A rotating water electrode photovoltaic power generation and heat storage system and a control method

Abstract

The application provides a rotating water electrode photovoltaic power generation and heat storage system and a control method, and solves the problems of water electrode polarization and low-cost photovoltaic maximum power tracking in the process of heating the water electrode boiler by the photovoltaic array. The rotating water electrode photovoltaic power generation and heat storage system mainly comprises a heat storage tank, a water electrode group, a photovoltaic power supply system and a monitoring system. The water electrode group comprises m rotating water electrodes, a rotating water electrode rotating connecting rod, m+1 fixed water electrodes and a water electrode U-shaped structure. The m rotating water electrodes are arranged at equal intervals and staggered in the middle of the m+1 fixed water electrodes through the water electrode rotating connecting rod. Each rotating water electrode rotates synchronously through the water electrode rotating connecting rod, changes the longitudinal relative position with the fixed water electrode and synchronously changes the mirror image area of the rotating water electrode and the fixed water electrode. The application realizes initialization setting, photovoltaic maximum power point tracking, fast locking of the photovoltaic maximum power point section and fine photovoltaic maximum power tracking control.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of heat supply and new energy, and particularly relates to a rotating water electrode photovoltaic power generation and heat storage system and a control method. BACKGROUND

[0002] The rapid development of solar photovoltaic power generation and the instability of photovoltaic power generation result in the phenomenon of light and wind abandonment. High proportion of local renewable energy consumption can solve the problems of grid stability and line loss on the one hand, and the local load demand on the other hand. However, the friendliness of local consumption to the grid and the controllability of the load are the key technologies. For enterprises and regions with heat and gas supply demands, water electrode boiler heat storage is a relatively ideal controllable load.

[0003] For example, in high-altitude and high-latitude regions with abundant solar energy resources, the load characteristics are mainly heat supply, and the water comes from glacial meltwater, which is relatively low in temperature. Therefore, the photovoltaic power generation is locally consumed through heat storage, which improves the local quality of life, reduces carbon emissions, and improves the stability of the grid by using flexible load control.

[0004] The current electrode hot water boiler heating principle is that the basic three-phase voltage current releases a large amount of heat energy through the water body with a set conductivity, directly converts electrical energy into heat energy, and generates steam. The heating power can be steplessly adjusted. Since the water resistance directly heats, the electrical energy is 100% converted into heat, and the efficiency is high, and almost no heat is lost. It is a high-efficiency heating method.

[0005] The water electrode hot water boiler is powered by alternating current, and the photovoltaic power generation output by the inverter meets the power supply requirements of the water electrode hot water boiler. However, the efficiency of the inverter is greatly reduced under low light, and the photovoltaic power generation cannot be efficiently utilized, and the relative cost is relatively high.

[0006] If the photovoltaic power generation is directly applied to the water electrode boiler heat storage, the efficiency and cost will be improved. However, there are two major problems:

[0007] 1. The direct current output power of photovoltaic power generation acts on the water electrode, and the water electrode will undergo polarization reaction. Since water is composed of hydrogen ions and oxygen ions, if there is an electrode, ion separation will break the metal bond, and water will be divided into two poles. If there are other minerals in the water, calcium carbonate and other impurities will be formed on the cathode, and the alternating voltage will not exist. Therefore, the problem of efficient and lossless photovoltaic power generation polarity conversion needs to be solved.

[0008] Due to the characteristics of photovoltaic power generation, how to match the load characteristics with the characteristics of photovoltaic power generation, that is, the problem of maximum power tracking of photovoltaic power generation. SUMMARY

[0009] In order to solve the problems of water electrode polarization and photovoltaic maximum power tracking in the water electrode boiler heating of the photovoltaic array, realize efficient utilization of photovoltaic power generation, the application provides a rotating water electrode photovoltaic power generation heating and heat storage system and a control method, which realizes initialization setting, photovoltaic maximum power point tracking, fast locking of the photovoltaic maximum power point section and fine photovoltaic maximum power tracking control.

[0010] In order to achieve the above-mentioned purposes, the technical scheme adopted by the application is as follows:

[0011] A rotating water electrode photovoltaic power generation heating and heat storage system, comprising a heat storage tank, a water electrode group, a photovoltaic power supply system and a monitoring system.

[0012] The water electrode group is arranged in the heat storage tank, the photovoltaic power supply system is arranged around the heat storage tank, and the heat storage tank is provided with a water inlet, a water outlet, an exhaust pipeline and a pressure reducing valve.

[0013] The water electrode group comprises a first rotating water electrode, a second rotating water electrode, a third rotating water electrode, an mth rotating water electrode, a rotating water electrode rotating connecting rod, a conductive ring, a stepping motor, a first fixed water electrode, a second fixed water electrode, a third fixed water electrode, an mth fixed water electrode, an m+1th fixed water electrode, a fixed water electrode conductive plate and a water electrode U-shaped structure.

[0014] Wherein, m is an integer greater than or equal to 1; the first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode, and the first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode are metal conductive thin plates, and a plurality of holes are formed in the metal conductive thin plates, which are beneficial to the flow of water and reduce the disturbance of bubbles generated in the water heating process to the water electrode.

[0015] The first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode are fan-shaped structures, and are installed on the water electrode rotating connecting rod through the centers of the circles where the fan-shaped structures are located; the first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode, and the first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode have equal spacing.

[0016] The first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode, and the m+1th fixed water electrode are rectangular structures, are installed equidistantly on the fixed support, and are connected together on one side by the fixed water electrode conductive plate. The fixed water electrode conductive plate is connected with the first power line for water electrode heating through the fixed water electrode terminal, and supplies power to the first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode, and the m+1th fixed water electrode.

[0017] Further, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode are connected through the water electrode rotating connecting rod, the first rotating water electrode is arranged between the first fixed water electrode and the second fixed water electrode, the second rotating water electrode is arranged between the second fixed water electrode and the third fixed water electrode, the third rotating water electrode is arranged between the third fixed water electrode and the mth fixed water electrode, and the mth rotating water electrode is arranged between the mth fixed water electrode and the m+1th fixed water electrode.

[0018] Further, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode are synchronously rotated through the water electrode rotating connecting rod, the longitudinal relative positions of the first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode, and the m+1th fixed water electrode are changed, and the mirror image areas of the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode and the first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode, and the m+1th fixed water electrode are synchronously changed.

[0019] Further, the water electrode U-shaped structure comprises: a left U-shaped support, a right U-shaped support, a left bearing, a right bearing, a left fixed support, a right fixed support and a water electrode fixed support; wherein the water electrode U-shaped structure is an insulator material, the first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode and the m+1th fixed water electrode are fixedly installed on the upper end of the water electrode fixed support of the water electrode U-shaped structure, the lower end of the water electrode fixed support of the water electrode U-shaped structure is close to the edge, and the left fixed support and the right fixed support are respectively installed; the water electrode U-shaped structure is fixedly connected with the bottom of the heat storage tank through the left fixed support and the right fixed support; the left U-shaped support of the water electrode U-shaped structure is embeddedly installed with the left bearing close to the top, the right U-shaped support is embeddedly installed with the right bearing, and the rotating water electrode rotating link is fixed on the water electrode U-shaped structure through the left bearing and the right bearing; thus, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode are arranged in the middle of the first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode and the m+1th fixed water electrode through the water electrode rotating link.

[0020] Further, the rotating water electrode rotating link is an insulator, one end of which penetrates the wall of the heat storage tank and is connected with the synchronous motor, and a conductive ring is installed at 1 / 3 of the length of the rotating water electrode rotating link on the side of the synchronous motor and is connected with the second power line of the heating water electrode; the other 2 / 3 of the length of the rotating water electrode rotating link is hollow, and the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode are arranged and installed on the hollow part; the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode are connected with the conductive ring through the rotating link in the hollow part, so that the second power line of the water electrode heating is connected with the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode through the conductive ring; at this time, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode to the mth rotating water electrode are rotated through the rotating water electrode rotating link under the drive of the stepping motor, so as to change the relative position and mirror area of the first fixed water electrode, the second fixed water electrode, the third fixed water electrode to the mth fixed water electrode and the m+1th fixed water electrode.

