Optimization control method, system, terminal and medium of frequency-modulated energy power supply

Abstract

The present invention discloses an optimization control method for a frequency-modulated energy-type power supply, and discloses a system, a terminal and a medium having the optimization control method for a frequency-modulated energy-type power supply. The optimization control method for the frequency-modulated energy-type power supply can be based on an approximate optimal control trajectory, can take into account coordination with traditional synchronous generators, ensure system frequency stability while reducing frequency modulation costs.

Description

Technical Field

[0001] The present invention relates to the technical field of power system operation, and in particular to an optimization control method, system, terminal and medium for a frequency-modulated energy-type power supply. Background Art

[0002] Since the "dual carbon" goals were proposed, an increasing number of converter-interfaced power sources, including renewable energy sources, have been connected to the grid. The decreasing proportion of traditional generators has weakened their inertia support and primary frequency regulation capabilities. Furthermore, the increasing scale of UHVDC transmission has also increased the potential for system disturbances, making system frequency stability increasingly problematic.

[0003] As the converter interface power supply gradually becomes the main installed capacity and power source of the system, the system requires the converter interface power supply to provide frequency regulation capability to prevent frequency stability risks. However, the primary energy supply of the converter interface power supply represented by new energy units is uncontrollable, and its reserve for upward standby requires reducing long-term output so that it can provide frequency support during power shortages, which requires an extremely high economic cost.

[0004] Some power sources in the system can provide short-term frequency support during power shortages by releasing limited energy, such as the rotational kinetic energy of wind turbines. These power sources are collectively referred to as frequency-modulated energy-releasing power sources. Efficiently utilizing this frequency-modulated energy can reduce the amount of power electronics required for backup, thereby improving economic efficiency. However, existing methods for utilizing frequency-modulated energy fail to fully exploit the flexibility of the converter, and their control strategies are limited in practicality, making them unsuitable for guiding the operational control of frequency-modulated energy-releasing power sources. Therefore, it is necessary to develop optimized control methods for frequency-modulated energy. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an optimized control method for a frequency-modulated energy-type power supply. This method is capable of ensuring system frequency stability while reducing frequency modulation costs based on an optimal control trajectory and taking into account coordination with traditional synchronous generators.

[0006] The present invention also provides a system, a terminal and a medium having the above-mentioned optimization control method of the frequency-modulated energy-type power supply.

[0007] The optimization control method of a frequency-modulated energy-type power supply according to the first embodiment of the present invention is characterized by comprising the following steps:

[0008] Monitor the frequency in real time. When the frequency difference exceeds the dead zone, calculate the disturbance power and the real-time power shortage.

[0009] If the disturbance power is greater than the preset critical disturbance power, the start output time and power distribution coefficient of each unit are calculated;

[0010] Each frequency-regulated energy-type power source releases energy to keep the frequency at the lowest allowable value until the sum of the generator output and the damping power meets the power shortage, at which point the control ends.

[0011] According to the optimization control method of the frequency-modulated energy power supply according to the embodiment of the present invention, there are at least the following beneficial effects: the optimization control method of the frequency-modulated energy power supply provided by the embodiment of the present invention provides an optimization control trajectory of the frequency-modulated energy, which can take into account the frequency-modulation characteristics of the synchronous machine and minimize the frequency-modulated energy while ensuring the stability of the system frequency; and a specific control strategy is proposed based on the above trajectory, by providing a square wave response method of the power output in the form of a time domain function, so that the frequency-modulated energy power supply can achieve short-term frequency support at critical moments.

[0012] According to some embodiments of the present invention, the magnitude of the critical disturbance power ΔP c Correspondingly, only the frequency regulation of conventional units can keep the frequency within the limit, that is, When the disturbance power is less than or equal to ΔP c When , the FM energy does not need to be released; where Δω max The maximum frequency deviation allowed by the system.

