CN109617041B - Energy management and control device of photovoltaic energy storage system - Google Patents

Abstract

The invention discloses an energy management and control device for a photovoltaic energy storage system, which includes a dual-input dual-output converter and a control circuit; the dual-input dual-output converter is derived from a dual-tube Buck-Boost converter, and the dual-tube Buck-Boost converter The input end of the converter is connected to the photovoltaic module, and the output end is connected to the load. At the same time, in order to overcome the fluctuation characteristics of the output power of photovoltaic modules, a branch is added to the input side and output side of the double-tube Buck‑Boost converter and connected to the energy storage unit. The branch on the input side controls the storage unit. The energy unit discharges, and the branch on the output side controls the charging of the energy storage unit. The control circuit includes an MPPT control unit, an error amplifier EA, a first comparator CMP1, a second comparator CMP2, a pulse modulation unit, a multiplex selection unit and a mode switching control unit. The invention has simple structure, low cost, high power density and high system efficiency, and can simultaneously realize the maximum power point tracking control of the photovoltaic component and the output constant voltage control of the load.

Description

An energy management and control device for photovoltaic energy storage systems

Technical field

The invention relates to the technical field of photovoltaic energy storage systems, in particular to an energy management and control device for a photovoltaic energy storage system.

Background technique

In recent years, with the intensification of environmental pollution and energy crisis, new energy power generation technology represented by solar energy has become a research hotspot. Since the output characteristics of photovoltaic (PV) arrays are closely related to environmental factors such as light and temperature, the output characteristics of photovoltaic arrays are random and volatile under different environmental conditions. Therefore, independent photovoltaic power generation systems must be equipped with energy storage units. To store and regulate electrical energy to meet the requirements of electrical loads for power supply continuity and stability. Traditional photovoltaic energy storage systems require a unidirectional DC-DC converter to connect to the photovoltaic array and achieve maximum power point tracking (MPPT) control. A unidirectional DC-DC converter provides stable output for the load. At the same time, a bidirectional DC-DC converter is required to connect to the energy storage unit to balance the power balance between the load and the photovoltaic array. This results in the traditional photovoltaic energy storage system being large in size and cost, and relatively complex in control, making it difficult to achieve centralized control. The use of multi-port converters instead of multiple single-input single-output converters can greatly reduce the cost of the system and improve the power density of the system. It can also achieve centralized control and make the control circuit design more flexible, which has attracted widespread attention from researchers. . Researchers have proposed a series of multi-port converter topologies, which are mainly divided into isolated and non-isolated. Isolated multi-port converters are mainly derived from half-bridge converters and full-bridge converters. They are characterized by high power levels and the ability to achieve Electrical isolation, etc. Non-isolated multi-port converters are generally derived from basic Buck, Boost, and Buck-Boost converters. Compared with isolated multi-port converters, non-isolated multi-port converters have higher power density. And the design is simpler. However, existing non-isolated multi-port converters generally include multiple inductors, making the system bulky and unable to achieve time-sharing control.

Inter-port energy management and control of independent photovoltaic energy storage systems based on multi-port converters are key to ensuring the stable operation of the entire system. Existing control methods mainly include two types. One is to use a multi-loop competition mechanism to realize system control and energy management. This method cannot achieve the maximum power output of photovoltaic modules and the constant load voltage at the same time. Another method is to use voltage-type centralized control. The principle is to achieve system energy management and control through complex modulation. This method is complex in design and has a narrow system adjustment range, which cannot be applied to drastic changes in input or load. occasion.

Contents of the invention

The purpose of the present invention is to provide an energy management and control device for a photovoltaic energy storage system.

The technical solutions to achieve the purpose of the present invention are as follows:

An energy management and control device for a photovoltaic energy storage system, including a dual-input dual-output converter and a control circuit;

The dual-input dual-output converter includes a dual-tube Buck-Boost converter, the buck-side switch tube is S ₁ , the boost-side switch tube is S ₂ , and the load-side switch tube is S ₃ ; the input terminal of the double-tube Buck-Boost converter and the output end are respectively connected to the photovoltaic component PV and load R of the photovoltaic energy storage system; the dual-input dual-output converter also includes an output side branch and an input side branch; the output side branch includes a diode D ₃ and a switch tube S _4. The positive electrode of _D3 is connected to the drain of _S2 , the negative electrode of _D3 is connected to the drain of _S4 , and the source of _S4 is connected to the positive electrode of the energy storage unit of the photovoltaic energy storage system; input side branch It includes a diode D ₄ and a switching tube S ₅ . The cathode of D ₄ is connected to the source of S ₁ , the anode of D ₄ is connected to the source of S ₅ , and the drain of S ₅ is connected to the energy storage of the photovoltaic energy storage system. The positive electrode of the unit; the negative electrode of the energy storage unit is connected to the source of S ₂ ;

