Compressed air power generation control system based on mechanical virtual inertia and power generation method

Abstract

The invention discloses a compressed air power generation control system based on mechanical virtual inertia and a power generation method, and belongs to the technical field of distributed power generation microgrids. Comprising a mechanical control system and a virtual inertial system. The mechanical control system comprises an air storage tank, an air compressor, a switch valve, a pressure sensor, a temperature sensor, a hydraulic motor, a magnetic gearbox, a power generation system and a power grid load. The air storage tank, the air compressor, the switch valve, the hydraulic motor, the magnetic gear box, the power generation system and the power grid load are connected in sequence; and the pressure sensor and the temperature sensor are respectively connected with the air compressor. The power generation stability is controlled through the mechanical virtual inertia method, the efficiency of the compressed air power generation system is improved, and stable operation of the compressed air power generation system under different working conditions is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed power generation microgrids, and more particularly to a compressed air power generation control system and a power generation method based on mechanical virtual inertia. Background Art

[0002] As a new energy storage and power generation technology, compressed air power generation technology plays an important role in the consumption of photovoltaic / wind power, peak load shaving and valley filling of power grids, and safe and stable operation. It has huge social benefits in promoting the popularization of photovoltaic / wind power, improving the safety and stability of microgrids, and supporting green smart energy. However, there are changes in internal working conditions and loads during system operation. Traditional electrical control methods cannot be simply applied to this system. Increasing the system inertia is a feasible solution to improve the stability of compressed air power generation.

[0003] Inertia is an inherent physical property of the power system, which manifests itself as the power system's resistance to frequency changes. Inertia is a measure of the size of inertia. The inertia form and response law of the compressed air power generation system are different from those of the traditional power grid. The equivalent inertia of the power grid is greatly reduced, resulting in a rapid drop in frequency in a short period of time under disturbance. In the traditional power grid, rotating elements such as synchronous generators and induction motors are the main sources of inertia. Therefore, new energy power grid control technology mostly uses virtual synchronous machines to simulate synchronous generators to increase the inertia of the power grid.

[0004] The traditional virtual synchronous machine method has problems such as low efficiency and unadjustable inertia. The distributed microgrid power generation field pays great attention to power generation efficiency, and a more efficient and energy-saving power generation system control method is urgently needed. At the same time, the unadjustable inertia leads to the contradiction that the inherent inertia of the system is too small to meet the load matching requirements; the inherent inertia is too large, and the system response speed slows down. Summary of the invention

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] The present invention provides a compressed air power generation control system based on mechanical virtual inertia, comprising: a mechanical control system and a virtual inertia system;

[0007] The mechanical control system includes: an air storage tank, an air compressor, a switch valve, a pressure sensor, a temperature sensor, a hydraulic motor, a magnetic gear box, a power generation system and a grid load;

[0008] The gas storage tank, air compressor, switch valve, hydraulic motor, magnetic gear box, power generation system and grid load are connected in sequence;

[0009] The pressure sensor and the temperature sensor are respectively connected to the air compressor;

[0010] The virtual inertial system includes a control signal processor and a control system;

[0011] The control signal processor collects signals from the pressure sensor, the temperature sensor, and the grid load;

[0012] The control signal processor transmits a signal to the control system;

[0013] The control system controls the hydraulic motor, the magnetic gear box and the power generation system respectively.

[0014] Preferably, the power generation system comprises: a permanent magnet synchronous generator, a rectifier, a filter, and an inverter;

[0015] The magnetic gearbox, permanent magnet synchronous generator, filter, inverter, rectifier and grid load are connected in sequence;

[0016] The control system controls the rectifier.

[0017] Preferably, the control system is provided with a hydraulic motor swash plate control module, a magnetic gear box control module, and an electrical control module;

[0018] The hydraulic motor swash plate control module changes the swash plate angle of the hydraulic motor to a set value according to the input parameters and the virtual inertia model;

[0019] The magnetic gearbox control module inputs the power quality of the generated electricity and outputs the excitation current, and controls the magnetic field of the gearbox by controlling the excitation current;

[0020] The electrical control module makes fine adjustments to the output of the power generation system through the current conversion control module to improve the quality of electric energy.

[0021] Another object of the present invention is to provide a method for compressed air power generation based on a compressed air power generation control system of mechanical virtual inertia, using the above-mentioned power generation control system, specifically including a virtual inertia system and a mechanical control control construction;

[0022] Virtual inertia system: By building a virtual synchronous machine model, the input signal is converted into the synchronous generator input voltage and power, the output is the synchronous generator torque, and then the output is converted into the required output signal. The virtual synchronous machine inertia is changed according to the system conditions to achieve system adjustable virtual inertia control;

[0023] Mechanical control system: includes a magnetic gearbox and a hydraulic motor. The system power generation is controlled through the hydraulic motor swash plate and the magnetic gearbox. The specific controlled physical quantities are the swash plate angle and the magnetic gearbox excitation current. The mechanical virtual inertia control is achieved by combining the virtual inertia algorithm with the mechanical system.