[0013] According to some embodiments of the present invention, the frequency modulation energy type power supply output speed is v add The control method uses the real-time frequency change rate to predict the time required for the frequency to drop to the minimum allowable value. When this time is equal to the time required for the power supply to increase the real-time power shortage, the frequency-modulated energy-type power supply starts to output power:

[0014]

[0015] According to some embodiments of the present invention, the control method is expressed as:

[0016]

[0017] The optimization control system of the frequency-modulated energy power supply according to the second embodiment of the present invention is characterized by comprising:

[0018] The disturbance monitoring module can monitor the frequency in real time. When the frequency difference exceeds the dead zone, it calculates the disturbance power and the real-time power shortage.

[0019] The frequency modulation control module calculates the start output time and power distribution coefficient of each unit if the disturbance power is greater than the preset critical disturbance power;

[0020] The energy release module enables each frequency-regulated energy source to release energy to keep the frequency at the lowest allowable value until the sum of the generator output and the damping power meets the power shortage, at which point the control ends.

[0021] According to some embodiments of the present invention, the magnitude of the critical disturbance power ΔP c Correspondingly, only the frequency regulation of conventional units can keep the frequency within the limit, that is, When the disturbance power is less than or equal to ΔP c When , the FM energy does not need to be released; where Δω max The maximum frequency deviation allowed by the system.

[0022] According to some embodiments of the present invention, the start time of the control process of the system satisfies the following formula:

[0023]

[0024] According to some embodiments of the present invention, the control process of the system satisfies the following formula:

[0025]

[0026] According to the terminal of the third embodiment of the present invention, the terminal includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned optimization control method of the frequency-modulated energy-type power supply is implemented.

[0027] According to a fourth aspect of an embodiment of the present invention, a computer-readable storage medium stores computer-executable instructions, which are used to execute the above-mentioned optimization control method of the frequency-modulated energy-type power supply.

[0028] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0030] Figure 1 A schematic diagram of a system frequency response model provided by an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of the steps of the optimization control method of the frequency-modulated energy-type power supply provided by an embodiment of the present invention;

[0032] Figure 3 This is a structural block diagram of the optimization control system of the frequency-modulated energy-type power supply provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0034] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0035] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0037] 1. Optimal control problem of frequency modulation energy.

[0038] In the traditional system frequency response model used in the prior art to analyze the frequency dynamic response, such as Figure 1 As shown, the primary frequency modulation effects of all power backup power sources can be aggregated into a first-order link, and the power generated by the frequency modulation energy power source is the input quantity u(t).

[0039] Reference Figure 1 , where ΔP d is the disturbance power, Δω is the frequency deviation, H is the equivalent inertia constant of the system's conventional units, D is the equivalent aggregate damping coefficient of the system, T G is the aggregate frequency modulation time constant, R G is the adjustment coefficient, and F is the proportional constant of the high-pressure cylinder.

[0040] The purpose of control is to keep the system frequency within the allowable range with the minimum frequency modulation cost, that is, the minimum frequency modulation energy release. Therefore, the optimal control problem is established as follows:

[0041] a) Performance functional:

[0042]

[0043] b) System mathematical model:

[0044]

[0045]

[0046] c) Control constraints:

[0047] 0≤u(t)

[0048] d) State constraints:

[0049] -Δω max ≤Δω(t)

[0050] e) Boundary conditions:

[0051] Δω(0)=0

[0052] ΔP G (0)=0

[0053] ΔP G (t f )-DΔω(t f )=ΔP d

[0054] In this optimal control problem, u(t) is the control quantity, i.e., the power when the frequency modulation energy is released, t f To control the terminal moment, Δω, ΔP G They are the system frequency and the generator primary frequency modulation power, which are the two state quantities of the system. The disturbance is set to the power shortage that occurs at time 0, ΔP d is a constant greater than zero.

[0055] Based on the above system model, in order to facilitate the solution and analysis of optimal control, the following assumptions are made:

[0056] To ensure control reliability, the output power is required to be no less than zero when energy is released.

[0057] In order to give full play to the plasticity of power electronic power supply, only its segmented continuity is required.

[0058] No upper limit is set for the output of the power electronic power supply. It is assumed that it can provide the required power and the issue is only considered from the perspective of minimizing the energy cost.

