A control method and device for a single-system variable-frequency low-temperature triple supply

Abstract

The present application provides a single-system variable-frequency low-temperature triple-supply control method and device. By superimposing a detected harmonic component on the triple-supply voltage signal to obtain a detected voltage signal, performing voltage vector synthesis on the detected voltage signal to obtain a triple-supply voltage eigenvalue, determining a phase angle deviation amount based on the triple-supply voltage eigenvalue and the mains voltage signal, and further determining the duty ratio of a pulse width modulation controller according to the temperature deviation signal of the constant-temperature water tank and the phase angle deviation amount. According to the duty ratio of the pulse width modulation controller, a variable-frequency voltage signal is input to a heat exchange motor through the output end of the pulse width modulation controller, and the low-temperature flue gas waste heat is conducted to the constant-temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user, and the water temperature control accuracy of the triple-supply system can be improved when there is a phase angle deviation amount between the triple-supply voltage signal output by the triple-supply system and the mains voltage signal.

Description

Technical Field

[0001] The present application relates to the technical field of temperature control for combined cooling, heating and power systems. More specifically, the present application relates to a control method and device for a single-system variable-frequency low-temperature combined cooling, heating and power supply. Background Art

[0002] Single-system combined cooling, heating and power (CCHP) refers to a technology that integrates heating, ventilation and air-conditioning functions in one system. This system usually uses one device to complete all three functions, thus providing a complete indoor environment solution for buildings. Existing single-system CCHP systems usually use natural gas as the main fuel to drive an internal combustion engine power generation device to operate, so as to generate electricity to meet the electricity demand of users. The waste heat generated by the internal combustion engine power generation device is collected by a heat exchanger and used to provide heating and cooling loads for users near the CCHP system, completing the cascade recovery and utilization of energy, and greatly enhancing the utilization efficiency of gas resources.

[0003] However, in existing CCHP systems, the power supply of the heat exchanger often mainly relies on the electricity generated by the CCHP system itself, with the mains power as the backup power supply. Usually, when the electricity generated by the CCHP system itself and the mains power supply the heat exchanger alternately, due to the phase angle deviation between the three-phase voltage signal of the electricity generated by the CCHP system itself and the mains voltage signal, the parameters such as current, voltage and power inside the heat exchanger change, thus affecting the working state of the heat exchanger. If the same control method is used to control the heat exchanger, the power of the heat exchanger will be unstable, making it difficult to achieve the expected water temperature control accuracy. Summary of the Invention

[0004] The present application provides a control method and device for a single-system variable-frequency low-temperature combined cooling, heating and power supply to solve the technical problem that it is difficult for the CCHP system to achieve the expected water temperature control accuracy when there is a phase angle deviation between the CCHP voltage signal output by the CCHP system and the mains voltage signal.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a control method for a single-system variable-frequency low-temperature combined cooling, heating and power supply, including:

[0007] Collect the three-phase alternating voltage output by the CCHP internal combustion engine power generation device to obtain a CCHP voltage signal;

[0008] Superimpose a detection harmonic component on the CCHP voltage signal to obtain a detection voltage signal, perform voltage vector synthesis on the detection voltage signal to obtain a CCHP voltage characteristic value, and determine a phase angle deviation based on the CCHP voltage characteristic value and the mains voltage signal;

[0009] Detect the temperature of the liquid in the constant temperature water tank, obtain the current water temperature value, compare the current water temperature value with the water temperature value preset by the user to obtain a temperature deviation signal, and determine the duty cycle of the pulse width modulation controller according to the temperature deviation signal and the phase angle deviation amount;

[0010] According to the duty cycle of the pulse width modulation controller, input a variable frequency voltage signal to the heat exchange motor through the output end of the pulse width modulation controller, and conduct the low-temperature flue gas waste heat of the combined heat, power and cooling internal combustion engine power generation device to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user.

[0011] In some embodiments, performing voltage vector synthesis on the detected voltage signal to obtain combined heat, power and cooling voltage characteristic values includes:

[0012] Dividing the detected voltage signal into a leading voltage signal component, a current voltage signal component, and a lagging voltage signal component;

[0013] Transforming the leading voltage signal component, the current voltage signal component, and the lagging voltage signal component to a three-phase stationary coordinate system and performing vector synthesis to obtain a combined heat, power and cooling voltage synthesis vector;

[0014] Taking the real part and the imaginary part of the combined heat, power and cooling voltage synthesis vector in the complex domain together as the combined heat, power and cooling voltage characteristic values.

[0015] In some embodiments, determining the phase angle deviation amount according to the combined heat, power and cooling voltage characteristic values and the mains voltage signal includes:

[0016] Establishing a mains voltage synchronous two-dimensional rotating coordinate system in the complex domain according to the frequency of the mains voltage signal;

[0017] Projecting the combined heat, power and cooling voltage synthesis vector onto the mains voltage synchronous two-dimensional rotating coordinate system, and determining the coordinate value of the combined heat, power and cooling voltage synthesis vector in the mains voltage synchronous two-dimensional rotating coordinate system according to the combined heat, power and cooling voltage characteristic values;

[0018] Determining the phase angle deviation amount between the combined heat, power and cooling voltage signal and the mains voltage signal according to the coordinate value of the combined heat, power and cooling voltage synthesis vector in the mains voltage synchronous two-dimensional rotating coordinate system.

