Power optimization control method and device for organic Rankine cycle power generation system

Abstract

The present application relates to the field of organic Rankine cycle, and discloses a power optimization control method and device for an organic Rankine cycle power generation system. The power generation system uses low-temperature waste heat to generate electricity, and includes a permanent magnet synchronous generator and an expander, the expander is directly connected to the permanent magnet synchronous generator, and the power optimization control method includes: obtaining the speed of the permanent magnet synchronous generator; obtaining the power of the permanent magnet synchronous generator; based on the variable step size hill climbing search method, calculating the speed difference between the current speed of the permanent magnet synchronous generator and the given speed, and operating the speed difference to output a given electromagnetic torque; based on vector control, calculating the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque, operating the torque difference, and outputting a control current to change the electromagnetic torque of the permanent magnet synchronous generator. The power optimization control method can change the engine speed so that it can keep running at maximum power, thereby improving energy utilization efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of organic Rankine cycle, and more specifically, to a power optimization control method, an operation protection device, a power optimization control device, an electronic device and a storage medium of an organic Rankine cycle power generation system. Background Art

[0002] Although my country's total energy supply is large, due to the huge population, my country's per capita energy reserves are still in short supply. According to statistics in 2000, the average primary energy consumption per person in my country was 1.22 tons of oil, lower than the world average of 1.67 tons per person; and the per capita electricity consumption level was only 1535 kWh, less than 3 / 5 of the world average consumption. In order to solve the energy crisis and alleviate environmental problems, we need to further improve the development and utilization of renewable energy. Among them, low-temperature waste heat power generation technology can reduce primary energy consumption without damaging the environment, so more and more people are conducting relevant analysis and research.

[0003] Organic Rankine Cycle (ORC) is a technology that uses low-temperature waste heat to generate electricity. It can convert low-grade thermal energy into high-grade electrical energy, and is an effective means to solve the problems of low energy utilization and high power consumption. At the same time, ORC technology can recycle different types of low-temperature waste heat, including industrial waste heat, geothermal energy, solar energy, internal combustion engine exhaust, and ocean temperature difference energy.

[0004] However, due to the complex composition of the heat source, the complex environment, the instability of the heat source and other factors, it is difficult for the generator to maintain stable operation at the highest power. In addition, due to factors such as temperature and pressure, the operation and management of the generator is difficult, affecting normal power generation. Therefore, it is necessary to analyze and study the power generation efficiency of the organic Rankine cycle power generation system. Summary of the invention

[0005] In view of this, the embodiments of the present application are committed to providing a power optimization control method, an operation protection device, a power optimization control device, an electronic device and a storage medium for an organic Rankine cycle power generation system to solve the problem that it is difficult for the generator to maintain stable operation at the highest power.

[0006] In a first aspect, the present specification provides a power optimization control method for an organic Rankine cycle power generation system, wherein the power generation system generates electricity using low-temperature waste heat and comprises a permanent magnet synchronous generator and an expander, wherein the expander is directly connected to the permanent magnet synchronous generator, and the power optimization control method comprises:

[0007] Get the speed of the permanent magnet synchronous generator;

[0008] Obtain the power of the permanent magnet synchronous generator;

[0009] Based on the variable step-size hill climbing search method, the speed difference between the current speed and the given speed of the permanent magnet synchronous generator is calculated, and the speed difference is calculated to output a given electromagnetic torque;

[0010] Based on vector control, the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque is calculated, and the torque difference is operated to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator, wherein the control current is the quadrature axis current component of the three-phase stator current of the permanent magnet synchronous generator after transformation in the dq coordinate system;

[0011] The step size of the variable step size hill climbing search method is determined by the step size disturbance coefficient, and the step size disturbance coefficient represents the relationship between the power difference and the speed difference corresponding to the permanent magnet synchronous generator after the speed is adjusted.

