Optical storage and charging energy management system for limiting power grid energy taking

Abstract

The invention discloses a light storage and charging energy management system for limiting power grid energy taking, which comprises a power grid and a light storage and charging system, and is characterized in that the light storage and charging system is connected to the power grid and comprises a photovoltaic panel, a DC / DC, a high-voltage box and a battery PACK which are connected in sequence, and the high-voltage box and the DC / DC are also connected with a PCS; the photovoltaic panel converts solar energy into direct current, and the direct current is converted into direct current suitable for the optical storage and charging system through the DC / DC; the high-voltage box manages and distributes energy flow to the battery PACK, the battery PACK receives and stores electric energy from the photovoltaic panel, the high-voltage box controls connection and disconnection of direct current and PCS connection at the same time, and monitoring and management are conducted through a secondary BMS in the high-voltage box; the PCS converts direct current of the high-voltage box and the DC / DC into alternating current, and the charging pile is connected with the PCS to obtain the alternating current to charge equipment. According to the invention, new energy photovoltaic and energy storage technologies are utilized, the electric energy of the power grid is fully utilized, and the electricity taking power of the power grid is limited and does not exceed the maximum limit value of the power grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage equipment, and in particular relates to a photovoltaic energy storage and charging management system that limits power grid energy intake. Background Art

[0002] China's new energy vehicle market has maintained a strong growth trend. With the increasing use of new energy vehicles, more and more public places need to add high-power charging piles for new energy vehicles, and the power of charging piles that support fast charging is getting higher and higher. Conventional ones have reached 60KW, and high-power ones may reach 100KW or more.

[0003] If more charging piles are added, the power will need to be increased significantly relative to the existing power supply system (assuming that 4 60kW charging heads are configured, 240KW of power is required, and 240kW of power is added to the original distribution system). The incoming line of the substation or power grid cannot bear the power of the newly added charging piles, and it is necessary to apply to the power grid company for capacity expansion. That is, the existing technology uses the expansion of the distribution system to solve the problem that the power supply capacity of the power grid is insufficient to support the addition of new charging piles. The expansion faces major rectification and long-term power outages, and may even require the replacement of the substation distribution transformer.

[0004] Some patents propose a photovoltaic + energy storage solution. Photovoltaic and energy storage use AC coupling. Photovoltaic has a separate photovoltaic inverter (DC / AC) to operate independently. This architecture has low photovoltaic utilization and serious light abandonment. At the same time, in the system control system, photovoltaics, as a supplement to the power supply of the power grid, only play the role of reducing the power drawn from the power grid. There is no real-time limit on the power drawn from the power grid according to the actual load size, and it does not solve the limitation of the power drawn from the power grid. Even if this set of photovoltaic storage and charging system is used, the existing distribution system needs to be expanded. At the same time, the existing technology does not have a system without overall coordination between multiple photovoltaic storage and charging systems, and obtains the power of the power grid according to priority, resulting in the system being unable to store energy in the best energy storage method. Most photovoltaic systems that have been used currently use AC coupling, which has low utilization efficiency; in addition, since there is no automatic on-grid switching device, it does not support on-grid switching and can only run on the grid. Once the power grid is out of power, the charging pile cannot be charged. Summary of the invention

[0005] In view of the above-mentioned defects, the present invention provides a photovoltaic storage and charging energy management system that limits the energy intake of the power grid. The photovoltaic storage and charging energy management system is designed using new energy photovoltaic and energy storage technologies. While making full use of the power of the power grid, the power intake of the power grid is limited to not exceed the maximum limit value of the power grid. At the same time, in order to cooperate with the system and maximize the role of photovoltaics and energy storage, optimizations are also made to the system architecture and hardware design of the conventional solution.

[0006] Technical solution:

[0007] A photovoltaic storage and charging energy management system that limits power grid energy intake includes a power grid and a photovoltaic storage and charging system. The photovoltaic storage and charging system is connected to the power grid, including a photovoltaic panel, a DC / DC converter, a high-voltage box, and a battery PACK connected in sequence, and the high-voltage box and the DC / DC converter are also connected to a PCS; the photovoltaic panel converts solar energy into direct current, and converts it into direct current suitable for the photovoltaic storage and charging system through a DC / DC converter; the high-voltage box manages and distributes energy flow to the battery PACK, the battery PACK receives and stores electrical energy from the photovoltaic panel, and the high-voltage box simultaneously controls the on and off of the DC and PCS connections, and is monitored and managed through a secondary BMS in the high-voltage box; the PCS converts the direct current of the high-voltage box and the DC / DC converter into alternating current, and the charging pile obtains alternating current by connecting to the PCS to charge the device.