[0019] In some embodiments, determining the duty cycle of the pulse width modulation controller according to the temperature deviation signal and the phase angle deviation amount includes:

[0020] Inputting the temperature deviation signal into a duty cycle control circuit to obtain the duty cycle of the pulse width modulation controller to be corrected;

[0021] Input the duty cycle of the pulse width modulation controller to be corrected and the phase angle deviation amount into a preset proportional control link to obtain the duty cycle of the pulse width modulation controller.

[0022] In some embodiments, the detected harmonic component is an even harmonic component of the combined heat and power supply voltage signal.

[0023] In some embodiments, the detected voltage signal is a linear superposition of the combined heat and power supply voltage signal and the detected harmonic component.

[0024] In some embodiments, before inputting a variable frequency voltage signal to the heat exchange motor through the pulse width modulation controller, it further includes:

[0025] Control the frequency of the output voltage signal at the output end of the pulse width modulation controller through a rectification circuit, a filtering device, and a three-phase inverter bridge provided at the output end of the pulse width modulation controller to obtain a variable frequency voltage signal.

[0026] In a second aspect, the present application provides a single-system variable frequency low-temperature combined heat and power supply control device, which includes a temperature control unit, and the temperature control unit includes:

[0027] A combined heat and power supply voltage signal acquisition module, configured to collect three-phase AC voltage output by a combined heat and power supply internal combustion engine power generation device to obtain a combined heat and power supply voltage signal;

[0028] A phase angle deviation amount determination module, configured to superimpose a detected harmonic component on the combined heat and power supply voltage signal to obtain a detected voltage signal, perform voltage vector synthesis on the detected voltage signal to obtain a combined heat and power supply voltage characteristic value, and determine a phase angle deviation amount according to the combined heat and power supply voltage characteristic value and the mains voltage signal;

[0029] A duty cycle determination module, configured to detect the liquid temperature in the constant temperature water tank, obtain the current water temperature value, compare the current water temperature value with the water temperature value preset by the user to obtain a temperature deviation signal, and determine the duty cycle of the pulse width modulation controller according to the temperature deviation signal and the phase angle deviation amount;

[0030] A water temperature control module, configured to input a variable frequency voltage signal to the heat exchange motor through the output end of the pulse width modulation controller according to the duty cycle of the pulse width modulation controller, and conduct the low-temperature flue gas waste heat of the combined heat and power supply internal combustion engine power generation device to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user.

[0031] In a third aspect, the present application provides a computer device, which includes a memory and a processor; the memory stores code, and the processor is configured to obtain the code and execute the above-mentioned single-system variable frequency low-temperature combined heat and power supply control method.

[0032] Fourthly, the present application provides a computer-readable storage medium storing a computer program, which when executed by a processor implements the above single-system variable-frequency low-temperature combined heat, power and cooling control method.

[0033] The technical solutions provided by the disclosed embodiments of the present application have the following beneficial effects:

[0034] In the single-system variable-frequency low-temperature combined heat, power and cooling control method and device provided by the present application, first, a combined heat, power and cooling voltage signal output by a combined heat, power and cooling internal combustion engine power generation device is collected, and then a detection harmonic component is superimposed on the combined heat, power and cooling voltage signal to obtain a detection voltage signal. The detection voltage signal is subjected to voltage vector synthesis to obtain a combined heat, power and cooling voltage eigenvalue. According to the combined heat, power and cooling voltage eigenvalue and the mains voltage signal, a phase angle deviation amount is determined. Then, the temperature of the liquid in the constant temperature water tank is detected and compared with the water temperature value preset by the user to obtain a temperature deviation signal. According to the temperature deviation signal and the phase angle deviation amount, the duty cycle of a pulse width modulation controller is determined. According to the duty cycle of the pulse width modulation controller, a variable-frequency voltage signal is input to a heat exchange motor through the output end of the pulse width modulation controller. The low-temperature flue gas waste heat of the combined heat, power and cooling internal combustion engine power generation device is conducted to the constant temperature water tank through the heat exchange motor, and then the current water temperature is controlled to return to the water temperature value preset by the user. When there is a phase angle deviation amount between the combined heat, power and cooling voltage signal output by the combined heat, power and cooling system and the mains voltage signal, the output power and frequency of the heat exchange motor can be accurately controlled within an ideal range, so as to accurately control the temperature of the constant temperature water tank to return to the water temperature value preset by the user, and finally improve the water temperature control accuracy of the combined heat, power and cooling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is an exemplary flowchart of a single-system variable-frequency low-temperature combined heat, power and cooling control method according to some embodiments of the present application;

[0036] Figure 2 is a schematic diagram of a mains voltage two-dimensional rotating coordinate system in the complex domain according to some embodiments of the present application;

[0037] Figure 3 is a schematic diagram of exemplary hardware and / or software of a temperature control unit according to some embodiments of the present application;