[0012] According to the first aspect, in a possible implementation manner, the vector control is the direct axis current component i d =0 control method.

[0013] According to the first aspect, in a possible implementation manner, the method further includes: if the power of the permanent magnet synchronous generator decreases after the speed adjustment, reducing the step disturbance coefficient.

[0014] According to the first aspect, in a possible implementation manner, the method further includes:

[0015] Get the pressure at the expander inlet;

[0016] When the temperature of the heat source changes, the pressure at the inlet of the expander is adjusted based on the relationship between the isentropic efficiency of the expander and the working pressure.

[0017] In a second aspect, the present specification provides an operation protection device using the power optimization control method of the organic Rankine cycle power generation system, the operation protection device comprising:

[0018] A thermocouple is used to detect the temperature at the inlet of the expander;

[0019] A pressure detector for detecting the pressure at the inlet of the expander;

[0020] Expander stop valve, used to open or close the pipeline inlet of the expander;

[0021] Condenser stop valve, used to open or close the pipeline inlet of the condenser of the organic Rankine cycle power generation system;

[0022] The PLC controller is used for receiving the temperature information from the thermocouple and the pressure information from the pressure detector, and controlling the expander stop valve and the condenser stop valve according to a predetermined rule.

[0023] According to the second aspect, in a possible implementation, when the organic Rankine cycle power generation system is started, the expander stop valve is closed and the condenser stop valve is opened;

[0024] When the temperature and pressure at the expander inlet reach the allowable conditions required for the operation of the expander, close the condenser stop valve and open the expander stop valve.

[0025] According to the second aspect, in one possible implementation, when the temperature at the inlet of the expander is continuously lower than the controllable temperature of the system for more than a preset minimum time threshold, the organic Rankine cycle power generation system is shut down;

[0026] When the temperature at the expander inlet exceeds the maximum operating temperature of the system, close the expander stop valve and open the condenser stop valve;

[0027] When the temperature at the expander inlet is continuously higher than the maximum operating temperature for more than a preset maximum time threshold, the organic Rankine cycle power generation system is shut down.

[0028] In a third aspect, the present specification provides a power optimization control device for an organic Rankine cycle power generation system, which is applied to an organic Rankine cycle power generation system, wherein the power generation system generates electricity using low-temperature waste heat and includes a permanent magnet synchronous generator and an expander, wherein the expander is directly connected to the permanent magnet synchronous generator, including:

[0029] A first acquisition module is used to acquire the rotation speed of the permanent magnet synchronous generator;

[0030] A second acquisition module is used to acquire the power of the permanent magnet synchronous generator;

[0031] A speed controller, used for calculating the speed difference between the current speed of the permanent magnet synchronous generator and the given speed based on a variable step-size hill climbing search method, and performing calculations on the speed difference to output a given electromagnetic torque;

[0032] A torque controller, for calculating the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque based on vector control, and operating the torque difference to output a control current, wherein the control current is a quadrature axis current component of the three-phase stator current of the permanent magnet synchronous generator after transformation in a dq coordinate system;

[0033] The step size of the variable step size hill climbing search method is determined by the step size disturbance coefficient, and the step size disturbance coefficient represents the relationship between the power difference and the speed difference corresponding to the permanent magnet synchronous generator after the speed is adjusted.

[0034] In a fourth aspect, this specification provides an electronic device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute each step in any one of the described methods.

