Direct current side scheduling control method and system based on power loop driving

Abstract

The invention discloses a direct current side scheduling control method and system based on power loop driving, and the method comprises the steps: locking the output power of a battery end when the load sudden change power Pload is greater than Pt, determining a tracking direction according to a slope, stopping MPPT tracking control, and recording the voltage Vstart and the power value Ps of a current PV end; power loop tracking control is started, IV curve scanning is carried out, whether PV end power meets a power gap or not is judged, if yes, scanning is stopped, the voltage reference value of the PV end is the voltage value corresponding to the current power point, otherwise, scanning is continued until the power is equal to PS, and the maximum voltage value Vmax corresponding to the maximum power point Pmax serves as the voltage reference value of the PV end; the power loop tracks, controls and drives the voltage of the PV end to be increased to the maximum voltage value Vmax, the output power of the battery end is released, and response is carried out according to the current load; and exiting the power loop tracking control, and starting MPPT tracking control. According to the invention, the power waste of the photovoltaic panel caused by the response speed difference of the battery and the photovoltaic panel to the sudden change of the load is avoided.

Description

Technical Field

[0001] The present invention relates to a DC side dispatching control method and system based on power loop drive, belonging to the technical field of photovoltaic energy storage inverter control. Background Art

[0002] Photovoltaic energy storage inverter is a power regulation device composed of semiconductor devices, mainly used to convert DC power into AC power, generally composed of a boost circuit and an inverter bridge circuit. The boost circuit boosts the DC voltage of the solar cell to the DC voltage required for the inverter output control; the inverter bridge circuit converts the boosted DC voltage into an AC voltage of a common frequency.

[0003] When the load power changes suddenly, the output power of the photovoltaic panel is affected by the MPPT tracking algorithm, and the tracking speed is slow, the output power changes slowly, while the battery can respond quickly to changes in load demand. Therefore, when the load increases, the battery power will be used first, resulting in a waste of PV panel power. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned deficiencies in the prior art and to propose a DC side scheduling control method and system based on power loop drive to address the problem of PV panel power waste caused by traditional battery response.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A DC side dispatching control method based on power loop drive comprises the following steps:

[0007] S1 sets the load power threshold Pt;

[0008] S2 When the load suddenly changes power △P loadinc >Pt, lock the output power of the battery end, determine the maximum power tracking direction according to the slope, stop MPPT tracking control, and record the current PV end voltage Vstart and power value Ps;

[0009] S3 starts the power loop tracking control, performs IV curve scanning, and determines whether the PV end power meets the power gap. If yes, proceeds to step S4, otherwise proceeds to step S5;

[0010] S4 stops IV curve scanning, the voltage reference value of the PV terminal is the voltage value corresponding to the current power point, and enters step S6;

[0011] S5 continues to scan the IV curve until the power is equal to P S, record the maximum power point Pmax during the IV curve scanning process, and use the maximum voltage value Vmax corresponding to the maximum power point Pmax as the voltage reference value of the PV end. The power loop tracking control drives the voltage of the PV end to increase to the maximum voltage value Vmax, and enter step S6;

[0012] S6 releases the output power of the battery terminal and responds according to the current load;

[0013] S7 exits the power loop tracking control and starts the MPPT tracking control.

[0014] Preferably, in step S3, IV curve scanning is performed along the power increasing direction with a step length of 0.5 V and a period of 1 ms.

[0015] Preferably, in step S1, Pt is 500-1500 kW.

[0016] The present invention also proposes a DC side dispatching and control system based on power ring drive, the system comprising an inverter, a PV terminal electrically connected to the inverter, a battery terminal, a load, and a mains terminal;

[0017] It includes an MPPT tracking control module for performing MPPT tracking control, a power loop tracking control module for performing power loop tracking control, and a battery control instruction set module for performing battery terminal locking and release control;

[0018] The MPPT tracking control module is electrically connected to the inverter and the PV end respectively, the power loop tracking control module is electrically connected to the inverter and the PV end respectively, and the battery control instruction set module is electrically connected to the inverter and the battery end respectively.

[0019] The beneficial effects of the present invention are mainly reflected in:

[0020] 1. Through power tracking switching control, the waste of panel power caused by the difference in response speed of batteries and photovoltaic panels to sudden load changes is avoided, so that the power of photovoltaic panels can be utilized to the maximum extent.