[0038] Figure 4 is a schematic diagram of the structure of a computer device for a single-system variable-frequency low-temperature combined heat, power and cooling control method provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The core of this application is to collect the trigeneration voltage signal output by the trigeneration internal combustion engine power generation device, and then superimpose a detection harmonic component on the trigeneration voltage signal to obtain a detection voltage signal. Perform voltage vector synthesis on the detection voltage signal to obtain a trigeneration voltage characteristic value; determine the phase angle deviation amount according to the trigeneration voltage characteristic value and the mains voltage signal; further detect the liquid temperature in the constant temperature water tank and compare it with the water temperature value preset by the user to obtain a temperature deviation signal; determine the duty cycle of the Pulse Width Modulation (PWM) controller according to the temperature deviation signal and the phase angle deviation amount; according to the duty cycle of the PWM controller, input a variable frequency voltage signal to the heat exchange motor through the output end of the PWM controller; conduct the low-temperature flue gas waste heat of the trigeneration internal combustion engine power generation device to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user.

[0040] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the specification drawings and specific embodiments.

[0041] In step 101, collect the three-phase alternating current voltage output by the trigeneration internal combustion engine power generation device to obtain a trigeneration voltage signal.

[0042] It should be noted that the trigeneration internal combustion engine power generation device is a gas power generation equipment, which adopts the method of converting chemical energy into mechanical energy. The energy of gas combustion drives the generator rotor to rotate, so as to output three-phase alternating current voltage to supply power to users; in addition, the remaining temperature of the boiler of the internal combustion engine power generation device is also collected by the waste heat recovery device (heat exchanger) in the trigeneration system to provide cooling and heating for users, realizing trigeneration of cooling, heat and power.

[0043] In step 102, superimpose a detection harmonic component on the trigeneration voltage signal to obtain a detection voltage signal, perform voltage vector synthesis on the detection voltage signal to obtain a trigeneration voltage characteristic value, and determine the phase angle deviation amount according to the trigeneration voltage characteristic value and the mains voltage signal.

[0044] In some embodiments, the detection harmonic component may be an even harmonic component of the trigeneration voltage signal, and the frequency of the detection harmonic component has an even integer ratio relationship with the frequency of the trigeneration voltage signal.

[0045] In some preferred embodiments of this application, it is necessary to perform voltage vector synthesis on the detection voltage signal to obtain a trigeneration voltage characteristic value. Specifically, the following method can be adopted, that is:

[0046] Divide the detection voltage signal into an advanced voltage signal component, a current voltage signal component and a lagging voltage signal component;

[0047] Transform the leading voltage signal component, the current voltage signal component, and the lagging voltage signal component into a three-phase stationary coordinate system and perform vector synthesis to obtain a combined heat, power, and cooling voltage synthesis vector;

[0048] Use the real part and the imaginary part of the combined heat, power, and cooling voltage synthesis vector in the complex domain as the combined heat, power, and cooling voltage characteristic values.

[0049] In some other embodiments, the fourth harmonic component of the combined heat, power, and cooling voltage signal can be used as the detected harmonic component to be superimposed to obtain a detected voltage signal. Specifically, in implementation, the detected voltage signal is the linear superposition of the combined heat, power, and cooling voltage signal and the detected harmonic component; additionally, to ensure the accuracy of the phase angle coordinate offset, the amplitude of the detected harmonic component cannot be too large. For example, the amplitude of the detected harmonic component can be 0.5% of the average voltage of the combined heat, power, and cooling voltage signal.

[0050] It should be noted that since the detected harmonic component and the frequency of the combined heat, power, and cooling voltage signal are in even integer multiples, the obtained detected voltage signal is also a three-phase AC voltage signal. Therefore, according to the different phase angle positions of the three-phase AC voltage signal, one of the single-phase AC voltage signals of the detected voltage signal can be selected as the current voltage signal component, another single-phase AC voltage signal with a phase angle greater than the current voltage signal component can be selected as the leading voltage signal component, and another single-phase AC voltage signal with a phase angle less than the current voltage signal component can be selected as the lagging voltage signal component;

[0051] For example, in specific implementation, the current voltage signal component can be expressed by the following formula:

[0052]

[0053] where U n is the current voltage signal component, k is the harmonic order of the detected harmonic component, E is the voltage amplitude of the combined heat, power, and cooling voltage signal, and the plus and minus signs of the subscript represent the amplitudes of the current voltage signal during positive sequence operation and negative sequence operation respectively. It should be noted that in some embodiments, the amplitude of the voltage signal can also be the amplitude of the calibrated combined heat, power, and cooling voltage signal, calibrated as a constant, ω is the frequency of the combined heat, power, and cooling voltage signal, α0 is the initial phase angle of the combined heat, power, and cooling voltage signal, and the plus and minus signs of the subscript represent the initial phase angles during positive sequence operation and negative sequence operation respectively; t is the time value; similarly, the other voltage signal components have similar expression forms and each have a 120° phase angle deviation from the current voltage signal component.