[0008] Preferably, the management system also includes an energy storage branch meter, one end of which is connected to the power grid, and the other end is connected to the PCS through the STS, so that switching between the power grid and the photovoltaic storage and charging system is realized based on the STS; the management system also includes a main meter, which is connected to the bus of the power grid.

[0009] Preferably, the system also includes a station-controlled energy management system EMS, which monitors the energy flow of the entire system. The EMS is communicated with the main electricity meter, energy storage branch electricity meter, STS, PCS, high-voltage box, DC / DC converter and charging pile, and controls the working status of each component according to the charging demand, photovoltaic panel output power and grid conditions.

[0010] Preferably, the EMS monitors the output power of the photovoltaic panel through a DC / DC converter, and monitors the status of the battery PACK through a high-voltage box. When the output power of the photovoltaic panel is high and the grid demand is low, the EMS instructs the DC / DC converter to store excess electrical energy in the battery PACK; when the grid demand is high and the photovoltaic panel output is insufficient, the EMS instructs the battery PACK to discharge; the EMS adjusts the charging and discharging strategies according to the SOC and health status of the battery PACK.

[0011] Preferably, the EMS controls the conversion of DC and AC through the PCS. When the battery PACK needs to discharge to supply the power grid or charging pile, the EMS instructs the PCS to convert DC to AC; when the power grid needs to be taken and stored in the battery PACK, the EMS instructs the PCS to convert AC to DC.

[0012] Preferably, the EMS monitors the charging demand through the charging pile. When the charging pile has a charging demand, the EMS instructs the PCS to convert DC power into AC power to supply the charging pile. When the grid demand is high and the photovoltaic panel output is insufficient, the EMS gives priority to using the power of the battery PACK to supply the charging pile.

[0013] Preferably, one photovoltaic, storage and charging energy management system corresponds to one photovoltaic, storage and charging integrated machine. When multiple charging piles are needed, multiple photovoltaic, storage and charging integrated machines are connected in parallel to the AC electrical line. At the same time, the EMS is connected to an Ethernet switch, and one of the EMSs is configured as the host, and the EMSs of other photovoltaic, storage and charging integrated machines are slaves. At this time, the total electricity meter only communicates with the EMS that serves as the host.

[0014] As a preferred option, the energy management strategy of EMS is: for a system consisting of n photovoltaic storage and charging devices connected in parallel, for the i-th photovoltaic storage and charging device, 1≤i≤n, the current remaining capacity of the battery energy storage is wi; in the grid-connected state, any photovoltaic storage and charging device,

[0015] When wi>96%, the station control EMS controls the photovoltaic energy of this device to no longer be used for charging, and its PCS converts all photovoltaic electricity into AC power and integrates it into the grid;

[0016] When 30%≤wi≤96%, the output power of the PCS inside the device is the output power of the charging pile. The photovoltaic power supplies the charging pile with the maximum power it can obtain, and the excess is used to charge the battery.

[0017] When 10%≤wi≤30%, and the connected charging gun is charging externally, it is the first priority grid power supply state. If the host detects a photovoltaic storage and charging integrated device that uses the first priority grid power supply, the main control EMS will supplement the grid power according to the current total meter power;

[0018] When wi is less than 10%, it is the second priority grid power supply state. At this time, the low capacity warning light will be on and the output of the charging gun will be stopped. If there is no photovoltaic storage and charging integrated machine in the first priority grid power supply state, the main control EMS will supplement the grid power according to the current total meter power.

[0019] As a preferred embodiment, the energy management strategy of EMS is: suppose the maximum power that the power grid can provide is Pm, the power of the total electricity meter is Pf, the power consumed by the charging pile is Poi, the power provided by photovoltaic is Pgi, and the maximum charging power of the battery is Pc. When wi>96%, the master EMS determines that if all photovoltaic storage and charging integrated machines with wi>96% satisfy ΣPgi≤Pf-10kWh, then all photovoltaics are connected to the grid; if all photovoltaic storage and charging integrated machines with wi>96% ΣPgi>Pf-10kWh, the master EMS calculates the percentage coefficient u, so that u×(ΣPgi)=Pf-10kWh, and the master EMS sends the coefficient u to each photovoltaic storage and charging integrated station EMS with wi>96%. The station control EMS as a slave sets the maximum limit power obtained by MPPT according to u*Pgi; after being connected to the grid, the master EMS monitors Pf in real time. If Pf≠10kW, u is increased or decreased to make Pf>10kW but closest to 10kW.