[0035] In a fifth aspect, the present specification provides a computer-readable storage medium, the computer-readable storage medium including a stored program, wherein the program executes each step in any one of the described methods.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] Different from the prior art, the power optimization control method of the organic Rankine cycle power generation system provided by the present invention obtains the speed of the permanent magnet synchronous generator; obtains the power of the permanent magnet synchronous generator; based on the variable step size hill climbing search method, calculates the speed difference between the current speed of the permanent magnet synchronous generator and the given speed, and operates the speed difference to output a given electromagnetic torque; based on vector control, calculates the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque, and operates the torque difference to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator. The present invention controls the speed of the generator through the outer loop and the electromagnetic torque of the generator through the inner loop, so that the engine speed can be changed, and the generator can be kept running stably at the highest power, thereby improving the power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0039] Figure 1 A schematic flow chart of a power optimization control method for an organic Rankine cycle power generation system provided for at least one embodiment of this specification;

[0040] Figure 2 A schematic diagram of a curve showing the relationship between power and speed of an engine using a hill climbing search method provided for at least one embodiment of the present specification;

[0041] Figure 3 A schematic diagram of a curve of change of the isentropic efficiency of an expander and the system working pressure under a certain organic working fluid provided in at least one embodiment of the present specification;

[0042] Figure 4A schematic diagram of an organic Rankine cycle power generation system including an operation protection device provided for at least one embodiment of the present specification;

[0043] Figure 5 A schematic diagram of a power optimization control device 500 for an organic Rankine cycle power generation system provided for at least one embodiment of the present specification;

[0044] Figure 6 A schematic diagram of speed regulation based on a power optimization control method is provided for at least one embodiment of this specification. DETAILED DESCRIPTION

[0045] Unless otherwise defined, the technical terms or scientific terms used in the embodiments of this specification shall have the common meanings understood by persons with ordinary skills in the field to which this specification belongs. The words "first", "second" and similar words used in the embodiments of this specification do not indicate any order, quantity or importance, but are only used to avoid confusion of constituent elements.

[0046] Unless the context requires otherwise, throughout the specification, "plurality" means "at least two", and "including" is interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples", "specific examples" or "some examples" are intended to indicate that a particular feature, structure, material or characteristic associated with the embodiment or example is included in at least one embodiment or example of the specification. The schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0047] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this specification.

[0048] As mentioned in the background technology, the organic Rankine cycle power generation system in the prior art has problems such as low efficiency. In order to solve the above problems, the embodiments of the present application provide a power optimization control method, an operation protection device, a power optimization control device, an electronic device and a storage medium for an organic Rankine cycle power generation system.

[0049] like Figure 1As shown, a power optimization control method for an organic Rankine cycle power generation system provided by an embodiment of the present invention is provided. The power generation system utilizes low-temperature waste heat to generate electricity, and includes a permanent magnet synchronous generator and an expander. The expander is directly connected to the permanent magnet synchronous generator. The power optimization control method may specifically include the following steps.

[0050] Step S110: obtaining the rotation speed of the permanent magnet synchronous generator;

[0051] Step S120: obtaining the power of the permanent magnet synchronous generator;

[0052] Step S130: Based on the variable step size hill climbing search method, the speed difference between the current speed of the permanent magnet synchronous generator and the given speed is calculated, and the speed difference is calculated to output a given electromagnetic torque;

[0053] Step S140: based on vector control, calculating the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque, and operating the torque difference to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator, wherein the control current is the quadrature-axis current component of the three-phase stator current of the permanent magnet synchronous generator after transformation in the dq coordinate system;

[0054] The step size of the variable step size hill climbing search method is determined by the step size disturbance coefficient, and the step size disturbance coefficient represents the relationship between the power difference and the speed difference corresponding to the permanent magnet synchronous generator after the speed is adjusted.

[0055] In the above method, the speed of the permanent magnet synchronous generator can be first obtained through the speed monitoring device, and then the power of the permanent magnet synchronous generator can be obtained through the power monitoring device. Then, based on the variable step size hill climbing search method, the speed of the permanent magnet synchronous generator is controlled, and finally, based on vector control, the electromagnetic torque of the permanent magnet synchronous generator is controlled. The outer loop obtains the speed and outputs the given electromagnetic torque, and the inner loop calculates and outputs the control current by the given electromagnetic torque and the current electromagnetic torque. The control current can be transformed by coordinates to control the trigger signal of the inverter, change the torque of the generator, and thus achieve a change in speed. The given speed can be the historical speed of the generator during operation, or it can be a preset speed of the generator set in advance. Similarly, the given electromagnetic torque can be the historical electromagnetic torque of the generator during operation, or it can be a preset electromagnetic torque of the generator set in advance.