[0054] It should be noted that in this embodiment, when detecting the harmonic component during the vector synthesis of the combined heat, power and cooling voltage signal, the phase angle of the combined heat, power and cooling voltage synthesis vector in the complex domain remains unchanged, but the corresponding modulus value will increase. Therefore, the magnitude of the combined heat, power and cooling voltage eigenvalue can be increased, thereby improving the accuracy of the phase angle deviation. And because the current voltage signal component is expressed by combining the positive sequence and negative sequence, the symmetry of the detected voltage signal is enhanced. Therefore, the voltage imbalance that may be brought by adding the detected harmonic component can be effectively filtered out. In some other embodiments, for the convenience of calculation, the detected harmonic component may not be superimposed, and a certain phase combined heat, power and cooling voltage signal in the positive sequence direction may be used alone as the current voltage signal component, which will not be elaborated here.

[0055] It should be noted that the current voltage signal component can be projected onto the three-phase stationary coordinate system according to the Clarke transformation to obtain the current voltage signal vector. The leading voltage signal component and the lagging voltage signal component can also be projected onto the three-phase stationary coordinate system in the same way to obtain the leading voltage signal vector and the lagging voltage signal vector. According to the vector synthesis principle, the current voltage signal vector can be synthesized into a combined heat, power and cooling voltage synthesis vector, and the combined heat, power and cooling voltage synthesis vector can be expressed by the following formula:

[0056]

[0057] where, is the combined heat, power and cooling voltage synthesis vector, λ1 is the current voltage signal component, λ2 is the leading voltage signal component, λ3 is the lagging voltage signal component, j is the unit imaginary number, π is the natural circumference ratio, and e is the natural logarithm.

[0058] It should be noted that according to the three-phase voltage characteristics, the combined heat, power and cooling voltage synthesis vector is a vector with an angular velocity of ωt and rotating around the center point, and can be transformed into a complex number with a real part and an imaginary part according to Euler's formula. Preferably, in some embodiments, the combined heat, power and cooling voltage eigenvalue can be obtained according to the coordinate value of the combined heat, power and cooling voltage synthesis vector in the complex domain. Specifically, when implementing, the real part and the imaginary part of the combined heat, power and cooling voltage synthesis vector in the complex domain can be used together as the combined heat, power and cooling voltage eigenvalue;

[0059] For example, the combined heat, power and cooling voltage synthesis vector can be expressed in the following complex form according to Euler's formula:

[0060]

[0061] where, is the combined heat, power and cooling voltage synthesis vector, Q s is the real part of the combined heat, power and cooling voltage synthesis vector, Q xis the imaginary part of the combined heat, power and cooling voltage synthesis vector, and j is the unit imaginary number; both the real part and the imaginary part of the combined heat, power and cooling voltage synthesis vector are the combined heat, power and cooling voltage eigenvalues.

[0062] In some preferred embodiments of the present application, determining the phase angle deviation amount according to the combined heat, power and cooling voltage eigenvalue and the mains voltage signal can be achieved by the following method, that is:

[0063] Establish a mains voltage synchronous two-dimensional rotation coordinate system in the complex domain according to the mains voltage signal frequency;

[0064] Project the combined heat, power and cooling voltage synthesis vector onto the mains voltage synchronous two-dimensional rotation coordinate system, and determine the coordinate value of the combined heat, power and cooling voltage synthesis vector in the mains voltage synchronous two-dimensional rotation coordinate system according to the combined heat, power and cooling voltage eigenvalue;

[0065] Determine the phase angle deviation amount between the combined heat, power and cooling voltage signal and the mains voltage signal according to the coordinate value of the combined heat, power and cooling voltage synthesis vector in the mains voltage synchronous two-dimensional rotation coordinate system.

[0066] It should be noted that the mains voltage synchronous two-dimensional rotation coordinate system can be a two-dimensional rotation coordinate system with the origin of the complex domain coordinate as the origin of the coordinate system and the mains voltage frequency as the rotation frequency, and the included angle between its coordinate axes is 90°. In some other preferred embodiments, the initial phase angle calibration of the mains voltage synchronous two-dimensional coordinate system can also use the initial phase angle of the voltage synthesis vector of the mains voltage signal as the initial phase angle of the mains voltage synchronous two-dimensional coordinate system according to the Clarke transform.

[0067] When specifically implemented, for example, refer to Figure 2 , this figure is the schematic diagram of the mains voltage synchronous two-dimensional rotation coordinate system in the complex domain shown in some embodiments of the present application. Among them, ROJ is the complex coordinate system, where OR is the real axis and OJ is the imaginary axis. XOY is the mains voltage synchronous two-dimensional rotation coordinate system, and its initial phase angle is 45°, and the mains voltage frequency is used as the rotation speed of the mains voltage synchronous two-dimensional rotation coordinate system. In this embodiment, the rotation speed of the mains voltage synchronous two-dimensional rotation coordinate system is 100π / s; the coordinate value Q of the synthesis vector in the complex coordinate system s 、Q x are the combined heat, power and cooling voltage eigenvalues; according to the geometric coordinate relationship in the complex domain space, the coordinate value of the combined heat, power and cooling voltage synthesis vector in the mains voltage synchronous two-dimensional rotation coordinate system can be determined from the combined heat, power and cooling voltage eigenvalues.