The control circuit includes an MPPT control unit, an error amplifier EA, a first comparator CMP1, a second comparator CMP2, a pulse modulation unit, a multiplex selection unit and a mode switching control unit;

The input terminals of the MPPT control unit input the output voltage V _pv and the output current I _pv of the photovoltaic module PV respectively. The output terminal is connected to one input terminal of CMP1, and the other input terminal of CMP1 inputs the inductor current i of the double-tube Buck-Boost converter. _L ;

The input terminal of the error amplifier EA inputs the output voltage V _o and the voltage reference value _{Vo_ref} of the dual-tube Buck-Boost converter respectively. The output terminal is connected to one input terminal of CMP2, and the other input terminal of CMP2 inputs the dual-tube Buck-Boost converter. The inductor current i _L of the device;

The pulse modulation unit includes SR flip-flop 2#, SR flip-flop 3#, SR flip-flop 4#, logical XOR gate XOR1, logical XOR gate XOR2, logical NOT gate NO1, logical NOT gate NO2 and logical NOT gate NO3; more The channel selection unit includes a two-way selector MUX1, a two-way selector MUX2, a two-way selector MUX3 and a two-way selector MUX4;

The output terminal c ₁ of CMP1 is connected to the reset terminal of SR flip-flop 2# and SR flip-flop 3# respectively; the output terminal c ₂ of CMP2 is connected to the set terminal of SR flip-flop 3#, and c _{2 is} connected to SR after passing through NO2 The reset terminal of flip-flop 4# is connected; the clock signal clk is connected to the set terminal of SR flip-flop 2# and SR flip-flop 4# respectively; the output terminal Q of SR flip-flop 2# is connected to the gate of S ₁ , and at the same time, The output terminal Q of SR flip-flop 2# is connected to an input terminal of XOR1, the output terminal Q of SR flip-flop 3# is connected to the other input terminal of XOR1, the output terminal of XOR1 is connected to the first input terminal of MUX1, MUX1 The second input terminal of is connected to low level, the output terminal of MUX1 is connected to the gate of S ₄ ; the output of XOR1 is connected to the first input terminal of MUX2 via NO1, and the output terminal Q of SR flip-flop 4# is connected via NO3 Connect to the second input terminal of MUX2, the output terminal of MUX2 is connected to the gate of S ₃ ; the output terminal Q of SR flip-flop 2# is connected to the first input terminal of MUX3, and the output terminal Q of SR flip-flop 4# Connect to the second input of MUX3, the output of MUX3 is connected to the gate of _S2 ; the output Q of SR flip-flop 2# is connected to an input of XOR2, and the output Q of SR flip-flop 4# is connected to XOR2 The other input terminal of XOR2 is connected to the second input terminal of MUX4, the first input terminal of MUX4 is connected to low level, and the output terminal of MUX4 is connected to the gate of S ₅ ;

The mode switching control unit includes subtractor SUB, comparator CMP3, comparator CMP4 and SR flip-flop 1#; the input terminal of SUB inputs the output voltage _Vo and voltage reference value _{Vo_ref} of the double-tube Buck-Boost converter respectively, and the output terminal Connect to one input terminal of CMP3 and CMP4 respectively, the other input terminal of CMP3 inputs the preset voltage threshold ΔV, the other input terminal of CMP4 inputs the preset voltage threshold value -ΔV, and the output terminals of CMP3 and CMP4 are respectively triggered by SR The reset terminal and set terminal of SR flip-flop 1# are connected, and the output terminal Q of SR flip-flop 1# is connected to the selection terminals of MUX1, MUX2, MUX3 and MUX4 at the same time.

Compared with the prior art, the beneficial effects of the present invention are:

1. It has the advantages of simple structure, low cost, high power density, high system efficiency and the ability to achieve centralized control.

2. It can simultaneously realize the maximum power point tracking control of photovoltaic modules and the output constant voltage control of the load. The control principle is simpler, the design is more flexible, and it is easy to be extended to other systems with similar structures.

