A self-organizing network management photovoltaic water heating system and method

Abstract

The present invention relates to a self-organizing network management photovoltaic water heating system, and also to a corresponding method, belonging to the technical field of solar water heaters. The system includes a photovoltaic power generation panel array and a household electric water heater equipped with an AC heating tube and a DC heating tube connected to the mains; the photovoltaic power generation panel array is connected to the corresponding DC heating tube through the water tank controller of the household electric water heater via a collective cable; the central control unit of the water tank controller has corresponding signal input ports respectively connected to photovoltaic voltage, current detection and water tank temperature sensors, and its corresponding control end is respectively connected to the controlled end of the AC and DC heating tubes, and its communication end is connected to the water tank controller of each household electric water heater through the communication port. After adopting the present invention, the system reasonably decides to put in or withdraw the DC heating tube by real-time monitoring of the change of photovoltaic voltage, so that the effective output power of photovoltaic power generation can always be in a relatively high section, and the operation is stable and reliable.

Description

Technical Field

[0001] The invention relates to a water heater system, in particular to a self-organizing network management photovoltaic water heating system, and also relates to a corresponding method, belonging to the technical field of solar water heaters. Background Art

[0002] Solar water heaters are widely welcomed due to their significant advantages of energy saving and environmental protection. However, for users on the lower floors of high-rise buildings, it is often necessary to use long pipes to lead the hot water heated by the solar collector on the roof to the water use location. Not only is the installation and construction inconvenient, but the pipes also leak a lot of heat, which greatly reduces the utilization rate of solar energy. To this end, Chinese patent application number 201710775520.3 discloses a photovoltaic power converter for solar electric water heaters and a control method thereof, which efficiently converts the constantly changing low-voltage direct current emitted by the solar panel assembly into a stable direct current with an effective value of 220V, and through MPPT control, the electric energy is continuously and equivalently converted into heat energy and stored in the heat-insulating electric water heater for use at any time. The installation is very simple and maintenance-free. The photovoltaic power converter has the characteristics of small size, light weight, high power conversion efficiency, low cost and long life. In addition to being specifically used for solar electric water heaters, it can also be used for other small and medium-sized isolated boost DC / DC converters; when the output voltage of the photovoltaic power converter is adjusted from 220Vdc to 400Vdc and the corresponding circuit parameters are adjusted, it can also be used as the front stage of small and medium-sized solar photovoltaic grid-connected or off-grid inverters or the front stage of small and medium-sized uninterruptible power supplies. Although this technical solution can avoid the inconvenience of long pipeline construction, it requires an inverter to invert the DC power output by the photovoltaic system into AC power for use in the water heater, which not only increases the cost but also reduces the conversion efficiency due to the self-power consumption of the inverter. It also does not involve relevant solutions for adaptive regulation of photovoltaic loads.

[0003] In addition, the Chinese patent application number 202010744716.8 discloses a distributed collaborative device of a multi-agent system and a control method thereof, which belongs to smart home control, including a photovoltaic power generation component, the output end of which is electrically connected to the input end of a first relay and a second relay, respectively, the output end of the second relay is electrically connected to the input end of a battery, and the battery is connected in parallel with a second voltage sensor. In the present invention, through the mutual cooperation between the designed first microcontroller, the second microcontroller, the third microcontroller, the photovoltaic grid-connected module, the battery, the power switching module, the electric heater, the temperature sensor, and the water flow sensor, personal resources and public equipment work together to avoid inconveniences to people's lives caused by failures in the mains power supply system, and can reduce the use of electricity and gas to a high degree, while ensuring the use effect of the gas water heater. Although this technical solution focuses on using excess electricity from photovoltaic power generation to power other electrical appliances, it also requires the configuration of inverters, batteries and their control systems, which are complex and costly. In addition, electrical and related system modifications to electrical appliances such as elevators and gas water heaters are required, which poses a certain degree of difficulty in application.

[0004] In summary, in addition to the complex system structure, the above-mentioned existing technologies have failed to consider how to make full use of photovoltaic power with the help of flexible network pipelines. Summary of the invention

[0005] The purpose of the present invention is to: in view of the problems existing in the above-mentioned prior art, propose a self-organizing network management photovoltaic water heating system that can fully and reasonably utilize photovoltaic power, and also provide corresponding methods.

