Energy control method of optical storage system

Abstract

The invention discloses an energy control method for an optical storage system, and the method comprises the steps: Mppt1 is connected with a DC load through a DC ammeter, and the DC load is connected with a DC side of an energy storage converter after passing through the DC ammeter; the Mppt1 and the battery are connected to the direct current side of the energy storage converter, and the Mppt1 and the battery are connected with the energy control system; the Mppt2 is connected with an AC load, and the Mppt2 and the AC ammeter are both connected with an energy control system; the Mppt2 and the alternating-current load are connected to the alternating-current side of the energy storage converter, and the power grid is connected with the alternating-current side of the energy storage converter through the alternating-current electricity meter. The maximum output power of the Mppt2 needs to be controlled only when the battery is in the forced discharging mode and the charging forbidding mode and the real-time power of the Mppt2 is larger than the alternating current load power, and the maximum photovoltaic utilization rate and the minimum power grid utilization rate can be achieved only by controlling the maximum output power of the Mppt1 and the real-time power of the energy storage converter under other conditions. And the energy storage system is in a safe and stable state.

Description

Technical Field

[0001] This invention relates to the field of energy scheduling technology for photovoltaic energy storage systems, and in particular to an energy control method for photovoltaic energy storage systems. Background Technology

[0002] With the increasing global demand for clean energy and the booming development of the electric vehicle market, integrated photovoltaic, energy storage, and charging equipment has emerged as a new comprehensive energy utilization solution. Traditional energy supply systems often rely on a single power grid. When facing peak electricity demand, the power grid is under tremendous load pressure, which not only challenges the stability of power supply but also easily leads to energy waste. Integrated photovoltaic, energy storage, and charging equipment combines the clean and renewable nature of photovoltaic power generation, the peak shaving and valley filling function of energy storage systems, and the convenience of charging facilities. However, there are still many problems in energy control of current integrated photovoltaic, energy storage, and charging equipment that need to be solved.

[0003] With the large-scale grid connection of photovoltaic (PV) power generation, the randomness and volatility of PV power pose increasing challenges to grid stability. On the one hand, PV power generation is affected by natural factors such as sunlight intensity and weather changes, resulting in highly unstable output power. Existing energy control methods struggle to accurately and in real-time coordinate the charging and discharging of energy storage batteries with load power consumption based on sunlight fluctuations, often leading to unreasonable energy allocation and failing to fully leverage the synergistic advantages of PV and energy storage. On the other hand, the performance and lifespan of energy storage batteries are significantly reduced under different operating conditions, such as frequent charging and discharging, high or low temperature environments, and there is a lack of effective battery management strategies to ensure reliable system operation. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an energy control method for a photovoltaic-storage system that can achieve maximum photovoltaic utilization, minimum grid utilization, and ensure that the energy storage system is in a safe and stable state.

[0005] The objective of this invention is achieved through the following technical solution: an energy control method for a photovoltaic energy storage system, comprising two sets of MPpts, a battery, an energy storage converter, an energy control system, an AC load, a DC load, a power grid, a battery, a DC meter, and an AC meter, wherein the energy storage converter and the energy control system are connected.

[0006] Mppt1 is connected to the DC load via a DC meter, and the DC load is connected to the DC side of the energy storage converter via the DC meter; both Mppt1 and the battery are connected to the DC side of the energy storage converter, and both Mppt1 and the battery are connected to the energy control system.

[0007] Mppt2 is connected to the AC load, and both Mppt2 and the AC meter are connected to the energy control system. Both Mppt2 and the AC load are connected to the AC side of the energy storage converter, and the power grid is connected to the AC side of the energy storage converter through the AC meter.