[0021] Further, the photovoltaic power supply system comprises: a photovoltaic array and a power electronic square wave commutator; the output positive electrode and the output negative electrode of the photovoltaic array are connected with the power electronic square wave commutator, the power electronic square wave commutator converts the output positive electrode and the output negative electrode of the photovoltaic array into square wave output power through power electronic switches, and the square wave output end of the power electronic square wave commutator is connected with the fixed water electrode terminal and the conductive ring through the first power line and the second power line respectively, so as to provide the water electrode group with positive and negative period change power supply.

[0022] Furthermore, the monitoring system includes a controller, a water electrode current sensor, a water electrode voltage sensor, and a thermal storage tank temperature sensor; wherein the controller is placed around the thermal storage tank and connected to all sensors via communication cables, and connected to all controlled units and stepper motors via control cables; the controller reads sensor data in real time and controls the controlled units according to algorithms, models, and control strategies.

[0023] This invention also provides a control method for a rotating water electrode photovoltaic power generation and thermal storage system, specifically including the following steps:

[0024] Step 1: Initialization settings, specifically including:

[0025] (1.1) Input photovoltaic array parameters: The parameters include installed capacity, array tilt angle, array orientation, horizontal diffuse reflection coefficient, open circuit voltage, short circuit current, photovoltaic power generation, total solar irradiance and typical photovoltaic maximum power point table;

[0026] (1.2) Determine the power of the rotating water electrode heating water resistance corresponding to the maximum power point of photovoltaic power under the local maximum and minimum irradiance. and the number of rotation angles n θ ;

[0027] (1.3) Establish the segmented stepper motor rotation angle points for quickly locking the maximum power point of photovoltaic power generation under different illumination conditions;

[0028] Step 2: Photovoltaic power point tracking to quickly locate the photovoltaic power point segment with the highest power output.

[0029] Step 3: Perform refined maximum power point tracking (MPPT) control for photovoltaic power generation, specifically including:

[0030] Step 2 quickly identifies the section with the maximum power output of the photovoltaic power generation, and the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv and the maximum power point of segmented photovoltaic power generation Compare and judge separately or And determine mod(P) based on the mod modulo function. pv ,α)≥0.5 and mod(P pv When α) < 0.5, then according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number, the following steps are controlled:

[0031] Step A: The controller adjusts the increment / decrement Δn based on the previous time step. θ_1 Subtracting one disturbance rotation angle from each rotation angle yields the current increase or decrease Δn.θ The rotation angle is Δn θ =Δn θ_1 -1 controls the stepper motor to rotate, changing the heating water resistance R. w The controller continues to read the photovoltaic power generation current I. pv and voltage U pv The output power of photovoltaic power generation was calculated. And compared with the photovoltaic power generation at the previous moment Compare;

[0032] When judging The controller repeats step A.

[0033] When judging At that time, determine the heating water resistance R generated by the current mirror area Sg of the rotating water electrode. w Adapted to the maximum power point of photovoltaic power generation

[0034] in, This represents the current output power of photovoltaic power generation; The photovoltaic power generation at the previous moment; Δn θ_1 The increment or decrement of rotation angles at the previous moment; Δn θ This represents the current increase or decrease in rotation angle;

[0035] Step B, the controller adjusts the increment / decrement Δn based on the previous time step. θ_1 Adding a perturbation rotation angle to the rotation angle gives the current increase / decrease Δn. θ The rotation angle is Δn θ =Δn θ_1 +1 controls the stepper motor to rotate, changing the heating water resistance R. w The controller continues to read the photovoltaic power generation current I. pv and voltage U pv The output power of photovoltaic power generation was calculated. And compared with the photovoltaic power generation at the previous moment Compare;

[0036] When judging The controller repeats step B.

[0037] When judging At that time, determine the heating water resistance R generated by the current mirror area Sg of the rotating water electrode. w Adapted to the maximum power point of photovoltaic power generation

[0038] Further, step 1.2 specifically includes:

[0039] Due to the heating water resistance power Pwaterm Also the number of rotation angle n θ The heating water resistance power of the rotating water electrode

[0040]

[0041] Thus, by the local typical irradiance intensity and the photovoltaic maximum power point corresponding table, the photovoltaic maximum power point P under the local maximum irradiance intensity is found respectively mppt_max And the corresponding photovoltaic maximum power point voltage, and the photovoltaic maximum power point P under the minimum irradiance intensity mppt_min And the corresponding photovoltaic maximum power point voltage, according to The heating water resistance power of the rotating water electrode is found in turn Equal to the photovoltaic maximum power point P mppt_max That is Thus, the number of rotating water electrode angle is found correspondingly The heating water resistance power of the rotating water electrode is found in turn Equal to the photovoltaic maximum power point P mppt_min That is Thus, the number of rotating water electrode angle is found correspondingly

[0042] Wherein, n θ = 0, 1, 2, …… max; min0 and max0 ∈ [0, max]; P mppt_max The photovoltaic maximum power point under the local maximum irradiance intensity; P mppt_min The photovoltaic maximum power point under the local minimum irradiance intensity;

[0043] Max is the maximum number of rotating water electrode angle Max0 is the photovoltaic maximum power point P found under the local maximum irradiance intensity mppt_max And the corresponding calculated rotating water electrode angle Max0 ≤ max; min0 is the photovoltaic maximum power point P found under the minimum irradiance intensity mppt_min And the corresponding calculated rotating water electrode angle Min0 ≥ 0;

[0044] Thus, the controller controls the rotating water electrode angle number of the step motor And The rotating water electrode photovoltaic power generation and heat storage system can realize the maximum power point tracking under the local typical maximum and minimum irradiance intensity conditions

[0045] Further, the step 1.3 specifically comprises:​

[0046] Considering the response speed of mechanical photovoltaic maximum power tracking, segmented photovoltaic maximum power tracking is adopted; first, based on the input photovoltaic array parameters and irradiance, a table of fast locking of segmented photovoltaic maximum power points under different illuminations is established; the stepper motor rotates by an angle Rotating the rotating water electrode The angle number of the photovoltaic maximum power point range under the local maximum irradiance And the photovoltaic maximum power point range under the local minimum irradiance That is

[0047]

[0048] Quantifying again by 10 Get the number of segmented photovoltaic maximum power points under different illuminations, that is And the photovoltaic maximum power point corresponding to the segmented endpoint:

[0049]

[0050] That is Thus, the photovoltaic maximum power point value at each segmented point is determined by table lookup The photovoltaic maximum power point difference of each adjacent segment is a constant α, that is:

[0051]

[0052] Wherein, mp is the number of segmented photovoltaic maximum power points; is the photovoltaic maximum power point value under the local maximum irradiance; is the photovoltaic maximum power point value under the local minimum irradiance; Δθ is the angle of the stepper motor rotation; θ is the number of stepper motor rotation angles; is the photovoltaic maximum power point under the stepper motor rotation angle of number n θ ; is the photovoltaic maximum power point voltage under the stepper motor rotation angle of number n θ ; is the photovoltaic maximum power point current under the stepper motor rotation angle of number n θ ; α is the photovoltaic maximum power point difference of each adjacent segment; is the photovoltaic maximum power point corresponding to each segmented point, n m = 1, 2, 3, …, mp.

