Electric water heater control method, system and controller participating in load regulation

Abstract

The present application belongs to the technical field of building flexible load, and particularly relates to a unified control method and system of electric water heaters participating in building flexible load adjustment. In view of the deficiency that the existing technology does not disclose how the electric water heaters participate in load adjustment, the present application adopts the following technical scheme: the unified control method of electric water heaters participating in building flexible load adjustment, comprising: obtaining relevant information of each electric water heater through a direct current bus; receiving a load adjustment instruction, calculating total response power allocated to all electric water heaters; determining a control strategy for the working state of each electric water heater according to the total response power and the relevant information of each electric water heater; sending the control strategy to each electric water heater, and each electric water heater adjusts its own working state according to the control strategy. The present application has the beneficial effect of realizing that the electric water heaters actively participate in load adjustment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building flexible load, and particularly relates to an electric water heater control method, system and controller participating in load regulation. BACKGROUND

[0002] In the process of low-carbon development, the new energy structure mainly based on renewable energy puts forward new requirements for the power system. The intermittency, volatility and unpredictability of renewable energy make the AC power grid bear new pressure. In the existing building power system, AC power distribution is mostly used, while most household appliances use DC power, which needs to frequently convert AC to DC, reduces the system stability, increases the system power consumption, and also makes it difficult to be controlled uniformly. Through the realization of building flexibility and building DC power consumption, renewable energy can be largely accommodated, the dependence on the power grid can be reduced, and the low-carbon construction of the power system can be promoted.

[0003] The household appliance control system with flexible regulation capability and supporting DC power distribution system has broad application prospects. Among them, the electric water heater is one of the best options for realizing building flexible load regulation due to its particularity of low time and power requirements. Although the Design Standard for DC Power Distribution of Civil Buildings has made a simple explanation of the active change of DC bus voltage and the change of power consumption of the load. However, so far, there is no relevant literature to disclose the specific control process of the DC electric water heater participating in load response. The intelligent control strategy of the DC electric water heater needs to be developed to realize the flexible energy consumption regulation of the electric appliance based on the principle of "light storage direct flexible" system. SUMMARY

[0004] The present application provides an electric water heater control method participating in building flexible load regulation to solve the problem that the specific way of electric water heater participating in load regulation is not disclosed in the prior art. The power of the electric water heater is adjusted according to the DC bus voltage to make the electric water heater participate in load regulation and improve the ability of building electric appliances to participate in load regulation. The present application also provides an electric water heater control system participating in building flexible load regulation.

[0005] To achieve the above object, the present application adopts the following technical scheme: an electric water heater control method participating in building flexible load regulation, which comprises:

[0006] Obtaining relevant information of each electric water heater through a DC bus;

[0007] Receiving a load regulation instruction, calculating the total response power allocated to all electric water heaters;

[0008] According to the total response power and the relevant information of each electric water heater, determining the control strategy of the working state of each electric water heater;

[0009] The control strategy is sent to each electric water heater, and each electric water heater adjusts its working state according to the control strategy.

[0010] The electric water heater unified control method for participating in building flexible load adjustment receives a load adjustment instruction, calculates total response power allocated to all electric water heaters, i.e., total operation power of all electric water heaters in a response period, determines a control strategy according to the total response power and related information of each electric water heater, and adjusts the working state of each electric water heater; the related information of each electric water heater is obtained through a DC bus, and no additional communication means is needed.

[0011] As an improvement, the electric water heater unified control method further comprises pre-acquiring a curve of power of each electric water heater changing with a DC bus voltage, determining the control strategy according to the total response power, the related information of each electric water heater, and the curve of each electric water heater, and the control strategy comprises a unified DC bus response voltage. The curve of the power of each electric water heater changing with the DC bus voltage shows the corresponding relationship between the power of the water heater and the DC bus voltage value. Through the curve, the power of the electric water heater at a certain DC bus voltage value can be determined, so that a suitable DC bus voltage value can be determined to match the total response power of each electric water heater. The unified DC bus response voltage serves as a trigger signal, and each electric water heater adjusts its working state according to the DC bus response voltage. In other schemes, the DC bus response voltage can also be a voltage change value. As an improvement, the related information of the electric water heater comprises user setting information, state information, and operation power.