[0056] Maximum power point tracking (MPPT) is commonly used in solar panels, expanders and other types of renewable energy power generation systems. Hill climbing search is an important control method in maximum power point tracking.

[0057] The organic Rankine cycle power generation system is a very complex control object. In view of its time-varying, nonlinear, large inertia and large hysteresis characteristics, this application will use the hill climbing search method to control the speed of the permanent magnet synchronous generator, that is, continuously adding a positive or negative disturbance to the system to change the working state of the system. By observing the output change, the positive or negative disturbance value at the next moment is determined. In the waste heat power generation system, if the output power of the system increases, the direction of the disturbance change remains unchanged, so that the output power continues to increase until a certain moment, when the system output power begins to decrease, and then the disturbance direction is changed at the next moment. The above process is repeated continuously to eventually reach the maximum power point. The schematic diagram of the relationship curve between the power and speed of the engine using the hill climbing search method is shown in the figure. Figure 2 As shown. Figure 2 It can be seen that there is a unique speed in each power-speed curve. When the system works near the maximum power point, the output power and speed are parabolic, making the output power maximum, that is:

[0058]

[0059] like Figure 2 As shown in the figure, when the system is running stably, if the working point drifts to point A, the generator speed is increased to make the output power approach the ideal working point along the rising area curve. When the working point drifts to point E, on the contrary, it approaches the ideal working point along the falling area curve.

[0060] The control structure of the hill climbing search method is simple and widely used in various fields. This control method continuously changes the generator speed to achieve the maximum power point tracking. Therefore, if the adjustment step size is large, the control accuracy is low. The system frequently changes the direction of the disturbance near the maximum power point, which will cause the generator speed to oscillate. At the same time, it also causes a large amount of energy loss and reduces the efficiency of the system. If the oscillation is to be reduced, it can be achieved by reducing the step size, but the reduction of the adjustment step size will reduce the tracking speed of the system, and too long tracking time will also cause energy loss. This has caused the situation that the tracking speed and tracking accuracy of the traditional maximum power tracking system based on the hill climbing search method cannot be achieved at the same time. In order to solve this problem, the present application proposes a variable step size hill climbing search method in which the step size is determined by the step size disturbance coefficient, wherein the step size disturbance coefficient characterizes the relationship between the power change and the speed change of the permanent magnet synchronous generator. For example, the step size disturbance coefficient can be set to the ratio of the power change value and the speed change value of the generator.

[0061] The permanent magnet synchronous generator of this application adopts vector control, that is, under the premise of orientation in the rotor magnetic field, the stator current is decomposed into excitation component and torque component, and then the PI regulator is used to achieve independent regulation of the two, and then pulse modulation is used to synthesize the reference voltage vector. Vector control is achieved by controlling the quadrature axis current after the coordinate transformation of the motor parameters. Vector control mainly includes the direct axis current component i d =0 control, constant flux control, weak flux control, maximum torque current ratio control, In order to achieve accurate and rapid speed control and track the maximum power point, vector control uses the direct axis current component i d =0 control method.

[0062] In at least one embodiment of the present application, the power optimization control method further includes: if the power of the permanent magnet synchronous generator decreases after the speed adjustment, reducing the step disturbance coefficient.

[0063] according to Figure 2 It can be seen that during the power adjustment process, if the power becomes smaller after adjustment, the power is on a downward curve at this time. Therefore, the step disturbance coefficient can be reduced while changing the disturbance direction (positive and negative disturbance values), so as to adjust the power more quickly to basically reach the maximum power.

[0064] In at least one embodiment of the present application, the minimum step size disturbance coefficient can be set as needed to avoid too frequent power adjustment and affect the stability of system operation.