[0024] The swash plate angle control of the hydraulic motor based on virtual inertia includes the following steps:

[0025] Step 1: Obtain the grid load voltage and frequency as system control input;

[0026] Step 2: According to the relationship between the swash plate angle and the output torque of the hydraulic motor, the system transfer function G1(s) is obtained;

[0027] Step 3: According to the synchronous generator dynamic equation, virtual inertia is introduced into the system to obtain the virtual inertia transfer function Gsg(s), the grid parameters are used as the control input, and the swash plate angle is used as the control output;

[0028] Step 4: Dynamically adjust the virtual inertia according to the swash plate angle and grid voltage and frequency.

[0029] Preferably, the function expression of the hydraulic motor swash plate angle and the output torque is:

[0030] M L 2πn=ΔpQ s =Δpqn

[0031]

[0032] Among them, M L is the theoretical torque, Δp is the inlet and outlet differential pressure, q is the motor displacement, Q s is the actual flow rate, z is the number of plungers, R is the radius of the plunger distribution circle, d is the plunger diameter, and β is the inclination angle of the swash plate;

[0033] According to the above formula, the transfer function G1(s) of the swash plate angle control motor output torque is obtained:

[0034]

[0035] The input signal of the virtual inertia system is determined by G1(s), where the virtual inertia system is obtained by simulating the mathematical model of the synchronous generator, and its transfer function Gsg(s) is expressed as:

[0036]

[0037] The virtual generator is controlled to control the motor output torque, and the control system has adjustable inertia. PID control is adopted, and the transfer function H1(s) is expressed as:

[0038]

[0039]

[0040] Among them, J is the virtual inertia, D is the virtual damping, L is the virtual synchronous machine winding inductance, R is the virtual synchronous winding resistance, and K is the virtual synchronous machine structure parameter.

[0041] According to the above transfer function, the control system transfer function is obtained as follows:

[0042] H1(s)=k·P·A·(1+G PID (s))

[0043]

[0044] Preferably, controlling the power generation of the system by means of a magnetic gearbox comprises the following steps:

[0045] Step 1: Obtain the grid load voltage and frequency as system control input;

[0046] Step 2: According to the relationship between the excitation current and output torque of the magnetic gearbox, the system transfer function G1(s) is obtained;

[0047] Step 3: According to the dynamic equation of the synchronous generator, virtual inertia is introduced into the system to obtain the virtual inertia transfer function Gsg(s), the grid parameters are used as the control input, and the excitation current is used as the control output;

[0048] Step 4: Dynamically adjust the virtual inertia according to the excitation current and grid voltage and frequency.

[0049] Preferably, the expression of the function of the magnetic gearbox excitation current and the output torque is:

[0050]

[0051]

[0052] Where μ0 is the magnetic permeability of vacuum, p out and p in are the number of magnetic pole pairs of the outer rotor and the inner rotor, B out and B in are the magnetic field strength of the outer air gap and the inner air gap, T in is the magnetic gearbox input torque, N is the number of turns of the electromagnet, L is the length of the electromagnet, and I is the excitation current

[0053] According to the above formula, the transfer function G1(s) of the swash plate angle control motor output torque is obtained:

[0054]

[0055] The input signal of the virtual inertia system is determined by G1(s), where the virtual inertia system is obtained by simulating the mathematical model of the synchronous generator, and its transfer function Gsg(s) is expressed as:

[0056]

[0057] The virtual generator is controlled to control the motor output torque, and the control system has adjustable inertia. PID control is adopted, and the transfer function H1(s) is expressed as:

[0058]

[0059]

[0060] Among them, J is the virtual inertia, D is the virtual damping, L is the virtual synchronous machine winding inductance, R is the virtual synchronous winding resistance, and K is the virtual synchronous machine structure parameter.

[0061] According to the above transfer function, the control system transfer function is obtained as follows:

[0062] H1(s)=k·P·A·(1+G PID (s))

[0063]

[0064] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0065] The present invention provides a feasible method and solution for achieving stability and energy efficiency improvement of a compressed air energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0067] Figure 1 This is a diagram of a mechanical virtual inertia-based compressed air power generation control system proposed in the present invention; 1-air storage tank, 2-air compressor, 3-switch valve, 4-temperature sensor, 5-pressure sensor, 6-hydraulic motor, 7-magnetic gearbox, 8-permanent magnet synchronous generator, 9-filter, 10-inverter, 11-rectifier, 12-power generation system, 13-grid load, 14-control system.