[0020] Preferably, the energy management strategy of the EMS is as follows: when wi ≤ 30%, further judge the magnitudes of Pm and Pf. When Pm - Pf > 10 kW, the main control EMS distributes the maximum grid power taking for each integrated PV energy storage charging system that takes power from the first-priority grid according to ΔP = (Pm - Pf) / n, where n is the number of integrated PV energy storage charging systems that take power from the first-priority grid. After the integrated PV energy storage charging systems that take power from the first-priority grid are allocated power, for the integrated PV energy storage charging systems with 10% ≤ wi ≤ 30%, the power output by the PCS changes from Poi to Poi - ΔP, and the PV power is preferably used first. For the integrated PV energy storage charging systems with wi < 10%, the PCS charging power is ΔP. If ΔP + Pgi < Pc, the battery is charged according to the total power ΔP + Pgi. If ΔP + Pgi > Pc, the battery is charged according to the total power Pc, and the grid power taking is reduced to ensure that the total charging power does not exceed Pc. After the capacity is greater than 20%, the second-priority grid power taking state is exited.

[0021] The beneficial effects of the present invention are as follows:

[0022] (1) The integrated PV energy storage charging energy management system for restricting grid power taking disclosed by the present invention designs an integrated PV energy storage charging energy management system by using new energy PV and energy storage technologies. The energy management system dedicated to the expansion of charging piles runs on the station control EMS of the system, collects and regulates the electrical data of each electrical circuit, and uses new energy PV to the maximum extent

[0023] and stores the excess PV. When there is no PV, it is used as a supplement, while ensuring that the grid power taking does not exceed the maximum limit provided by the grid;

[0024] (2) The integrated PV energy storage charging energy management system for restricting grid power taking disclosed by the present invention supports the cascading between multiple integrated PV energy storage charging energy management systems, distributes the priority and power of grid power taking according to the power demand situation of the charging piles, and can perform energy distribution between systems well;

[0025] (3) The integrated PV energy storage charging energy management system for restricting grid power taking disclosed by the present invention adopts a DC coupling electrical scheme, has a high PV utilization rate, and can directly charge the battery;

[0026] (4) The integrated PV energy storage charging energy management system for restricting grid power taking disclosed by the present invention uses a grid-connected / off-grid fast switching switch in the electrical scheme. When the grid power fails, it can quickly switch to PV and battery power supply, and the output of the charging pile is continuous and uninterrupted during the switching process;

[0027] (5) The photovoltaic storage and charging energy management system disclosed in the present invention that limits grid power intake is designed to design an energy management strategy for scenarios where the grid power intake is limited, aiming at scenarios where charging piles are expanded without changing the original power distribution system. The charging piles are provided with power by photovoltaic power generation, excess power when the grid load is low, and battery storage. At the same time, the charging piles are charged by photovoltaic power generation and excess power when the grid load is low, which solves the problem of grid access or electrical capacity expansion of the distribution room required for the construction of additional charging piles, as well as power outages and renovations caused by electrical capacity expansion.

[0028] (6) The photovoltaic energy storage and charging management system disclosed in the present invention that limits the power drawn from the power grid strategically maximizes the use of photovoltaic energy and reduces the power drawn from the power grid. At the same time, it cooperates to obtain the power of the load that does not exceed the rated power of the power drawn from the power grid, thereby realizing power supply to the charging pile and charging the battery at the same time.

[0029] (7) The photovoltaic storage and charging energy management system disclosed in the present invention that limits the power grid energy consumption can be connected in parallel with multiple AC measuring devices. At the same time, the EMS of each photovoltaic storage and charging integrated device is connected to a switch through a network cable, and one of them is configured

[0030] EMS is the host, and the host is based on the output power requirements of the charging piles of each solar storage and charging system, the battery power,

[0031] The photovoltaic power and other conditions determine the priority and allocate the power drawn from the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0033] Figure 1 is a topological diagram of key electrical components of one embodiment of the present invention;

[0034] Figure 2 is a schematic diagram of system component installation according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of cascading multiple integrated photovoltaic storage and charging devices according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 are within the scope of protection of the present invention.