[0021] 2. Reducing unnecessary battery power consumption is beneficial to increasing the effective service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0023] Figure 1 It is a flow chart of a DC side dispatching control method based on power loop drive of the present invention.

[0024] Figure 2 It is a working condition curve diagram of Example 1 in the present invention.

[0025] Figure 3 It is a working condition curve diagram of the second embodiment of the present invention.

[0026] Figure 4 It is a structural schematic diagram of a DC side dispatching control system based on power ring drive of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0028] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the inventions. It should also be noted that, for ease of description, only the parts related to the relevant inventions are shown in the accompanying drawings. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0029] The present invention provides a DC side dispatching control method based on power ring drive, such as Figure 1 As shown, the following steps are included:

[0030] Set the load power threshold Pt.

[0031] When the load power △P loadinc >Pt, lock the output power of the battery end, determine the tracking direction of the maximum power according to the slope, stop MPPT tracking control, and record the current PV end voltage Vstart and power value Ps.

[0032] Start the power loop tracking control and scan the IV curve to determine whether the PV end power meets the power gap;

[0033] If yes, stop IV curve scanning, and the voltage reference value of the PV terminal is the voltage value corresponding to the current power point;

[0034] Otherwise, continue to scan the IV curve until the power is equal to P S , record the maximum power point Pmax during the IV curve scanning process, and the maximum voltage value Vmax corresponding to the maximum power point Pmax is used as the voltage reference value of the PV end. The power loop tracking control drives the voltage of the PV end to increase to the maximum voltage value Vmax;

[0035] After the PV end is regulated according to the voltage reference value, the output power of the battery end is released and responds according to the current load;

[0036] Exit power loop tracking control and start MPPT tracking control.

[0037] Specific implementation process and principle description:

[0038] Generally, Pt is 500-1500kW. When the load power increases and exceeds the set threshold value Pt, the current given power at the battery end is locked.

[0039] Record the current PV voltage value Vstart and power value Ps, and determine the maximum power tracking direction based on the slope.

[0040] Stop the MPPT tracking algorithm and enable the power loop tracking algorithm, that is, scan the IV curve in the direction of increasing power with a step size of 0.5V and a period of 1ms.

[0041] During the scanning process, once the power gap is met, the scanning stops. If the current maximum power still cannot meet the power gap, the scanning stops when the scanned power is equal to the starting power Ps. And according to the scanning record of the curve, the maximum power Pmax is determined. Through the power loop drive, the maximum power point Pmax is quickly reached. The battery is released and the battery responds according to the current load conditions. The power loop exits and the MPPT algorithm takes effect again.

[0042] The MPPT tracking control is the maximum power tracking method, which belongs to the existing technology and will not be described in detail here.

[0043] Embodiment 1

[0044] like Figure 2 As shown in the figure, in the initial state, the system carries a 3kW load, all powered by the PV end, and the PV end performs MPPT tracking near point a. If another 2kW load is connected at this moment, since the load sudden change power is greater than the threshold 1000kW, the conditions for entering the power ring scheduling algorithm are met.

[0045] like Figure 4 As shown, the battery end locks the current battery state through the B battery control instruction set, and the photovoltaic panel end determines the maximum power tracking direction. Record the current PV terminal voltage Vstart, and the current power is Ps = 3kW.

[0046] The control strategy is Figure 4The A2MPPT tracking control in the program is switched to the A1 power loop tracking control, that is, the MPPT tracking control is stopped and the power loop tracking control is enabled. In the direction of increasing power, the IV curve is scanned with a step size of 0.5V and a cycle of 1ms. When the scan reaches Figure 1 At point b in the figure, the PV output power increases by 2kW to meet the new load demand, so the scan stops and the voltage value Vend corresponding to the current power point is the PV reference voltage value.

[0047] pass Figure 4 The B battery control instruction set in the MCU releases the battery terminal, and the control strategy switches from A1 to A2, that is, the power loop exits and the MPPT algorithm takes effect again.

[0048] Embodiment 2

[0049] like Figure 3 As shown, in the initial state, the system carries a 3kW load, all of which is powered by the PV end. The PV end performs MPPT tracking near point a. Under the current working conditions, the maximum power that the panel can provide is 4kW.

