judgment threshold;

[0081] If the forward active power is less than the judgment threshold, the energy storage converter 2 stops the inverter output.

[0082] The judgment threshold is 3kW.

[0083] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A solar storage and charging control system, characterized in that: It includes a grid connection point E and a main control module, wherein the grid connection point E is connected to the node D through a first air circuit breaker QF1; The node D is connected to the node B via the third AC contactor KM3; The node B is connected to the energy storage converter (2); The energy storage converter (2) is connected to the photovoltaic energy storage module; The grid connection point E is connected to the node C via the second air circuit breaker QF2 and the first AC contactor KM1 connected in series; The node C is connected to the node B via the second AC contactor KM2; The node C is connected to the load (4) via a third air circuit breaker QF3; The first AC contactor KM1 is interlocked with the second AC contactor KM2, and the second AC contactor KM2 is interlocked with the third AC contactor KM3; The main control module is used to obtain the forward active power data of the grid connection point E, and control the output power of the energy storage converter (2) according to the forward active power data of the grid connection point E. The photovoltaic energy storage module includes an energy storage battery (5), a DC-DC module (6) and a photovoltaic string (7). The photovoltaic string (7) is connected to the DC-DC module (6). The DC-DC module (6) is connected to the node A through a first DC contactor KZ1. The node A is connected to KZ2 through a second DC contactor. The node A is connected to the energy storage converter (2). A bidirectional meter (1) is provided at the grid connection point E. The signal output end of the bidirectional meter (1) is connected to the signal input end of the main control module.

2. A solar storage and charging control system according to claim 1, characterized in that: The node D is connected to a charging module (3), and the charging module (3) is used to charge the electric vehicle.

3. The solar storage and charging control system according to claim 1, characterized in that: The main control module and the energy storage converter (2) communicate via CAN; the main control module and the charging module (3) also communicate via CAN.

4. The solar storage and charging control system according to claim 3, characterized in that: The main control module communicates with the bidirectional meter (1) via RS485.

5. The solar storage and charging control system according to claim 1, characterized in that: The pins DI1, DI2, DI3, DI4 and DI5 of the main control module are respectively connected to the feedback contact of the first AC contactor KM1, the feedback contact of the second AC contactor KM2, the feedback contact of the third AC contactor KM3, the feedback contact of the first DC contactor KZ1 and the feedback contact of the second DC contactor KZ2; Pins DO1, DO2, DO3, DO4 and DO5 of the main control module correspond to the coil control state of the first AC contactor KM1, the coil control state of the second AC contactor KM2, the coil control state of the third AC contactor KM3, the coil control state of the first DC contactor KZ1 and the coil control state of the second DC contactor KZ2 respectively.

6. A method for controlling solar storage and charging, characterized in that: The following steps are involved: Obtain the forward active power data of the grid connection point E and transmit it to the main control module; The photovoltaic energy storage module is connected to the grid or absorbed through the energy storage converter (2), and the main control module controls the inverter output power of the energy storage converter (2) according to the forward active power data; When the grid is out of power, the photovoltaic energy storage module supplies power to the load (4) through the off-grid inversion of the energy storage converter (2); When the power grid switches from energized to de-energized, the first AC contactor KM1 and the third AC contactor KM3 are first disconnected, and then the second AC contactor KM2 is closed, and the energy storage converter (2) is started synchronously to perform off-grid inverter output; When the grid is powered on again, the second AC contactor KM2 is disconnected first, the off-grid inverter output of the energy storage converter is stopped synchronously, and then the first AC contactor KM1 and the third AC contactor KM3 are closed; When controlling the inverter output power of the energy storage converter (2) according to the forward active power data, it specifically includes: If the forward active power is greater than the rated output power of the energy storage converter + the judgment threshold, the main control module controls the energy storage converter (2) to output full power inverter; If the judgment threshold < forward active power < rated output power of the energy storage converter, the main control module controls the inverter output of the energy storage converter (2) to be: forward active power - judgment threshold; If the forward active power is less than the judgment threshold, the energy storage converter (2) stops the inverter output.

7. A method for controlling solar storage and charging according to claim 6, characterized in that: The judgment threshold is 3kW.

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