Electric power system frequency modulation method and system based on electrolytic aluminum load, and storage medium

Abstract

The embodiment of the invention discloses an electrolytic aluminum load-based power system frequency modulation method, the power system comprises a plurality of generator sets, and the method comprises the following steps: constructing an electrolytic aluminum load model, and determining the active power of the electrolytic aluminum load; determining a maximum adjustable active power range and a frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load; enabling the electrolytic aluminum load to be equivalent to power generation equipment, and determining the active power frequency response of the power generation equipment; determining power system frequency modulation parameters according to the active power frequency responses of the power generation equipment and the plurality of generator sets; and performing frequency modulation on the power system according to the power system frequency modulation parameter. The electrolytic aluminum load is equivalent to the power generation equipment to participate in power system frequency modulation, so that the frequency modulation capability of the power system is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system frequency modulation, and particularly to a power system frequency modulation method, system and storage medium based on the load of electrolytic aluminum. Background Art

[0002] With the rapid development of new energy, its proportion in the power system is continuously increasing, while the proportion of traditional units is correspondingly decreasing. This leads to a decrease in the overall inertia level of the power system, thereby affecting the frequency modulation ability of the system and reducing its stability in the face of frequency fluctuations.

[0003] At present, although new energy sources such as wind power and photovoltaic power also participate in frequency modulation, the volatility of their output makes the frequency modulation ability insufficient, and may even cause a secondary drop in frequency. Therefore, the frequency modulation resources based on the power supply side can no longer meet the operating requirements of the power system. Summary of the Invention

[0004] Based on this, it is necessary to propose a power system frequency modulation method based on the load of electrolytic aluminum for the above problems.

[0005] A power system frequency modulation method based on the load of electrolytic aluminum, the power system includes a plurality of generating sets, and the method includes:

[0006] Construct an electrolytic aluminum load model to determine the active power of the electrolytic aluminum load;

[0007] Determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0008] Equivalent the electrolytic aluminum load to a generating device, and determine the active power frequency response of the generating device;

[0009] Determine the power system frequency modulation parameters according to the active power frequency responses of the generating device and the plurality of generating sets;

[0010] Perform frequency modulation on the power system according to the power system frequency modulation parameters.

[0011] In the above solution, the electrolytic aluminum further includes electrolytic cells. An electrolytic aluminum load model is constructed according to the topological structure of the electrolytic cells and the electrolytic aluminum load, the charge relationship between the electrolytic cells and the electrolytic aluminum load is equivalent, and combined with the DC voltage U of the electrolytic aluminum load model d Determine the active power of the electrolytic aluminum load:

[0012]

[0013] Wherein, R d is the equivalent resistance, E d is the back electromotive force, Ud is the DC voltage of the electrolytic cell, I d is the DC current of the electrolytic cell.

[0014] In the above solution, the DC voltage U combined with the electrolytic aluminum load model d To determine the active power of the electrolytic aluminum load, it further includes:

[0015] Adjust the commutation saturation angle α of the electrolytic aluminum load model by adjusting the magnitude of the control current of the saturable reactor:

[0016]

[0017] In the formula, ω is the power system angular frequency; N g is the number of turns of the working winding; A t is the cross-sectional area of the iron core; B b is the saturation magnetic density; μ is the magnetic permeability; N c is the number of turns of the control winding; I c is the control current; E is the effective value of the power system voltage;

[0018] Determine the DC voltage U of the electrolytic aluminum load model through the commutation saturation angle α and the regulation coefficient of the saturable reactor d :

[0019]

[0020] In the formula, U L is the effective value of the line voltage, U d0 is the maximum value of the DC voltage, k sr is the regulation coefficient of the saturable reactor;

[0021] Adjust the active power of the electrolytic aluminum load according to the DC voltage U of the electrolytic aluminum load model d In the above solution, to determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load, it specifically includes:

[0022] Calculate the maximum adjustable active power of the electrolytic aluminum load according to the current regulation limit of the electrolytic cell and the voltage regulation ability of the saturable reactor:

[0023] ΔP max = min{ΔP max1 , ΔP max2}

[0024] where, ΔP max1 is determined by the current derating constraint, and ΔP max2 is determined by the voltage regulation limit of the saturable reactor;

[0025] The frequency response control strategy includes determining the electrolyzer current reference value according to the system frequency deviation, and setting a frequency dead zone and current limit.