3. It can adapt to extreme situations such as photovoltaic power mutation and load power mutation, ensuring the reliability and stable operation of the system.

Description of the drawings

Figure 1 is a structural diagram of the energy management and control device of the photovoltaic energy storage system;

Figure 2 is the schematic diagram of a dual-input dual-output converter;

Figure 3(a) and Figure 3(b) are respectively the equivalent circuit and steady-state waveform of the dual-input dual-output converter in dual-output mode;

Figure 4(a) and Figure 4(b) are respectively the equivalent circuit and steady-state waveform of the dual-input dual-output converter in dual-input mode;

Figure 5 is a schematic diagram of the mode switching control unit of the control circuit;

Figure 6 is a schematic diagram of the pulse modulation unit and multiplex selection unit of the control circuit;

Figure 7 is the simulation waveform when the system is running in dual output mode; Figure 7(a) is the steady-state simulation waveform of the system, and Figure 7(b) is the system transient simulation waveform when the load changes suddenly in dual output mode;

Figure 8 is the transient simulation waveform when the system’s operating mode switches from dual output mode to dual input mode due to the reduction of photovoltaic power;

Figure 9 is the simulation waveform when the system is running in dual-input mode; Figure 9(a) is the steady-state simulation waveform of the system, and Figure 9(b) is the system transient simulation waveform when the load changes suddenly in dual-input mode;

Figure 10 shows the transient simulation waveform of the system when the operating mode switches from dual input mode to dual output mode due to the increase in photovoltaic power.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

Figure 1 shows that the system includes a main power circuit and a control circuit. The main power circuit consists of a dual-input dual-output converter and photovoltaic components, energy storage units, and load units connected to it. The control circuit consists of an MPPT control unit, an error amplifier EA, a first comparator CMP1, a second comparator CMP2, a pulse modulation unit, a mode switching control unit and a multiplex selection unit. The output voltage V _pv and output current I _pv of the photovoltaic module are used as input signals of the MPPT control unit. The output of the MPPT control unit is connected to one input terminal of CMP1, the inductor current i _L is connected to the other input terminal of CMP1, and the output of the error amplifier EA Connect one input terminal of CMP2, the inductor current i _L is connected to the other input terminal of CMP2, the output of CMP1, the output of CMP2 and the clock signal clk are all sent to the pulse modulation unit, and the output of the pulse modulation unit is used as the input of the multiplex selection unit , the output of the multiplex selection unit controls the switching tube in the dual-input dual-output converter. The output voltage _Vo and the reference voltage _{Vo_ref} are used as inputs of the mode switching control unit, and the output of the mode switching control unit is connected to the multiplexing unit as a selection signal of the multiplexing unit.

Figure 2 shows the schematic diagram of the dual-input dual-output converter, including the photovoltaic module PV, energy storage unit, load unit R, photovoltaic module access diode D ₁ , input filter capacitor C _in , Buck end switch S ₁ , Boost end switch Tube S ₂ , energy storage inductor L, load branch switch tube S ₃ , energy storage unit charging branch diode D ₃ , energy storage unit charging branch switch tube S ₄ , energy storage unit discharge branch diode S ₅ , output terminal Filter capacitor C _out .

The dual-input dual-output converter is derived from the dual-tube Buck-Boost converter. The input end of the dual-tube Buck-Boost converter is connected to the photovoltaic module and the output end is connected to the load. At the same time, in order to overcome the fluctuation characteristics of the output power of photovoltaic modules, a branch is added to the input side and output side of the double-tube Buck-Boost converter and connected to the energy storage unit. The branch on the input side controls the storage unit. The energy unit discharges, and the branch on the output side controls the charging of the energy storage unit.

In order to achieve energy balance between photovoltaic modules and loads, the operating mode of the system is divided into dual output mode and dual input mode according to the relationship between the maximum output power of photovoltaic modules and the power required by the load. In the dual output mode, the maximum output power of the photovoltaic module is greater than the power required by the load (P _max >P _o ), and the excess power generated by the photovoltaic module flows to the energy storage unit to charge the energy storage unit; in the dual input mode, the photovoltaic module When the maximum output power is less than the power required by the load (P _max <P _o ), the output power of the photovoltaic module cannot meet the load demand, and the energy storage unit provides insufficient power through discharge to ensure the normal operation of the load.