[0059] 2. Solving the optimal control trajectory.

[0060] According to the homogeneity of linear systems, if the input is scaled proportionally by a factor of k, the output will also be scaled by a factor of k. Furthermore, the superposition property indicates that the frequency response corresponding to the allowable control with the lowest energy cost must reach the maximum frequency deviation at a certain moment. Assuming that the time at which the maximum energy deviation is first reached is t1, the optimal control trajectory can be divided into two segments. According to the optimality principle of dynamic programming, regardless of the control of the first segment, the state formed by the second segment with respect to the first segment is always the optimal control. Therefore, the optimal control trajectory is solved in segments.

[0061] First, let’s analyze the second stage of control. The convolution theorem can be used to obtain the relationship between the generator’s primary frequency modulation output increase and the frequency in the time domain:

[0062]

[0063] The lower the frequency trajectory, the faster the generator output increases. In the second stage, according to the law of conservation of energy, we can get:

[0064]

[0065] The left side of formula (2) is the energy corresponding to the second-stage control quantity, the first term on the right side is the deficit energy, the second term is the sum of the energy generated by the primary frequency modulation and the damping power, and the third term is the inertia energy, that is, the rotor kinetic energy absorption energy of the traditional generator.

[0066] When the frequency trajectory is kept at the lowest allowable value, at any moment, the sum of the primary frequency modulation energy and the damping energy is the maximum value under any control strategy, and the generator rotor kinetic energy absorption is zero. At this time, the corresponding frequency modulation energy is minimum. Let the control be u * And the control terminal moment is For any admissible control u′ that satisfies the constraints, let its control terminal time be t′ f , there must be:

[0067]

[0068] If and only if the admissible control takes u * When , both equal signs hold true. Therefore, the optimal control strategy for the second stage should keep the frequency at the lowest allowable value until the sum of the primary frequency modulation power and the damping power meets the power deficit, and the control ends. The optimal control trajectory for the second stage can be obtained as:

[0069]

[0070] And the trajectory of generator output increase:

[0071]

[0072] The optimal control strategy for the first stage and the end time t1 of the first stage control are further determined to optimize the overall objective functional. The present invention first provides the optimal control strategy for the first stage and proves its optimality. The optimal control strategy for the first stage is: after the disturbance, no energy is released, that is, the control quantity remains at 0, the frequency naturally drops to the minimum allowable value and reaches the end time of the first stage. At time t1, the control quantity jumps from zero to the initial value of the second stage control trajectory. It is now proved that:

[0073] According to the state space equation of the system, the state transfer equation of the system can be obtained:

[0074]

[0075] The matrix B is the input matrix in the system state space expression. The state transfer matrix can directly analyze and calculate the impact of the input on the state quantity. For any power injection form, the frequency change at any time t after the disturbance is:

[0076]

[0077]

[0078]

[0079] According to the frequency response characteristics, let the lowest point of the frequency response when no control is applied be t n , t n Satisfy r t n +φ1=π. Therefore, when τ=0: when t takes t n When t is less than t n When t is greater than t n When , the integral object is less than 0. Further, the equation before the control input u(τ) in the integral sign is differentiated with respect to τ:

[0080]

[0081]

[0082] Under the system parameters, φ1 is in the second quadrant, and φ2 is in the first quadrant, when t is less than or equal to t n When the derivative function is greater than zero within 0-t, that is, for 0-t n At any moment in time, the power injected before that moment will increase the frequency at that moment. Therefore, it can be seen that releasing energy before t1 will cause the frequency curve before t1 to increase rather than decrease.