[0053] Further, the step 2 specifically includes fast locking of photovoltaic maximum power point segments:

[0054] The controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Based on the output power P pv Compared with the previous moment's maximum photovoltaic power generation The difference is calculated at the points, that is:

[0055]

[0056] (2.1) When ΔP pv When the photovoltaic power generation capacity increases (>0), the photovoltaic power generation output power P will be... pv Divide by the constant α of the maximum power difference point of photovoltaic power generation in each adjacent segment, that is:

[0057]

[0058] The result of the divisor is rounded to one decimal place, and the modulo function is used to determine the remainder.

[0059] mod(P pv ,α)≥0.5 (17)

[0060] in, n represents the point at which photovoltaic power generation reaches its maximum power at the previous moment. θ_1 The point at which photovoltaic power generation reaches its maximum power at the previous moment. The number of rotation angles of the stepper motor; I pv U represents the current photovoltaic power generation current. pv P represents the current photovoltaic power generation voltage. pv This represents the current output power of photovoltaic power generation;

[0061] 1) For example, the modulo modulo function determines mod(P) pv When α)≥0.5, then according to the floor function:

[0062]

[0063] Using the principle of rounding up to the nearest whole number, determine the maximum power point of photovoltaic power generation in a certain segment. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the nth stepper motor rotation angle θ =n m ×10 stepper motor rotation angles minus the previous moment's maximum photovoltaic power generation point The number of rotation angles n of the stepper motor θ_1The increase or decrease of the stepper motor Δn is obtained. θ One rotation angle, i.e., Δn θ =10n m -n θ_1 ;

[0064] Where, n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, increasing the mirror area of ​​the rotating water electrode, thereby reducing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step A in step 3;

[0065] Where mod is the modulo function; INT is the integer function; The maximum power point for photovoltaic power generation is defined in nm segments; For n m The maximum power point of photovoltaic power generation in the -1 segment; n is the number of rotation angles of the stepper motor. θ The point at which photovoltaic power generation reaches its maximum power; nθ_1 represents the point where photovoltaic power generation is at its maximum power level at the previous moment. The number of rotation angles of the stepper motor; Δn θ To increase or decrease the number of rotation angles of the stepper motor;

[0066] 2) For example, the modulo modulo function determines mod(P) pv When α) < 0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the nth stepper motor rotation angle θ =n m ×10 stepper motor rotation angles minus the previous moment's maximum photovoltaic power generation point The number of rotation angles n of the stepper motor θ_1 The increase or decrease of the stepper motor Δn is obtained. θ One rotation angle, i.e., Δnθ =10n m -n θ_1 , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, increasing the mirror area Sg of the rotating water electrode, thereby reducing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step B in step 3;

[0067] in, The maximum power point for photovoltaic power generation is defined in nm segments; The maximum power point for photovoltaic power generation is defined in the nm+1 segment; The point where the photovoltaic power generation reaches its maximum at the nθ angles of rotation of the stepper motor; Δn θ To increase or decrease the number of rotation angles of the stepper motor;

[0068] (2.2) When ΔP pv When the photovoltaic power generation power decreases by less than 0, the current photovoltaic power generation output power P will be reduced. pv Divide by the constant α of the maximum power difference point of photovoltaic power generation in each adjacent segment, as shown in equation (16). The divisor result is rounded to one decimal place, and mod(P) is determined according to the mod remainder function. pv ,α)≥0.5;

[0069] 1) For example, the modulo modulo function determines mod(P) pv When α)≥0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the photovoltaic power generation maximum power point at the previous moment. The number of rotation angles of the stepper motor, nθ_1, minus n θ =n m Multiply by 10 stepper motor rotation angles to obtain the stepper motor increase / decrease Δn. θ One rotation angle, i.e., Δn θ =n θ_1-10n m , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, reducing the mirror area Sg of the rotating water electrode, thereby increasing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step A in step 3;

[0070] 2) For example, the modulo modulo function determines mod(P) pv When α) < 0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the photovoltaic power generation maximum power point at the previous moment. The number of rotation angles of the stepper motor nθ_1 minus n θ =n m Multiply by 10 stepper motor rotation angles to obtain the stepper motor increase / decrease Δn. θ One rotation angle, i.e., Δn θ =n θ_1 -10n m , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization; at this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, reducing the mirror area Sg of the rotating water electrode, thereby increasing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step B in step 3.

[0071] This invention has the following characteristics:

[0072] (1) The cost is relatively lower than that of inverters;

[0073] (2) Adaptable to 100% fluctuations in photovoltaic power generation, with high efficiency;

[0074] (3) The switching loss is small. For example, the switching loss of a second-level switching time is much smaller than that of a 50Hz switching loss.

[0075] (4) The controller has a simple structure and high reliability;

[0076] (5) High maximum power point tracking efficiency of photovoltaic power generation across all time domains. Attached Figure Description

[0077] Figure 1 This is a structural diagram of a rotating water electrode photovoltaic power generation and thermal storage system according to the present invention;

[0078] Figure 2 This is a schematic diagram showing the connection relationship between components of a rotating water electrode photovoltaic power generation and thermal storage system according to the present invention;

[0079] Figure 3 This is a schematic diagram of the rotating water electrode in a photovoltaic power generation and thermal storage system according to the present invention.

[0080] Figure 4 This is a control flowchart of a rotating water electrode photovoltaic power generation and thermal storage system according to the present invention. Detailed Implementation

[0081] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0082] like Figure 1 and Figure 2 As shown, the rotating water electrode photovoltaic power generation and heat storage system of the present invention mainly includes a heat storage tank 18, a water electrode group, a photovoltaic power supply system and a monitoring system;

[0083] The water electrode assembly is placed in the thermal storage tank 18, and the photovoltaic power supply system is placed around the thermal storage tank 18. The thermal storage tank 18 is equipped with an inlet 31, an outlet 33, an exhaust pipe 17, and a pressure reducing valve 32.

[0084] The water electrode group comprises a first rotating water electrode 6, a second rotating water electrode 7, a third rotating water electrode 8, and an mth rotating water electrode 9, a rotating water electrode rotating connecting rod 14, a conductive ring 30, a stepping motor 19, a first fixed water electrode 1, a second fixed water electrode 2, a third fixed water electrode 3, and an mth fixed water electrode 4, an m+1th fixed water electrode 5, a fixed water electrode conductive plate 10, and a water electrode U-shaped structure; the water electrode group is placed in the heat storage tank 18 except the stepping motor 19.

[0085] Wherein, m≥1 and is an integer; the first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 and the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3, and the mth fixed water electrode 4, and the m+1th fixed water electrode 5 are metal conductive thin plates, and a plurality of holes are formed on the metal conductive thin plates, which are beneficial to water flow and reduce the disturbance of bubbles generated in the water heating process to the water electrode.

[0086] The first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 are in a fan-shaped structure and are installed on the water electrode rotating connecting rod 14 through the center of the circle where the fan-shaped structure is located. The first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 and the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3, and the mth fixed water electrode 4, and the m+1th fixed water electrode 5 have equal spacing.

[0087] The first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3, and the mth fixed water electrode 4, and the m+1th fixed water electrode 5 are in a rectangular structure and are installed on the fixed support 11 at equal distances. The fixed water electrode conductive plate 10 connects the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3, and the mth fixed water electrode 4, and the m+1th fixed water electrode 5 together on one side. The fixed water electrode conductive plate 10 is connected to the first power line 20 for heating the water electrode through the fixed water electrode connecting terminal 27, and supplies power to the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3, and the mth fixed water electrode 4, and the m+1th fixed water electrode 5.

[0088] The first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8 to the mth rotating water electrode 9 are fixedly connected with the heat storage tank 18 through the water electrode rotating connecting rod 14, and the first rotating water electrode 6 is arranged between the first fixed water electrode 1 and the second fixed water electrode 2; the second rotating water electrode 7 is arranged between the second fixed water electrode 2 and the third fixed water electrode 3; the third rotating water electrode 8 is arranged between the third fixed water electrode 3 and the mth fixed water electrode 4; and the mth rotating water electrode 9 is arranged between the mth fixed water electrode 4 and the m+1th fixed water electrode 5.