Figure 3 shows the equivalent circuit and steady-state waveform of a dual-input dual-output converter in dual-output mode. In one switching cycle, the system includes three switching states. The first switching state refers to the switching tubes S ₁ and S ₂ is turned on, the photovoltaic module charges the inductor L through the diode D ₁ , and the inductor current rises; the second switching state means that the switch tubes S ₁ and S ₂ are turned off, the switch tube S ₃ is turned on, and the inductor L is charged to the load through the diode D ₂ Discharge, the inductor current decreases; the third switching state means that the switch tube _S3 is turned off, the switch tube _S4 is turned on, the inductor L discharges to the energy storage unit through the diode _D2 , and the inductor current continues to decrease.

Figure 4 shows the equivalent circuit and steady-state waveform of the dual-input dual-output converter in dual-input mode. In one switching cycle, the system includes three switching states. The first switching state refers to the switching tubes S ₁ and S ₂ is turned on, the photovoltaic module charges the inductor L through the diode D ₁ , and the inductor current rises; the second switching state means that the switch tube S ₁ is turned off, the switch tubes S ₂ and S ₅ are turned on, and the energy storage unit charges the inductor L through the diode D ₄ . The inductor L is charged, and the inductor current continues to rise; the third switching state means that the switch tubes _S2 and _S5 are turned off, the switch tube _S3 is turned on, the inductor L discharges to the load through the diode _D2 , and the inductor current decreases.

In order to realize the system operating mode shown in Figure 3 and Figure 4, a control circuit is designed. The control circuit includes an MPPT control unit, an error amplifier EA, a first comparator CMP1, a second comparator CMP2, a pulse modulation unit, a multi-channel Selection unit and mode switching control unit.

The control circuit samples the output voltage V _pv and output current I _pv of the photovoltaic module and sends them to the MPPT control unit for MPPT calculation. The output of the MPPT control unit is sent to the comparator CMP1. CMP1 compares the output of the MPPT control unit with the dual-input dual-output conversion. The size of the inductor current in the converter; the control circuit samples the load voltage _Vo of the dual-input dual-output converter, and uses Vo _and the output reference voltage _{Vo_ref} as the input of the error amplifier EA. The output of EA is sent to the comparator CMP2, and CMP2 compares The output of EA and the size of the inductor current in the dual-input dual-output converter; the output c ₁ of CMP1, the output c ₂ of CMP2, and the clock signal clk are used as the input signals of the pulse modulation unit, and the output of the pulse modulation unit is used as a multiplex selection As the input of the unit, the multiplex selection unit determines its output switching signal through the mode selection signal mel, thereby achieving control of the system in the corresponding mode.

The pulse modulation unit includes SR flip-flop 2#, SR flip-flop 3#, SR flip-flop 4#, logic XOR gate XOR1, logic XOR gate XOR2, logic NOT gate NO1, logic NOT gate NO2, logic NOT gate NO3. The multiplex selection unit includes a two-way selector MUX1, a two-way selector MUX2, a two-way selector MUX3, a two-way selector MUX4, and a two-way selector MUX5. The output c ₁ of CMP1 is connected to the reset terminal of SR flip-flop 2# and SR flip-flop 3# respectively; the output c ₂ of CMP2 is connected to the set terminal of SR flip-flop 3#, and c ₂ is connected to the SR flip-flop after NO2 The reset terminal of 4# is connected; clk is connected to the set terminal of SR flip-flop 2# and SR flip-flop 4# respectively. The output terminal Q of SR flip-flop 2# serves as the switching control signal of switch S1. At the same time, the output terminal Q of SR flip-flop 2# is connected to an input terminal of XOR1, and the output terminal Q of SR flip-flop 3# is connected to an input terminal of XOR1. The other input terminal, the output terminal of XOR1 is connected to the first input terminal of MUX1, the second input terminal of MUX1 is connected to low level, and the output terminal of MUX1 is used as the switching control signal of switch tube S4. The output of XOR1 is connected to the first input terminal of MUX2 via NO1, the output terminal Q of SR flip-flop 4# is connected to the second input terminal of MUX2 via NO3, and the output of MUX2 is used as the switching control signal of switch tube S3. The output terminal Q of SR flip-flop 2# is connected to the first input terminal of MUX3, the output terminal Q of SR flip-flop 4# is connected to the second input terminal of MUX3, and the output of MUX3 is used as the switching control signal of switch tube S2. The output terminal Q of SR flip-flop 2# is connected to an input terminal of XOR2, the output terminal Q of SR flip-flop 4# is connected to the other input terminal of XOR2, the output terminal of XOR2 is connected to the second input terminal of MUX4, MUX4 The first input terminal is connected to low level, and the output terminal of MUX4 is used as the switching control signal of switch S5. The multi-channel selection unit determines which switch signal is output by each two-way selector through the mel signal. If mel makes the system work in dual output mode, then each two-way selector outputs the first switch signal. If mel makes the system work, In dual input mode, each two-way selector outputs the second switch signal.