[0065] In at least one embodiment of the present application, a minimum time interval for adjusting (reducing) the step size disturbance coefficient may be set to further enhance the stability of the power adjustment process.

[0066] In at least one embodiment of the present application, the power generation system adopts space vector pulse width modulation.

[0067] Space Vector Pulse Width Modulation (SVPWM) is a modulation method used in three-phase circuits to generate a circular rotating magnetic field, thereby generating ideal sinusoidal current and voltage waveforms in AC motors. The main idea of ​​SVPWM is to use the ideal stator flux circle of a three-phase symmetrical motor when powered by a three-phase symmetrical sinusoidal voltage as a reference standard, and to form a PWM (Pulse Width Modulation) wave by appropriately switching different switching modes of the three-phase inverter, so that the actual flux vector formed can track its accurate flux circle. Compared with the traditional SPWM method, SVPWM can more effectively reduce harmonics and improve the operating efficiency of the motor.

[0068] In at least one embodiment of the present application, the power optimization control method also includes: obtaining the pressure at the inlet of the expander; when the temperature of the heat source changes, based on the relationship between the isentropic efficiency and the working pressure of the expander, adjusting the pressure at the inlet of the expander.

[0069] Generally speaking, the efficiency of an expander is expressed by a characteristic ratio, as shown in formula (1).

[0070]

[0071] Among them, n1 is the circumferential speed of the outer edge of the working disk, and Cs is the isentropic ideal speed.

[0072] When the system is working stably, the characteristic ratio can effectively reflect the influence of the expander speed on the isentropic efficiency of the system. By changing the characteristic ratio of the expander, the working efficiency of the expander can be improved.

[0073] The relationship between the characteristic ratio, speed and working fluid thermodynamics is shown in formula (2):

[0074]

[0075] Where ω is the speed and h is the enthalpy change of the working fluid. The enthalpy change is directly related to the thermodynamic energy and pressure of the working fluid. The relationship between pressure p and temperature T is obtained based on the Antoine equation.

[0076]

[0077] Among them, A, B, and C are all constants related to the characteristics of the working fluid itself, p is the pressure, and T is the thermodynamic temperature.

[0078] In superheated steam, temperature and pressure are directly related, so equation (2) can be written as the following equation (4):

[0079]

[0080] Here, p is the pressure. This converts the ratio of n1 to Cs, which is difficult to adjust and control, into a function of the speed ω and pressure p, which is easier to control. By adjusting the speed according to the pressure and keeping the characteristic ratio near the ideal working point, the performance of the expander can be fully utilized.

[0081] For a specific working fluid, there is always a certain relationship between the isentropic efficiency of the expander and the working pressure. Figure 3 As shown in the figure, the isentropic efficiency of the expander and the system working pressure change curve under a certain organic working fluid. It can be seen from the figure that when the heat source temperature is 90℃ and the evaporation pressure is 0.65MPa, the expander achieves a maximum efficiency of 7.33%, and the output power is 228W at this time.

[0082] It can be seen that there is always an optimal working pressure that makes the isentropic efficiency reach the maximum value. Therefore, adjusting the heat source temperature and the system working pressure so that the working pressure changes with the change of the heat source state can facilitate the generator power to maintain the highest operation and improve energy utilization.

[0083] Based on the above power optimization control method of the organic Rankine cycle power generation system, the present application also designs an operation protection device. Figure 4 FIG. 1 is a schematic diagram of an organic Rankine cycle power generation system including an operation protection device provided in an embodiment of the present application, wherein the operation protection device includes:

[0084] A thermocouple is used to detect the temperature at the inlet of the expander;

[0085] A pressure detector for detecting the pressure at the inlet of the expander;

[0086] Expander stop valve 1, used to open or close the pipeline inlet of the expander;

[0087] A condenser stop valve 2, used to open or close a pipeline inlet of a condenser of an organic Rankine cycle power generation system;

[0088] A PLC controller (not shown) is used to receive temperature information from the thermocouple and pressure information from the pressure detector, and control the expander stop valve and the condenser stop valve according to a predetermined rule.