[0008] Let the maximum output power of Mppt1 be P. Mppt1_now_max The real-time output power of Mppt1 is P Mppt1_now The maximum output power of Mppt2 is P. Mppt2_now_max The real-time output power of Mppt2 is P. Mppt2_now The power measured by the AC meter is P. meter_ac The battery's maximum charging power is P. change_max The maximum discharge power is P dischange_max The forced charging power is P change_force The forced discharge power is P dischange_force The real-time power of the energy storage converter during charging and discharging is P. pcs_now The set power for charging and discharging of the energy storage converter is P. pcs_set The power of the AC load is P. loader_ac The power of the DC load is P loader_dc The difference P between the AC load power and the real-time power of Mppt2 loader_ac_diff The following relationship must be satisfied:

[0009] P loader_ac_diff =P meter_ac +P pcs_now ;

[0010] The energy control system dynamically adjusts the maximum output power of Mppt and the charging and discharging power settings of the energy storage converter according to different battery states.

[0011] The battery states include the following six: forced charging mode, forced discharging mode, charging prohibited mode, discharging prohibited mode, chargeable and dischargeable mode, and charging and discharging prohibited mode; the energy control methods for these six battery states are as follows:

[0012] (1) Forced charging mode:

[0013] P Mppt1_now_max =P loader_ac_diff +P change_force +P loader_dc

[0014] P pcs_set =P Mppt1_now -P change_force -P loader_dc ;

[0015] (2) Forced discharge mode, if the real-time power of Mppt2 is not greater than the AC load power:

[0016] P Mppt1_now_max =P loader_ac_diff -P dischange_force +P loader_dc

[0017] Ppcs_set =P loader_ac_diff

[0018] If the real-time power of Mppt2 is greater than the AC load power, and the power grid prohibits power feeding, the maximum output power of Mppt2 also needs to be adjusted:

[0019] P Mppt2_now_max =P Mppt2_now +P loader_ac_diff ;

[0020] (3) Charging disabled mode:

[0021] P Mppt1_now_max =P loader_ac_diff +P loader_dc

[0022] P pcs_set =P Mppt1_now -P loader_dc

[0023] If the real-time power of Mppt2 is greater than the AC load power, and the power grid prohibits power feeding, the maximum output power of Mppt2 also needs to be adjusted:

[0024] P Mppt2_now_max =P Mppt2_now +P loader_ac_diff ;

[0025] (4) Discharge Prohibition Mode:

[0026] P Mppt1_now_max =P loader_ac_diff +P loader_dc

[0027] P pcs_set =P Mppt1_now -P loader_dc ;

[0028] (5) Rechargeable and dischargeable mode:

[0029] P Mppt1_now_max =P loader_ac_diff +P change_max +P loader_dc

[0030] P pcs_set =P pcs_now +P meter_ac ;

[0031] (6) No charging / no discharging mode:

[0032] P Mppt1_now_max =P loader_dc +P pcs_now

[0033] P pcs_set=P Mppt1_now -P loader_dc .

[0034] The beneficial effects of this invention are: this invention only requires controlling the maximum output power of Mppt2 when the battery is in forced discharge mode (in which the battery is also prohibited from charging) and prohibited charging mode, and the real-time power of Mppt2 is greater than the AC load power. In other cases, it is only necessary to control the maximum output power of Mppt1 and the real-time power of the energy storage converter to achieve the maximum efficiency utilization of photovoltaics, achieve the maximum photovoltaic utilization rate and the minimum grid utilization rate, and keep the energy storage system in a safe and stable state. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the energy control system of the photovoltaic energy storage system of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0037] An energy control method for a photovoltaic-storage system includes two sets of MPpts, a battery, an energy storage converter, an energy control system, an AC load, a DC load, a power grid, a battery, a DC meter, and an AC meter. The energy storage converter and the energy control system are connected, and its structure is as follows: Figure 1 As shown;

[0038] Mppt1 is connected to the DC load via a DC meter, and the DC load is connected to the DC side of the energy storage converter via the DC meter; both Mppt1 and the battery are connected to the DC side of the energy storage converter, and both Mppt1 and the battery are connected to the energy control system.