The mode switching control unit includes the subtractor SUB, comparator CMP3, comparator CMP4, SR flip-flop 1#, the output voltage V _o and the voltage reference value V _{o_ref} as the inputs of SUB, and the output of SUB is connected to one of the comparators CMP3 and CMP4 respectively. The input terminal is connected, the other input terminal of CMP3 is connected to the preset voltage threshold ΔV, the other input terminal of CMP4 is connected to the preset voltage threshold - ΔV, the output terminals of CMP3 and CMP4 are respectively connected to the reset of SR flip-flop 1# terminal and the set terminal are connected. The output terminal Q of SR flip-flop 1# is the mode switching control signal mel.

The specific working principle is as follows: the control circuit samples the output voltage V _pv and output current I _pv of the photovoltaic module, and sends them to the MPPT control unit for MPPT operation. The MPPT algorithm uses the perturbation observation method, and the operation result v _mppte is used as the output of the MPPT operation unit, and Sent to comparator CMP1, CMP1 compares the inductor current i _L and v _mppte . If i _L is greater than v _mppte , CMP1 output c ₁ is high level. If i _L is less than v _mppte , CMP1 output c ₁ is low level. flat; at the same time, the load voltage _Vo of the converter is sampled, and Vo _and the output reference voltage _{Vo_ref are} used as the input of the error amplifier EA, and the error amplified signal v _oe is used as the output of the EA and sent to the comparator CMP2, which compares the inductor. The magnitude of current i _L and v _oe , if i _L is less than v _oe , then CMP2 output c ₂ is high level, if i _L is greater than v _oe , then CMP2 output c ₂ is low level; c ₁ , c ₂ and clock The signal clk is used as the input of the pulse modulation unit. The output of the pulse modulation unit includes two sets of signals. One is the switching signal when the system works in dual input mode. The other is the switching signal when the system works in dual output mode. Both sets of signals are used as The input of the multi-channel selection unit determines its output switching signal through the mode selection signal mel, thereby achieving control of the system in the corresponding mode.

Figure 5 shows the schematic diagram of the mode switching control unit of the control circuit, which calculates the difference between the output voltage _Vo and the reference voltage _{Vo_ref} in real time, and sends the calculation results to the comparator CMP3 and the comparator CMP4 respectively, which are compared with the preset values. The threshold ΔV is compared with -ΔV. If V _o -V _{o_ref} > ΔV, CMP3 outputs high level and resets SR flip-flop 1#, the mel signal is 0, and the system operates in dual output mode. If V _o -V _{o_ref} <-ΔV), CMP4 outputs high level and sets SR flip-flop 1#, the mel signal is 1, and the system operates in dual input mode.

Figure 6 shows the schematic diagram of the pulse modulation unit and multiplex selection unit of the control circuit. The c ₁ and c ₂ output by the comparators CMP1 and CMP2 and the clock signal clk are used as the input of the pulse modulation unit. The specific working principle is described as follows: In the dual output mode, the mel signal is 0, and each multiplexer MUX in the multiplex selection unit selects the first signal as the output, so the switch S ₅ is always in the off state. At the beginning of the switching cycle, clk SR flip-flop 2# and SR flip-flop 3# are set, switches S ₁ and S ₂ are turned on, and the inductor current rises. When the inductor current rises to v _mppte , c ₁ output by comparator CMP1 is high level and causes SR flip-flop 2# and SR flip-flop 3# are reset, switches S ₁ and S ₂ are turned off, S ₃ is turned on, and the inductor current begins to decrease. When the inductor current drops to v _oe , the c ₂ output by the comparator CMP2 is High level sets SR flip-flop 3#, switch tube _S4 is turned on, switch tube _S3 is turned off, and the inductor current continues to decrease until the next switching cycle arrives. In the dual input mode, the mel signal is 1, and each multiplexer MUX in the multiplex selection unit selects the second signal as the output, so the switch _S4 is always in the off state. At the beginning of the switching cycle, clk SR flip-flop 2# and SR flip-flop 3# are set, switches _S1 and _S2 are turned on, and the inductor current rises. When the inductor current rises to v _oe , c ₁ output by comparator CMP1 is high level and causes SR flip-flop 2# and SR flip-flop 3# are reset, switch S ₁ is turned off, S ₅ is turned on, and the inductor current continues to rise. When the inductor current rises to v _oe , c ₂ output by comparator CMP2 is low level And the SR flip-flop 4# is reset, the switch _S3 is turned on, and the inductor current begins to decrease until the next switching cycle arrives.