[0050] If a 2kW load is connected at this time, first Figure 4 The B battery control instruction set in locks the current battery status and determines the tracking direction of the PV maximum power.

[0051] Record the current PV voltage Vstart, the current power is Ps = 3kW.

[0052] The control strategy is switched from the A2 MPPT algorithm to the A1 power loop scheduling algorithm, that is, the IV curve is scanned in the direction of increasing power with a step size of 0.5V and a period of 1ms. When the scan reaches point c, the PV output power is equal to Ps, and the scan stops. According to the maximum power point Pmax recorded during the scan, the PV voltage is quickly pulled to Vmax by the A1 power loop, and finally stabilized at point b.

[0053] pass Figure 4 The B battery control instruction set in the circuit releases the battery, and the battery makes up for the remaining 1kW power gap. Finally, the panel side control strategy switches back from A1 to A2, that is, the power loop exits and the MPPT algorithm takes effect again.

[0054] A DC side dispatching control system based on power ring drive, such as Figure 4 As shown, it includes an inverter, a PV terminal electrically connected to the inverter, a battery terminal, a load, and a mains terminal.

[0055] This case includes an MPPT tracking control module for MPPT tracking control, a power loop tracking control module for power loop tracking control, and a battery control instruction set module for battery terminal locking and release control.

[0056] The MPPT tracking control module is electrically connected to the inverter and the PV end respectively, the power loop tracking control module is electrically connected to the inverter and the PV end respectively, and the battery control instruction set module is electrically connected to the inverter and the battery end respectively.

[0057] Among them, the MPPT tracking control module and the power loop tracking control module are software and hardware mechanisms that can realize power tracking. Only the modules that need to meet the power tracking requirements are within the protection scope of this case, and the battery control instruction set module is a control module. The mechanisms that meet the locking, releasing and controlling of the battery end are all within the protection scope of this case.

[0058] From the above description, it can be found that through power tracking switching control, the panel power waste caused by the difference in response speed between the battery and the photovoltaic panel to the sudden change of load is avoided, so that the power of the photovoltaic panel can be utilized to the maximum extent. Reducing unnecessary power consumption of the battery is conducive to increasing the effective service life of the battery.

[0059] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0060] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A DC side dispatching control method based on power ring drive, characterized in that The steps include: S1 sets the load power threshold Pt; S2 When the load suddenly changes power △P loadinc >Pt, lock the output power of the battery end, determine the maximum power tracking direction according to the slope, stop MPPT tracking control, and record the current PV end voltage Vstart and power value Ps; S3 starts the power loop tracking control, performs IV curve scanning, and determines whether the PV end power meets the power gap. If yes, proceeds to step S4, otherwise proceeds to step S5; S4 stops IV curve scanning, the voltage reference value of the PV terminal is the voltage value corresponding to the current power point, and enters step S6; S5 continues to scan the IV curve until the power is equal to P S , record the maximum power point Pmax during the IV curve scanning process, and use the maximum voltage value Vmax corresponding to the maximum power point Pmax as the voltage reference value of the PV end. The power loop tracking control drives the voltage of the PV end to increase to the maximum voltage value Vmax, and enter step S6; S6 releases the output power of the battery terminal and responds according to the current load; S7 exits the power loop tracking control and starts the MPPT tracking control.

2. According to the DC side dispatching control method based on power ring drive according to claim 1, it is characterized in that: In step S3, IV curve scanning is performed along the power increasing direction with a step length of 0.5 V and a period of 1 ms.

3. According to the DC side dispatching control method based on power ring drive according to claim 1, it is characterized in that: In the step S1, Pt is 500-1500 kW.

4. A DC side dispatching and control system based on power ring drive, used to execute the DC side dispatching and control method according to any one of claims 1 to 3, the system comprising an inverter, a PV terminal electrically connected to the inverter, a battery terminal, a load, and a mains terminal; characterized in that: It includes an MPPT tracking control module for performing MPPT tracking control, a power loop tracking control module for performing power loop tracking control, and a battery control instruction set module for performing battery terminal locking and release control; The MPPT tracking control module is electrically connected to the inverter and the PV end respectively, the power loop tracking control module is electrically connected to the inverter and the PV end respectively, and the battery control instruction set module is electrically connected to the inverter and the battery end respectively.

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