[0068] In specific implementation, according to the cogeneration voltage eigenvalue, determining the coordinate value of the cogeneration voltage synthesis vector in the two-dimensional rotating coordinate system with the same frequency as the mains can be determined according to the geometric relationship of vectors in the complex number domain. In some preferred embodiments of the present application, the coordinate value of the cogeneration voltage synthesis vector in the two-dimensional rotating coordinate system with the same frequency as the mains can be expressed by the following formula:

[0069]

[0070] Where K X is the coordinate value of the cogeneration voltage synthesis vector on the OX axis of the two-dimensional rotating coordinate system with the same frequency as the mains, and K Y is the coordinate value of the cogeneration voltage synthesis vector on the OY axis of the two-dimensional rotating coordinate system with the same frequency as the mains, Q s and Q x are cogeneration voltage eigenvalues, μ is the frequency of the mains voltage, t is the operating time of the mains voltage, and C is the initial phase angle, calibrated as 45°.

[0071] After determining the coordinate value of the cogeneration voltage synthesis vector in the two-dimensional rotating coordinate system with the same frequency as the mains, according to the trigonometric function relationship between the cogeneration voltage synthesis vector and the two-dimensional rotating coordinate system with the same frequency as the mains, the phase angle deviation amount between the cogeneration voltage signal and the mains voltage signal can be determined. In specific implementation, determining the phase angle deviation amount between the cogeneration voltage signal and the mains voltage signal can be achieved through the following method, that is:

[0072]

[0073]

[0073] X is the coordinate value of the cogeneration voltage synthesis vector on the OX axis of the two-dimensional rotating coordinate system with the same frequency as the mains, and K Y is the coordinate value of the cogeneration voltage synthesis vector on the OY axis of the two-dimensional rotating coordinate system with the same frequency as the mains.

[0074] In step 103, detect the liquid temperature in the constant temperature water tank to obtain the current water temperature value; compare the current water temperature value with the water temperature value preset by the user to obtain a temperature deviation signal, and determine the duty cycle of the PWM controller according to the temperature deviation signal and the phase angle deviation amount.

[0075] In some embodiments, a temperature sensor can be used to detect the temperature of the liquid in the constant temperature water tank, or other devices or equipment that can achieve liquid temperature detection can also be used. There is no specific limitation here. The temperature deviation signal is the difference between the current water temperature value and the water temperature value preset by the user. Therefore, when the temperature deviation signal is large, the output power of the heat exchange motor can be controlled to increase, so as to control the current water temperature back to the water temperature value preset by the user.

[0076] It should be noted that the input end of the PWM controller is connected to the combined heat, power and cooling voltage signal, and the output end of the PWM controller is used to supply the input voltage of the heat exchange motor. During the high-level time when the PWM controller is turned on, the PWM controller supplies the combined heat, power and cooling voltage signal to the heat exchange motor. During the low-level time when the PWM controller is turned off, the supply of the combined heat, power and cooling voltage signal to the heat exchange motor by the PWM controller is blocked. Therefore, when the frequency of the PWM controller is high, by adjusting the duty cycle of the PWM controller, the voltage amplitude of the voltage input to the heat exchange motor can be adjusted according to the area equivalence principle of voltage. For example, if the area enclosed by the voltage curve of the variable frequency voltage signal obtained by the PWM controller in one cycle is equal to the area enclosed by the voltage curve of the required input voltage in the same time period, then the same output power can be obtained when the voltage frequency is high. Therefore, in some embodiments, to make the waveform of the input voltage signal of the heat exchanger more stable, the duration of a control cycle including high and low levels of the PWM controller should be much smaller than the voltage cycle duration of the combined heat, power and cooling voltage signal. Generally, the voltage cycle duration (minimum voltage cycle) of the combined heat, power and cooling voltage signal is 0.02S.

[0077] In some preferred embodiments of the present application, the duty cycle of the PWM controller can be determined according to the temperature deviation signal and the phase angle deviation amount in the following manner:

[0078] First, input the temperature deviation signal into the duty cycle control circuit to obtain the duty cycle of the PWM controller to be corrected;

[0079] Secondly, input the duty cycle of the PWM controller to be corrected and the phase angle deviation amount into a preset proportional control link to obtain the duty cycle of the PWM controller.

[0080] When specifically implemented, the duty cycle control circuit can adopt the existing proportional-integral-derivative (PID) control technology. In a preferred embodiment provided by the present application, the transfer function of the duty cycle control circuit can adopt the following form:

[0081]

[0082] Among them, T o is the duty cycle of the PWM controller to be corrected, G(s) is the transfer function of the mathematical model of the heat exchange motor, and k p , k i , k d are the proportional coefficient, the differential coefficient, and the integral coefficient respectively, which are calibrated as constants through experiments according to the mathematical model of the heat exchange motor. Δρ is the temperature deviation signal, and t is the time value.

[0083] Due to the integral control characteristic in the duty cycle control circuit, that is, when the temperature deviation signal is not zero, there is always an increasing duty cycle, which makes the output speed of the heat exchange motor increase, thereby increasing the liquid temperature in the constant temperature water tank.

