A method for controlling operation mode switching of a DC stacking light system

Abstract

The present invention relates to the technical field of power supply for a DC stacked light system, and discloses an operation mode switching control method applied to a DC stacked light system, the steps of which are as follows: recording the output voltage of the junction box when there is no current output before the DC stacked light system is started; executing different processes according to the length of time after the DC stacked light system is started. The present invention estimates the impedance of the two-section lines of the stacked light system through the operation information of the parallel stacked light system, and updates it as needed, thereby realizing the estimation of the line voltage drop, and thus realizing the monitoring of the voltage of the base station power supply system by the stacked light system. The present invention realizes the overload protection function of the parallel stacked light system, which is beneficial to improving the utilization rate of photovoltaic power generation and solving abnormalities such as overcharging of the base station power supply system, thereby improving the reliability of the stacked light system.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply for a DC stacked light system, and in particular to an operation mode switching control method applied to a DC stacked light system. Background Art

[0002] With the emergence of 5G equipment, the proportion of electricity costs will increase, and electricity costs will increase. The cost increase caused by the increase in power consumption has affected the deployment scope of 5G equipment, especially the deployment of 5G base stations. The power consumption of 5G equipment is a severe challenge facing operators and an important obstacle to our promotion of 5G construction. Photovoltaic has entered the era of grid parity, and the cost of photovoltaic power generation continues to decline. Therefore, it is imperative to introduce new energy from the power generation side and reduce electricity costs from the source.

[0003] In communication base stations with existing mains electricity, photovoltaic equipment is installed in idle spaces such as the base station room roof and surrounding open space as a supplementary energy source for the mains electricity, and photovoltaic power supply is used first. According to the different connection methods of photovoltaic modules, DC stacking systems are divided into series and parallel. The parallel system consists of modules, adapters, junction boxes and DC meters, while the series system consists of modules, optimizers, controllers, DC meters, etc.

[0004] Traditional parallel stacked light system adapters cannot accurately monitor the voltage of the base station power system and limit power too late or too early, which greatly limits the utilization of photovoltaic energy and may even harm the base station power system. Summary of the invention

[0005] In view of the shortcomings and defects of the prior art, the present invention provides an operation mode switching control method applied to a DC stacked light system, which enables the base station parallel stacked light system to accurately monitor the voltage of the base station power supply system, and implements a power limiting scheme for the base station parallel stacked light system, thereby improving the utilization rate of photovoltaic energy and improving the reliability of the parallel stacked light system.

[0006] The purpose of the present invention can be achieved through the following technical solutions.

[0007] An operation mode switching control method applied to a DC stacking light system comprises the following steps:

[0008] Step 1: Record the output voltage V when there is no current output from the combiner box before the DC stacking system is turned on com-0out ;

[0009] Step 2: Execute different processes according to the time after the DC stacking system is turned on:

[0010] A. Within t hours after the DC stacking system is turned on:

[0011] A1, repeatedly record the combiner box output voltage V when the combiner box output current is below I com-out , combiner box output current I com-out 、Each adapter output voltage V ad-out 、Each adapter output current I ad-out , and calculate the line impedance based on the recorded data, and take the average value to obtain the estimated line impedance;

[0012] A2, based on the estimated line impedance and recorded data, obtain the estimated line voltage drop and base station power system voltage;

[0013] A3, determine whether the estimated voltage value of the base station power system exceeds the battery floating charge voltage; determine whether the system input power and equipment temperature exceed the set value;

[0014] According to the judgment result, it is selected to operate in normal MPPT mode or power limiting mode;

[0015] B, t hours after the DC stacking system is turned on:

[0016] B1, record the output voltage V of the combiner box twice at a fixed time interval com-out1 、V com-out2 , combiner box output current I com-out1 ,I com-out2 , each adapter output voltage V ad-out1 、V ad-out2 , each adapter output current I ad-out1 ,I ad-out2 , calculate the line impedance based on the recorded data, and take the average value to get the estimated value of line impedance;

[0017] B2, based on the estimated line impedance and recorded data, obtain the estimated line voltage drop and base station power system voltage;

[0018] B3, determine whether the estimated voltage value of the base station power system exceeds the battery floating charge voltage; determine whether the system input power and equipment temperature exceed the set value;

[0019] According to the judgment result, it is selected to operate in normal MPPT mode or limited power mode.