[0006] In order to achieve the above-mentioned purpose, the basic technical scheme of the self-organizing network management photovoltaic water heating system of the present invention is: comprising a photovoltaic power generation panel array laid on the top of a building and a household electric water heater installed in each household of the building, wherein the water tank of the household electric water heater is equipped with an AC heating tube and a DC heating tube connected to the mains;

[0007] The photovoltaic panel array outputs DC power of a predetermined voltage to the aggregation cable, and the aggregation cable is connected to the corresponding DC heating tube through the water tank controller of the household electric water heater;

[0008] The water tank controller includes a central control unit, which has corresponding signal input ports respectively connected to photovoltaic voltage detection, photovoltaic current detection and water tank temperature sensors. The corresponding control ends of the central control unit are respectively connected to the controlled ends of the AC heating tube and the DC heating tube. The communication end of the central control unit is communicated with the water tank controllers of each household electric water heater through the communication port.

[0009] When the system of the present invention is running, the self-organizing network management steps are:

[0010] The first step is to set one of the water tank controllers as the master controller according to a predetermined rule;

[0011] Step 2: The main control machine allocates the priority of the DC heating pipe of each household water heater according to the setting information of each household water heater collected through the network communication;

[0012] Step 3: The main control machine determines whether the voltage provided by the aggregation cable is greater than or equal to the preset shutdown voltage according to the voltage detection. If yes, proceed to step 5; otherwise, proceed to the next step;

[0013] Step 4: The main control machine determines whether the DC heating tube with the lowest priority is turned off step by step. If not, it controls it to be turned off and returns to step 3 after delaying for a predetermined time.

[0014] Step 5: The main control machine determines whether the voltage provided by the aggregation cable is greater than or equal to the preset start voltage according to the voltage detection. If yes, proceed to the next step; otherwise, return to step 3;

[0015] Step 6: The main control machine determines step by step whether the DC heating tube with the highest priority is turned on. If not, the controller turns on and returns to step 3 after a delay of a preset time. If yes, proceed to the next step.

[0016] Step 7: Calculate the load power of each DC heating tube currently powered, and find out the instantaneous total load power consumption of the photovoltaic DC circuit, and proceed to the next step;

[0017] Step 8: The main control machine determines whether the DC heating tube with the highest current priority is the last level. If not, proceed to the next step. If yes, proceed to the tenth step.

[0018] Step 9: Determine whether the calculated current load power is greater than the previously calculated load power. If not, return to step 3; if yes, return to step 6.

[0019] Step 10: End the photovoltaic load control cycle.

[0020] The present invention is further improved in that the other path of the aggregation cable is connected to the grid via a grid-connected inverter; the grid-connected inverter and the water tank controller of each household electric water heater are connected in communication. In this way, when there is surplus photovoltaic power generation, the electric energy can be transmitted to the grid.

[0021] A further improvement of the present invention is that in the first step, when the current master loses communication, a new master is generated according to a predetermined rule, so that the advantages of the ad hoc network can be fully utilized and the stability and reliability of the system can be ensured through replacement backup.

[0022] After adopting the present invention, not only can the AC heating tube be automatically started when the water temperature of the photovoltaic DC power supply fails to reach the set temperature, so that the DC and AC heating are organically combined; but the system can also reasonably decide to put in or withdraw the DC heating tube by real-time monitoring the change of the photovoltaic voltage, so that the effective output power of the photovoltaic power generation can always be in a relatively high section, and the operation is stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the system structure of the first embodiment of the present invention.

[0024] Figure 2 yes Figure 1 A block diagram of a system control circuit of an embodiment.

[0025] Figure 3 It is a schematic diagram of the AC carrier communication circuit adopted in the present invention.

[0026] Figure 4 It is a schematic diagram of the present invention using a dedicated network line communication circuit.

[0027] Figure 5 It is a schematic diagram of the wireless communication circuit adopted in the present invention.

[0028] Figure 6 yes Figure 1 Schematic diagram of water tank controller circuit of an embodiment.