[0083] Apply any allowable control u″ to the first stage, and the end time of the first stage is t″1. Regardless of the first stage control, the second stage continues to use the optimal control strategy of this stage. During the period 0-t″1, the frequency curve Δω″ under u″ control will not be lower than the frequency curve Δω corresponding to the optimal control. * , the generator output at time t″1 must increase by And the control end moment must have

[0084] For the 0-t″1 stage, the law of conservation of energy yields:

[0085]

[0086] From the effect of frequency on the generator output increase and damping power, it can be seen that the sum of the generator output increase and damping power under optimal control provides the maximum energy, that is:

[0087]

[0088] If and only if u″=u * When the equality sign holds, the optimal control trajectory of the first stage is proved, so the complete expression of the optimal control process is:

[0089]

[0090] Since the damping power is small and difficult to estimate accurately, and the sum of the primary frequency modulation power and the damping power can be directly estimated by using the system frequency change rate, the damping power is directly moved to the attenuation term. In this way, the power at the start of output time t1 remains unchanged, while the subsequent power increases to a certain extent. This also ensures the reliability and feasibility of the control, and amplifies the optimal control trajectory to approximate the optimal trajectory:

[0091]

[0092] 3. Frequency modulation energy optimization control strategy.

[0093] Based on the approximate optimal trajectory obtained above, the optimal control method of the frequency-modulated energy-type power supply formulated according to the trajectory is as follows: Figure 2 As shown, including:

[0094] Step S100: monitor the frequency in real time. When the frequency difference exceeds the dead zone, calculate the disturbance power and the real-time power shortage.

[0095] Critical disturbance power ΔP c Correspondingly, only the frequency regulation of conventional units can make the system frequency not exceed the limit, that is, When the disturbance power is less than or equal to ΔP c , the FM energy does not need to be released.

[0096] The disturbance power and real-time power shortage are obtained by multiplying the frequency change rate by 2H. The PMU is used to measure the corresponding frequencies of multiple generator rotors and calculate their average value to avoid the influence of frequency distribution characteristics.

[0097] Step S200: If the disturbance power is greater than the preset critical disturbance power, the output start time and power distribution coefficient of each unit are calculated.

[0098] The aggregated inertia time constant, primary frequency modulation time constant, and adjustment coefficient can be used by the dispatching center to simultaneously issue parameter sizes each time a power on / off command is issued. Conservative parameters can also be set to reduce communication requirements and provide a safety margin.

[0099] Assume that the output speed of frequency-modulated energy source is v add , use the real-time frequency change rate to predict the time required for the system frequency to drop to the minimum allowable value. When it is equal to the time required for the power supply to increase the real-time power shortage, the frequency-modulated energy-type power supply starts to output:

[0100]

[0101] Step S300: Each frequency-modulated energy power source releases energy to keep the frequency at the lowest allowable value.

[0102] Step S400: When the sum of the generator output and the damping power meets the power shortage, the control ends.

[0103] The power distribution ratio between each power supply is determined according to the frequency modulation energy. When the power command decreases to 0, the energy release phase ends.

[0104] Furthermore, the embodiment of the present application provides an optimization control system for a frequency-modulated energy-type power supply, such as Figure 3 As shown, the system 30 includes:

[0105] The disturbance monitoring module 301 can monitor the frequency in real time. When the frequency difference exceeds the dead zone, it calculates the disturbance power and the real-time power shortage.

[0106] The frequency modulation control module 302 calculates the output start time and power allocation coefficient of each unit if the disturbance power is greater than the preset critical disturbance power;

[0107] The energy release module 303 enables each frequency-modulated energy power source to release energy to keep the frequency at the lowest allowable value.

[0108] The stop module 304 ends the control when the sum of the generator output and the damping power meets the power shortage.

[0109] Furthermore, the magnitude of the critical disturbance power ΔPc Correspondingly, only the frequency regulation of conventional units can keep the frequency within the limit, that is, When the disturbance power is less than or equal to ΔP c When , the FM energy does not need to be released; where Δω max The maximum frequency deviation allowed by the system.

[0110] Furthermore, the aggregated frequency modulation time constant T G , adjustment coefficient R G As well as the high-pressure cylinder proportional constant F, the dispatch center can use it to send parameter sizes at the same time when issuing a power on / off command. It can also reduce communication requirements and provide a safety margin by setting conservative parameters.