[0089] The first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8 to the mth rotating water electrode 9 are synchronously rotated through the water electrode rotating connecting rod 14, the longitudinal relative positions of the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3 to the mth fixed water electrode 4 and the m+1th fixed water electrode 5 are changed, and the mirror image areas of the first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8 to the mth rotating water electrode 9 and the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3 to the mth fixed water electrode 4 and the m+1th fixed water electrode 5 are synchronously changed.

[0090] The water electrode U-shaped structure comprises a left U-shaped support 15, a right U-shaped support 16, a left bearing 28, a right bearing 29, a left fixed support column 13, a right fixed support column 12 and a water electrode fixed support 11.

[0091] The water electrode U-shaped structure is made of an insulator material, the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3 to the mth fixed water electrode 4 and the m+1th fixed water electrode 5 are fixedly installed on the upper end of the water electrode fixed support 11 of the water electrode U-shaped structure at equal distances, the left fixed support column 13 and the right fixed support column 12 are respectively installed at the edge close to the lower end of the water electrode fixed support 11 of the water electrode U-shaped structure, the water electrode U-shaped structure is fixedly connected with the bottom of the heat storage tank 18 through the left fixed support column 13 and the right fixed support column 12, the left U-shaped support 15 of the water electrode U-shaped structure is embeddedly installed with the left bearing 28 close to the top, the right U-shaped support 16 is embeddedly installed with the right bearing 29, and the rotating water electrode rotating connecting rod 14 is fixed on the water electrode U-shaped structure through the left bearing 28 and the right bearing 29, so that the first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8 to the mth rotating water electrode 9 are arranged at equal distances and staggered in the middle of the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3 to the mth fixed water electrode 4 and the m+1th fixed water electrode 5 through the water electrode rotating connecting rod 14;

[0092] The rotating water electrode rotating link 14 is an insulator, one end passes through the wall of the heat storage tank 18 and is connected with the synchronous motor 19, and the conductive ring 30 is installed at 1 / 3 of the length of the rotating water electrode rotating link 14 on the side of the synchronous motor 19 and is connected with the second power line 21 for heating the water electrode. The other 2 / 3 of the length of the rotating water electrode rotating link 14 is hollow, and the first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 are arranged and installed on the upper surface. The first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 are connected with the conductive ring 30 through the hollow part of the rotating link 14, and thus the second power line 21 for water electrode heating is connected with the first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 through the conductive ring 30.

[0093] At this time, the first rotating water electrode 6, the second rotating water electrode 7, the third rotating water electrode 8, and the mth rotating water electrode 9 are driven by the stepping motor 19 and rotate through the rotating water electrode rotating link 14 to change the relative position and mirror area with the first fixed water electrode 1, the second fixed water electrode 2, the third fixed water electrode 3, the mth fixed water electrode 4, and the m+1th fixed water electrode 5.

[0094] The photovoltaic power supply system comprises a photovoltaic array 25 and a power electronic square wave commutator 24.

[0095] The positive electrode 22 and the negative electrode 23 of the photovoltaic array 25 are connected with the power electronic square wave commutator 24, the power electronic square wave commutator 24 switches through power electronic switches to convert the power supply output by the positive electrode 22 and the negative electrode 23 of the photovoltaic array 25 into a square wave output power supply, and the square wave output end of the power electronic square wave commutator 24 is connected with the fixed water electrode terminal 27 and the conductive ring 30 through the first power line 20 and the second power line 21 respectively to provide a water electrode group positive and negative period change power supply. The power electronic square wave commutator 24 switches the square wave output at a frequency of seconds or minutes, and the switching loss time of the power electronic device is in the nanosecond level and can be ignored. The switching frequency of the inverter is 5K-20K, and the loss is greatly reduced.

[0096] The monitoring system comprises a controller 26, a water electrode current sensor, a water electrode voltage sensor, and a heat storage tank 18 temperature sensor.

[0097] The controller 26 is arranged on the periphery of the heat storage tank 18, is connected with all the sensors through a communication cable, and is connected with all the controlled units and the stepping motor 19 through a control cable. The controller reads the sensor data in real time and controls the controlled units according to an algorithm, a model, and a control strategy.

[0098] The water electrode heat storage principle of a rotating water electrode photovoltaic power generation and heat storage system of the application is as follows:

[0099] (1) Based on the heating principle of the electrode hot water boiler, a large amount of heat energy is released by the water body with a set conductivity through the three-phase voltage and current, directly converting the electric energy into heat energy and generating steam. The heating power can be steplessly adjusted. Since the water resistance is directly heated, the electric energy is 100% converted into heat, and the efficiency is high, and almost no heat is lost.

[0100] Based on the mathematical expression of the electric power principle:

[0101]

[0102] It can be seen that under the same voltage U water , the smaller the heating water resistance R w , the greater the current flowing through, based on the mathematical expression of Joule's law: And Q = I 2 Rt respectively:

[0103]

[0104] And

[0105] It can be seen that under the same time t, the change of voltage U water or current I water , the heat Q water changes exponentially, the greater the voltage U water or current I water , the greater the heat Q water .

[0106] The size of the current I water is related to the heating water resistance, and the size of the heating water resistance is related to the mirror area of the two electrodes and the distance between the two electrodes. In the electrode hot water boiler, only the distance between the two electrodes and the corresponding heating water resistance of the mirror area are considered. When the distance between the two electrodes is constant, the greater the mirror area of the electrode, the smaller the equivalent parallel resistance, and the greater the current. Thus, by adjusting the mirror area of the water electrode, the heating power of the water electrode can be changed.

[0107] (2) Analysis of the mirror area, angle and heating water resistance R w of the rotating water electrode and the fixed water electrode:

[0108] Based on the formula of the sector area:

[0109] Wherein, π is the circular constant; r is the radius of the sector; S is the area of the sector: θ is the central angle of the sector. Thus, the change of the central angle θ of the sector changes the area of the sector.

[0110] Since the stepper motor rotates an angle of Δθ, the rotating water electrode sector area is:

[0111]

[0112] When the rotating water electrode is fully rotated out, that is, the rotating water electrode sector side edge is parallel to the fixed water electrode upper edge side, and the sector central angle θ is defined as zero, that is, θ = 0; at this time, it is the initial state of the rotating water electrode, and the mirror image area of the rotating water electrode and the fixed water electrode is equal to zero, that is,

[0113] When the stepper motor rotates an angle of Δθ, the minimum area of the rotating water electrode sector is obtained:

[0114]

[0115] When the stepper motor rotates n θ = max angles of Δθ, the rotating water electrode is fully rotated into the fixed water electrode, and at this time, the mirror image area of the rotating water electrode and the fixed water electrode is maximum, that is,

[0116] Wherein, the mirror image area of the rotating water electrode and the fixed water electrode is Sg, that is, Sg = Sx; the mirror image area Sg of the fixed water electrode is equal to the mirror image area Sx of the rotating water electrode; n θ is the number of rotations of the stepper motor, n θ = 0, 1, 2, 3,..., max;

[0117] Due to the sector area structure of the rotating water electrode, it is placed between the two fixed water electrodes, and the distance between them is half of the fixed water electrode distance Lg, that is, Therefore, the rotating water electrode and the fixed water electrode have two mirror image areas. Since the heating water resistance R w is concentratedly distributed between the mirror image areas of the fixed water electrode and the rotating water electrode, without considering the peripheral electric field distribution of the fixed water electrode and the rotating water electrode and the area reduction of the hole on the water electrode, each rotating water electrode and fixed water electrode mirror image area is 2S g . The heating water resistance R w should be: the distance between the fixed water electrode and the rotating water electrode and the product of the water conductivity ρ d is the ratio of the rotating water electrode and the fixed water electrode mirror image area 2S g , that is:

[0118]

[0119] There is also a distributed water resistance outside the mirror area and between the fixed water electrode. This part of the water resistance value is relatively large and will not be considered in the following analysis.