[0089] Before the power generation system is started and in operation, problems such as uneven heating, low temperature, high temperature, and water vapor may occur, affecting the normal start-up and operation of the equipment. This solution monitors the temperature, pressure and other information of the system in real time and controls it according to preset rules, thereby ensuring the safe and stable operation of the power generation system, reducing accidents and improving operating efficiency.

[0090] In at least one embodiment of the present application, when the organic Rankine cycle power generation system is started, the expander stop valve is closed and the condenser stop valve is opened; when the temperature and pressure at the expander inlet reach the permissible conditions required for the operation of the expander, the condenser stop valve is closed and the expander stop valve is opened. The permissible conditions include that the temperature and pressure at the expander inlet reach a range suitable for normal startup. Through this solution, the safe and smooth startup of the power generation system is guaranteed.

[0091] In at least one embodiment of the present application, when the temperature at the inlet of the expander is continuously lower than the controllable temperature of the system for more than a preset minimum time threshold, the organic Rankine cycle power generation system is shut down; when the temperature at the inlet of the expander exceeds the maximum operating temperature of the system, the expander stop valve is closed and the condenser stop valve is opened; when the temperature at the inlet of the expander is continuously higher than the maximum operating temperature for more than a preset maximum time threshold, the organic Rankine cycle power generation system is shut down. The preset minimum time threshold and the preset maximum time threshold can be set and adjusted according to actual conditions, for example, the minimum time threshold is set to 10 minutes, and the preset maximum time threshold is set to 3 minutes. Through this solution, the stability of the operation of the power generation system is guaranteed, and more efficient use of heat sources for power generation is achieved.

[0092] like Figure 5 As shown, an embodiment of the present invention provides a schematic diagram of a power optimization control device 500 for an organic Rankine cycle power generation system. The device is applied to an organic Rankine cycle power generation system, which generates electricity using low-temperature waste heat and includes a permanent magnet synchronous generator and an expander, wherein the expander is directly connected to the permanent magnet synchronous generator. The device includes:

[0093] A first acquisition module 510 is used to acquire the rotation speed of the permanent magnet synchronous generator;

[0094] A second acquisition module 520 is used to acquire the power of the permanent magnet synchronous generator;

[0095] The speed controller 530 is used to calculate the speed difference between the current speed of the permanent magnet synchronous generator and the given speed based on the variable step size hill climbing search method, and to calculate the speed difference to output a given electromagnetic torque;

[0096] The torque controller 540 is used to calculate the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque based on vector control, and to operate on the torque difference to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator, wherein the control current is the quadrature axis current component of the three-phase stator current of the permanent magnet synchronous generator after transformation in the dq coordinate system;

[0097] The step size of the variable step size hill climbing search method is determined by the step size disturbance coefficient, and the step size disturbance coefficient represents the relationship between the power difference and the speed difference corresponding to the permanent magnet synchronous generator after the speed is adjusted.

[0098] In the above-mentioned device, the speed of the permanent magnet synchronous generator is obtained through the first acquisition module, and then the power of the permanent magnet synchronous generator can be obtained through the second acquisition module. Then, the speed controller is used to calculate the speed difference between the current speed of the permanent magnet synchronous generator and the given speed based on the variable step size hill climbing search method, and the speed difference is calculated to output a given electromagnetic torque. Finally, the torque controller is used to calculate the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque based on vector control, and the torque difference is calculated to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator, wherein the control current is the cross-axis current component of the three-phase current of the stator of the permanent magnet synchronous generator after transformation in the dq coordinate system. Among them, the step size of the variable step size hill climbing search method is determined by the step size disturbance coefficient, and the step size disturbance coefficient characterizes the relationship between the power difference and the speed difference corresponding to the speed adjustment of the permanent magnet synchronous generator. Figure 6 As shown, the outer loop obtains the speed and outputs the given electromagnetic torque, and the inner loop calculates the given electromagnetic torque and the current electromagnetic torque to output the control current. The control current can be transformed by coordinates to control the trigger signal of the inverter, change the torque of the generator, and thus achieve the speed change. The given speed can be the historical speed of the generator during operation, or the preset speed of the generator set in advance. Similarly, the given electromagnetic torque can be the historical electromagnetic torque of the generator during operation, or the preset electromagnetic torque of the generator set in advance.