[0012] As an improvement, the user setting information of the electric water heater comprises a preset priority, a preset power, and / or a preset temperature, and the preset priority comprises following the change of the bus voltage and stopping heating.

[0013] As an improvement, the preset priority further comprises not participating in load adjustment.

[0014] As an improvement, for the electric water heater preset to not participate in load adjustment, its working state is not affected by the control strategy.

[0015] As an improvement, the control strategy is preset to follow the change of the power of the bus voltage, and when the change of the power of the bus voltage cannot meet the demand, part of the electric water heaters stop heating.

[0016] As an improvement, the control strategy further comprises setting a round value sequence for the electric water heater whose priority is preset to stop heating.

[0017] As an improvement, the electric water heater comprises a gear type electric water heater and a stepless adjustment electric water heater.

[0018] The control process of the power of the gear type electric water heater changing with the bus voltage during peak clipping is: the control strategy includes actively reducing the direct current bus response voltage, when the direct current bus response voltage is lower than the voltage threshold, the response power is gradually reduced with the decrease of the direct current bus voltage; when the direct current bus response voltage is equal to or greater than the voltage threshold, the response power will not change with the direct current bus response voltage.

[0019] The control process of the power of the stepless adjustment electric water heater changing with the bus voltage during peak clipping is: the control strategy includes actively reducing the direct current bus response voltage, when the direct current bus response voltage is lower than the voltage threshold, the response power is continuously reduced with the decrease of the direct current bus voltage; when the direct current bus voltage is equal to or greater than the voltage threshold, the response power will not change with the direct current bus response voltage.

[0020] As an improvement, the state information of the electric water heater includes whether the electric water heater is turned on or not, the hot water temperature of the electric water heater, the hot water flow and the water storage capacity.

[0021] The electric water heater unified control system participating in building flexible load regulation includes:

[0022] An alternating current power grid;

[0023] An alternating current / direct current converter;

[0024] A building direct current bus;

[0025] A plurality of electric water heaters and corresponding direct current / direct current converters, the heating power of at least one electric water heater being adjustable;

[0026] A unified controller;

[0027] Wherein, the alternating current / direct current converter is connected between the alternating current power grid and the direct current bus, and the direct current / direct current converter is connected between the building direct current bus and the electric water heater;

[0028] Wherein, the unified controller has a strategy generation module, which determines the control strategy for the working state of each electric water heater according to the load regulation instruction and the relevant information of each electric water heater, and sends the control strategy to each electric water heater, and each electric water heater adjusts its working state according to the control strategy and responds to the load regulation. The unified controller is used to control the electric water heater on the direct current building,

[0029] The unified controller is used to obtain the relevant information of each electric water heater through the direct current bus;

[0030] The unified controller is also used to receive the load regulation instruction and calculate the total response power allocated to all electric water heaters;

[0031] The unified controller is further configured to determine a control strategy for the working state of each electric water heater according to the total response power and the related information of each electric water heater.

[0032] The unified controller is further configured to send the control strategy to each electric water heater, and each electric water heater adjusts the working state according to the control strategy.

[0033] The electric water heater unified control method for participating in building flexible load regulation has the following advantages: according to the load regulation instruction and the related information of each electric water heater, a control strategy for the working state of each electric water heater is determined, different models and different working modes of electric water heaters are uniformly managed, and the electric water heater actively participates in load regulation.

[0034] The electric water heater unified control system for participating in building flexible load regulation adopts the electric water heater unified control method for participating in building flexible load regulation, and has all the advantages of the electric water heater unified control method for participating in building flexible load regulation.

[0035] The unified controller realizes that the electric water heater actively participates in load regulation. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The figure is a system architecture diagram of the electric water heater unified control system for participating in building flexible load regulation according to an embodiment of the present application.

[0037] Figure 2 The figure is a flowchart of the electric water heater unified control method for participating in building flexible load regulation according to an embodiment of the present application.

[0038] Figure 3 The figure is a principle diagram of control strategy generation of the electric water heater unified control method for participating in building flexible load regulation according to an embodiment of the present application.