[0120] Equation (5) shows that the mirror area S of the rotating water electrode and the fixed water electrode is... g With heating water resistance R w Inversely proportional, the mirror area S of the rotating water electrode and the fixed water electrode g The larger the heating water resistance R w The smaller,

[0121] Based on the principle of electrical work:

[0122]

[0123] Substituting equations (4) and (5) into equation (6) yields the mirror area S of a rotating water electrode and two fixed water electrodes. g Relationship with power:

[0124]

[0125] The mirror area S of m rotating water electrodes g With power P waterm The relationship is:

[0126]

[0127] Due to the π, sector radius r, angle Δθ, and distance L between the fixed water electrodes in equation (8) g and water conductivity ρ d Both the number of rotating water electrodes and the number of rotating water electrodes are constants.

[0128] make If is a constant, then we have:

[0129]

[0130] Equation (9) shows that when the resistance R of the heating water is applied... w voltage U water Under constant conditions, the rotating water electrode rotates by one angle. There is a corresponding water heating resistor power P waterm .

[0131] Because the photovoltaic power generation is applied to the heating water resistance R between the rotating water electrode and the fixed water electrode. w Above, as the stepper motor rotates from one angle arrive During the angular change process, photovoltaic power is applied to the heating water resistance R. w The power outputs on each grid correspond one-to-one to the maximum power output of photovoltaic power generation. The square of the maximum power point voltage of photovoltaic power generation The ratio of water resistance to water conductivity:

[0132]

[0133] Wherein, S g is the area of the rotating water electrode S x is the area of the fixed water electrode projection, also known as the mirror area of the fixed water electrode and the rotating water electrode; R w is the heating water resistance value; L n is the distance between the fixed water electrode and the rotating water electrode; δ d is the water conductivity; n θ is the number of step motor rotation angles, n θ =1, 2, 3…smax…max, smax is the second maximum value; P water is the heating water resistance power under the mirror area S g of one rotating water electrode and two fixed water electrodes; P waterm is the heating resistance power under the mirror area S g of m rotating water electrodes, which is described in the subsequent description;

[0134] is the maximum power point of photovoltaic power generation under the number of step motor rotation angles n θ is the maximum power point voltage of photovoltaic power generation under the number of step motor rotation angles n θ

[0135] The control method of the rotating water electrode photovoltaic power generation and heat storage system of the application specifically includes the following steps:

[0136] Step 1, initialization setting, specifically including:

[0137] (1.1) input photovoltaic array parameters: the parameters include installed capacity, array inclination, array orientation, horizontal diffuse reflection coefficient, open circuit voltage, short circuit current, photovoltaic power generation power, total solar radiation intensity and typical photovoltaic maximum power point table;

[0138] (1.2) determine the rotating water electrode heating water resistance power and the number of rotation angles n θ under the maximum and minimum radiation intensity of photovoltaic maximum power point

[0139] Since the heating water resistance power P waterm is also the rotating water electrode heating water resistance power under the number of rotation angles n θ obtained from equation (9): ​​​​

[0140]

[0141] Thus, by the local typical irradiance intensity and photovoltaic maximum power point corresponding table, the photovoltaic power generation maximum power point P mppt_max and the corresponding photovoltaic power generation maximum power point voltage under the local maximum irradiance intensity are found respectively, and the photovoltaic power generation maximum power point P mppt_min and the corresponding photovoltaic power generation maximum power point voltage under the minimum irradiance intensity are found, and the rotating water electrode heating water resistance power is found in turn according to formula (10) equal to the photovoltaic power generation maximum power point P mppt_max , that is Thus, the rotating water electrode angle number is found correspondingly, and the rotating water electrode heating water resistance power equal to the photovoltaic power generation maximum power point P mppt_min , that is Thus, the rotating water electrode angle number

[0142] Wherein, n θ = 0, 1, 2, …… max; min0 and max0 ∈ [0, max]; P mppt_max is the photovoltaic power generation maximum power point under the local maximum irradiance intensity; P mppt_min is the photovoltaic power generation maximum power point under the local minimum irradiance intensity;

[0143] max is the maximum number of rotating water electrode angles ; max0 is the photovoltaic power generation maximum power point P mppt_max found under the local maximum irradiance intensity and the corresponding calculated rotating water electrode angle maximum number, max0 ≤ max; min0 is the photovoltaic power generation maximum power point P mppt_min found under the minimum irradiance intensity and the corresponding calculated rotating water electrode angle minimum number, min0 ≥ 0;

[0144] Thus, the controller controls the stepping motor to drive the rotating water electrode angle number and The rotating water electrode photovoltaic power generation and heat storage system can realize the maximum power point tracking under the local typical maximum and minimum irradiance intensity conditions.

[0145] (1.3) Establish a fast locking photovoltaic power generation maximum power point segmented stepping motor rotating angle point under different illuminations:

[0146] Considering the response speed of mechanical photovoltaic maximum power tracking, a segmented photovoltaic maximum power tracking is adopted. First, based on the input photovoltaic array parameters and irradiance, a table of fast locking of segmented photovoltaic maximum power points under different irradiance is established. A stepper motor rotates an angle of The rotating water electrode is rotated The angle number of the photovoltaic maximum power point range under the local maximum irradiance and the photovoltaic maximum power point range under the local minimum irradiance , that is:

[0147]

[0148] Then, the segmented number of the photovoltaic maximum power point under different irradiance is obtained by quantifying , that is , and the photovoltaic maximum power point corresponding to the segmented endpoint is:

[0149]

[0150] , that is Thus, the photovoltaic maximum power point value at each segmented point is determined by the table lookup method The photovoltaic maximum power point difference of each adjacent segment is a constant α, that is:

[0151]

[0152] , where mp is the segmented number of the photovoltaic maximum power point; is the photovoltaic maximum power point value under the local maximum irradiance; is the photovoltaic maximum power point value under the local minimum irradiance; Δθ is the angle of the stepper motor rotation; θ is the number of the stepper motor rotation angle; is the photovoltaic maximum power point under the stepper motor rotation angle of number n θ ; is the photovoltaic maximum power point voltage under the stepper motor rotation angle of number n θ ; is the photovoltaic maximum power point current under the stepper motor rotation angle of number n θ ; α is the constant difference of the photovoltaic maximum power point of each adjacent segment; is the photovoltaic maximum power point corresponding to each segmented point, n m = 1, 2, 3, …, mp;

[0153] Step 2, photovoltaic maximum power point tracking, fast locking of the photovoltaic maximum power point segment, specifically including:

[0154] The controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Based on the output power P pv Compared with the previous moment's maximum photovoltaic power generation The difference is calculated at the points, that is:

[0155]

[0156] (2.1) When ΔP pv When the photovoltaic power generation capacity increases (>0), the photovoltaic power generation output power P will be... pv Divide by the constant α of the maximum power difference point of photovoltaic power generation in each adjacent segment, that is:

[0157]

[0158] The result of the divisor is rounded to one decimal place, and the modulo function is used to determine the remainder.