[0111] Furthermore, the control process of the system satisfies the following equation:

[0112]

[0113] Another embodiment of the present application provides a terminal, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned optimization control method of the frequency-modulated energy-type power supply.

[0114] Specifically, a processor may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. A processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like.

[0115] Specifically, the processor is connected to the memory via a bus. The bus may include a path for transmitting information. The bus may be a PCI bus or an EISA bus. The bus may be divided into an address bus, a data bus, a control bus, etc.

[0116] The memory may be a ROM or other type of static storage device that can store static information and instructions, a RAM or other type of dynamic storage device that can store information and instructions, or an EEPROM, CD-ROM or other optical disk storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), magnetic disk storage medium or other magnetic storage device, 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 to these.

[0117] Optionally, the memory is used to store the code of the computer program that executes the solution of the present application, and the processor controls the execution. The processor is used to execute the application code stored in the memory to implement the operation of the optimization control system of the frequency-modulated energy power supply provided by the above embodiment.

[0118] Another embodiment of the present application provides a computer-readable storage medium storing computer-executable instructions for executing the above-mentioned Figure 2 The optimization control method of the frequency-modulated energy-type power supply is shown.

[0119] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, i.e., they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0120] Those skilled in the art will appreciate that all or some of the steps and systems in the method disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include computer storage media (or non-transitory media) and communication media (or temporary media). As known to those skilled in the art, the term computer storage media is included in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data) and is volatile and non-volatile, removable, and non-removable. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technology, CD-ROM, digital versatile disks (DVD), or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage, or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0121] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above implementation mode. Technical personnel familiar with the field can also make various equivalent modifications or substitutions without violating the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A method for optimizing and controlling a frequency-modulated energy-type power supply, characterized in that: The following steps are involved: Monitor the frequency in real time. When the frequency difference exceeds the dead zone, calculate the disturbance power and the real-time power shortage. If the disturbance power is greater than the preset critical disturbance power, the start output time and power distribution coefficient of each unit are calculated; wherein the magnitude of the critical disturbance power is Correspondingly, only the frequency regulation of conventional units can keep the frequency within the limit, that is, , when the disturbance power is less than or equal to , the FM energy does not need to be released; The maximum frequency deviation allowed by the system; Use the real-time frequency change rate to predict the time required for the frequency to drop to the minimum allowed value. When this time is equal to the time required for the power supply to increase the real-time power shortage, the frequency-modulated energy-type power supply starts to output power. The formula is: in, Increase the output speed of frequency-modulated energy power supply; Each frequency-regulated energy-type power source releases energy to keep the frequency at the lowest allowable value until the sum of the generator output and the damping power meets the power shortage, at which point the control ends.

2. The method according to claim 1, characterized in that The expression of the control method is: u(t) The input quantity is the instruction to increase the power of the frequency-modulated energy power supply.

3. An optimization control system for a frequency-modulated energy-type power supply, characterized in that: include: The disturbance monitoring module can monitor the frequency in real time. When the frequency difference exceeds the dead zone, it calculates the disturbance power and the real-time power shortage. The frequency control module calculates the start output time and power distribution coefficient of each unit if the disturbance power is greater than the preset critical disturbance power; wherein the magnitude of the critical disturbance power Correspondingly, only the frequency regulation of conventional units can keep the frequency within the limit, that is, , when the disturbance power is less than or equal to , the FM energy does not need to be released; The maximum frequency deviation allowed by the system; the real-time frequency change rate is used to predict the time required for the frequency to drop to the minimum allowed value. When this time is equal to the time required for the power supply to increase the real-time power shortage, the frequency-modulated energy-type power supply starts to output: in, v add Increase the output speed of frequency-modulated energy power supply; The energy release module enables each frequency-regulated energy source to release energy to keep the frequency at the lowest allowable value until the sum of the generator output and the damping power meets the power shortage, at which point the control ends.

4. The system according to claim 3, characterized in that The control process of the system satisfies the following formula: 。 5. A terminal comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method according to any one of claims 1 to 2. 6 . A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the method according to claim 1 .

Images