Use PSIM simulation software to perform time domain simulation analysis on the system of this embodiment. The simulation parameters of the system are set as: C _in = C _out = 470 μF, L = 330 μH, load power P _o = 100W, load voltage V _o = 48V, battery terminal The voltage V _bat =25V, the switching frequency is f _s =100kHz, and the system simulation results are as follows.

Figure 7(a) shows the steady-state waveform of the system operating in dual output mode, including the turn-on timing of each switch tube, the inductor current and the voltage waveform across the inductor. It can be seen from the figure that the turn-on timing of the switch tube is related to The theoretical analysis is consistent, and the inductor current shows an "up-down-down" change trend; Figure 7(b) shows the transient response waveform of a sudden load change when the system is running in dual output mode. At this time, the maximum output power of the photovoltaic module is 120W. At the initial moment, the photovoltaic module outputs at maximum power, the load power consumption is 100W, and the energy storage unit absorbs power is 20W. At 0.5s, the load power decreases from 100W to 50W, and the energy storage unit absorbs power suddenly to 70W. At 0.7s The load power is increased from 50W to 100W, and the system operation is consistent with the initial state.

Figure 8 shows the simulation waveform of the system operating mode switching from dual output mode to dual input mode. At the initial moment, the photovoltaic module outputs a maximum power of 120W, the load consumes 100W power, and the energy storage unit absorbs 20W power. In 0.3s, the photovoltaic module The maximum output power of the module suddenly changed from 120W to 60W. The output power of the photovoltaic module could not meet the load demand. In order to ensure the normal operation of the system, the system operating mode was switched to dual input mode, and the energy storage unit discharged to the load with a discharge power of 40W.

Figure 9(a) shows the steady-state waveform of the system operating in dual-input mode, including the turn-on timing of each switch tube, the inductor current and the voltage waveform across the inductor. It can be seen from the figure that the turn-on timing of the switch tube is related to The theoretical analysis is consistent, and the inductor current shows a "rising-falling" trend; Figure 9(b) shows the transient response waveform of the load mutation when the system is running in dual-input mode. At this time, the maximum output power of the photovoltaic module is 60W. The initial moment, the photovoltaic module outputs at maximum power, the energy storage unit output power is 40W, and the load power is 100W. At 0.5s, the load power increases from 100W to 120W, and the energy storage unit output power suddenly changes to 60W. At 0.7s, the load power is from 120W is reduced to 100W, and the system operation is consistent with the initial state.

Figure 10 shows the simulation waveform of the system operating mode switching from dual input mode to dual output mode. At the initial moment, the photovoltaic module outputs a maximum power of 60W, the energy storage unit output power is 40W, and the load power consumption is 100W. At 0.3s, the photovoltaic module outputs a maximum power of 60W. The maximum output power of the module suddenly changed from 60W to 120W. The output power of the photovoltaic module was greater than the power required by the load. In order to ensure the normal operation of the system, the system operating mode was switched to dual output mode, and the energy storage unit was switched to charging mode with a charging power of 20W.

It can be seen from the above simulation results that the energy management and control method of the photovoltaic energy storage system proposed by the present invention can achieve the maximum power output of the photovoltaic module and the constant load voltage, and the system can reasonably adjust the power of the photovoltaic module and the load when the power of the photovoltaic module and the load changes. Allocate power between ports and flexibly implement mode switching to ensure stable and efficient operation of the system.