[0068] Figure 2 It is a signal diagram of the mechanical virtual inertia algorithm proposed in the present invention; 14-control system, 15-control algorithm.

[0069] Figure 3It is the control block diagram of the mechanical virtual inertia compressed air power generation control system proposed in the present invention; 16-compressed air system transfer function G1(s), 17-hydraulic motor and magnetic gearbox transfer function G2(s), 18-virtual inertia model transfer function H1(s). DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] Example 1

[0072] This embodiment provides a compressed air power generation control system based on mechanical virtual inertia, including: a mechanical control system and a virtual inertia system;

[0073] The mechanical control system includes: an air storage tank 1, an air compressor 2, a switch valve 3, a pressure sensor 5, a temperature sensor 4, a hydraulic motor 6, a magnetic gear box 7, a power generation system 12 and a grid load 13;

[0074] The gas storage tank 1, the air compressor 2, the switch valve 3, the hydraulic motor 6, the magnetic gear box 7, the power generation system 12 and the grid load 13 are connected in sequence;

[0075] The pressure sensor 5 and the temperature sensor 4 are respectively connected to the air compressor 2;

[0076] The virtual inertial system includes a control signal processor and a control system 14;

[0077] The control signal processor collects signals from the pressure sensor 5, the temperature sensor 4, and the grid load 13;

[0078] The control signal processor transmits a signal to the control system 14;

[0079] The control system 14 controls the hydraulic motor 6 , the magnetic gear box 7 , and the power generation system 12 respectively.

[0080] In this embodiment, the power generation system 12 includes: a permanent magnet synchronous generator 8, a rectifier 11, a filter 9, and an inverter 10;

[0081] The magnetic gearbox 7, the permanent magnet synchronous generator 8, the filter 9, the inverter 10, the rectifier 11 and the grid load 13 are connected in sequence;

[0082] The control system 14 controls the rectifier 11 .

[0083] Preferably, the control system 14 is provided with a hydraulic motor swash plate control module, a magnetic gearbox control module, and an electrical control module;

[0084] The hydraulic motor swash plate control module changes the swash plate angle of the hydraulic motor to a set value according to input parameters and a virtual inertia model;

[0085] The input of the magnetic gearbox control module is the power quality of the generator, and the output is the excitation current. The magnetic field of the gearbox is controlled by controlling the excitation current;

[0086] The electrical control module makes fine adjustments to the output of the power generation system through the inverter control module to improve the power quality.

[0087] Example 2

[0088] This embodiment provides a method for compressed air power generation based on a compressed air power generation control system of mechanical virtual inertia, which adopts the above-mentioned power generation control system, specifically including a virtual inertia system and a mechanical control construction;

[0089] Virtual inertia system: By building a virtual synchronous machine model, the input signal is converted into the synchronous generator input voltage and power, the output is the synchronous generator torque, and then the output is converted into the required output signal. The virtual synchronous machine inertia is changed according to the system conditions to achieve system adjustable virtual inertia control;

[0090] Mechanical control system: includes a magnetic gearbox and a hydraulic motor. The system power generation is controlled through the hydraulic motor swash plate and the magnetic gearbox. The specific controlled physical quantities are the swash plate angle and the magnetic gearbox excitation current. The mechanical virtual inertia control is achieved by combining the virtual inertia algorithm with the mechanical system.

[0091] The swash plate angle control of the hydraulic motor based on virtual inertia includes the following steps:

[0092] Step 1: Obtain the grid load voltage and frequency as system control input;

[0093] Step 2: According to the relationship between the swash plate angle and the output torque of the hydraulic motor, the system transfer function G1(s) is obtained;

[0094] Step 3: According to the synchronous generator dynamic equation, virtual inertia is introduced into the system to obtain the virtual inertia transfer function Gsg(s), the grid parameters are used as the control input, and the swash plate angle is used as the control output;

[0095] Step 4: Dynamically adjust the virtual inertia according to the swash plate angle and grid voltage and frequency.