[0037] Example 1

[0038] This application mainly considers the scenario of adding new energy vehicle charging piles under the background of limited power intake from the power grid. While making full use of the power of the power grid, the power intake of the power grid is limited to not exceed the maximum limit of the power grid. At the same time, DC-coupled photovoltaics are added to allow photovoltaics to supplement the power limit of the power grid. If the photovoltaic charging pile has excess electricity, it can directly charge the battery for use when there is no photovoltaic.

[0039] The present invention discloses a photovoltaic storage and charging energy management system for limiting power grid energy intake, such as Figure 1 As shown, it includes key components such as bidirectional converter (PCS), direct current converter (DC / DC), static switching switch (STS), dual-way charging piles, photovoltaic panels, battery PACK, high-voltage box, station control energy management system (station control EMS), energy storage branch meter, etc., and cooperates with the total meter outside the system to display the total power used by the current load.

[0040] The functions of each key component of the system are as follows:

[0041] Photovoltaic panels: used to convert solar energy into electrical energy. The number of photovoltaic panels is configured according to the DC / DC power.

[0042] DC / DC converter: Contains MPPT, connected to photovoltaic panels, can track the maximum power of photovoltaic panels, and convert the photovoltaic voltage to a suitable voltage output for battery charging or PCS conversion into AC output. In this embodiment, the DC / DC power is 100kW, and the specifications can be adjusted according to needs.

[0043] High-voltage distribution box: As the core hub of the system, it not only connects the DC / DC converter, but also manages and distributes energy flows from different sources to the battery PACK;

[0044] Battery PACK: It is composed of battery cells, which receive and store the electricity generated by the photovoltaic panels, and provide energy reserves for the stable operation of the system. This embodiment uses 16 280mAh battery cells connected in series, and integrates the first-level BMS battery monitoring board to monitor the battery parameters and control the balance of the battery cells. The whole system uses a total of 15 battery PACKs in series;

[0045] High-voltage box: manages the battery PCAK, controls the on / off of the DC and PCS connections, integrates the second-level BMS, aggregates the data of each PACK and exchanges data with the EMS

[0046] Power conversion system (PCS): connects the high-voltage distribution box and the DC / DC converter, has a bidirectional conversion function, and can efficiently convert DC to AC and vice versa to meet the needs of different equipment. In this embodiment, the PCS power is 125kW, and the specifications can be adjusted according to needs.

[0047] DC charging pile: A charging pile with two charging gun heads, which obtains AC power by connecting to PCS to charge electric vehicles or other electrical equipment. In this embodiment, the power of each charging gun head is 60kW, and the specifications can be adjusted according to needs;

[0048] Static Transfer Switch (STS): STS mainly realizes automatic switching between on-grid and off-grid, and can ensure that the switching time is less than one cycle;

[0049] Station-controlled energy management system (EMS): collects data and operating status of all devices with communication interfaces, analyzes the collected results and issues control instructions to each device. At the same time, the equipment has a remote communication interface (4G, 5G, Ethernet, etc.) and can communicate with remote cloud servers;

[0050] Energy storage branch meter: used to measure the power obtained by the solar energy storage and charging system from the grid. In the energy management strategy, the data from this meter can be used to know whether the solar energy storage and charging system has obtained power from the grid, and to control the power obtained by the solar energy storage and charging system from the grid;

[0051] In addition to key components, necessary auxiliary components are also required, such as battery thermal management systems (such as battery air cooling systems), automatic fire protection systems, uPS, etc. By connecting the communication lines and AC and DC electrical lines of each component, the hardware part of the system can be realized.

[0052] Figure 1 In the figure, the solid line represents the connection of AC power, the dash-dot line represents the connection of DC power, and the dotted line represents the communication line for data transmission and control signals.

[0053] The system works as follows:

[0054] The photovoltaic panel converts solar energy into direct current, and converts it into direct current suitable for the light storage and charging system through a DC / DC converter; the high-voltage box manages and distributes the energy flow to the battery PACK, the battery PACK receives and stores the electrical energy from the photovoltaic panel, and the high-voltage box simultaneously controls the on and off of the DC and PCS connections, and monitors and manages them through the secondary BMS in the high-voltage box; the PCS converts the direct current of the high-voltage box and the DC / DC converter into alternating current, and the charging pile obtains alternating current by connecting to the PCS to charge the device.