[0084] It should be noted that when the combined heat and power supply voltage signal and the mains voltage signal are used to supply power to the heat exchange motor at the same time, due to the phase angle deviation between the combined heat and power supply voltage signal and the mains voltage signal, the peak time of the combined heat and power supply voltage signal is not at the center of each voltage wave cycle, resulting in a decrease in the overall voltage area. Therefore, after using PID to control the duty cycle of the PWM controller, there is also a difference between the expected output magnitude and the actual output magnitude of the variable-frequency voltage signal determined according to the duty cycle, resulting in that the output speed of the heat exchange motor cannot always reach the expected effect, the user water temperature rises slowly, and the existence of the phase angle deviation is equivalent to introducing an inertial lag link in the water temperature control system, that is, equivalent to introducing a pole in the water temperature control process, increasing the order of the water temperature control system. When the phase angle deviation is too large, it is easy to cause the instability of the water temperature control system; therefore, a proportional control link is required to correct the duty cycle of the PWM controller to be corrected to obtain the duty cycle of the PWM controller.

[0085] In some embodiments, the proportional control link can be implemented by a proportional control circuit or a programmable logic controller (PLC) with the same transfer function as the proportional control link, which is not limited here.

[0086] According to the voltage area equivalence principle, the area of the expected output voltage signal within a single voltage wave time should be the same as the area of the actual output variable-frequency voltage signal within a single voltage wave time. For this purpose, the transfer function of the proportional control link can be expressed by the following formula:

[0087]

[0088] Among them, σ is the duty cycle of the PWM controller, θ is the phase angle deviation between the combined heat and power supply voltage signal and the mains voltage signal, and U P is the expected voltage output amplitude, and To is the duty cycle of the PWM controller to be calibrated, π is the natural circular constant, ω2 is the angular frequency of the desired variable-frequency voltage signal, T is the period of the desired variable-frequency voltage signal, U max is the peak voltage of the combined heat and power supply voltage signal, ω1 is the angular frequency of the combined heat and power supply voltage signal, T c is the time period of the PWM controller, t is the time value, ζ is the integration length. It should be noted that the integral is an integral with respect to the time value, and the integration length is the length of a single wave crest of the combined heat and power supply voltage signal. For example, in some embodiments, if the combined heat and power supply voltage signal is a three-phase full-wave rectified voltage signal, one-sixth of the period of the combined heat and power supply voltage signal can also be used as the integration length in the proportional control link.

[0089] In step 104, according to the duty cycle of the PWM controller, a variable-frequency voltage signal is input to the heat exchange motor through the output end of the PWM controller, and the low-temperature flue gas waste heat of the combined heat and power supply internal combustion engine power generation device is conducted to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user.

[0090] Specifically, the heat exchange motor is the motor of the heat exchanger in the waste heat recovery device. Inputting the variable-frequency voltage signal into the heat exchange motor can control the motor output speed of the heat exchange motor, so as to conduct the low-temperature flue gas waste heat of the combined heat and power supply internal combustion engine power generation device to the constant temperature water tank, and realize the single-system combined heat and power supply variable-frequency low-temperature control of user water use.

[0091] In addition, to meet the speed regulation and frequency modulation requirements of the heat exchanger, in some embodiments, before inputting the variable-frequency voltage signal to the heat exchange motor through the PWM controller according to the duty cycle of the PWM controller, it may further include:

[0092] Controlling the frequency of the output voltage signal of the output end of the PWM controller through a rectifier circuit, a filtering device, and a three-phase inverter bridge provided at the output end of the PWM controller to obtain a variable-frequency voltage signal. Specifically, the PWM controller converts the voltage of the DC power supply into a rectangular pulse signal through a high-frequency switch, and filters it through the rectifier circuit and the filtering device to obtain a smooth DC voltage signal, and then converts the DC voltage signal into a three-phase AC voltage signal through the three-phase inverter bridge. The output end of the PWM controller can control the frequency and amplitude of the rectangular pulse signal by controlling the switching period and duty cycle of the high-frequency switch, so as to realize the control of the variable-frequency voltage signal.

[0093] The frequency control of the variable-frequency voltage signal is the key to realizing the variable-frequency speed regulation of the three-phase AC motor. Through the rectifier circuit, filtering device, and three-phase inverter bridge set at the output end of the PWM controller, variable-frequency voltage signals with different frequencies can be obtained by adjusting the switching period and duty cycle of the high-frequency switch according to different application requirements, so as to realize the variable-frequency control of the three-phase AC motor. And through the variable-frequency voltage signal, the soft start of the heat exchange motor can be realized, meeting the speed regulation and frequency modulation requirements of the heat exchange motor, and achieving the purpose of energy conservation and emission reduction.