[0029] Figure 7 yes Figure 1 A logic block diagram of photovoltaic load regulation and management of a water tank controller in an embodiment. DETAILED DESCRIPTION

[0030] Embodiment 1

[0031] The basic structure of the self-organizing network management photovoltaic water heating system of this embodiment is as follows: Figure 1 and Figure 2 As shown, a plurality of photovoltaic panels 1-1 are connected in series to form a group, and each group is connected in parallel to form a photovoltaic panel array 1 laid on the top of a building. Household electric water heaters 2 (2.1, 2.2...2.N) are installed in the building. The water tank 2-1 of each household electric water heater 2 is equipped with upper and lower AC heating tubes 2-2 connected to the mains and a DC heating tube 2-3 located at the bottom. The AC heating tube 2-2 and the DC heating tube 2-3 are controlled by corresponding relays 2-4.

[0032] The photovoltaic power generation panel array 1 after paralleling outputs DC power of a predetermined voltage to the aggregation cable, one of which is connected to each DC heating tube through the water tank controller 3 of the household electric water heater 2. The other is connected to the grid-connected inverter 5 to connect to the power grid. The grid-connected inverter and the water tank controller of the household electric water heater communicate with each other through the communication connection line 4.

[0033] Water tank controller 3 Figure 6 As shown, it contains a central processing chip IC5 (N76E003AT20) as a central control unit. The photovoltaic voltage detection plug-in terminal P2, which is connected across the positive and negative cables of the aggregation cable, isolates and samples the DC voltage through the optoelectronic isolation device U4 and its peripheral circuits, and then connects it to the input terminal of the voltage reference chip U10.2. After passing through the voltage detection processing circuit composed of U10.2 and its peripheral devices, it is sent to the voltage signal input terminal 6 of the central processing chip IC5. The Hall effect current sensor chip U7, which is connected in series in the aggregation cable, isolates and samples the DC current and then connects it to the signal input terminal of the current reference chip U8.1. After passing through the current detection processing circuit composed of U8.1 and its peripheral devices, it is connected to the current signal input terminal 14 of the central processing chip IC5.

[0034] In addition, the water tank temperature sensor 2-6 is connected to the temperature signal input port of the central control unit, the heating control end of the central control unit IC5 is respectively connected to the corresponding relay 2-4 as the controlled end of the AC heating tube 2-2 and the DC heating tube 2-3, and the communication end of the central control unit IC5 is connected to the communication end of other water heaters and grid-connected inverters through the RS-485 communication circuit containing IC2 via the communication port 2 and 3 pins. L1, TR1, U1 and their peripheral components constitute the power supply circuit, providing the +5V and +12V DC voltages required by the water tank controller.

[0035] When the system is running, follow the steps below to manage the self-organizing network:

[0036] The first step is to set the master control unit according to a predetermined rule, for example, setting the central control unit of the household water heater with the smallest number as the master control unit; when the current master control unit loses communication, the next one with the smallest code will be the master control unit.

[0037] In the second step, the main control machine assigns the priority of each household water heater's DC heating tube according to the setting parameters such as the working mode of each household water heater and the water temperature of the water tank collected through the network communication; for example, the instant heating mode that requires immediate startup to provide hot water, the timing mode that requires hot water to be provided within a set time period, the standby mode that waits for heating to provide hot water in the startup state, and the shutdown mode. The priority order is: instant heating mode takes precedence over → timing mode (the priority can be further subdivided according to the order of set time) takes precedence over → standby mode (the priority can be further subdivided according to the probability of water use on the day obtained through statistics and analysis of users' hot water usage habits) takes precedence over → shutdown mode.

[0038] Step 3: The main control machine determines whether the voltage provided by the aggregation cable is greater than or equal to the preset shutdown voltage based on voltage detection. If so, proceed to step 5; otherwise, proceed to the next step.

[0039] Since the photovoltaic power generation capacity varies with the amount of irradiation, when the load far exceeds its current load capacity, the output voltage will drop significantly, and the effective output power of photovoltaic power generation will also drop significantly. Setting the shutdown voltage threshold can effectively ensure that the output power of photovoltaic power generation is always in a relatively appropriate range.