[0099] In at least one embodiment of the present application, in order to achieve accurate and rapid speed control and track the maximum power point, the vector control uses the direct axis current component i d =0 control method.

[0100] In at least one embodiment of the present application, the speed controller is further configured to reduce the step disturbance coefficient if the power of the permanent magnet synchronous generator decreases after the speed adjustment.

[0101] In at least one embodiment of the present application, the power generation system adopts space vector pulse width modulation.

[0102] In at least one embodiment of the present application, the power optimization control device further includes:

[0103] A pressure acquirer, for acquiring the pressure at the inlet of the expander;

[0104] The speed controller is also used to adjust the pressure at the inlet of the expander based on the relationship between the isentropic efficiency and the working pressure of the expander when the temperature of the heat source changes. There is always an optimal working pressure that makes the isentropic efficiency reach the maximum value. Therefore, adjusting the heat source temperature and the system working pressure so that the working pressure changes with the change of the heat source state can facilitate the generator power to maintain the highest operation and improve energy utilization.

[0105] Based on the embodiments of the present application, the present application also provides an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute each step in the power optimization control method of the organic Rankine cycle power generation system of the aforementioned technical solution.

[0106] Based on the embodiments of the present application, the present application also provides a computer-readable storage medium, wherein computer instructions are used to enable a computer to execute each step in the power optimization control method of the organic Rankine cycle power generation system of the aforementioned technical solution.

[0107] Based on the embodiments of the present application, the present application further provides a processor, which is used to run a program, wherein when the program is running, each step in the power optimization control method of the organic Rankine cycle power generation system of the aforementioned technical solution is executed.

[0108] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0109] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the described embodiment, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0110] A person skilled in the art may understand that all or part of the steps of implementing the method of the embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0111] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0112] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the embodiments are exemplary and cannot be construed as limiting the present invention. A person of ordinary skill in the art may change, modify, replace and modify the embodiments within the scope of the present invention.

[0113] The above is only a specific implementation of this specification, but the protection scope of this specification is not limited to this. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this specification, which should be included in the protection scope of this specification. Therefore, the protection scope of this specification should be based on the protection scope of the claims.

Claims

1. A power optimization control method for an organic Rankine cycle power generation system, characterized in that: The power generation system utilizes low-temperature waste heat to generate electricity, and includes a permanent magnet synchronous generator and an expander, wherein the expander is directly connected to the permanent magnet synchronous generator, and the power optimization control method includes: Obtaining the rotation speed of the permanent magnet synchronous generator; Obtaining the power of the permanent magnet synchronous generator; Based on a variable step size hill climbing search method, a speed difference between a current speed of the permanent magnet synchronous generator and a given speed is calculated, and the speed difference is operated to output a given electromagnetic torque; Based on vector control, a torque difference between a current electromagnetic torque of the permanent magnet synchronous generator and a given electromagnetic torque is calculated, and the torque difference is operated to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator, wherein the control current is a quadrature-axis current component of a stator three-phase current of the permanent magnet synchronous generator after transformation in a dq coordinate system; The step size of the variable step size hill climbing search method is determined by a step size disturbance coefficient, and the step size disturbance coefficient represents the relationship between the power difference corresponding to the permanent magnet synchronous generator after the speed adjustment and the speed difference; By setting the minimum step size disturbance coefficient, we can avoid frequent power adjustments that may affect the stability of system operation. By setting a minimum time interval for adjusting the step size disturbance coefficient, the stability of the power adjustment process is further enhanced; The power optimization control method can obtain the pressure at the inlet of the expander, and when the temperature of the heat source changes, the pressure at the inlet of the expander is adjusted based on the relationship between the isentropic efficiency and the working pressure of the expander; When the temperature at the inlet of the expander continues to be lower than the controllable temperature of the system for more than a preset minimum time threshold, the organic Rankine cycle power generation system is shut down; when the temperature at the inlet of the expander exceeds the maximum operating temperature of the system, the expander stop valve is closed and the condenser stop valve is opened; when the temperature at the inlet of the expander continues to be higher than the maximum operating temperature for more than a preset maximum time threshold, the organic Rankine cycle power generation system is shut down. The preset minimum time threshold and the preset maximum time threshold can be set and adjusted according to actual conditions.