[0159] mod(P pv ,α)≥0.5 (17)

[0160] in, nθ_1 represents the point where photovoltaic power generation is at its maximum power level at the previous moment. The number of rotation angles of the stepper motor; I pv U represents the current photovoltaic power generation current. pv P represents the current photovoltaic power generation voltage. pv This represents the current output power of photovoltaic power generation; specifically,

[0161] 1) For example, the modulo modulo function determines mod(P) pv When α)≥0.5, then according to the floor function:

[0162]

[0163] Using the principle of rounding up to the nearest whole number, determine the maximum power point of photovoltaic power generation in a certain segment. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the nth stepper motor rotation angle θ =n m ×10 stepper motor rotation angles minus the previous moment's maximum photovoltaic power generation point The number of rotation angles nθ_1 of the stepper motor is used to obtain the increase or decrease Δn of the stepper motor. θOne rotation angle, i.e., Δn θ =10n m -n θ_1 .

[0164] Where, n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, increasing the mirror area of ​​the rotating water electrode, thereby reducing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step A in step 3.

[0165] Where mod is the modulo function; INT is the integer function; For n m The maximum power point of segmented photovoltaic power generation; For n m The maximum power point of photovoltaic power generation in the -1 segment; n is the number of rotation angles of the stepper motor. θ The point at which photovoltaic power generation reaches its maximum power; n represents the point at which photovoltaic power generation reaches its maximum power at the previous moment. θ_1 The point at which photovoltaic power generation reaches its maximum power at the previous moment. The number of rotation angles of the stepper motor; Δn θ To increase or decrease the number of rotation angles of the stepper motor;

[0166] 2) For example, the modulo modulo function determines mod(P) pv When α) < 0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the nth stepper motor rotation angle θ =n m ×10 stepper motor rotation angles minus the previous moment's maximum photovoltaic power generation point The number of rotation angles n of the stepper motor θ_1 The increase or decrease of the stepper motor Δn is obtained. θ One rotation angle, i.e., Δn θ=10n m -n θ_1 , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, increasing the mirror area Sg of the rotating water electrode, thereby reducing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step B in step 3.

[0167] in, The maximum power point for photovoltaic power generation is defined in nm segments; For n m The maximum power point of photovoltaic power generation in the +1 segment; n is the number of rotation angles of the stepper motor. θ The point at which photovoltaic power generation reaches its maximum power; Δn θ To increase or decrease the number of rotation angles of the stepper motor;

[0168] (2.2) When ΔP pv When the photovoltaic power generation power decreases by less than 0, the current photovoltaic power generation output power P will be reduced. pv Divide by the constant α of the maximum power difference point of photovoltaic power generation in each adjacent segment, as shown in equation (16). The divisor result is rounded to one decimal place, and mod(P) is determined according to the mod remainder function. pv ,α)≥0.5. Specifically,

[0169] 1) For example, the modulo modulo function determines mod(P) pv When α)≥0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the photovoltaic power generation maximum power point at the previous moment. The number of rotation angles of the stepper motor, nθ_1, minus n θ =n m Multiply by 10 stepper motor rotation angles to obtain the stepper motor increase / decrease Δn. θ One rotation angle, i.e., Δn θ=n θ_1 -10n m , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, reducing the mirror area Sg of the rotating water electrode, thereby increasing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step A in step 3.

[0170] 2) For example, the modulo modulo function determines mod(P) pv When α) < 0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the photovoltaic power generation maximum power point at the previous moment. The number of rotation angles of the stepper motor nθ-1 minus n θ =n m Multiply by 10 stepper motor rotation angles to obtain the stepper motor increase / decrease Δn. θ One rotation angle, i.e., Δn θ =n θ_1 -10n m , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization. At this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, reducing the mirror area Sg of the rotating water electrode, thereby increasing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step B in step 3.

[0171] Step 3: Perform refined maximum power point tracking (MPPT) control for photovoltaic power generation, specifically including:

[0172] After the fast locking photovoltaic power generation maximum power point section of step 2, the controller reads the photovoltaic power generation current I pv and voltage U pv in real time, calculates the photovoltaic power generation output power P pv , compares it with the segmented photovoltaic power generation maximum power point , respectively judges or , and determines mod(P pv , α) ≥ 0.5 and mod(P pv , α) < 0.5 according to the mod remainder function, and then controls the following steps according to the integer function INT of formula (18) and the principle of rounding 5 up:

[0173] Step A: the controller obtains the current increment / decrement Δn θ of rotation angle by subtracting a perturbation rotation angle from the increment / decrement Δn θ_1 of rotation angle of the previous moment, that is, Δn θ = Δn θ_1 - 1, controls the rotation of the stepper motor to change the resistance value of the heating water resistor R w , and the controller continues to read the photovoltaic power generation current I pv and voltage U pv , calculates the photovoltaic power generation output power P , and compares it with the photovoltaic power generation power P of the previous moment.

[0174] When it is judged that , the controller repeats step A.

[0175] When it is judged that , the heating water resistor R w generated by the current rotation of the water electrode mirror image area Sg is determined to be suitable for the photovoltaic power generation maximum power point

[0176] wherein, is the current photovoltaic power generation output power; is the photovoltaic power generation power of the previous moment; Δn θ_1 is the increment / decrement of rotation angle of the previous moment; Δn θ is the current increment / decrement of rotation angle;

[0177] Step B: the controller obtains the current increment / decrement Δn θ of rotation angle by adding a perturbation rotation angle to the increment / decrement Δn θ_1 of rotation angle of the previous moment, that is, Δn θ = Δn θ_1 + 1, controls the rotation of the stepper motor to change the resistance value of the heating water resistor Rw the resistance value, while the controller continues to read the photovoltaic power generation current I pv and voltage U pv , and calculates the photovoltaic power generation output power and compares it with the photovoltaic power generation power of the previous moment.

[0178] When it is determined that the controller repeats step B.

[0179] When it is determined that the heating water resistance R w generated by the current rotating water electrode mirror area Sg is determined, which is adapted to the photovoltaic power generation maximum power point

[0180] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A rotating water electrode photovoltaic power generation and heat storage system, characterized in that: It comprises a heat storage tank, a water electrode group, a photovoltaic power supply system and a monitoring system. The water electrode group is arranged in the heat storage tank, the photovoltaic power supply system is arranged around the heat storage tank, and the heat storage tank is provided with a water inlet, a water outlet, an exhaust pipeline and a pressure reducing valve. The water electrode group comprises a first rotating water electrode, a second rotating water electrode, a third rotating water electrode, an mth rotating water electrode, a rotating water electrode rotating connecting rod, a conductive ring, a stepping motor, a first fixed water electrode, a second fixed water electrode, a third fixed water electrode, an mth fixed water electrode, an m+1th fixed water electrode, a fixed water electrode conductive plate and a water electrode U-shaped structure. Wherein, m is an integer greater than or equal to 1; the first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode and the first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode and the m+1th fixed water electrode are metal conductive thin plates, and a plurality of holes are formed in the metal conductive thin plates to facilitate water flow and reduce the disturbance of air bubbles generated during water heating to the water electrode. The first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode are fan-shaped structures and are installed on the rotating water electrode rotating connecting rod through the center of the circle on which the fan-shaped structures are located; the first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode and the first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode and the m+1th fixed water electrode have equal spacing. The first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode and the m+1th fixed water electrode are rectangular structures and are installed on the fixed support at equal distances; the fixed water electrode conductive plate connects the first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode and the m+1th fixed water electrode together on one side; the fixed water electrode conductive plate is connected to the first power line for water electrode heating through the fixed water electrode terminal, and supplies power to the first fixed water electrode, the second fixed water electrode, the third fixed water electrode and the mth fixed water electrode and the m+1th fixed water electrode.

2. The rotating water-electrode photovoltaic power generation and heat storage system according to claim 1, characterized in that: The first rotating water electrode, the second rotating water electrode, the third rotating water electrode and the mth rotating water electrode are connected through the rotating water electrode rotating connecting rod; the first rotating water electrode is arranged between the first fixed water electrode and the second fixed water electrode; the second rotating water electrode is arranged between the second fixed water electrode and the third fixed water electrode; the third rotating water electrode is arranged between the third fixed water electrode and the mth fixed water electrode; and the mth rotating water electrode is arranged between the mth fixed water electrode and the m+1th fixed water electrode.