[0026] In the above solution, determining the power system frequency regulation parameter according to the active power frequency response of the power generation equipment and several generator sets further includes;

[0027] When the actual frequency of the power system exceeds the preset threshold f max or is lower than the preset threshold f min it is determined that the actual frequency of the power system is in the frequency response dead zone, and at this time, the power system is frequency regulated.

[0028] In the above solution, determining the power system frequency regulation parameter according to the active power frequency response of the power generation equipment specifically includes:

[0029] Equivalent the aluminum electrolysis load to the power generation equipment, and use the unified structure model to fit the active frequency of the power generation equipment;

[0030] Solve the model parameters of the unified structure model;

[0031] The unified structure model is:

[0032]

[0033] Among them, J u is the effective inertia, D u is the effective damping coefficient, K u is the effective static droop coefficient, and T0 is the droop time constant;

[0034] Obtain the power system frequency regulation parameter according to the model parameters of the unified structure model of each power generation equipment.

[0035] In the above solution, obtaining the power system frequency regulation parameter according to the model parameters of the unified structure model of each power generation equipment specifically includes:

[0036]

[0037] In the formula, t0 and t1 are respectively the initial time and the terminal time of the optimization trajectory; ΔP cm,ii (t) is the output power of the i-th power generation equipment for the common-mode frequency response, and ΔP cm,i (s) is its complex frequency domain form; ΔP′ cm,ii (t) is the equivalent output power of the i-th power generation equipment for the common-mode frequency response after being equivalent to the unified structure model, and ΔP′ cm,i (s) is its complex frequency domain form; G u,i (s) is the unified structure model of the i-th power generation equipment, and Δω cm(s) is the complex frequency domain form of the common mode frequency.

[0038] In the above solution, the frequency modulation of the power system according to the power system frequency modulation parameters specifically includes:

[0039] Determine the frequency response of the power system under a step power disturbance according to the power system frequency modulation parameters;

[0040] Perform frequency modulation on the power system according to the frequency response.

[0041] In the above solution, the frequency response is:

[0042]

[0043] In the formula, w i is the weight of each device, ΔP L (s) is the system equivalent disturbance, G i (s) is the frequency-active power transfer function of the i-th power generation device, Δω cm (s) is the common mode frequency response of the power system.

[0044] This application also discloses a power system frequency modulation system based on the electrolytic aluminum load. The system includes: an electrolytic aluminum load modeling unit, a strategy analysis unit, an equivalent fitting unit, a system integration unit, and a system frequency modulation unit;

[0045] The electrolytic aluminum load modeling unit is used to construct an electrolytic aluminum load model, determine the active power of the electrolytic aluminum load, and adjust the active power of the electrolytic aluminum load through a saturable reactor;

[0046] The strategy analysis unit is used to determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0047] The equivalent fitting unit is used to equivalent the electrolytic aluminum load to a power generation device, fit the active power-frequency response characteristics of the power generation device using a unified structure model, and solve the model parameters of the unified structure model of the power generation device;

[0048] The system integration unit is used to obtain the power system unified structure model parameters according to the model parameters of the unified structure model of each power generation device, and determine the frequency response of the power system under a step power disturbance;

[0049] The system frequency modulation unit is used to perform frequency modulation on the power system according to the frequency response.

[0050] This application also proposes a readable storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to execute the following steps:

[0051] Build an electrolytic aluminum load model to determine the active power of the electrolytic aluminum load;

[0052] Determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0053] Equivalent the electrolytic aluminum load to a power generation device and determine the active power frequency response of the power generation device;

[0054] Determine the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets;

[0055] Perform frequency modulation on the power system according to the power system frequency modulation parameters.

[0056] This application also proposes a computer device, including a memory and a processor. The memory stores a computer program, and the computer program is executed by the processor as follows:

[0057] Build an electrolytic aluminum load model to determine the active power of the electrolytic aluminum load;

[0058] Determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0059] Equivalent the electrolytic aluminum load to a power generation device and determine the active power frequency response of the power generation device;

[0060] Determine the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets;

[0061] Perform frequency modulation on the power system according to the power system frequency modulation parameters.