Claims (1)

1. The energy management and control device of the photovoltaic energy storage system is characterized by comprising a double-input double-output converter and a control circuit;

the double-input and double-output converter comprises a double-tube Buck-Boost converter, wherein a Buck end switching tube is S ₁ The Boost end switching tube is S ₂ The load end switch tube is S ₃ The method comprises the steps of carrying out a first treatment on the surface of the The input end and the output end of the double-tube Buck-Boost converter are respectively connected to a photovoltaic module PV and a load R of the photovoltaic energy storage system; the dual-input dual-output converter further comprises an output side branch and an input side branch; the output side branch comprises a diode D ₃ And a switch tube S ₄ ，D ₃ Is connected to S ₂ Drain electrode D of (2) ₃ Is connected to S ₄ Drain electrode S of (1) ₄ Is connected to the positive electrode of the energy storage unit of the photovoltaic energy storage system; the input side branch comprises a diode D ₄ And a switch tube S ₅ ，D ₄ Is connected to S ₁ Source of D ₄ Is connected to S ₅ Source of S ₅ Is connected to the positive electrode of the energy storage unit of the photovoltaic energy storage system; the negative electrode of the energy storage unit is connected to S ₂ A source of (a);

the control circuit comprises an MPPT control unit, an error amplifier EA, a first comparator CMP1, a second comparator CMP2, a pulse modulation unit, a multiplexing unit and a mode switching control unit;

the input ends of the MPPT control unit are respectively input with output voltage V of the photovoltaic module PV _pv And output current I _pv The output end is connected to one input end of the CMP1, and the other input end of the CMP1 inputs the inductance current i of the double-tube Buck-Boost converter _L ；

The input ends of the error amplifier EA are respectively input with the output voltage V of the double-tube Buck-Boost converter _o And a voltage reference value V _{o_ref} The output end is connected to one input end of the CMP2, and the other input end of the CMP2 inputs the inductance current i of the double-tube Buck-Boost converter _L ；

The pulse modulation unit comprises an SR trigger 2#, an SR trigger 3#, an SR trigger 4#, a logic exclusive OR gate XOR1, a logic exclusive OR gate XOR2, a logic NOT gate NO1, a logic NOT gate NO2 and a logic NOT gate NO3; the multi-path selection unit comprises a two-path selector MUX1, a two-path selector MUX2, a two-path selector MUX3 and a two-path selector MUX4;

output terminal c of CMP1 ₁ The reset terminals of the SR trigger 2# and the SR trigger 3# are respectively connected; output terminal c of CMP2 ₂ Is connected with the set end of the SR flip-flop 3#, and c ₂ The reset terminal of the SR trigger 4# is connected with the reset terminal of the SR trigger 4# after NO 2; the clock signal clk is respectively connected with the set ends of the SR flip-flop 2# and the SR flip-flop 4#; the output terminal Q of the SR flip-flop 2# is connected to S ₁ At the same time, the output terminal Q of the SR flip-flop 2# is connected to one input terminal of the XOR1, the output terminal Q of the SR flip-flop 3# is connected to the other input terminal of the XOR1, the output terminal of the XOR1 is connected to the first path input terminal of the MUX1, the second path input terminal of the MUX1 is connected to the low level, and the output terminal of the MUX1 is connected to S ₄ A gate electrode of (a); the output of XOR1 is connected to the first input of MUX2 via NO1, the output Q of SR flip-flop 4# is connected to the second input of MUX2 via NO3, and the output of MUX2 is connected to S ₃ A gate electrode of (a); the output end Q of the SR flip-flop 2# is connected to the first path input end of the MUX3, the output end Q of the SR flip-flop 4# is connected to the second path input end of the MUX3, and the output of the MUX3 is connected to S ₂ A gate electrode of (a); the output terminal Q of the SR flip-flop 2# is connected to one input terminal of the XOR2, the output terminal Q of the SR flip-flop 4# is connected to the other input terminal of the XOR2, the output terminal of the XOR2The output end is connected to the second input end of the MUX4, the first input end of the MUX4 is connected to the low level, and the output end of the MUX4 is connected to S ₅ A gate electrode of (a);

the mode switching control unit includes a subtractor SUB, a comparator CMP3, a comparator CMP4, and an SR flip-flop 1#; the input ends of the SUB are respectively input with the output voltage V of the double-tube Buck-Boost converter _o And a voltage reference value V _{o_ref} The output end is respectively connected with one input end of the CMP3 and the CMP4, the other input end of the CMP3 inputs a preset voltage threshold value delta V, the other input end of the CMP4 inputs a preset voltage threshold value delta V, the output ends of the CMP3 and the CMP4 are respectively connected with the reset end and the set end of the SR trigger 1#, and the output end Q of the SR trigger 1# issimultaneously connected to the selection ends of the MUX1, the MUX2, the MUX3 and the MUX 4.