3. The rotating water-electrode photovoltaic power generation and heat storage system according to claim 1, characterized in that: The first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode rotate synchronously through the water electrode rotating connecting rod, change the longitudinal relative positions with the first fixed water electrode, the second fixed water electrode, the third fixed water electrode, and the mth fixed water electrode, and synchronously change the mirror image areas of the first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode with the first fixed water electrode, the second fixed water electrode, the third fixed water electrode, and the mth fixed water electrode.

4. The rotating water electrode photovoltaic power generation and heat storage system according to claim 1, characterized in that: The water electrode U-shaped structure comprises a left U-shaped support, a right U-shaped support, a left bearing, a right bearing, a left fixed support column, a right fixed support column and a water electrode fixed support; wherein the water electrode U-shaped structure is made of an insulator material, the first fixed water electrode, the second fixed water electrode, the third fixed water electrode, and the mth fixed water electrode are fixedly installed on the upper end of the water electrode fixed support of the water electrode U-shaped structure at equal distances, the left fixed support column and the right fixed support column are respectively installed on the lower end of the water electrode fixed support of the water electrode U-shaped structure near the edge, and the water electrode U-shaped structure is fixedly connected with the bottom of the heat storage tank through the left fixed support column and the right fixed support column; the left U-shaped support of the water electrode U-shaped structure is embeddedly installed with the left bearing near the top, the right U-shaped support is embeddedly installed with the right bearing, and the rotating water electrode rotating connecting rod is fixed on the water electrode U-shaped structure through the left bearing and the right bearing, so that the first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode are placed in the middle of the first fixed water electrode, the second fixed water electrode, the third fixed water electrode, and the mth fixed water electrode at equal distances and staggered positions through the water electrode rotating connecting rod.

5. The rotating water-electrode photovoltaic power generation and heat storage system according to claim 1, characterized in that: The rotating water electrode rotating connecting rod is made of an insulator, one end of the rotating water electrode rotating connecting rod is connected with the synchronous motor through the wall of the heat storage tank, and the conductive ring is installed on the 1 / 3 length of the rotating water electrode rotating connecting rod on the side of the synchronous motor and connected with the second power line of the heating water electrode; the other 2 / 3 length of the rotating water electrode rotating connecting rod is hollow, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode are arranged and installed on the hollow part, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode are connected with the conductive ring through the hollow part of the rotating connecting rod, so that the second power line of the water electrode heating is connected with the first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode through the conductive ring; at this time, the first rotating water electrode, the second rotating water electrode, the third rotating water electrode, and the mth rotating water electrode rotate through the rotating water electrode rotating connecting rod under the drive of the stepping motor, change the relative positions with the first fixed water electrode, the second fixed water electrode, the third fixed water electrode, and the mth fixed water electrode, and change the mirror image areas.

6. The rotating water electrode photovoltaic power generation and heat storage system according to claim 1, characterized in that: The photovoltaic power supply system comprises a photovoltaic array and a power electronic square wave commutator; the output positive pole and the output negative pole of the photovoltaic array are connected with the power electronic square wave commutator; the power electronic square wave commutator converts the output positive pole and the output negative pole of the photovoltaic array into square wave output power through power electronic switches; the square wave output end of the power electronic square wave commutator is connected with the fixed water electrode terminal and the conductive ring through the first power line and the second power line, respectively, to provide the positive and negative period change power supply of the water electrode group.

7. The rotating water electrode photovoltaic power generation and heat storage system according to claim 1, characterized in that: The monitoring system comprises a controller, a water electrode current sensor, a water electrode voltage sensor and a heat storage tank temperature sensor; the controller is arranged around the heat storage tank, connected with all the sensors through a communication cable, and connected with all the controlled units and the stepping motor through a control cable; the controller reads the sensor data in real time, and controls the controlled units according to the algorithm, model and control strategy.

8. The control method of a rotating water electrode photovoltaic power generation and heat storage system according to any one of claims 1-7, characterized in that, Specifically comprising the following steps: Step 1, initialization setting, specifically comprising: (1.1) inputting photovoltaic array parameters: the parameters include installed capacity, array inclination, array orientation, horizontal diffuse reflection coefficient, open-circuit voltage, short-circuit current, photovoltaic power generation power, total solar radiation intensity and typical photovoltaic maximum power point table; (1.2) Determine the photovoltaic maximum power point corresponding to the rotating water electrode heating water resistance power under the local maximum, minimum irradiance and the number of rotation angles n θ ; (1.3) establishing a fast locking photovoltaic power generation maximum power point segmented stepping motor rotation angle point under different illuminations; Step 2, photovoltaic power generation maximum power point tracking, fast locking photovoltaic power generation maximum power point section; Step 3, performing fine photovoltaic power generation maximum power tracking control, specifically comprising: The maximum power point section of photovoltaic power generation is quickly locked in step 2, the controller reads photovoltaic power generation current I pv and voltage U pv in real time, calculates photovoltaic power generation output power P pv , compares with the segmented photovoltaic power generation maximum power point , respectively judges or , and determines mod(P pv , α) ≥ 0.5 and mod(P pv , α) < 0.5 according to the mod remainder function, then controls the following steps according to the integer function INT of formula (18) and the principle of rounding 5 up. Step A, the controller according to the previous time increment Δn θ_1 a rotation angle minus a disturbance rotation angle, to obtain the current increment Δn θ a rotation angle, namely Δn θ = Δn θ_1 -1, control the stepper motor to rotate, change the resistance value of the heating water resistance R w , and the controller continues to read the photovoltaic power generation current I pv and voltage U pv , calculate the photovoltaic power generation output power and compare it with the photovoltaic power generation power of the previous time. The controller repeats step A when it judges that the battery is not fully charged. When judging , the heating water resistance R w , adapted to photovoltaic power generation maximum power point wherein, is the current photovoltaic power output; is the previous photovoltaic power output; Δn θ_1 is the previous increment / decrement of the rotation angle; Δn θ is the current increment / decrement of the rotation angle; α is a constant; and β is the difference between the maximum power points of each adjacent section. Step B, the controller according to the previous time increment Δn θ_1 one rotation angle plus a perturbation rotation angle, the current increment Δn θ one rotation angle, namely Δn θ = Δn θ_1 + 1, control the stepper motor to rotate, change the resistance value of the heating water resistance R w , at the same time the controller continues to read the photovoltaic power generation current I pv and voltage U pv , calculate the photovoltaic power generation output power and compare with the photovoltaic power generation power of the previous time; The controller repeats step B when it judges that the battery is not fully charged. When judging , the heating water resistance R w , adapted to the maximum power point of photovoltaic power generation 9. The control method according to claim 8, characterized by, The step 1.2 specifically comprises: Since the water heating resistance power P waterm is also the number of rotation angles n θ The water heating resistance power of the lower rotating water electrode Thus by the local typical irradiance intensity and photovoltaic maximum power point corresponding table, find the photovoltaic power generation maximum power point P mppt_max and the corresponding photovoltaic power generation maximum power point voltage under the local maximum irradiance intensity, and the photovoltaic power generation maximum power point P mppt_min and the corresponding photovoltaic power generation maximum power point voltage under the minimum irradiance intensity, according to In turn find the rotating water electrode heating water resistance power Equal to the photovoltaic power generation maximum power point P mppt_max That is Thus the corresponding rotating water electrode angle number is found Similarly find the rotating water electrode heating water resistance power Equal to the photovoltaic power generation maximum power point P mppt_min That is Thus the corresponding rotating water electrode angle number is found Wherein, n θ = 0, 1, 2, … max; min0 and max0 ∈ [0, max]; P mppt_max is the maximum power point of photovoltaic power generation under the local maximum irradiance; P mppt_min is the maximum power point of photovoltaic power generation under the local minimum irradiance; max is the rotating water electrode angle maximum number; max0 is the maximum power point P of photovoltaic power generation found under the local maximum irradiance mppt_max and the corresponding calculated rotating water electrode angle maximum number, max0 ≤ max; min0 is the maximum power point P of photovoltaic power generation found under the minimum irradiance mppt_min and the corresponding calculated rotating water electrode angle minimum number, min0 ≥ 0; The controller controls the number of angles of the rotating water electrode driven by the stepping motor and The rotating water electrode photovoltaic power generation and heat storage system can be realized, and the maximum power point corresponding to the local typical maximum and minimum irradiation intensity conditions tracking.