[0096] The expression of the function of the hydraulic motor swash plate angle and output torque is:

[0097] ML 2πn=ΔpQ s =Δpqn

[0098]

[0099] Among them, M L is the theoretical torque, Δp is the inlet and outlet differential pressure, q is the motor displacement, Q s is the actual flow rate, z is the number of plungers, R is the radius of the plunger distribution circle, d is the plunger diameter, and β is the inclination angle of the swash plate;

[0100] According to the above formula, the transfer function G1(s) of the swash plate angle control motor output torque is obtained:

[0101]

[0102] The input signal of the virtual inertia system is determined by G1(s), where the virtual inertia system is obtained by simulating the mathematical model of the synchronous generator, and its transfer function Gsg(s) is expressed as:

[0103]

[0104] The virtual generator is controlled to control the motor output torque, and the control system has adjustable inertia. PID control is adopted, and the transfer function H1(s) is expressed as:

[0105]

[0106]

[0107] Among them, J is the virtual inertia, D is the virtual damping, L is the virtual synchronous machine winding inductance, R is the virtual synchronous winding resistance, and K is the virtual synchronous machine structure parameter.

[0108] According to the above transfer function, the control system transfer function is obtained as follows:

[0109] H1(s)=k·P·A·(1+G PID (s))

[0110]

[0111] Controlling the system power generation through the magnetic gearbox includes the following steps:

[0112] Step 1: Obtain the grid load voltage and frequency as system control input;

[0113] Step 2: According to the relationship between the excitation current and output torque of the magnetic gearbox, the system transfer function G1(s) is obtained;

[0114] Step 3: According to the dynamic equation of the synchronous generator, virtual inertia is introduced into the system to obtain the virtual inertia transfer function Gsg(s), the grid parameters are used as the control input, and the excitation current is used as the control output;

[0115] Step 4: Dynamically adjust the virtual inertia according to the excitation current and grid voltage and frequency.

[0116] Preferably, the expression of the function of the magnetic gearbox excitation current and the output torque is:

[0117]

[0118]

[0119] Where μ0 is the magnetic permeability of vacuum, p out and p in are the number of magnetic pole pairs of the outer rotor and the inner rotor, B out and B in are the magnetic field strength of the outer air gap and the inner air gap, T in is the magnetic gearbox input torque, N is the number of turns of the electromagnet, L is the length of the electromagnet, and I is the excitation current

[0120] According to the above formula, the transfer function G1(s) of the swash plate angle control motor output torque is obtained:

[0121]

[0122] The input signal of the virtual inertia system is determined by G1(s), where the virtual inertia system is obtained by simulating the mathematical model of the synchronous generator, and its transfer function Gsg(s) is expressed as:

[0123]

[0124] The virtual generator is controlled to control the motor output torque, and the control system has adjustable inertia. PID control is adopted, and the transfer function H1(s) is expressed as:

[0125]

[0126]

[0127] Among them, J is the virtual inertia, D is the virtual damping, L is the virtual synchronous machine winding inductance, R is the virtual synchronous winding resistance, and K is the virtual synchronous machine structure parameter.

[0128] According to the above transfer function, the control system transfer function is obtained as follows:

[0129] H1(s)=k·P·A·(1+G PID (s))

[0130]

[0131] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0132] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compressed air power generation control system based on mechanical virtual inertia, characterized in that: include: Mechanical control systems and virtual inertial systems; The mechanical control system includes: an air storage tank, an air compressor, a switch valve, a pressure sensor, a temperature sensor, a hydraulic motor, a magnetic gear box, a power generation system and a grid load; The gas storage tank, air compressor, switch valve, hydraulic motor, magnetic gear box, power generation system and grid load are connected in sequence; The pressure sensor and the temperature sensor are respectively connected to the air compressor; The virtual inertial system includes a control signal processor and a control system; The control signal processor collects signals from the pressure sensor, the temperature sensor, and the grid load; The control signal processor transmits a signal to the control system; The control system controls the hydraulic motor, the magnetic gear box and the power generation system respectively.

2. A compressed air power generation control system based on mechanical virtual inertia according to claim 1, characterized in that: The power generation system comprises: a permanent magnet synchronous generator, a rectifier, a filter, and an inverter; The magnetic gearbox, permanent magnet synchronous generator, filter, inverter, rectifier and grid load are connected in sequence; The control system controls the rectifier.

3. A compressed air power generation control system based on mechanical virtual inertia according to claim 2, characterized in that: The control system is provided with a hydraulic motor swash plate control module, a magnetic gear box control module, and an electrical control module; The hydraulic motor swash plate control module changes the swash plate angle of the hydraulic motor to a set value according to the input parameters and the virtual inertia model; The magnetic gearbox control module inputs the power quality of the generated electricity and outputs the excitation current, and controls the magnetic field of the gearbox by controlling the excitation current; The electrical control module makes fine adjustments to the output of the power generation system through the current conversion control module to improve the quality of electric energy.