[0039] Figure 4 The figure is a relationship diagram of the power of the gear control electric water heater and the DC bus voltage according to an embodiment of the present application.

[0040] Figure 5 The figure is a relationship diagram of the power of the continuously regulated electric water heater and the DC bus voltage according to an embodiment of the present application.

[0041] Figure 6 The figure is a flowchart of determining the electric water heater participating in load response according to a preset priority according to an embodiment of the present application.

[0042] In the figure, 1, building DC bus;

[0043] 2, AC / DC converter;

[0044] 3, AC power grid;

[0045] 4. An electric water heater;

[0046] 5. A DC / DC converter;

[0047] 6. A unified controller. DETAILED DESCRIPTION

[0048] The technical solutions of the embodiments of the present application are explained and described below. The following embodiments are only preferred embodiments of the present application, and not all. Based on the embodiments in the embodiments, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0049] Embodiments of the control system

[0050] Referring to Figure 1 and Figure 3 , the unified control system of the electric water heater participating in building flexible load regulation comprises:

[0051] An alternating current power grid 3;

[0052] An alternating current / direct current converter 2;

[0053] A building direct current bus 1;

[0054] A plurality of electric water heaters 4 and their corresponding direct current / direct current converters 5, the heating power of at least one electric water heater 4 being adjustable;

[0055] A unified controller 6;

[0056] Wherein, the alternating current / direct current converter 2 is connected between the alternating current power grid 3 and the building direct current bus 1, and the direct current / direct current converter 5 is connected between the building direct current bus 1 and the electric water heater 4;

[0057] Wherein, the unified controller 6 has a strategy generation module, which determines the control strategy of the working state of each electric water heater 4 according to the load regulation instruction and the relevant information of each electric water heater 4, and sends the control strategy to each electric water heater 4, and each electric water heater 4 adjusts its own working state according to the control strategy and responds to the load regulation.

[0058] Embodiments of the control method

[0059] Referring to Figures 1 to 6 , the unified control method of the electric water heater participating in building flexible load regulation comprises:

[0060] Obtaining the relevant information of each electric water heater through the direct current bus;

[0061] receiving the load regulation instruction, calculating the total response power allocated to all the electric water heaters;

[0062] determining a control strategy for the working state of each electric water heater according to the total response power and the related information of each electric water heater;

[0063] sending the control strategy to each electric water heater, and each electric water heater adjusts its working state according to the control strategy.

[0064] In the embodiment, the curve of the power of each electric water heater varying with the DC bus voltage is obtained in advance, and the control strategy is determined according to the total response power, the related information of each electric water heater and the curve of each electric water heater, and the control strategy includes a unified DC bus response voltage. The curve of the power of each electric water heater varying with the DC bus voltage shows the corresponding relationship between the power of the water heater and the DC bus voltage value. Through the curve, the power of the water heater at a certain DC bus voltage value can be determined, so that the appropriate DC bus voltage value can be determined, and the total power of each electric water heater matches the total response power. The curve of the power of the water heater and the DC bus voltage value takes the DC bus voltage value as the trigger signal for adjusting the power of the electric water heater. In other embodiments, the change value of the DC bus voltage can also be taken as the trigger signal for adjusting the power of the electric water heater.

[0065] Referring to Figure 1 , the control method of the embodiment is applied to Figure 1 the control system shown in the figure.

[0066] Referring to Figure 2 and Figure 3 , the overall flow of the control method of the embodiment, the required basic data includes the related information of each electric water heater, the load regulation instruction and the curve of the power of each electric water heater varying with the DC bus voltage, the strategy generation module of the unified controller obtains the control strategy according to the aforementioned basic data, the control strategy includes a unified DC bus response voltage, each electric water heater adjusts its working state according to the unified DC bus response voltage, adjusts the power, so that the sum of the powers of each electric water heater in the response period is substantially equal to the total response power required by the load regulation.

[0067] In the embodiment, the related information of the electric water heater includes user setting information, state information and operating power.

[0068] In the embodiment, the electric water heater includes a gear type electric water heater and a stepless regulation electric water heater.