[0062] Adopting the embodiments of the present invention has the following beneficial effects: This solution quantifies the active power regulation ability of the electrolytic aluminum load by building an electrolytic aluminum load model, and transforms the traditional rigid load into a virtual power generation resource with fast frequency response; by determining the maximum adjustable power range and control strategy of the electrolytic aluminum load, it can be equivalent to a power generation device with droop characteristics and participate in system frequency modulation synergistically with conventional units. This method utilizes the millisecond-level power regulation speed of the electrolytic aluminum load to significantly improve the dynamic response ability of the power system in the initial stage of frequency drop. At the same time, through optimizing the system-level frequency modulation parameters to achieve multi-resource collaborative control, it not only relieves the frequency modulation pressure of the generator sets, but also reduces the frequency modulation cost, and finally effectively suppresses frequency fluctuations and enhances the operation stability of the high-proportion renewable energy power grid. Description of the Drawings

[0063] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0064] Among them:

[0065] Figure 1 It is a schematic flow diagram of a power system frequency modulation method based on the electrolytic aluminum load in an embodiment;

[0066] Figure 2 It is the topological structure of the electrolytic aluminum load;

[0067] Figure 3 It is the internal structure of the saturable reactor;

[0068] Figure 4 It is the frequency response structure diagram of the electrolytic aluminum load;

[0069] Figure 5 It is the frequency response trajectory under step power disturbance;

[0070] Figure 6 It is a simulation system with wind power and electrolytic aluminum load;

[0071] Figure 7 It is the change of electrolytic aluminum power consumption under different conditions;

[0072] Figure 8 It is the primary frequency modulation process of the power system under different conditions;

[0073] Figure 9 It is the comparison of the frequency trajectories of the unified structure model and the time-domain model under different conditions. Specific implementation manners

[0074] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0075] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention; however, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details; in other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described, and it should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments presented here; on the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art.

[0076] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "a", "an" and "said / the" are also intended to include the plural forms, unless the context clearly indicates otherwise, and it should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0077] Existing research focuses on the frequency regulation capability of a single resource (such as the power supply side or the load side), and lacks a comprehensive optimization strategy for the coordinated frequency regulation of the load side (such as electrolytic aluminum) and the power supply side (such as new energy and energy storage). How to build a multi-source coordinated frequency regulation control framework to achieve rapid response and precise suppression of frequency fluctuations is still a key issue that needs to be solved in the field of stable operation of the current power system.

[0078] Therefore, this application provides a power system frequency regulation method based on electrolytic aluminum load. By establishing a high-precision system frequency response analysis model and exploring the coordinated frequency regulation mechanism between the load side and the power supply side, it has important theoretical significance and engineering application value for improving the stability of the power system.

[0079] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention; optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0080] like Figure 1 As shown, in one embodiment, a method for frequency regulation of a power system based on electrolytic aluminum load is provided. The method for frequency regulation of a power system based on electrolytic aluminum load includes steps S101 to S105, which are described in detail as follows:

[0081] S101, constructing an electrolytic aluminum load model to determine the active power of the electrolytic aluminum load;

[0082] By establishing an electrolytic aluminum load model, the electricity consumption characteristics of the electrolytic aluminum load can be accurately described, and the change of its active power can be monitored in real time. This is the basis for subsequent participation in frequency modulation and provides data support for accurately evaluating the frequency modulation potential of the electrolytic aluminum load.

[0083] As Figure 2 shown in the schematic diagram of the topological structure of the electrolytic cell and the electrolytic aluminum load, the electrolytic aluminum also includes electrolytic cells. Since the electrolytic cells use direct current with low voltage and high current during electrolysis, high-voltage AC buses are required to collect electric energy to the DC bus through a three-phase bridge rectification system. The rectification system contains multiple groups of parallel rectification circuits. Specifically, the electrolytic cells convert alumina into aluminum metal, which can be represented by an equivalent resistance R d and a back electromotive force E d connected in series.