[0094] In addition, on the other hand of the present application, in some embodiments, the present application provides a single-system variable-frequency low-temperature combined heat, power, and cooling control device, which includes a temperature control unit. Refer to Figure 3 , which is a schematic diagram of the exemplary hardware and / or software of the temperature control unit shown according to some embodiments of the present application. The temperature control unit 300 includes: a combined heat, power, and cooling voltage signal acquisition module 301, a phase angle deviation amount determination module 302, a duty cycle determination module 303, and a water temperature control module 304, which are described as follows:

[0095] The combined heat, power, and cooling voltage signal acquisition module 301. In the present application, the combined heat, power, and cooling voltage signal acquisition module 301 is mainly used to collect the three-phase AC voltage output by the combined heat, power, and cooling internal combustion engine power generation device to obtain the combined heat, power, and cooling voltage signal;

[0096] The phase angle deviation amount determination module 302. In the present application, the phase angle deviation amount determination module 302 is mainly used to superimpose a detection harmonic component on the combined heat, power, and cooling voltage signal to obtain a detection voltage signal, perform voltage vector synthesis on the detection voltage signal to obtain a combined heat, power, and cooling voltage characteristic value, and determine the phase angle deviation amount according to the combined heat, power, and cooling voltage characteristic value and the mains voltage signal;

[0097] The duty cycle determination module 303. In the present application, the duty cycle determination module 303 is mainly used to detect the liquid temperature in the constant temperature water tank, obtain the current water temperature value, compare the current water temperature value with the water temperature value preset by the user to obtain a temperature deviation signal, and determine the duty cycle of the PWM controller according to the temperature deviation signal and the phase angle deviation amount;

[0098] The water temperature control module 304. In the present application, the water temperature control module 304 is mainly used to input a variable-frequency voltage signal to the heat exchange motor through the output end of the PWM controller according to the duty cycle of the PWM controller, and conduct the low-temperature flue gas waste heat of the combined heat, power, and cooling internal combustion engine power generation device to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user.

[0099] In addition, the present application also provides a computer device, which includes a memory and a processor; the memory stores code, and the processor is configured to obtain the code and execute the above single-system variable-frequency low-temperature combined heat, power and cooling control method.

[0100] In some embodiments, referring to Figure 4 , Figure 4 is a schematic structural diagram of a computer device for implementing the single-system variable-frequency low-temperature combined heat, power and cooling control method provided by an embodiment of the present application. The single-system variable-frequency low-temperature combined heat, power and cooling control method in the above embodiment can be implemented by Figure 4 the computer device shown, which includes at least one processor 401, a communication bus 402, a memory 403, and at least one communication interface 404.

[0101] The processor 401 may be a general-purpose central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more for controlling the execution of the single-system variable-frequency low-temperature combined heat, power and cooling control method in the present application.

[0102] The communication bus 402 may include a path for transmitting information between the above components.

[0103] The memory 403 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM), or other optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disks, or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 403 may exist independently and be connected to the processor 401 through the communication bus 402. The memory 403 may also be integrated with the processor 401.

[0104] Among them, the memory 403 is used to store the program code for executing the solution of this application, and is controlled by the processor 401 to execute. The processor 401 is used to execute the program code stored in the memory 403. The program code may include one or more software modules. The determination of the temperature deviation signal in the above embodiments can be implemented by one or more software modules in the program code of the processor 401 and the memory 403.

[0105] The communication interface 404, using any device such as a transceiver, is used to communicate with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.

[0106] In a specific implementation, as an embodiment, the computer device may include multiple processors, and each of these processors may be a single-CPU processor or a multi-CPU processor. Here, the processor may refer to one or more devices, circuits, and / or processing cores for processing data (such as computer program instructions).

[0107] The above computer device may be a general-purpose computer device or a special-purpose computer device. In a specific implementation, the computer device may be a desktop computer, a laptop computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device, or an embedded device. The embodiments of this application do not limit the type of the computer device.

[0108] In addition, this application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above single-system variable-frequency low-temperature triple-cogeneration control method is implemented.

[0109] In summary, in the single-system variable-frequency low-temperature triple-cogeneration control method and device disclosed in the embodiments of the present application, first, a triple-cogeneration voltage signal output by a triple-cogeneration internal combustion engine power generation device is collected, and then a detection harmonic component is superimposed on the triple-cogeneration voltage signal to obtain a detection voltage signal. The detection voltage signal is subjected to voltage vector synthesis to obtain a triple-cogeneration voltage characteristic value. A phase angle deviation amount is determined according to the triple-cogeneration voltage characteristic value and the mains voltage signal. Furthermore, the temperature of the liquid in the constant temperature water tank is detected and compared with the water temperature value preset by the user to obtain a temperature deviation signal. The duty ratio of the PWM controller is determined according to the temperature deviation signal and the phase angle deviation amount. According to the duty ratio of the PWM controller, a variable-frequency voltage signal is input to the heat exchange motor through the output end of the PWM controller, and the low-temperature flue gas waste heat is conducted to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user, and the water temperature control accuracy of the triple-cogeneration system can be improved when there is a phase angle deviation amount between the triple-cogeneration voltage signal output by the triple-cogeneration system and the mains voltage signal.

[0110] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present application.