[0020] Preferably, the line impedance in step 3 includes the line impedance from the adapter to the combiner box and the line impedance from the combiner box to the base station power system, wherein the line impedance from each adapter to the combiner box needs to be calculated separately, and the average value of each line impedance is taken.

[0021] Preferably, in the process A, the line impedance R from the adapter to the combiner box is wire1 The calculation formula is as follows:

[0022]

[0023] Preferably, in the process A, the line impedance R from the combiner box to the base station power system is wire2 The calculation formula is as follows:

[0024]

[0025] Preferably, in the process B, the line impedance R from the adapter to the combiner box is wire1 , Line impedance R from combiner box to base station power system wire2 The calculation formula is as follows:

[0026]

[0027] Preferably, the process B is performed in a timed cycle.

[0028] Preferably, the line voltage drop ΔV and the base station power system voltage estimated value V b ' at The calculation formula is as follows:

[0029] ΔV=I ad-out R′ wire1 +I com-out R′ wire2 ;

[0030] V′ bat =V ad-out -ΔV;

[0031] Where: R′ wire1 is the estimated line impedance from the adapter to the combiner box, R′ wire2 Estimated value of line impedance from combiner box to base station power system.

[0032] Preferably, the MPPT function is implemented by an MPPT software module, and the equipment MPPT algorithm is a perturbation observation method.

[0033] Preferably, the power limiting mode is to stop the normal MPPT mode when the system input power is too high or the device temperature is too high or the base station power system voltage is too high.

[0034] Preferably, when in power limiting mode, the input voltage is changed through a dual closed-loop control algorithm so that the photovoltaic module voltage is kept away from the maximum power point voltage, thereby achieving the effect of limiting power.

[0035] Beneficial technical effects of the present invention: The present invention estimates the impedance of the two-section line of the stacked light system through the operation information of the parallel stacked light system, and updates it as needed, thereby realizing the estimation of the line voltage drop, thereby realizing the monitoring of the voltage of the base station power system by the stacked light system. The present invention realizes the overload protection function of the parallel stacked light system, which is conducive to improving the utilization rate of photovoltaic power generation and solving abnormalities such as overcharging of the base station power system, thereby improving the reliability of the stacked light system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the overall design flow chart of the present invention.

[0037] Figure 2 This is a flow chart of line impedance estimation and voltage drop calculation of the present invention.

[0038] Figure 3 This is a control flow chart of the power limiting scheme of the present invention.

[0039] Figure 4 It is a schematic diagram of the parallel stacked light system solution of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention.

[0041] Example: Figure 1 As shown, an operation mode switching control method applied to a DC stacking light system comprises the following steps:

[0042] Step 1: During the startup process of the parallel stacked light system, record the output voltage V of the combiner box when the current is zero before startup. com-0out ;

[0043] Step 2: Execute different processes according to the time after the DC stacking system is turned on:

[0044] A. Within 2 hours after the DC stacking system is turned on:

[0045] A1, after the parallel stacking system is turned on, record the output voltage V of the combiner box when the output current is 5A, 10A, and 15A com-out Current I com-out 、Each adapter output voltage V ad-out Current I ad-out , and calculate the line impedance based on the recorded data, and take the average value to get the line impedance estimate R′ wire1 , R′ wire2 ;

[0046] A2, based on the estimated line impedance and the real-time voltage and current data of the equipment, obtain the line voltage drop ΔV and the estimated voltage value V of the base station power system b ' at ;

[0047] A3, the DC stacking optical system operates normally, and system information is collected at the same time, and the estimated voltage of the base station power system is judged to be 55V, whether the power exceeds 600W, and whether the equipment temperature exceeds 70℃;

[0048] According to the judgment result, the normal MPPT mode or the power limiting mode is performed;

[0049] B, 2 hours after the DC stacking system is turned on:

[0050] B1, record the combiner box output voltage V for two consecutive times at a time interval of 1 second com-out1 、V com-out2 , combiner box output current I com-out1 ,I com-out2 , each adapter output current I ad-out1 ,I ad-out2 , calculate the line impedance based on the recorded data, repeat 3 times and use the average value;

[0051] B2, based on the estimated line impedance and the real-time voltage and current data of the equipment, obtain the line voltage drop ΔV and the estimated voltage value V of the base station power system b ' at ;

[0052] B3, the DC stacking optical system operates normally, and system information is collected at the same time, and the estimated voltage of the base station power system is judged to be 55V, whether the power exceeds 600W, and whether the equipment temperature exceeds 70℃;

[0053] According to the judgment result, the normal MPPT mode or the power limiting mode is performed;

[0054] like Figure 2 As shown, the line impedance estimation and voltage drop calculation are estimated based on the equipment operation information to monitor the base station power system voltage.