10. The control method according to claim 9, characterized by, The step 1.3 specifically comprises: Considering the response speed of mechanical photovoltaic maximum power tracking, the segmented photovoltaic maximum power tracking is adopted; firstly, based on the input photovoltaic array parameters and irradiance, the table of fast locking segmented photovoltaic power generation maximum power points under different illuminations is established; the stepper motor rotates by an angle The rotating water electrode is rotated The angle number of the photovoltaic power generation maximum power point range of the local maximum irradiance And the photovoltaic power generation maximum power point range of the local smaller irradiance , namely: Quantized by 10 again Get the number of segments of the maximum power point of photovoltaic power generation under different illumination, that is And the corresponding maximum power point of photovoltaic power generation That is Thus, the photovoltaic power generation maximum power point value at each segment point is determined by table lookup method The difference value of photovoltaic power generation maximum power point of each adjacent segment is constant α, that is: Wherein, mp is the number of segments of the maximum power point of photovoltaic power generation; The maximum power point value of photovoltaic power generation for the local maximum irradiance; The maximum power point value of photovoltaic power generation for the local minimum irradiance; Δθ is the angle of rotation of the stepper motor; θ The number of angles of rotation of the stepper motor; The maximum power point of photovoltaic power generation under the angle of rotation of the stepper motor for the number n θ The maximum power point of photovoltaic power generation under the angle of rotation of the stepper motor for the number n The maximum power point voltage of photovoltaic power generation under the angle of rotation of the stepper motor for the number n θ The maximum power point current of photovoltaic power generation under the angle of rotation of the stepper motor for the number n The maximum power point current of photovoltaic power generation under the angle of rotation of the stepper motor for the number n θ α is a constant for the difference value of the maximum power point of photovoltaic power generation of each adjacent segment; The maximum power point of photovoltaic power generation corresponding to each segment point, n m = 1, 2, 3, …, mp.

11. The control method according to claim 10, characterized by, The step 2 specifically comprises fast locking photovoltaic power generation maximum power point section: The controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Based on the output power P pv Compared with the previous moment's maximum photovoltaic power generation The difference is calculated at the points, that is: (2.1) when ΔP pv > 0, the photovoltaic power generation output power P pv is divided by the photovoltaic power generation maximum power point difference constant α of each adjacent section, that is: The divisor result is kept to one decimal place, and the remainder is determined according to the mod remainder function: mod(P pv ,α)≥0.5 (17) Wherein, Pmax(n-1) is the maximum power point of photovoltaic power generation at the previous moment; n θ_1 Pmax(n-1) is the maximum power point of photovoltaic power generation at the previous moment I is the number of stepping motor rotation angles; I pv I is the current photovoltaic power generation current; U pv I is the current photovoltaic power generation voltage; P pv I is the current photovoltaic power generation output power; 1) If mod(P pv ,α) ≥ 0.5, then according to the rounding function: and the principle of rounding off to the nearest integer, the maximum power point of the photovoltaic power generation of a certain section is determined and the maximum power point of the photovoltaic power generation is determined falls between and , thereby obtaining n θ = n m × 10 rotation angles of the stepper motor, according to the nth θ = n m × 10 rotation angles of the stepper motor minus the maximum power point of the photovoltaic power generation at the previous moment , the increment / decrement Δn θ_1 of the stepper motor is obtained, which is n θ rotation angles, i.e. Δn θ = 10n m -n θ_1 ; Wherein, n m The maximum power point of the photovoltaic power generation known for a certain segment The number of rotation angles of the stepper motor, which is set in the initialization. At this time, the controller controls the stepper motor to rotate by the increment Δn θ The number of rotation angles, increases the mirror area of the rotating water electrode, thereby reducing the resistance value of the heating water resistance R w , and quickly locks the maximum power point of the photovoltaic power generation segment At the same time, the controller reads the photovoltaic power generation current I pv and voltage U pv in real time, calculates the photovoltaic power generation output power P pv , and performs step A in step 3; Wherein, mod is the remainder function; INT is the integer function; n m Segmented photovoltaic power generation maximum power point; n m Segmented photovoltaic power generation maximum power point; n θ Segmented photovoltaic power generation maximum power point; n θ_1 Segmented photovoltaic power generation maximum power point n θ Segmented photovoltaic power generation maximum power point 2) For example, the modulo modulo function determines mod(P) pv When α) < 0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the nth stepper motor rotation angle θ =n m ×10 stepper motor rotation angles minus the previous moment's maximum photovoltaic power generation point The number of rotation angles nθ_1 of the stepper motor is used to obtain the stepper motor increment / decrement Δn. θ One rotation angle, i.e., Δn θ =10n m -n θ_1 , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization; at this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, increasing the mirror area Sg of the rotating water electrode, thereby reducing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step B in step 3; Wherein, n is the number of steps of the stepper motor m Segmented photovoltaic power generation maximum power point; n is the number of steps of the stepper motor m +1 segmented photovoltaic power generation maximum power point; n is the number of steps of the stepper motor θ Photovoltaic power generation maximum power point at Δn θ n is the number of steps of the stepper motor (2.2) when ΔP pv <0, the current photovoltaic power output P pv is divided by the maximum power point difference constant α of each adjacent section, as shown in formula (16), the result of the divisor is kept to one decimal place, and mod(P pv , α) ≥ 0.5 is judged according to the mod remainder function. 1) For example, the modulo modulo function determines mod(P) pv When α)≥0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the photovoltaic power generation maximum power point at the previous moment. The number of rotation angles n of the stepper motor θ_1 Subtract n θ =n m Multiply by 10 stepper motor rotation angles to obtain the stepper motor increase / decrease Δn. θ One rotation angle, i.e., Δn θ =n θ_1 -10n m , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization; at this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, reducing the mirror area Sg of the rotating water electrode, thereby increasing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step A in step 3; 2) For example, the modulo modulo function determines mod(P) pv When α) < 0.5, the maximum power point of photovoltaic power generation in a certain segment is determined according to the rounding function INT in equation (18) and the principle of rounding to the nearest whole number. And determine the maximum power point of photovoltaic power generation. Falling and Between, thus obtaining n θ =n m ×10 stepper motor rotation angles, based on the photovoltaic power generation maximum power point at the previous moment. The number of rotation angles n of the stepper motor θ_1 Subtract n θ =n m Multiply by 10 stepper motor rotation angles to obtain the stepper motor increase / decrease Δn. θ One rotation angle, i.e., Δn θ =n θ_1 -10n m , where n m The point where the maximum photovoltaic power generation is known for a certain segment. The number of rotation angles of the stepper motor is set during initialization; at this time, the controller adjusts the increment / decrement Δn accordingly. θ The rotation angle controls the stepper motor's rotation, reducing the mirror area Sg of the rotating water electrode, thereby increasing the heating water resistance R. w The resistance value is used to quickly pinpoint the maximum power point of segmented photovoltaic power generation. Simultaneously, the controller reads the photovoltaic power generation current I in real time. pv and voltage U pv The photovoltaic power output P was calculated. pv Proceed to step B in step 3.

Images