[0040] Step 4: Determine whether the DC heating tube with the lowest priority is turned off step by step. If not, control it to turn off and delay for a predetermined time and then return to step 3. For example, determine whether the Nth DC heating tube is turned off. If not, control it to turn off and delay for a predetermined time and then return to step 3. If yes, determine the N-1th level...; continue to determine according to this rule until the DC heating tube with the highest priority is turned off.

[0041] The instant output power of photovoltaic power generation is variable. When its load capacity is at a relatively low state, the DC heating tube with low heating priority is turned off first to ensure the operation of the DC heating tube with high priority. Setting the time interval for turning on the DC heating tube again can avoid frequent opening and closing of the DC heating tube, which not only protects the photovoltaic panel, but also protects the control circuit.

[0042] Step 5: The main control machine determines whether the voltage provided by the aggregation cable is greater than or equal to the preset start-up voltage based on voltage detection. If so, proceed to the next step; otherwise, return to step 3.

[0043] When the instantaneous power generation capacity of photovoltaic power generation increases and the load remains unchanged, the photovoltaic output voltage will increase significantly. When it reaches the preset start-up voltage (higher than the preset shutdown voltage), it means that the load capacity is relatively strong. At this time, the DC heating tube is further connected. If the photovoltaic voltage is between the start-up voltage and the shutdown voltage, the load capacity of photovoltaic power generation basically does not change, so the status quo is maintained.

[0044] Step 6: The main control machine determines step by step whether the DC heating tube with the highest priority is turned on. If not, the controller turns on and returns to step 3 after a delay of a preset time. If yes, proceed to the next step.

[0045] As the photovoltaic load capacity increases, the DC heating tubes with higher priority will be put into operation first.

[0046] Step 7: Calculate the load power Pi=U*Ii of each DC heating tube currently powered, and find out the instantaneous total load power consumption ΣPi of the photovoltaic DC circuit.

[0047] Where Pi is the power of the DC heating tube with relatively high priority, unit: kilowatt

[0048] U ——Unit: V

[0049] Ii——Current flowing through the DC heating tube with relatively high priority, unit: ampere

[0050] ΣPi——Current instantaneous total load power of photovoltaic, unit: kilowatt

[0051] Proceed to the next step.

[0052] Reasonable power configuration should be that every time a DC heating tube is added to work, its power consumption should be measured, and the instantaneous total power consumption of the entire photovoltaic power generation system should be calculated. Then, by judging the changing trend of the instantaneous total power consumption, the number of DC heating tubes to be put into operation can be determined.

[0053] Step 8: The main control computer determines whether the DC heating tube with the highest current priority is the last level. If not, proceed to the next level. If yes, proceed to the tenth level.

[0054] This allows the DC heating tubes with high priority to be put into operation first.

[0055] Step 9: Determine whether the calculated current load power is greater than the previously calculated load power. If not, return to step 3; if yes, return to step 6.

[0056] When the DC heating tube of this level is put into operation, the instantaneous total power consumption is on an increasing trend, indicating that the load capacity of photovoltaic power generation has not yet reached saturation and the next level of DC heating tube can be connected.

[0057] Step 10: End the photovoltaic load control cycle.

[0058] Compared with the prior art, the self-organizing network management photovoltaic water heating system and method of this embodiment has the following outstanding advantages:

[0059] 1) Unlike the prior art which usually sets a central controller to manage various devices within the system, the system of this embodiment has the characteristics of decentralized grid management. Each household electric water heater within the network within the system can undertake the system allocation and management of photovoltaic power generation load. Not only is the management and control flexible, but they also support each other, and the operational reliability is significantly improved.

[0060] 2) Considering the dynamic changes in the load capacity of photovoltaic power generation, improper load connection will significantly reduce the effective output of photovoltaic power generation. Therefore, the system of this embodiment monitors the changes in photovoltaic voltage in real time to choose whether to put into use a new high-priority DC heating tube or withdraw the working low-priority heating tube, so that the effective output power of photovoltaic power generation can always be in a relatively high section.

[0061] 3) Real-time monitoring of the impact of newly put-into-operation DC heating tubes on the total power further ensures that the effective output power of photovoltaic power generation is in a relatively high range.