[0039] Mppt2 is connected to the AC load, and both Mppt2 and the AC meter are connected to the energy control system. Both Mppt2 and the AC load are connected to the AC side of the energy storage converter, and the power grid is connected to the AC side of the energy storage converter through the AC meter.

[0040] Let the maximum output power of Mppt1 be P. Mppt1_now_max The real-time output power of Mppt1 is P Mppt1_now The maximum output power of Mppt2 is P. Mppt2_now_max The real-time output power of Mppt2 is P. Mppt2_now The power measured by the AC meter is P. meter_ac The battery's maximum charging power is P. change_max The maximum discharge power is P dischange_max The forced charging power is P change_force The forced discharge power is P dischange_force The real-time power of the energy storage converter during charging and discharging is P. pcs_nowThe set power for charging and discharging of the energy storage converter is P. pcs_set The power of the AC load is P. loader_ac The power of the DC load is P loader_dc The difference P between the AC load power and the real-time power of Mppt2 loader_ac_diff The following relationship must be satisfied:

[0041] P loader_ac_diff =P meter_ac +P pcs_now ;

[0042] The energy control system dynamically adjusts the maximum output power of MPpt and the charging and discharging setting power of the energy storage converter according to different battery states. The battery states include the following six modes: forced charging mode, forced discharging mode, prohibited charging mode, prohibited discharging mode, chargeable and dischargeable mode, and prohibited charging and discharging mode.

[0043] Of the above modes, only when the battery is in forced discharge mode (charging is also prohibited in this mode) and prohibited charging mode, and the real-time power of Mppt2 is greater than the AC load power, does it require controlling the maximum output power of Mppt2. In other cases, only the maximum output power of Mppt1 and the real-time power of the energy storage converter need to be controlled. As shown in the diagram, the battery needs to discharge to AC / DC loads or the grid, and the power of Mppt2 also needs to be released to the grid, AC load, or through the energy storage converter. When the DC load power is less than the battery's forced discharge power, the battery is also outputting power in forced discharge mode, and it's impossible to input the power of Mppt2 back to the DC side. In this case, the excess power can only be input to the grid. However, since the grid prohibits reverse flow, the power of Mppt2 must be reduced to maintain circuit balance.

[0044] The energy control methods for the six battery states are as follows:

[0045] (1) Forced charging mode:

[0046] P Mppt1_now_max =P loader_ac_diff +P change_force +P loader_dc

[0047] P pcs_set =P Mppt1_now -P change_force -P loader_dc ;

[0048] (2) Forced discharge mode, charging is not allowed in this mode; if the real-time power of Mppt2 is not greater than the AC load power:

[0049] P Mppt1_now_max =P loader_ac_diff -P dischange_force +Ploader_dc

[0050] P pcs_set =P loader_ac_diff

[0051] If the real-time power of Mppt2 is greater than the AC load power, and the power grid prohibits power feeding, the AC meter will show a negative value; the maximum output power of Mppt2 also needs to be adjusted.

[0052] P Mppt2_now_max =P Mppt2_now +P loader_ac_diff ;

[0053] The difference between the AC load power and the real-time power of Mppt2 is negative at this point; if it is positive, it means that the AC load power is large, so this operation is equivalent to reducing the output power of Mppt2.

[0054] (3) Charging disabled mode, if the real-time power of Mppt2 is not greater than the AC load power:

[0055] P Mppt1_now_max =P loader_ac_diff +P loader_dc

[0056] P pcs_set =P Mppt1_now -P loader_dc

[0057] If the real-time power of Mppt2 is greater than the AC load power, and the power grid prohibits power feeding, the AC meter will show a negative value; the maximum output power of Mppt2 also needs to be adjusted.

[0058] P Mppt2_now_max =P Mppt2_now +P loader_ac_diff ;

[0059] (4) Discharge Prohibition Mode:

[0060] P Mppt1_now_max =P loader_ac_diff +P loader_dc

[0061] P pcs_set =P Mppt1_now -P loader_dc ;

[0062] (5) Rechargeable and dischargeable mode:

[0063] P Mppt1_now_max =P loader_ac_diff +P change_max +P loader_dc

[0064] P pcs_set =Ppcs_mow +P meter_ac ;

[0065] (6) No charging / no discharging mode:

[0066] P Mppt1_now_max =P loader_dc +P pcs_now

[0067] P pcs_set =P Mppt1_now -P loader_dc .