[0069] Referring to Figure 4, the control process of the power of the gear type electric water heater changing with the bus voltage during peak clipping is: the control strategy includes actively reducing the DC bus response voltage, when the DC bus response voltage is lower than the voltage threshold, the response power decreases with the decrease of the DC bus voltage step by step; when the DC bus response voltage is equal to or greater than the voltage threshold, the response power will not change with the DC bus response voltage;

[0070] Referring to Figure 5 , the control process of the power of the stepless adjustment electric water heater changing with the bus voltage during peak clipping is: the control strategy includes actively reducing the DC bus response voltage, when the DC bus response voltage is lower than the voltage threshold, the response power decreases with the decrease of the DC bus voltage continuously; when the DC bus voltage is equal to or greater than the voltage threshold, the response power will not change with the DC bus response voltage.

[0071] In this embodiment, the user setting information of the electric water heater includes preset priority, preset power and / or preset temperature, and the preset priority includes following the change of the bus voltage and stopping heating.

[0072] In this embodiment, the preset priority also includes not participating in load adjustment.

[0073] In this embodiment, for the electric water heater preset to not participate in load adjustment, its working state is not affected by the control strategy. Referring to Figure 6 In this embodiment, the process of determining the electric water heater participating in adjustment is: obtaining the user preset priority queue information, if the user has no preset, it is included in the default priority queue, if the user has preset, the user preset is accepted, and finally the electric water heater participating in adjustment and the priority queue are obtained.

[0074] In this embodiment, the control strategy gives priority to following the change of the bus voltage, and when following the change of the bus voltage cannot meet the demand, part of the electric water heaters stop heating.

[0075] In this embodiment, the state information of the electric water heater includes whether the electric water heater is powered on or not, the hot water temperature, the hot water flow and the water storage capacity of the electric water heater.

[0076] The control process is described more specifically below, and for ease of description, parameters are simplified: assume that a direct-current building has 100 electric water heaters, and the 100 electric water heaters are all identical and all are stepless adjustment heat accumulating type, and the power range of each electric water heater is 1500 W to 2500 W. The direct-current bus voltage is 100 V. In a non-response period, the direct-current bus voltage is maintained between 99 V and 101 V. In a response period, the direct-current bus voltage is between 90 V and 99 V or between 101 V and 110 V. When the direct-current bus voltage is 100 V, the power of the electric water heater is 2000 W. When the direct-current bus voltage is 90 V, the power of the electric water heater is 1500 W, and when the direct-current bus voltage is 110 V, the power of the electric water heater is 2500 W.

[0077] At 9:00 am on a certain day, a load adjustment instruction is received, and according to the load adjustment instruction, it is required that the total response power of all electric water heaters in a response period of 19:00 to 21:00 is maintained at 180 kW. Assume that the 100 electric water heaters all participate in load adjustment and are all preset to vary with the bus voltage, and are all in a working state in the response period. Then, according to the total response power and the corresponding curve of the electric water heater power and the direct-current bus voltage value, it is obtained that the direct-current bus voltage should be 95 V (the water heater power corresponding to the voltage is 1800 W) in the response period, the unified controller adjusts the direct-current bus voltage from 100 V to 95 V, and each electric water heater receives the information that the direct-current bus voltage changes to 95 V, and adjusts the power of the electric water heater to 1800 W.

[0078] When part of the electric water heaters are set to not participate in load adjustment, assume that there are 50, and the 50 all run at a power of 2000 W in the response period, then 180 kW-2000 W*50=80 kW, 80 kW / 50=1600 W, the power of the remaining 50 electric water heaters participating in response is 1600 W, which can meet the response demand.

[0079] When there are 80 electric water heaters not participating in load adjustment and all of them are running at 2000W power in the response period, then 180kW-2000W*80=20kW, 20kW / 20=1000W, which is lower than the minimum power of electric water heater 1500W, then according to the preset priority of each electric water heater, some of them will be turned off, specifically, the power of 7 electric water heaters can be maintained at the minimum 1500W (the total power of 7 1500W is 10.5kW, which fluctuates within the allowed range), and the other 13 electric water heaters are turned off. The specific implementation of the electric water heater stopping heating can be that when the DC bus voltage continues to decrease from 90V to different values, the electric water heaters are stopped in turn, such as when the DC bus voltage decreases from 90V to 89V, one electric water heater is turned off, and when the DC bus voltage decreases from 90V to 80V, ten electric water heaters are turned off. The specific change value of the DC bus voltage can be adjusted accordingly according to the actual situation.