[0062] In addition to the above embodiments, the present invention may also have other implementations. For example, the communication port of the central control unit 2-5 of the household electric water heater 2 may also be connected to the AC power line through the AC carrier communication module 2-7 ( Figure 3 ), or communicate with each other through DC carrier communication modules 2-8 ( Figure 4 ), or communicate with each other through wireless communication modules 2-9 ( Figure 5 ). For another example, after each household water heater reaches the set temperature, it can disconnect the photovoltaic DC heating tube by itself and notify the main control machine; or the main control machine can notify the water heater controller to disconnect the photovoltaic DC heating tube. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A self-organizing network management method for a photovoltaic water heating system managed by a self-organizing network, wherein the photovoltaic water heating system managed by the self-organizing network comprises a photovoltaic power generation panel array laid on the top of a building and a household electric water heater installed in each household of the building, wherein the water tank of the household electric water heater is equipped with an AC heating tube and a DC heating tube connected to the mains; The photovoltaic panel array outputs DC power of a predetermined voltage to the aggregation cable, and the aggregation cable is connected to the corresponding DC heating tube through the water tank controller of the household electric water heater; The water tank controller includes a central control unit, which has corresponding signal input ports connected to photovoltaic voltage detection, photovoltaic current detection and water tank temperature sensors respectively, and corresponding control ends of the central control unit are respectively connected to the controlled ends of the AC heating tube and the DC heating tube, and the communication end of the central control unit is connected to the water tank controllers of each household electric water heater through the communication port; Features: The self-organizing network management method comprises the following steps: The first step is to set one of the water tank controllers as the master controller according to a predetermined rule; Step 2: The main control machine allocates the priority of the DC heating pipe of each household water heater according to the setting information of each household water heater collected through the network communication; Step 3: The main control machine determines whether the voltage provided by the aggregation cable is greater than or equal to the preset shutdown voltage according to the voltage detection. If yes, proceed to step 5; otherwise, proceed to the next step; Step 4: The main control machine determines whether the DC heating tube with the lowest priority is turned off step by step. If not, it controls it to be turned off and returns to step 3 after delaying for a predetermined time. Step 5: The main control machine determines whether the voltage provided by the aggregation cable is greater than or equal to the preset start voltage according to the voltage detection. If yes, proceed to the next step; otherwise, return to step 3; Step 6: The main control machine determines step by step whether the DC heating tube with the highest priority is turned on. If not, it controls it to be turned on and delays for a predetermined time before returning to step 3. If yes, proceed to the next step. Step 7: Calculate the load power of each DC heating tube currently powered, and find out the instantaneous total load power consumption of the photovoltaic DC circuit, and proceed to the next step; Step 8: The main control machine determines whether the DC heating tube with the highest current priority is the last level. If not, proceed to the next step. If yes, proceed to the tenth step. Step 9: Determine whether the calculated current instantaneous total load power consumption is greater than the load power calculated last time, if not, return to step 3, if yes, return to step 6; Step 10: End the photovoltaic load control cycle.

2. The method for managing a photovoltaic water heating system in an ad hoc network according to claim 1, characterized in that: The other path of the aggregation cable is connected to the power grid via a grid-connected inverter; the grid-connected inverter is communicatively connected to the water tank controllers of each household electric water heater.

3. The method for managing a photovoltaic water heating system through an ad hoc network according to claim 2, characterized in that: Several photovoltaic panels are connected in series to form groups, and then the groups are connected in parallel to form a photovoltaic panel array.

4. The method for managing a photovoltaic water heating system through an ad hoc network according to claim 3, characterized in that: The water tank of each household electric water heater is equipped with upper and lower AC heating tubes and a DC heating tube located at the bottom; the AC heating tube and the DC heating tube are controlled by corresponding relays.

5. The method for managing a photovoltaic water heating system in an ad hoc network according to claim 4, characterized in that: The communication method is one of AC carrier communication, DC carrier communication, and wireless communication.

6. The method for managing a photovoltaic water heating system in an ad hoc network according to claim 1, characterized in that: In the first step, when the current master control machine loses communication, a new master control machine is generated according to a predetermined rule.

7. The method for managing a photovoltaic water heating system through an ad hoc network according to claim 6, characterized in that: The working modes of each household water heater and their priority order are: instantaneous mode, timing mode, standby mode, and shutdown mode.

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