[0068] To better understand the application scenarios of this method, examples are provided for six different scenarios. Details are as follows:

[0069] (1) Forced charging mode

[0070] In this embodiment, the rated power of the energy storage converter is 120kW, and the real-time power of the energy storage converter is 0kW. The real-time power of Mppt1 is 20kW, the real-time power of Mppt2 is 120kW, the AC load power is 130kW, the DC load power is 17kW, and the AC meter reading is 10kW; the battery capacity is 100kWh, the maximum charge / discharge power is 50kW, the SOC = 0, and the forced charge / discharge power is 3kW. The parameters for the next moment are set as follows:

[0071] P Mppt1_now_max =10+3+17

[0072] P pcs_set =20-3 -17.

[0073] (2) Forced discharge mode

[0074] In this embodiment, the rated power of the energy storage converter is 120kW, and the real-time power of the energy storage converter is 0kW. The real-time power of Mppt1 is 20kW, the real-time power of Mppt2 is 120kW, the AC load power is 130kW, the DC load power is 17kW, and the AC meter reading is 10kW; the battery capacity is 100kWh, the maximum charge / discharge power is 50kW, the SOC is 100%, and the forced charge / discharge power is 3kW. Parameter settings for the next time step:

[0075] P Mppt1_now_max =10-3+17

[0076] P pcs_set =10

[0077] Mppt2's power is less than the AC load power, so there is no need to control Mppt2's maximum output power.

[0078] (3) Charging mode disabled

[0079] In this embodiment, the rated power of the energy storage converter is 120kW, and the real-time power of the energy storage converter is 0kW. The real-time power of Mppt1 is 20kW, the real-time power of Mppt2 is 120kW, the AC load power is 130kW, the DC load power is 17kW, and the AC meter reading is 10kW; the battery capacity is 100kWh, the maximum charge / discharge power is 50kW, the SOC is 100%, and the forced charge / discharge power is 3kW. Parameter settings for the next time step:

[0080] P Mppt1_now_max =10+17

[0081] P pcs_set =10.

[0082] (4) Discharge Prohibition Mode

[0083] In this embodiment, the rated power of the energy storage converter is 120kW, and the real-time power of the energy storage converter is 0kW. The real-time power of Mppt1 is 20kW, the real-time power of Mppt2 is 120kW, the AC load power is 130kW, the DC load power is 17kW, and the AC meter reading is 10kW; the battery capacity is 100kWh, the maximum charge / discharge power is 50kW, the SOC is 100%, and the forced charge / discharge power is 3kW. Parameter settings for the next time step:

[0084] P Mppt1_now_max =10+17

[0085] P pcs_set =20-17.

[0086] (5) Rechargeable and dischargeable mode

[0087] In this embodiment, the rated power of the energy storage converter is 120kW, and the real-time power of the energy storage converter is 0kW. The real-time power of Mppt1 is 20kW, the real-time power of Mppt2 is 120kW, the AC load power is 130kW, the DC load power is 17kW, and the AC meter reading is 10kW; the battery capacity is 100kWh, the maximum charge / discharge power is 50kW, the SOC is 50%, and the forced charge / discharge power is 3kW. Parameter settings for the next moment:

[0088] P Mppt1_now_max =10+50+17

[0089] P pcs_set =10.

[0090] (6) No charging / no discharging mode

[0091] In this embodiment, the rated power of the energy storage converter is 120kW, and the real-time power of the energy storage converter is 0kW. The real-time power of Mppt1 is 20kW, the real-time power of Mppt2 is 120kW, the AC load power is 130kW, the DC load power is 17kW, and the AC meter reading is 10kW; the battery capacity is 100kWh, the maximum charge / discharge power is 50kW, the SOC is 0, and the forced charge / discharge power is 3kW. Parameter settings for the next time step:

[0092] P Mppt1_now_max =0+17

[0093] P pcs_set =20–17.