[0080] For the control of turning off the electric water heater, it can also be designed more specifically to reduce the impact on the user. For example, 10 electric water heaters are set to stop heating when the DC bus voltage is 89V to 80V. When the DC bus voltage received by the electric water heater is 85V, it means that five electric water heaters need to stop heating, then the response period can be segmented (assuming the response time is two hours), then five electric water heaters can be turned off in the first hour and another five electric water heaters can be turned off in the second hour, realizing rotation work or stop. It can also be that the user presets the priority queue, such as when the user sets the priority, the user is prompted that there is "not participating in response, priority changing with bus voltage, closing in the Nth position", where N is the total number of water heaters in the building, the user can be encouraged to set N higher by fee discount. For example, N is set to 1-10, the maximum electricity bill discount can be obtained.

[0081] During the response process, when the user changes the preset priority and other situations occur, when the fluctuation is within the allowed range, the unified controller can not adjust the DC bus voltage, when the fluctuation exceeds the allowed range, such as multiple electric water heaters suddenly start working, etc., then the DC bus voltage value / voltage change value is adjusted again according to the preset priority, DC bus voltage value, water heater power and DC bus voltage value / voltage change value.

[0082] In other embodiments, special adjustment of one or more electric water heaters can also be realized by sending separate instructions, without relying entirely on the adjustment of the DC bus voltage.

[0083] The electric water heater unified control method for participating in building flexible load adjustment according to the load adjustment instruction, the related information of each electric water heater, and the curve of the electric water heater pre-direct current bus voltage value / voltage change value determines the control strategy for adjusting the direct current bus voltage, and the control strategy further comprises adjusting the direct current bus voltage value, and each electric water heater adjusts its own working state according to the direct current bus voltage value / voltage change value, so that the electric water heater actively participates in demand response; the response is rapid and quick, can be adjusted in real time according to needs, and can realize that the electric water heater participates in demand response only by actively adjusting the direct current bus voltage.

[0084] Embodiment of unified controller

[0085] Reference Figure 3 The embodiment of the present application discloses a unified controller for controlling electric water heaters to participate in load response in a direct current building,

[0086] The unified controller is used for obtaining the related information of each electric water heater through a direct current bus;

[0087] The unified controller is further used for receiving a load adjustment instruction, and calculating total response power distributed to all electric water heaters;

[0088] The unified controller is further used for determining a control strategy for the working state of each electric water heater according to the total response power and the related information of each electric water heater;

[0089] The unified controller is further used for sending the control strategy to each electric water heater, and each electric water heater adjusts its own working state according to the control strategy.

[0090] The unified controller has a strategy generation module, which obtains a control strategy according to the related information of the electric water heater (including water heater state information and user preset information), a load adjustment instruction (total response power distributed to the electric water heater can be calculated according to the load adjustment instruction), and a curve of the power of each electric water heater changing with the direct current bus voltage, and the control strategy comprises adjusting the bus voltage, and taking the bus voltage as an adjustment signal of the electric water heater.

[0091] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, and those skilled in the art should understand that the present application includes but is not limited to the content described in the above specific embodiment. Any modification without deviating from the functional and structural principles of the present application will be included in the scope of the claims.

Claims

1. A unified control method for electric water heaters participating in building flexible load regulation, characterized in that: The unified control method for electric water heaters participating in building flexible load regulation includes: The curves of power variation of each electric water heater with DC bus voltage are obtained in advance; Relevant information about each electric water heater is obtained through the DC bus; Receive load adjustment commands and calculate the total response power allocated to all electric water heaters; The control strategy is determined based on the total response power, relevant information of each electric water heater, and curves of each electric water heater. The control strategy includes a unified DC bus response voltage. The control strategy is sent to each water heater, and each water heater adjusts its own operating state according to the control strategy: each water heater adjusts its own operating state and power according to the unified DC bus response voltage, so that the sum of the power of each water heater during the response period is basically equal to the total response power required for load adjustment.