[0055] In step 1, when the combiner box outputs zero current, due to zero current, it is considered that there is no line voltage drop at this time, and the output voltage is the base station power system voltage. The line impedance is subsequently calculated based on this voltage.

[0056] The line impedance in step 2 includes two sections: the impedance estimation from the adapter to the combiner box and the impedance estimation from the combiner box to the base station power system. Since there are multiple adapters in the system, multiple impedances from the adapter to the combiner box need to be calculated, and the average value of each section of the line impedance is calculated to obtain the estimated result.

[0057] The impedance calculation formula from the adapter to the combiner box is as follows:

[0058]

[0059] Where: R′ wire1 is the estimated impedance of the line from the adapter to the combiner box, V ad-ou t is the adapter output voltage, V com-out is the combiner box output voltage, I ad-out is the output current of the adapter. The average value of the calculated results of three small currents of 5A, 10A and 15A is the line impedance from a single adapter to the combiner box. This process is completed in the software of each adapter.

[0060] The formula for estimating the line impedance from the combiner box to the base station power system is as follows:

[0061]

[0062] Where: R′ wire2 is the estimated line impedance of the power system from the combiner box to the base station, V com-out is the output voltage of the combiner box at different currents after it is turned on, V com-0out I is the output voltage when the combiner box is at zero current output before it is turned on. com-out The output current of the combiner box at different currents after it is turned on. The average value of the calculation results at three small currents of 5A, 10A, and 15A is taken as the line impedance from the combiner box to the base station power system. This process is completed in the combiner box software.

[0063] The process B described in step 2 is performed in a timed loop. The impedance estimation value is updated. The line impedance update estimation formula is as follows:

[0064]

[0065] Where: R′ wire1 is the estimated impedance of the line from the adapter to the combiner box, R′ wire2 is the estimated line impedance of the power system from the combiner box to the base station, I ad-out1 ,I ad-out2 The adapter output current is sampled twice at 1 second interval, V ad-out1 、V ad-out2 The adapter output voltage is sampled twice at 1 second interval, V com-out1 、V com-out2 is the output voltage of the combiner box sampled twice at a time interval of 1 second, I com-out1 ,I com-out2 It is the result of two samplings of the combiner box output current at a time interval of 1 second.

[0066] Step 2: The line voltage drop and base station power system voltage estimation formula are as follows:

[0067] ΔV=I ad-out R′ wire1 +I com-out R′ wire2 ;

[0068] V′ bat =V ad-out -ΔV;

[0069] Where: ΔV is the estimated value of line voltage drop, V′ bat is the estimated voltage of the base station power system, I ad-out is the adapter output current, R′ wire1 is the estimated impedance of the line from the adapter to the combiner box, I com-out is the adapter output current, R′ wire2 is the estimated impedance of the line from the adapter to the combiner box, V ad-out is the adapter output voltage.

[0070] like Figure 3 As shown, in the power limiting scheme, MPPT is the maximum power tracking control, which tracks the maximum power point of photovoltaic in real time to achieve the maximum power output of photovoltaic. The MPPT maximum power tracking function is implemented by the MPPT module in the software, and the MPPT algorithm of the equipment is the perturbation observation method.

[0071] The power limiting mode stops the maximum power tracking when the system input power is higher than 600W, the equipment temperature is higher than 70℃, and the base station power system voltage is higher than the battery floating charge voltage of 55V. The power limiting mode can achieve overload protection. The power limiting mode logic is: when in the power limiting mode, the input voltage is increased by 1V every 100ms through the voltage and current dual closed-loop control algorithm, and the photovoltaic panel voltage is kept away from the maximum power point voltage through the voltage and current dual closed-loop control algorithm, thereby achieving the effect of limiting power.

[0072] Figure 4 The schematic diagram of the base station parallel stacked light system used in the present invention includes a plurality of photovoltaic panels, a plurality of photovoltaic adapters, a junction box, a photovoltaic circuit breaker, and a base station power supply system. The photovoltaic panels convert solar energy into direct current electricity, which is controlled by the photovoltaic adapter to transmit energy to the junction box, and the junction box transmits energy to the base station power supply system to achieve efficient use of solar energy. The information collection function is completed by the junction box and the photovoltaic adapter. The junction box and the adapter communicate through a carrier wave, and the junction box can transmit information to a mobile phone APP through 4G. The junction box collects data and calculates and updates the line impedance from the junction box to the base station power supply system, and transmits it to the subordinate adapters through the carrier wave. Each adapter calculates the line impedance from the adapter to the junction box section, monitors the voltage of the base station power supply system through the voltage drop calculation, and operates normally or with limited power.