[0084] Since the equivalent resistance R d and the equivalent back electromotive force E d can be considered to remain unchanged for a determined aluminum plant, therefore, an electrolytic aluminum load model is constructed according to the topological structure of the electrolytic cell and the electrolytic aluminum load, the charge relationship between the electrolytic cell and the electrolytic aluminum load is equivalent, and combined with the DC voltage U d of the electrolytic aluminum load model to determine the active power of the electrolytic aluminum load:

[0085]

[0086] wherein, R d is the equivalent resistance, E d is the back electromotive force, U d is the DC voltage of the electrolytic cell, and I d is the DC current of the electrolytic cell.

[0087] As Figure 3 shown in the schematic diagram of the internal structure of the saturable reactor, the saturable reactor can achieve fine adjustment of the voltage. By adjusting the current Ic in the DC side control winding, the magnetic flux value of the iron core is changed to achieve the purpose of controlling the equivalent reactance size of the working winding. The size of the equivalent reactance can change the commutation time of the rectification circuit, which is represented by the commutation saturation angle α, and then achieve fine adjustment of the output voltage U d of the rectification circuit.

[0088] In some embodiments, determining the active power of the electrolytic aluminum load in combination with the DC voltage U d of the electrolytic aluminum load model further includes:

[0089] Adjusting the commutation saturation angle α of the electrolytic aluminum load model by the magnitude of the control current of the saturable reactor:

[0090]

[0091] where ω is the angular frequency of the power system; N g is the number of turns of the working winding; A t is the cross-sectional area of the iron core; B b is the saturation magnetic flux density; μ is the magnetic permeability; N c is the number of turns of the control winding; I c is the control current; E is the effective value of the power system voltage;

[0092] Determine the DC voltage U of the electrolytic aluminum load model through the commutation saturation angle α and the regulation coefficient of the saturable reactor d :

[0093]

[0094] where U L is the effective value of the line voltage, U d0 is the maximum value of the DC voltage, k sr is the regulation coefficient of the saturable reactor;

[0095] According to the DC voltage U of the electrolytic aluminum load model d Adjust the active power of the electrolytic aluminum load.

[0096] S102. Determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0097] Based on the active power data obtained in the first step, calculate the upper and lower limits of the active power that the electrolytic aluminum load can participate in regulating, and formulate specific strategies on how to adjust the load under different frequency deviations. This is equivalent to formulating an "action guide" for the electrolytic aluminum load to participate in frequency modulation, ensuring the safety, effectiveness of its regulation behavior, and maximizing its frequency modulation ability.

[0098] In fact, since the electrolytic aluminum load is a high-energy-consuming industrial load with good regulation potential, its adjustable frequency capacity mainly depends on its load reduction ability. By adjusting the working voltage and working current of the electrolytic cell, the active power consumption of the electrolytic aluminum load can be changed. However, considering actual situations such as production requirements and equipment safety, the adjustment ranges of voltage and current are limited.

[0099] The current stability of the electrolytic cell is the key to ensuring the stable production of the electrolytic aluminum load. When the current drops, it will lead to a reduction in output, but will not cause a decrease in quality and equipment damage. If the current drops by more than 10%, it will directly cause the production of electrolytic aluminum to stagnate, causing a greater impact. Therefore, during the normal production process of electrolytic aluminum, the current can be reduced by a minimum of 10%. At this time, the series voltage is:

[0100] U d ' = (1 - 10%)I d R d + Ed

[0101] At this time, the available active power limit of the electrolytic aluminum load is:

[0102] ΔP max1 = P d -(1 - 10%)I d U d '

[0103] In addition, when considering the voltage regulation capacity limit of the saturable reactor, the available active power limit of the electrolytic aluminum load is:

[0104]

[0105] Among them, is the voltage regulation limit depth of the saturable reactor, and I’ d is the series current corresponding to the limit voltage regulation of the saturable reactor, that is:

[0106]

[0107] Therefore, the maximum active power that the electrolytic aluminum load can provide when participating in frequency modulation is:

[0108] ΔP max = min{ΔP max1 , ΔP max2}.

[0109] It can be seen that the active power of the electrolytic aluminum load depends on the DC voltage of the electrolytic cell, and the change of the grid frequency will not directly change the DC voltage of the electrolytic cell, nor will it cause the change of the active power of the electrolytic aluminum load. Therefore, in order for the electrolytic aluminum load to participate in the grid frequency modulation, the system frequency deviation should be used as a feedback signal to adjust the electrolytic aluminum saturable reactor, so that the active power of the electrolytic aluminum load can automatically respond to the system frequency change.