4. A method for compressed air power generation based on a compressed air power generation control system of mechanical virtual inertia, characterized in that: The power generation control system according to claim 3 is adopted, which specifically includes a virtual inertial system and a mechanical control construction; Virtual inertia system: By building a virtual synchronous machine model, the input signal is converted into the synchronous generator input voltage and power, the output is the synchronous generator torque, and then the output is converted into the required output signal. The virtual synchronous machine inertia is changed according to the system conditions to achieve system adjustable virtual inertia control; Mechanical control system: includes a magnetic gearbox and a hydraulic motor. The system power generation is controlled through the hydraulic motor swash plate and the magnetic gearbox. The specific controlled physical quantities are the swash plate angle and the magnetic gearbox excitation current. The mechanical virtual inertia control is achieved by combining the virtual inertia algorithm with the mechanical system.

5. The method for compressed air power generation by a compressed air power generation control system based on mechanical virtual inertia according to claim 4 is characterized in that: Controlling the system power generation through the hydraulic motor swash plate includes the following steps: Step 1: Obtain the grid load voltage and frequency as system control input; Step 2: According to the relationship between the swash plate angle and the output torque of the hydraulic motor, the system transfer function G1(s) is obtained; Step 3: According to the synchronous generator dynamic equation, virtual inertia is introduced into the system to obtain the virtual inertia transfer function Gsg(s), the grid parameters are used as the control input, and the swash plate angle is used as the control output; Step 4: Dynamically adjust the virtual inertia according to the swash plate angle and grid voltage and frequency.

6. The method for compressed air power generation by a compressed air power generation control system based on mechanical virtual inertia according to claim 5 is characterized in that: The expression of the function of the hydraulic motor swash plate angle and output torque is: M L 2πn=ΔpQ s =Δpqn Among them, M L is the theoretical torque, Δp is the inlet and outlet differential pressure, q is the motor displacement, Q s is the actual flow rate, z is the number of plungers, R is the radius of the plunger distribution circle, d is the plunger diameter, and β is the inclination angle of the swash plate; According to the above formula, the transfer function G1(s) of the swash plate angle control motor output torque is obtained: The input signal of the virtual inertia system is determined by G1(s), where the virtual inertia system is obtained by simulating the mathematical model of the synchronous generator, and its transfer function Gsg(s) is expressed as: The virtual generator is controlled to control the motor output torque, and the control system has adjustable inertia. PID control is adopted, and the transfer function H1(s) is expressed as: Among them, J is the virtual inertia, D is the virtual damping, L is the virtual synchronous machine winding inductance, R is the virtual synchronous winding resistance, and K is the virtual synchronous machine structure parameter. According to the above transfer function, the control system transfer function is obtained as follows: H1(s)=k P A (1+G PID (s)) 7. The method for compressed air power generation by a compressed air power generation control system based on mechanical virtual inertia according to claim 4 is characterized in that: Controlling the system power generation through the magnetic gearbox includes the following steps: Step 1: Obtain the grid load voltage and frequency as system control input; Step 2: According to the relationship between the excitation current and output torque of the magnetic gearbox, the system transfer function G1(s) is obtained; Step 3: According to the dynamic equation of the synchronous generator, virtual inertia is introduced into the system to obtain the virtual inertia transfer function Gsg(s), the grid parameters are used as the control input, and the excitation current is used as the control output; Step 4: Dynamically adjust the virtual inertia according to the excitation current and grid voltage and frequency.

8. The method for compressed air power generation by a compressed air power generation control system based on mechanical virtual inertia according to claim 7 is characterized in that: The expression of the function of the magnetic gearbox excitation current and output torque is: Where μ0 is the magnetic permeability of vacuum, p out and p in are the number of magnetic pole pairs of the outer rotor and the inner rotor, B out and B in are the magnetic field strength of the outer air gap and the inner air gap, T in is the magnetic gearbox input torque, N is the number of turns of the electromagnet, L is the length of the electromagnet, and I is the excitation current According to the above formula, the transfer function G1(s) of the swash plate angle control motor output torque is obtained: The input signal of the virtual inertia system is determined by G1(s), where the virtual inertia system is obtained by simulating the mathematical model of the synchronous generator, and its transfer function Gsg(s) is expressed as: The virtual generator is controlled to control the motor output torque, and the control system has adjustable inertia. PID control is adopted, and the transfer function H1(s) is expressed as: Among them, J is the virtual inertia, D is the virtual damping, L is the virtual synchronous machine winding inductance, R is the virtual synchronous winding resistance, and K is the virtual synchronous machine structure parameter. According to the above transfer function, the control system transfer function is obtained as follows: H1(s)=k P A (1+G PID (s))

Images