[0094] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. An energy control method for a photovoltaic energy storage system, characterized in that, It includes two sets of MPpts, batteries, energy storage converters, energy control systems, AC loads, DC loads, power grid, batteries, DC meters and AC meters, with the energy storage converters and energy control systems connected together; Mppt1 is connected to the DC load via a DC meter, and the DC load is connected to the DC side of the energy storage converter via the DC meter. Both Mppt1 and the battery are connected to the DC side of the energy storage converter, and both Mppt1 and the battery are connected to the energy control system. Mppt2 is connected to the AC load, and both Mppt2 and the AC meter are connected to the energy control system. Both Mppt2 and the AC load are connected to the AC side of the energy storage converter, and the power grid is connected to the AC side of the energy storage converter through the AC meter. Let the maximum output power of Mppt1 be P. Mppt1_now_max The real-time output power of Mppt1 is P Mppt1_now The maximum output power of Mppt2 is P. Mppt2_now_max The real-time output power of Mppt2 is P. Mppt2_now The power measured by the AC meter is P. meter_ac The battery's maximum charging power is P. change_max The maximum discharge power is P dischange_max The forced charging power is P change_force The forced discharge power is P dischange_force The real-time power of the energy storage converter during charging and discharging is P. pcs_now The set power for charging and discharging of the energy storage converter is P. pcs_set The power of the AC load is P. loader_ac The power of the DC load is P loader_dc The difference P between the AC load power and the real-time power of Mppt2 loader_ac_diff The following relationship must be satisfied: P loader_ac_diff =P meter_ac +P pcs_now ; The energy control system dynamically adjusts the maximum output power of Mppt and the charging and discharging power settings of the energy storage converter according to different battery states.

2. The energy control method for a photovoltaic energy storage system according to claim 1, characterized in that, The battery states include the following six types: forced charging mode, forced discharging mode, prohibited charging mode, prohibited discharging mode, rechargeable and dischargeable mode, and prohibited charging and discharging mode.

3. The energy control method for a photovoltaic energy storage system according to claim 2, characterized in that, The energy control methods for the six battery states are as follows: (1) Forced charging mode: P Mppt1_now_max =P loader_ac_diff +P change_force +P loader_dc P pcs_set =P Mppt1_now -P change_force -P loader_dc ; (2) Forced discharge mode, if the real-time power of Mppt2 is not greater than the AC load power: P Mppt1_now_max =P loader_ac_diff -P dischange_force +P loader_dc P pcs_set =P loader_ac_diff If the real-time power of Mppt2 is greater than the AC load power, and the power grid prohibits power feeding, the maximum output power of Mppt2 also needs to be adjusted: P Mppt2_now_max =P Mppt2_now +P loader_ac_diff ; (3) Charging disabled mode, if the real-time power of Mppt2 is not greater than the AC load power: P Mppt1_now_max =P loader_ac_diff +P loader_dc P pcs_set =P Mppt1_now -P loader_dc If the real-time power of Mppt2 is greater than the AC load power, and the power grid prohibits power feeding, the maximum output power of Mppt2 also needs to be adjusted: P Mppt2_now_max =P Mppt2_now +P loader_ac_diff ; (4) Discharge Prohibition Mode: P Mppt1_now_max =P loader_ac_diff +P loader_dc P pcs_set =P Mppt1_now -P loader_dc ; (5) Rechargeable and dischargeable mode: P Mppt1_now_max =P loader_ac_diff +P change_max +P loader_dc P pcs_set =P pcs_now +P meter_ac ; (6) No charging / no discharging mode: P Mppt1_now_max =P loader_dc +P pcs_now P pcs_set =P Mppt1_now -P loader_dc 。

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