[0110] When the system suffers from load disturbances, in order to prevent the electrolytic aluminum from malfunctioning due to small frequency fluctuations, a frequency response dead zone is specially set. Only when the actual grid frequency exceeds the preset threshold f max , the electrolytic aluminum load will trigger the frequency modulation response function. Taking the system frequency deviation Δf as the input, through droop control, inertia control or a comprehensive inertia control combining the two, the reference value I ref d of the electrolytic cell series current is adjusted to change the active power of the electrolytic aluminum load and provide power support for the system. In order to prevent the excessive change of the electrolytic cell DC current from affecting the electrolytic aluminum production stagnation, a limiting link is also needed to ensure that the current drop does not exceed 10%. Among them, the frequency response structure diagram of the electrolytic aluminum load participating in frequency modulation is as Figure 4 shown.

[0111] S103. Equivalent the electrolytic aluminum load to a power generation device and determine the active power frequency response of the power generation device;

[0112] By "virtually" turning the electrolytic aluminum load into a generator, it can be incorporated into the original frequency modulation framework of the power system. Determining its active power frequency response means clarifying how this "virtual generator" adjusts its output when the frequency changes, laying a foundation for the subsequent coordinated control with real generator sets. This is equivalent to giving the electrolytic aluminum load the same "frequency modulation identity" as a generator.

[0113] S104. Determine the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets;

[0114] Comprehensively considering the frequency response characteristics of the "virtual generator" (electrolytic aluminum load) and real generator sets, calculate the optimal power system frequency modulation parameters. These parameters guide how the entire system distributes the frequency modulation tasks to achieve the fastest frequency recovery and the smallest frequency deviation. This is equivalent to formulating an "overall plan" for the power system frequency modulation to ensure the optimal utilization of various frequency modulation resources.

[0115] In some embodiments, determining the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets further includes:

[0116] When the actual frequency of the power system exceeds the preset threshold f max or is lower than the preset threshold f min , it is determined that the actual frequency of the power system is in the frequency response dead zone, and at this time, frequency modulation is performed on the power system.

[0117] In some embodiments, determining the power system frequency modulation parameters according to the active power frequency response of the power generation device specifically includes:

[0118] Equivalent the electrolytic aluminum load to a power generation device and use a unified structure model to fit the active frequency of the power generation device;

[0119] Solve the model parameters of the unified structure model;

[0120] The unified structure model is:

[0121]

[0122] where J u is the effective inertia, D u is the effective damping coefficient, K u is the effective static droop coefficient, and T0 is the droop time constant;

[0123] Obtain the power system frequency modulation parameters according to the model parameters of the unified structure model of each power generation device.

[0124] It should be noted that when solving the unified structure model parameters of each device, in order to avoid the generation of high-order terms, the droop time constants of each device are regarded as the same.

[0125] If we want to analyze the system frequency response, we need to know the models of all generating devices. However, if we comprehensively consider the detailed models of each device, it may lead to overly complex solutions and make the analysis extremely difficult. Therefore, this paper chooses to use a unified structure model to simplify and replace the detailed models of various generating devices, which can not only simplify the analysis process but also ensure a certain degree of accuracy.

[0126] Assume that the perturbation received by the system is a step power perturbation. Then the common-mode frequency response of the power system often shows a certain specific law, including the overshoot phenomenon that may occur in the initial stage of the response and the frequency deviation that may exist at steady state, as Figure 6 shown by the solid line in [reference]. A unified structure model based on three links of differential-proportional-first-order lag is adopted. This unified structure model can well fit the variation law of the above-mentioned common-mode frequency response and can provide an effective tool for the frequency stability analysis of the power system.

[0127] Since the aluminum electrolysis load can also provide power support for the system by reducing the load when the system is subjected to a load perturbation, the aluminum electrolysis load can be equivalently regarded as a generating device in this case. According to the control strategy when the aluminum electrolysis load participates in frequency regulation, the frequency-active power transfer function G AL (s) similar to that of the synchronous machine can also be obtained.