[0055] EMS monitors the output power of photovoltaic panels through DC / DC converters. When the output power of photovoltaic panels is high and the grid demand is low, EMS instructs the DC / DC converter to store excess electrical energy in the battery PACK; when the grid demand is high, EMS instructs the DC / DC converter to supply the electrical energy of photovoltaic panels directly to the grid or charging pile.

[0056] EMS monitors the status of the battery PACK through the high-voltage box. When the grid demand is low and the photovoltaic panel output is high, EMS instructs the battery PACK to charge; when the grid demand is high and the photovoltaic panel output is insufficient, EMS instructs the battery PACK to discharge, and converts DC power into AC power through PCS to supply the grid or charging pile; EMS adjusts the charging and discharging strategy according to the SOC and health status of the battery PACK.

[0057] EMS monitors charging demand through charging piles. When there is charging demand at the charging piles, EMS instructs PCS to convert DC power into AC power to supply the charging piles. When the grid demand is high and the output of the photovoltaic panels is insufficient, EMS gives priority to using the power of the battery PACK to supply the charging piles.

[0058] The system disclosed in this application realizes a complete chain from solar energy collection to electric energy storage and final use through the coordinated work of various components, while reducing dependence on traditional power grids, improving energy utilization efficiency and the self-sufficiency of the system. In addition, the system disclosed in this application adopts a DC coupled electrical solution with high photovoltaic utilization rate. The battery can be charged directly.

[0059] Example 2

[0060] This embodiment discloses a system implementation scheme on hardware, such as Figure 2 As shown, the system runs on the station control EMS inside the photovoltaic storage and charging integrated machine.

[0061] The system components are installed in a metal cabinet with an IP65 protection level and can be placed outdoors. The cabinet is divided into three parts: battery compartment, electrical compartment, and charging pile. The battery compartment mainly houses the battery PCAK, high-voltage box, automatic fire protection system, and air conditioning cooling system. Because the battery is a high-risk item, it is isolated from other compartments in an isolated space. The electrical compartment mainly consists of EMS, PCS, STS, DC / DC, energy storage branch meter and other equipment. The charging pile has two car charging heads, and the system is also equipped with an operating status indicator light and an emergency stop button controlled by EMS. The system can be placed as a whole at the location required by the customer, and can work purely off-grid or connected to the grid.

[0062] Basic equipment setup and control:

[0063] The STS is set to automatic mode, and automatically switches to off-grid mode or grid-connected mode when the power grid is out or powered on, without the need for manual intervention or master control equipment, and can ensure that the switching time is less than 20ms.

[0064] The output voltage of DCDC is configured as the maximum possible total voltage of the battery. This ensures that when the PCS is working, it can give priority to using the power provided by photovoltaics. When there is excess photovoltaic power, the battery is charged. When there is insufficient photovoltaic power, the battery is supplemented. This achieves automatic power regulation on the DC side.

[0065] Example 3

[0066] This embodiment discloses an energy management strategy of an EMS based on the photovoltaic storage and charging energy management system of Embodiment 1 and the photovoltaic storage and charging integrated device of Embodiment 2.

[0067] The overall idea of ​​the EMS energy management strategy is:

[0068] 1. Make full use of new energy photovoltaics, and at the same time cooperate to obtain the power of the load power that does not exceed the rated power of the power grid, so as to power the charging pile and charge the battery at the same time.

[0069] 2. When the grid load is heavy, instead of drawing electricity from the grid, photovoltaic and battery energy storage are used to provide power to the charging piles.

[0070] 3. When the grid load is not large and there is a lot of power margin, if the photovoltaic power is insufficient and the battery energy storage is low, power is taken from the grid for charging and supply to the charging piles, and the total load is controlled not to exceed the rated power of the grid incoming line.

[0071] Specifically,

[0072] For a system consisting of n photovoltaic storage and charging integrated machines in parallel (n is an integer greater than or equal to 1), let the maximum power that the power grid can provide be Pm, the power of the total electric meter be Pf, and for the i-th photovoltaic storage and charging integrated machine, the power provided by photovoltaic power is Pgi, the power consumed by the charging pile is Poi, the current remaining capacity of the battery energy storage is wi, and the maximum charging power of the battery is Pc. According to the value of wi, it is divided into four gears: high power state, medium-high power state, medium-low power state, and low power state. In this embodiment, the high power state is wi>96%, the medium-high power state is 30%≤wi≤96%, the medium-low power state is 10%≤wi≤30%, and the low power state is wi<10%. The setting value of the total electric meter power is 10kW. It should be noted that the threshold value in this embodiment is the default value of the device. In actual applications, the threshold value of each state quantity can be adjusted by setting the master EMS.