[0073] The above embodiments are descriptions of specific implementation methods of the present invention rather than limitations of the present invention. Technical personnel in the relevant technical field may make various changes and modifications to obtain corresponding equivalent technical solutions without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. An operation mode switching control method applied to a DC stacking light system, characterized in that: The following steps are involved: Step 1: Record the output voltage V when there is no current output from the combiner box before the DC stacking system is turned on com-0out ; Step 2: Execute different processes according to the time after the DC stacking system is turned on: A. Within t hours after the DC stacking system is turned on: A1, repeatedly record the combiner box output voltage V when the combiner box output current is below I com-out , combiner box output current I com-out 、Each adapter output voltage V ad-out 、Each adapter output current I ad-out , and calculate the line impedance based on the recorded data, and take the average value to obtain the estimated line impedance; A2, based on the estimated line impedance and recorded data, obtain the estimated line voltage drop and base station power system voltage; line voltage drop ΔV and base station power system voltage estimated value V b ' at The calculation formula is as follows: ΔV=I ad-out R′ wire1 +I com-out R′ wire2 ; V b ′ at =V ad-out -ΔV; Where: R′ wire1 is the estimated line impedance from the adapter to the combiner box, R′ wire2 Estimated value of line impedance from combiner box to base station power system; A3, determine whether the estimated voltage value of the base station power system exceeds the battery floating charge voltage; determine whether the system input power and equipment temperature exceed the set value; According to the judgment result, it is selected to operate in normal MPPT mode or power limiting mode; B, t hours after the DC stacking system is turned on: B1, record the output voltage V of the combiner box twice at a fixed time interval com-out1 、V com-out2 , combiner box output current I com-out1 ,I com-out2 , each adapter output voltage V ad-out1 、V ad-out2 , each adapter output current I ad-out1 ,I ad-out2 , calculate the line impedance based on the recorded data, and take the average value to get the estimated value of line impedance; B2, based on the estimated line impedance and recorded data, obtain the estimated line voltage drop and base station power system voltage; B3, determine whether the estimated voltage value of the base station power system exceeds the battery floating charge voltage; determine whether the system input power and equipment temperature exceed the set value; According to the judgment result, it is selected to operate in normal MPPT mode or limited power mode.

2. The operation mode switching control method applied to a DC stacking light system according to claim 1, characterized in that: The line impedance in steps A1 and B1 includes the line impedance from the adapter to the combiner box and the line impedance from the combiner box to the base station power system, wherein the line impedance from each adapter to the combiner box needs to be calculated separately, and the average value of each line impedance is taken.

3. The operation mode switching control method applied to a DC stacking light system according to claim 2, characterized in that: In the process A, the line impedance from the adapter to the combiner box is R wire1 The calculation formula is as follows:

4. The operation mode switching control method applied to a DC stacking light system according to claim 2, characterized in that: In the process A, the line impedance R from the combiner box to the base station power system wire2 The calculation formula is as follows:

5. The operation mode switching control method applied to a DC stacking light system according to claim 2, characterized in that: In the process B, the line impedance from the adapter to the combiner box is R wire1 , Line impedance R from combiner box to base station power system wire2 The calculation formula is as follows:

6. The operation mode switching control method applied to a DC stacking light system according to claim 1, characterized in that: The process B is performed in a regular cycle.

7. The operation mode switching control method applied to a DC stacking light system according to claim 1, characterized in that: The MPPT function is implemented by the MPPT software module, and the equipment MPPT algorithm is the disturbance observation method.

8. The operation mode switching control method applied to a DC stacking light system according to claim 1, characterized in that: The power limiting mode stops the normal MPPT mode when the system input power is too high, the device temperature is too high, or the base station power system voltage is too high.

9. The operation mode switching control method applied to a DC stacking light system according to claim 8, characterized in that: When in power limiting mode, the input voltage is changed through a dual closed-loop control algorithm to keep the PV module voltage away from the maximum power point voltage, thereby achieving the effect of limiting power.

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