[0128] Solving the parameters of the unified structure model of each generating device essentially means finding appropriate J u,i , D u,i , K u,i and T0 parameters so that the response of the device unified structure model G u,i (s) can approximate the accurate response of the frequency-active power transfer function G i (s) as much as possible. Since the common-mode frequency response can represent the system frequency response, only the responses of G u,i (s) and G i (s) to the common-mode frequency Δω cm input need to be analyzed. Therefore, it is necessary to solve the parameters of the unified structure model of the generating device.

[0129] In some embodiments, the power system frequency regulation parameters are obtained according to the model parameters of the unified structure model of each generating device, specifically including:

[0130]

[0131] where t0 and t1 are the initial time and terminal time of the optimization trajectory respectively; ΔPcm,i (t) is the output power of the i-th power generation equipment for the common-mode frequency response, ΔP cm,i (s) is its complex frequency domain form; ΔP′ cm,i (t) is the equivalent output power of the i-th power generation equipment for the common-mode frequency response after being equivalent to a unified structure model, ΔP′ cm,i (s) is its complex frequency domain form; G u,i (s) is the unified structure model of the i-th power generation equipment, Δω cm (s) is the complex frequency domain form of the common-mode frequency.

[0132] S105. Frequency modulation is performed on the power system according to the power system frequency modulation parameters.

[0133] Preferably, the power response of the system is equal to the sum of the power responses of all equipment. Therefore, the method for solving the parameters of the unified structure model of the system is to add up the J u , D u , K u parameters, that is Then, frequency modulation is performed on the power system according to the superimposed power system frequency modulation parameters.

[0134] According to the calculated frequency modulation parameters, real-time frequency modulation control is performed on the power system. This includes adjusting the output of the generator set and the power consumption of the electrolytic aluminum load, so that the system frequency quickly returns to the set value and remains stable. This is the goal and foothold of the entire solution, realizing the closed-loop control and optimization of the power system frequency.

[0135] In some embodiments, frequency modulation is performed on the power system according to the power system frequency modulation parameters, specifically including:

[0136] Determining the frequency response of the power system under step power disturbance according to the power system frequency modulation parameters;

[0137] Performing frequency modulation on the power system according to the frequency response.

[0138] In some embodiments, the frequency response is:

[0139]

[0140] In the formula, w i is the weight of each device, ΔP L (s) is the equivalent disturbance of the system, G i (s) is the frequency-active transfer function of the i-th power generation equipment, Δω cm (s) is the common-mode frequency response of the power system.

[0141] Among them, the system common-mode frequency is an effective index for the frequency change of the new energy high-penetration system, which can reflect the consistent part in the frequency responses of each node.

[0142] Let the parameters of the unified structure model of the power system be denoted as J us , D us , K us .

[0143] At this time, under the equivalent power step disturbance ΔP L (s) = -P0 / s of the power system, the system frequency response is:

[0144]

[0145] Taking the inverse Laplace transform of the above formula, the system frequency response trajectory based on the unified structure model of the differential-proportional-first-order lag link can be obtained as shown by the dashed line in Figure 5 . In contrast, Figure 5 Although the PID unified structure model shown by the dash-dotted line in can perform well when simulating the area near the lowest point of the original trajectory, its accuracy will be significantly reduced when describing the trajectory after the lowest point.

[0146] In some embodiments, set the load sudden increase fault to 35MW, and the power consumption changes and the primary frequency regulation process of the electrolytic aluminum load when not participating in frequency regulation, with a small frequency modulation coefficient, and a large frequency modulation coefficient are as shown in Figure 7 , Figure 8 . The parameters of the unified structure model obtained by solving in the three cases are shown in Table 1.

[0147] Table 1 Parameters of the unified structure model in three cases

[0148]

[0149] As can be seen from Table 1, as the degree of participation of the electrolytic aluminum load in the system frequency regulation increases, that is, the greater the power support provided, the effective inertia J u and the effective damping coefficient D u in the unified structure model of the system are also greater, indicating that the participation of the electrolytic aluminum load in the system frequency regulation can effectively improve the overall inertia level of the system.

[0150] Comparing the system frequency trajectory approximately obtained based on the unified structure model with the frequency trajectory obtained from the time-domain model, the results are as shown in Figure 9 . It can be seen that using the unified structure model to analyze the system frequency response with the participation of electrolytic aluminum load has high accuracy.