2. The method according to claim 1, characterized in that in, The vector control is a direct-axis current component id=0 control method.

3. The method according to claim 2, characterized in that Also includes: If the power of the permanent magnet synchronous generator decreases after the speed adjustment, the step disturbance coefficient is reduced.

4. A running protection device using the method according to claim 1, characterized in that: The operation protection device comprises: a thermocouple, used to detect the temperature at the inlet of the expander; A pressure detector, used to detect the pressure at the inlet of the expander; An expander stop valve, used to open or close the pipeline inlet of the expander; A condenser stop valve, used to open or close a pipeline inlet of a condenser of the organic Rankine cycle power generation system; A PLC controller is used to receive the temperature information from the thermocouple and the pressure information from the pressure detector, and control the expander stop valve and the condenser stop valve according to a predetermined rule.

5. The device according to claim 4, characterized in that When the organic Rankine cycle power generation system is started, the expander stop valve is closed and the condenser stop valve is opened; When the temperature and pressure at the inlet of the expander reach the permissible conditions required for the operation of the expander, the condenser stop valve is closed and the expander stop valve is opened.

6. The device according to claim 4 or 5, characterized in that When the temperature at the inlet of the expander is continuously lower than the controllable temperature of the system for more than a preset minimum time threshold, shutting down the organic Rankine cycle power generation system; When the temperature at the inlet of the expander exceeds the maximum operating temperature of the system, the expander stop valve is closed and the condenser stop valve is opened; When the temperature at the inlet of the expander is continuously higher than the maximum operating temperature for more than a preset maximum time threshold, the organic Rankine cycle power generation system is shut down.

7. A power optimization control device for an organic Rankine cycle power generation system, characterized in that: Applied to an organic Rankine cycle power generation system, the power generation system uses low-temperature waste heat to generate electricity and includes a permanent magnet synchronous generator and an expander, the expander is directly connected to the permanent magnet synchronous generator, and the device includes: A first acquisition module is used to acquire the rotation speed of the permanent magnet synchronous generator; A second acquisition module, used to acquire the power of the permanent magnet synchronous generator; A speed controller, used for calculating the speed difference between the current speed of the permanent magnet synchronous generator and the given speed based on a variable step size hill climbing search method, and performing operation on the speed difference to output a given electromagnetic torque; A torque controller is used to calculate the torque difference between the current electromagnetic torque of the permanent magnet synchronous generator and the given electromagnetic torque based on vector control, and to operate on the torque difference to output a control current to change the electromagnetic torque of the permanent magnet synchronous generator, wherein the control current is the quadrature-axis current component of the stator three-phase current of the permanent magnet synchronous generator after transformation in the dq coordinate system.

8. An electronic device, characterized in that: include: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can perform each step in the method described in any one of claims 1 to 3.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein the program executes each step of the method according to any one of claims 1 to 3.

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