[0111] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A control method for a single - system variable - frequency low - temperature triple - supply, characterized in that, Including: Collecting three-phase AC voltage output by a combined heat and power internal combustion engine power generation device to obtain a combined heat and power voltage signal; Superimposing a detected harmonic component on the combined heat and power voltage signal to obtain a detected voltage signal, performing voltage vector synthesis on the detected voltage signal to obtain a combined heat and power voltage eigenvalue, and determining a phase angle deviation amount based on the combined heat and power voltage eigenvalue and a mains voltage signal; Detecting the liquid temperature in a constant temperature water tank to obtain a current water temperature value, comparing the current water temperature value with a user-predefined water temperature value to obtain a temperature deviation signal, and determining the duty cycle of a pulse width modulation controller based on the temperature deviation signal and the phase angle deviation amount; According to the duty cycle of the pulse width modulation controller, inputting a variable frequency voltage signal to a heat exchange motor through an output end of the pulse width modulation controller, and conducting the low-temperature flue gas waste heat of the combined heat and power internal combustion engine power generation device to the constant temperature water tank through the heat exchange motor, thereby controlling the current water temperature to return to the user-predefined water temperature value; Among them, performing voltage vector synthesis on the detected voltage signal to obtain a combined heat and power voltage eigenvalue includes: Dividing the detected voltage signal into a leading voltage signal component, a current voltage signal component, and a lagging voltage signal component; Transforming the leading voltage signal component, the current voltage signal component, and the lagging voltage signal component to a three-phase stationary coordinate system and performing vector synthesis to obtain a combined heat and power voltage synthesis vector; Taking the real part and the imaginary part of the combined heat and power voltage synthesis vector in the complex domain together as the combined heat and power voltage eigenvalue; Among them, determining the phase angle deviation amount based on the combined heat and power voltage eigenvalue and the mains voltage signal includes: Establishing a mains voltage co-frequency two-dimensional rotating coordinate system in the complex domain according to the frequency of the mains voltage signal; Projecting the combined heat and power voltage synthesis vector onto the mains voltage co-frequency two-dimensional rotating coordinate system, and determining the coordinate value of the combined heat and power voltage synthesis vector in the mains voltage co-frequency two-dimensional rotating coordinate system according to the combined heat and power voltage eigenvalue; Determining the phase angle deviation amount between the combined heat and power voltage signal and the mains voltage signal according to the coordinate value of the combined heat and power voltage synthesis vector in the mains voltage co-frequency two-dimensional rotating coordinate system.

2. The method according to claim 1, characterized in that, Determining the duty cycle of the pulse width modulation controller based on the temperature deviation signal and the phase angle deviation amount includes: Inputting the temperature deviation signal into a duty cycle control circuit to obtain a duty cycle of the pulse width modulation controller to be corrected; Inputting the duty cycle of the pulse width modulation controller to be corrected and the phase angle deviation amount into a preset proportional control link to obtain the duty cycle of the pulse width modulation controller.

3. The method according to claim 1, characterized in that, The detected harmonic component is an even harmonic component of the combined heat and power voltage signal.

4. The method according to claim 1, characterized in that, The detected voltage signal is a linear superposition of the combined heat and power voltage signal and the detected harmonic component.

5. The method according to claim 1, characterized in that, Before inputting a variable frequency voltage signal to the heat exchange motor through the pulse width modulation controller, it further includes: Controlling the frequency of the output voltage signal at the output end of the pulse width modulation controller through a rectifying circuit, a filtering device, and a three-phase inverter bridge provided at the output end of the pulse width modulation controller to obtain a variable frequency voltage signal.

6. A control device for a single - system variable - frequency low - temperature triple - supply, which is controlled by the method according to any one of claims 1 to 5, characterized in that, The device includes a temperature control unit, and the temperature control unit includes: The combined heat, power and cooling voltage signal acquisition module is used to collect the three-phase AC voltage output by the combined heat, power and cooling internal combustion engine power generation device to obtain the combined heat, power and cooling voltage signal; The phase angle deviation amount determination module is used to superimpose a detection harmonic component on the combined heat, power and cooling voltage signal to obtain a detection voltage signal, perform voltage vector synthesis on the detection voltage signal to obtain the combined heat, power and cooling voltage characteristic value, and determine the phase angle deviation amount according to the combined heat, power and cooling voltage characteristic value and the mains voltage signal; The duty cycle determination module is used to detect the liquid temperature in the constant temperature water tank, obtain the current water temperature value, compare the current water temperature value with the water temperature value preset by the user to obtain a temperature deviation signal, and determine the duty cycle of the pulse width modulation controller according to the temperature deviation signal and the phase angle deviation amount; The water temperature control module is used to input a variable frequency voltage signal to the heat exchange motor through the output end of the pulse width modulation controller according to the duty cycle of the pulse width modulation controller, and conduct the low-temperature flue gas waste heat of the combined heat, power and cooling internal combustion engine power generation device to the constant temperature water tank through the heat exchange motor, so as to control the current water temperature to return to the water temperature value preset by the user.

7. A computer device, characterized in that, The computer device includes a memory and a processor; the memory stores code, and the processor is configured to obtain the code and execute the single-system variable-frequency low-temperature combined heat, power and cooling control method according to any one of claims 1 to 5.

8. A computer - readable storage medium, the computer - readable storage medium stores a computer program, characterized in that, When the computer program is executed by the processor, it implements the single-system variable-frequency low-temperature combined heat, power and cooling control method according to any one of claims 1 to 5.

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