[0073] In the grid-connected state, any photovoltaic storage and charging device:

[0074] ① When in a high power state, the station control EMS controls the photovoltaic energy of this device and no longer uses it for charging. Its PCS converts all photovoltaic electricity into AC power and integrates it into the grid.

[0075] The station control EMS as the host determines:

[0076] If ΣPgi≤Pf-10kWh (where i is all photovoltaic storage and charging devices in a high power state), all photovoltaics are connected to the grid;

[0077] If ΣPgi>Pf-10kWh (where i is all the integrated PV-storage-charging machines in a high power state), the station-controlled EMS as the host will further calculate a percentage coefficient u, so that u×(ΣPgi)=Pf-set value (where i is all the integrated PV-storage-charging machines in a high power state). The station-controlled EMS as the host will send the coefficient to each integrated PV-storage-charging station-controlled EMS in a high power state. The station-controlled EMS as the slave will set the maximum power limit obtained by MPPT according to u*Pgi. After being connected to the grid, the station-controlled EMS as the host will monitor Pf in real time. If Pf≠set value, u will be increased or decreased so that Pf>set value but closest to the set value.

[0078] In actual projects, due to load fluctuations and delays in regulation, some small amounts of photovoltaic power may be charged into the energy storage battery, causing wi to grow slowly. If the station control EMS detects that wi>98%, the photovoltaic power is turned off and the battery power is connected to the grid according to u*Pgi until it is no longer in a high power state.

[0079] ② When the battery is in a medium or high power state, the output power of the PCS inside the device is the output power of the charging pile. The photovoltaic system supplies power to the charging pile at the maximum power it can obtain, and the excess is used to charge the battery.

[0080] ③ When the battery is in a medium or low power state and the connected charging gun is charging externally, it is the first priority grid power supply state.

[0081] If the host detects a photovoltaic storage and charging integrated device that draws power from the first priority grid, the station control EMS as the host will supplement the grid power according to the current total meter power.

[0082] When Pm-Pf>10kW, the master EMS allocates the maximum power of the grid to each PV-storage-charging integrated machine that draws power from the first-priority grid according to ΔP=(Pm-Pf) / n, where n is the number of PV-storage-charging integrated machines that draw power from the first-priority grid.

[0083] After the photovoltaic storage and charging integrated device that draws electricity from the first priority grid is allocated power, the power output of the PCS changes from Poi to Poi-ΔP, and photovoltaic power is used first.

[0084] ④ When the battery is low, it is the second priority grid power supply state. At this time, the low capacity warning light is on and the charging gun head stops outputting. If there is no photovoltaic storage and charging integrated device in the first priority grid power supply state at this time, the station control as the host

[0085] EMS supplements the grid power according to the current total meter power.

[0086] When Pm - Pf > the set value, the station control EMS serving as the host distributes the maximum grid power taking for the integrated PV energy storage chargers in the power-taking state of each first-priority power grid according to ΔP = (Pm - Pf) / n, where n is the number of integrated PV energy storage chargers in the power-taking state of the first-priority power grid.

[0087] After the integrated PV energy storage charger in the power-taking state of the first-priority power grid is allocated power, the PCS charging power is ΔP. If ΔP + Pgi < Pc, the battery is charged according to the total power ΔP + Pgi. If ΔP + Pgi > Pc, the battery is charged according to the total power Pc, and the grid power taking is reduced to ensure that the total charging power does not exceed Pc. After the capacity is greater than 20%, it exits the power-taking state of the second-priority power grid.

[0088] After the grid power outage, the STS automatically disconnects the connection to the grid and switches to the off-grid mode. At this time, the energy stored in each integrated PV energy storage charger and the PV energy are only used for its own charging gun head.

[0089] In the off-grid working state, the PV and the battery supply power to the charging gun head together. The PV energy is preferentially used, and the excess electricity is used to charge the battery. When the PV energy charges the battery, the station control EMS will monitor the battery power. When it reaches 99%, the PV power is limited to 0 kW to prevent the BMS system of the battery from controlling a trip. When it drops below 10%, the warning light for low capacity is lit and the output of the charging gun head is stopped. After the capacity is greater than 20%, it returns to the normal state.