[0151] This application also discloses a power system frequency regulation system based on electrolytic aluminum load, and the system includes: an electrolytic aluminum load modeling unit, a strategy analysis unit, an equivalent fitting unit, a system integration unit, and a system frequency regulation unit;

[0152] The electrolytic aluminum load modeling unit is used to build an electrolytic aluminum load model, determine the active power of the electrolytic aluminum load, and adjust the active power of the electrolytic aluminum load through a saturable reactor;

[0153] The strategy analysis unit is used to determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0154] The equivalent fitting unit is used to equivalent the electrolytic aluminum load to a power generation device, fit the active power-frequency response characteristics of the power generation device by using a unified structure model, and solve the model parameters of the unified structure model of the power generation device;

[0155] The system integration unit is used to obtain the unified structure model parameters of the power system according to the model parameters of the unified structure model of each power generation device, and determine the frequency response of the power system under a step power disturbance;

[0156] The system frequency modulation unit is used to perform frequency modulation on the power system according to the frequency response.

[0157] This application also proposes a readable storage medium storing a computer program, which when executed by a processor causes the processor to perform the following steps:

[0158] Build an electrolytic aluminum load model and determine the active power of the electrolytic aluminum load;

[0159] Determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0160] Equivalent the electrolytic aluminum load to a power generation device and determine the active power frequency response of the power generation device;

[0161] Determine the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets;

[0162] Perform frequency modulation on the power system according to the power system frequency modulation parameters.

[0163] This application also proposes a computer device including a memory and a processor, and the memory stores a computer program, which when executed by the processor performs the following steps:

[0164] Build an electrolytic aluminum load model and determine the active power of the electrolytic aluminum load;

[0165] Determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load;

[0166] Equivalent the electrolytic aluminum load to a power generation device and determine the active power frequency response of the power generation device;

[0167] Determine the frequency modulation parameters of the power system according to the active power frequency response of the power generation equipment and several generator sets;

[0168] Perform frequency modulation on the power system according to the frequency modulation parameters of the power system.

[0169] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0170] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0171] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. The above-disclosed are only the preferred embodiments of the present invention, and of course, the scope of the present invention cannot be limited thereby. Therefore, the equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A power system frequency modulation method based on the load of electrolytic aluminum, the power system includes a number of generator sets, characterized in that, The method includes: Constructing an electrolytic aluminum load model to determine the active power of the electrolytic aluminum load; Determining the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load; Equivalently converting the electrolytic aluminum load into a power generation device to determine the active power frequency response of the power generation device; Determining the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets; Performing frequency modulation on the power system according to the power system frequency modulation parameters.

2. The power system frequency modulation method based on the electrolytic aluminum load according to claim 1, wherein, The electrolytic aluminum further includes an electrolytic cell. An electrolytic aluminum load model is constructed according to the topological structure of the electrolytic cell and the electrolytic aluminum load, the charge relationship between the electrolytic cell and the electrolytic aluminum load is equivalent, and the DC voltage U of the electrolytic aluminum load model is combined d Determine the active power of the electrolytic aluminum load: Among them, R d is the equivalent resistance, E d is the back electromotive force, U d is the DC voltage of the electrolytic cell, I d is the DC current of the electrolytic cell.

3. The power system frequency modulation method based on the electrolytic aluminum load according to claim 2, wherein The DC voltage U in combination with the aluminum electrolysis load model d Determining the active power of the aluminum electrolysis load further includes: Adjusting the commutation saturation angle α of the electrolytic aluminum load model by the magnitude of the control current of the saturable reactor: where ω is the angular frequency of the power system; N g is the number of turns of the working winding; A t is the cross-sectional area of the iron core; B b is the saturation magnetic flux density; μ is the permeability; N c is the number of turns of the control winding; I c is the control current; E is the effective value of the power system voltage; Determine the DC voltage U of the electrolytic aluminum load model through the commutation saturation angle α and the regulation coefficient of the saturable reactor d : Where, U L is the effective value of the line voltage, U d0 is the maximum value of the DC voltage, and k sr is the regulation coefficient of the saturable reactor; According to the DC voltage U of the aluminum electrolysis load model d Adjust the active power of the aluminum electrolysis load.