2. The unified control method for electric water heaters participating in building flexible load regulation according to claim 1, characterized in that: Information related to electric water heaters includes user settings, status information, and operating power.

3. The unified control method for electric water heaters participating in building flexible load regulation according to claim 2, characterized in that: The user settings information for electric water heaters include preset priority, preset power and / or preset temperature. The preset priority includes following changes in bus voltage and stopping heating. The preset priority also includes not participating in load regulation. For electric water heaters that are preset not to participate in load regulation, their operating status is not affected by the control strategy.

4. The unified control method for electric water heaters participating in building flexible load regulation according to claim 3, characterized in that: The control strategy is set to prioritize power following the bus voltage change. When the power cannot meet the demand due to the bus voltage change, some electric water heaters will stop heating.

5. The unified control method for electric water heaters participating in building flexible load regulation according to claim 4, characterized in that: The control strategy also includes setting a rotation sequence for electric water heaters whose priority is preset to stop heating.

6. The unified control method for electric water heaters participating in building flexible load regulation according to claim 1, characterized in that: Electric water heaters include tach-type electric water heaters and stepless adjustable electric water heaters; During peak shaving, the control process of the power of the tiered electric water heater changing with the bus voltage is as follows: The control strategy includes actively reducing the DC bus response voltage. When the DC bus response voltage is lower than the voltage threshold, the response power decreases step by step as the DC bus voltage decreases. When the DC bus response voltage is equal to or greater than the voltage threshold, the response power will not change with the DC bus response voltage. During peak shaving, the control process of the continuously variable electric water heater power changing with the bus voltage is as follows: The control strategy includes actively reducing the DC bus response voltage. When the DC bus response voltage is lower than the voltage threshold, the response power continuously decreases as the DC bus response voltage decreases. When the DC bus voltage is equal to or greater than the voltage threshold, the response power will not change with the DC bus response voltage.

7. The unified control method for electric water heaters participating in building flexible load regulation according to claim 2, characterized in that: The status information of an electric water heater includes whether the water heater is turned on, the water temperature, the water flow rate, and the water storage capacity.

8. A unified control system for electric water heaters participating in building flexible load regulation, characterized in that: The unified control system for electric water heaters participating in building flexible load regulation includes: AC power grid; AC / DC converter; Building DC bus; Multiple electric water heaters and their corresponding DC / DC converters, with the heating power of at least one electric water heater being adjustable; Unified controller; The AC / DC converter is connected to the AC power grid and the DC bus at both ends, while the DC / DC converter is connected to the building DC bus and the electric water heater at both ends. The unified controller has a strategy generation module. The strategy generation module determines the control strategy for the working state of each water heater based on the total response power allocated to all water heaters calculated based on the load adjustment command, the relevant information of each water heater, and the pre-acquired curve of the power of each water heater changing with the DC bus voltage. The unified controller sends the control strategy to each water heater, and each water heater adjusts its own working state according to the control strategy to respond to the load adjustment. The control strategy includes a unified DC bus response voltage. Each electric water heater adjusts its operating state and power according to the unified DC bus response voltage, so that the sum of the power of each electric water heater during the response period is basically equal to the total response power required for load adjustment.

9. A unified controller, characterized in that: The unified controller is used to acquire relevant information about each electric water heater through the DC bus; The unified controller is also used to receive load adjustment commands and calculate the total response power allocated to all electric water heaters; The unified controller is also used to determine the control strategy for the working state of each electric water heater based on the total response power allocated to all electric water heaters calculated based on the load adjustment command, the relevant information of each electric water heater, and the pre-acquired curve of the power of each electric water heater changing with the DC bus voltage. The unified controller is also used to send the control strategy to each electric water heater, and each electric water heater adjusts its own working state according to the control strategy; The control strategy includes a unified DC bus response voltage. Each electric water heater adjusts its operating state and power according to the unified DC bus response voltage, so that the sum of the power of each electric water heater during the response period is basically equal to the total response power required for load adjustment.

Images