[0090] After the grid power is restored, the STS automatically connects to the grid and resumes grid-connected operation.

[0091] The threshold values of the above control algorithms can all be set and modified through the interface of the station control EMS, and this embodiment does not make any limitations in this regard.

[0092] The integrated PV energy storage charging energy management system and the integrated PV energy storage charger disclosed in this application adopt PV power generation and battery energy storage technologies, cooperate with a specific energy management system, coordinate the energy output of PV, energy storage, and the grid to the charging pile, limit the grid power taking not to exceed the maximum power of the incoming line, and at the same time try to use the PV energy as much as possible and store part of the energy for the supplement of the PV energy. It avoids the power limit of grid power taking, realizes dynamic electrical capacity expansion, solves the problem that the distribution system needs to be rectified and expanded due to the addition of charging piles, and at the same time saves the electricity cost. When multiple charging piles need to be expanded, this energy management system supports multi-stage cascading and coordinates the energy distribution between different devices.

[0093] The control system of this application runs on the station control EMS inside the integrated PV energy storage charger. The EMS controls the internal devices to realize energy management, realizes dynamic capacity expansion, and at the same time preferentially uses the PV electric energy in the system to reduce the electricity cost. The battery stores the excess PV to ensure the continuous operation of the charging pile.

[0094] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A photovoltaic storage and charging energy management system that limits power grid energy intake, characterized in that: It includes a power grid and a photo-storage and charging system. The photo-storage and charging system is connected to the power grid, including photovoltaic panels, DC / DC converters, high-voltage boxes, and battery PACKs connected in sequence. The high-voltage box and DC / DC converter are also connected to PCS. The photovoltaic panels convert solar energy into direct current, and convert it into direct current suitable for the photo-storage and charging system through the DC / DC converter; the high-voltage box manages and distributes energy flow to the battery PACK, and the battery PACK receives and stores electrical energy from the photovoltaic panels. The high-voltage box simultaneously controls the on and off of the DC and PCS connections, and is monitored and managed through the secondary BMS in the high-voltage box; the PCS converts the DC power of the high-voltage box and the DC / DC converter into AC power, and the charging pile obtains AC power by connecting to the PCS to charge the equipment.

2. The photovoltaic storage and charging energy management system for limiting grid energy extraction according to claim 1 is characterized in that: The management system also includes an energy storage branch meter, one end of which is connected to the power grid and the other end is connected to the PCS through the STS, and the switching between the power grid and the photovoltaic storage and charging system is realized based on the STS; the management system also includes a main meter, which is connected to the bus of the power grid.

3. The photovoltaic storage and charging energy management system for limiting grid energy extraction according to claim 2 is characterized in that: The system also includes a station-controlled energy management system EMS, which monitors the energy flow of the entire system. The EMS is connected to the main electricity meter, energy storage branch electricity meter, STS, PCS, high-voltage box, DC / DC converter and charging pile in communication, and controls the working status of each component according to charging demand, photovoltaic panel output power and grid conditions.

4. The photovoltaic storage and charging energy management system for limiting grid energy intake according to claim 3 is characterized in that: EMS monitors the output power of the photovoltaic panel through the DC / DC converter, and monitors the status of the battery PACK through the high-voltage box. When the output power of the photovoltaic panel is higher than the power required by the grid, EMS instructs the DC / DC converter to store the excess energy in the battery PACK; when the grid demand is higher than the output power of the photovoltaic panel, EMS instructs the battery PACK to discharge; EMS adjusts the charging and discharging strategies according to the SOC and health status of the battery PACK.

5. The photovoltaic storage and charging energy management system for limiting grid energy extraction according to claim 3 is characterized in that: EMS controls the conversion of DC and AC through PCS. When the battery PACK needs to discharge to supply the grid or charging pile, EMS instructs PCS to convert DC to AC; when the grid needs to take power and store it in the battery PACK, EMS instructs PCS to convert AC to DC.

6. The photovoltaic storage and charging energy management system for limiting grid energy extraction according to claim 3 is characterized in that: EMS monitors charging demand through charging piles. When there is charging demand at the charging piles, EMS instructs PCS to convert DC power into AC power to supply the charging piles. When the power grid demand power photovoltaic panels are insufficient to provide, EMS will also use the power of the battery PACK as a supplement to the photovoltaic energy to supply the charging piles.