4. The power system frequency regulation method based on the electrolytic aluminum load according to claim 1, characterized in that The determining the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load specifically includes: Calculating the maximum adjustable active power of the electrolytic aluminum load according to the electrolytic cell current regulation limit and the voltage regulation ability of the saturable reactor; ΔP max = min{ΔP max1 , ΔP max2} where, ΔP max1 is determined by the current derating constraint, and ΔP max2 is determined by the voltage regulation limit of the saturable reactor; The frequency response control strategy includes determining the electrolytic cell current reference value according to the system frequency deviation and setting a frequency dead zone and current limit.

5. The power system frequency modulation method based on the electrolytic aluminum load according to claim 1, wherein The determining the power system frequency modulation parameters according to the active power frequency responses of the power generation device and several generator sets further includes; When the actual frequency of the power system exceeds the preset threshold f max or is lower than the preset threshold f min it is determined that the actual frequency of the power system is in the frequency response dead zone, and at this time, frequency modulation is performed on the power system.

6. The power system frequency modulation method based on the electrolytic aluminum load according to claim 5, characterized in that The determining the power system frequency modulation parameters according to the active power frequency response of the power generation device specifically includes: Equivalently converting the electrolytic aluminum load into a power generation device and fitting the active power frequency of the power generation device by using a unified structure model; Solving the model parameters of the unified structure model; The unified structure model is: Among them, J u is the effective inertia, D u is the effective damping coefficient, K u is the effective static droop coefficient, and T0 is the droop time constant; Obtaining the power system frequency modulation parameters according to the model parameters of the unified structure model of each power generation device.

7. The power system frequency modulation method based on the electrolytic aluminum load according to claim 6, wherein, The obtaining the power system frequency modulation parameters according to the model parameters of the unified structure model of each power generation device specifically includes: where \(t_0\) and \(t_1\) are the initial time and the terminal time of the optimized trajectory respectively; \(\Delta P\) cm,i (t) is the output power of the \(i\)-th power generation device for the common-mode frequency response, \(\Delta P\) cm,i (s) is its complex frequency domain form; \(\Delta P'\) cm,i (t) is the equivalent output power of the \(i\)-th power generation device for the common-mode frequency response after being equivalent to a unified structure model, \(\Delta P'\) cm,i (s) is its complex frequency domain form; \(G\) u,i (s) is the unified structure model of the \(i\)-th power generation device, \(\Delta\omega\) cm (s) is the complex frequency domain form of the common-mode frequency.

8. The power system frequency modulation method based on the electrolytic aluminum load according to claim 1, wherein The performing frequency modulation on the power system according to the power system frequency modulation parameters specifically includes: Determining the frequency response of the power system under a step power disturbance according to the power system frequency modulation parameters; Performing frequency modulation on the power system according to the frequency response.

9. The power system frequency modulation method based on the electrolytic aluminum load according to claim 1, characterized in that The frequency response is: where, w i is the weight of each device, ΔP L (s) is the equivalent system disturbance, G i (s) is the frequency-active power transfer function of the i-th power generation device, Δω cm (s) is the common-mode frequency response of the power system.

10. A power system frequency modulation system based on the load of electrolytic aluminum, characterized in that, The system includes: an electrolytic aluminum load modeling unit, a strategy analysis unit, an equivalent fitting unit, a system integration unit, and a system frequency modulation unit; The electrolytic aluminum load modeling unit is used to construct an electrolytic aluminum load model, determine the active power of the electrolytic aluminum load, and adjust the active power of the electrolytic aluminum load through a saturable reactor; The strategy analysis unit is used to determine the maximum adjustable active power range and frequency response control strategy of the electrolytic aluminum load according to the active power of the electrolytic aluminum load; The equivalent fitting unit is used to equivalently convert the electrolytic aluminum load into a power generation device, fit the active power-frequency response characteristic of the power generation device by using a unified structure model, and solve the model parameters of the unified structure model of the power generation device; The system integration unit is used to obtain the power system unified structure model parameters according to the model parameters of the unified structure model of each power generation device and determine the frequency response of the power system under a step power disturbance; The system frequency modulation unit is used to perform frequency modulation on the power system according to the frequency response.

11. A readable storage medium stores a computer program. When the computer program is executed by a processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 9.

12. A computer device includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 9.

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