7. The photovoltaic storage and charging energy management system for limiting grid energy intake according to any one of claims 1 to 6, characterized in that: One photovoltaic, storage and charging energy management system corresponds to one photovoltaic, storage and charging integrated machine. When multiple charging piles are needed, multiple photovoltaic, storage and charging integrated machines are connected in parallel to the AC electrical line. At the same time, the EMS is connected to an Ethernet switch, and one of the EMSs is configured as the host, and the EMSs of other photovoltaic, storage and charging integrated machines are slaves. At this time, the total electricity meter only communicates with the EMS that serves as the host.

8. The photovoltaic storage and charging energy management system for limiting grid energy intake according to claim 7 is characterized in that: The energy management strategy of EMS is as follows: for a system consisting of n PV-storage-charging devices connected in parallel, for the i-th PV-storage-charging device, 1≤i≤n, the remaining capacity of the battery energy storage is wi, which is divided into four levels according to the value of wi: high power state, medium-high power state, medium-low power state, and low power state. The threshold value of each state quantity is set and adjusted by the master control EMS; in the grid-connected state, any PV-storage-charging device, When the battery is in high power state, the station control EMS controls the photovoltaic energy of the device to no longer be used for charging, and its PCS converts all photovoltaic electricity into AC power and integrates it into the grid; When the battery is in a medium or high power state, the output power of the PCS inside the device is the output power of the charging pile. The photovoltaic system supplies power to the charging pile at the maximum power it can obtain, and the excess is used to charge the battery. When the battery is in a medium or low power state and the connected charging gun is charging externally, it is in the first priority grid power supply state. If the host detects a photovoltaic storage and charging integrated device that uses the first priority grid power supply, the main control EMS will supplement the grid power according to the current total meter power; When the battery is in a low-battery state, it is in the second-priority grid power-drawing state. At this time, the low-capacity warning light is on and the charging gun head stops outputting. If there is no photovoltaic storage and charging integrated machine in the first-priority grid power-drawing state, the main control EMS will supplement the grid power according to the current total meter power.

9. The photovoltaic storage and charging energy management system for limiting grid energy intake according to claim 8 is characterized in that: The energy management strategy of EMS is as follows: suppose the maximum power that the power grid can provide is Pm, the power of the total electric meter is Pf, the power consumed by the charging pile is Poi, the power provided by photovoltaic is Pgi, and the maximum charging power of the battery is Pc. When in a high power state, the master EMS determines that if the photovoltaic storage and charging integrated machine in the high power state satisfies ΣPgi≤Pf-set value, then all photovoltaic energy is used for grid connection; if all photovoltaic storage and charging integrated machines in the high power state ΣPgi>Pf-set value, the master EMS calculates the percentage coefficient u, so that u×(ΣPgi)=Pf-set value, and the master EMS sends the coefficient u to the station control EMS of each photovoltaic storage and charging integrated machine in the high power state. The station control EMS as a slave sets the maximum limit power obtained by MPPT according to u*Pgi; after grid connection, the master EMS monitors Pf in real time. If Pf≠set value, u is increased or decreased so that Pf>set value but is closest to the set value.

10. The photovoltaic storage and charging energy management system for limiting grid energy intake according to claim 9 is characterized in that: The energy management strategy of the EMS is as follows: when in the medium-low and low power states, further judge the magnitudes of Pm and Pf. When Pm - Pf > the set value, the main control EMS distributes the maximum power for grid power extraction to each integrated photovoltaic energy storage charging unit for grid power extraction at the first priority level according to ΔP = (Pm - Pf) / n, where n is the number of integrated photovoltaic energy storage charging units for grid power extraction at the first priority level; after the integrated photovoltaic energy storage charging unit for grid power extraction at the first priority level is allocated power, for the integrated photovoltaic energy storage charging unit in the medium-low power state, the power output by the PCS changes from Poi to Poi - ΔP, and the power of the photovoltaic is preferentially used; for the integrated photovoltaic energy storage charging unit in the low power state, the PCS charging power is ΔP. If ΔP + Pgi < Pc, the battery is charged with the total power of ΔP + Pgi. If ΔP + Pgi > Pc, the battery is charged with the total power of Pc, reducing the grid power extraction to ensure that the total charging power does not exceed Pc. After the capacity is greater than 20%, it exits the state of grid power extraction at the second priority level.

Images