A method and device for evaluating primary frequency modulation capability in a power system

Abstract

A primary frequency modulation capability evaluation method and device for a power system, characterized in that the method comprises the following steps: Step 1, collecting the device parameters of synchronous generator sets and grid-connected inverters in the power system to calculate the frequency deviation coefficients of the synchronous generator sets and grid-connected inverters; Step 2, collecting the frequency regulation characteristics of static loads and dynamic loads in the power system to obtain the frequency regulation factors of the loads; Step 3, obtaining the operating power of the synchronous generator sets, the grid-connected inverters and the loads, the frequency deviation in the power system, and solving the primary frequency modulation capability index of the power system based on the calculation results of Step 1 and Step 2, thereby evaluating the primary frequency modulation capability of the power system. The algorithm is simple, comprehensively considers the frequency modulation capabilities and frequency modulation participation situations of various different power system subjects, and provides reliable evaluation basis.

Description

Technical Field

[0001] This invention relates to the field of power systems, and more specifically, to a method and apparatus for evaluating the primary frequency regulation capability of a power system. Background Technology

[0002] When the frequency of the power system changes beyond the specified insensitivity zone, the regulating control system of the generator units in the system automatically controls the increase or decrease of the active power of the units, which will cause the system frequency to drop or rise. This is the primary frequency regulation process of the units. The actual active power consumed by the loads related to frequency characteristics will also change with the system frequency.

[0003] The primary frequency regulation capability of a power grid is mainly related to two factors: the frequency regulation capability of generating units and the frequency characteristics of the load. With the increasing scale of power generation equipment from renewable energy sources and the rising proportion of renewable energy output, conventional generating units are being largely replaced, leading to a continuous decline in the primary frequency regulation capability of the power grid. Although there has been extensive research in recent years on frequency regulation during renewable energy grid-connected operation, aiming to enable renewable energy to actively support system frequency regulation, the proactive frequency regulation capability of renewable energy grid connection remains a priority.

[0004] In addition, although different types of frequency regulation resources can adjust active power output or power consumption according to the actual frequency deviation of the system, there is a lack of unified quantitative evaluation indicators among different frequency regulation resources, and it is impossible to specifically quantify and evaluate the actual primary frequency regulation capability of the system, which brings difficulties to the arrangement of system operation mode.

[0005] To address the above problems, this invention proposes a method and apparatus for evaluating the primary frequency regulation capability in a power system. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method and apparatus for evaluating the primary frequency regulation capability of a power system, which comprehensively determines the primary frequency regulation capability of the power system by considering the operating status of synchronous generator sets, grid-connected inverters, and loads.

[0007] The present invention adopts the following technical solution.

[0008] A method for evaluating the primary frequency regulation capability of a power system includes the following steps: Step 1, collecting equipment parameters of synchronous generator sets and grid-connected inverters in the power system to calculate the frequency deviation coefficients of the synchronous generator sets and grid-connected inverters; Step 2, collecting the frequency regulation characteristics of static and dynamic loads in the power system to obtain the frequency regulation factor of the load; Step 3, obtaining the operating power of the synchronous generator sets, grid-connected inverters, and loads, the frequency deviation in the power system, and solving the primary frequency regulation capability index of the power system based on the calculation results of Step 1 and Step 2, thereby evaluating the primary frequency regulation capability of the power system.

[0009] Preferably, the equipment parameters of the synchronous generator set include the synchronous generator set number participating in frequency regulation in the power system, the frequency regulation dead zone, the operating power, and the rated power; the equipment parameters of the grid-connected inverter include the grid-connected inverter number participating in frequency regulation in the power system, the frequency regulation dead zone, the operating power, the rated power, and the frequency control method.

[0010] Preferably, the frequency deviation coefficient of the synchronous generator set is

[0011]

[0012] Where i is the number of the synchronous generator unit participating in frequency regulation in the power system, and its value ranges from 1 to I, K Gi P is the frequency deviation correction factor for the i-th synchronous generator set. Gi Let P be the operating power of the i-th synchronous generator unit. G∑ It is the sum of the rated power of all synchronous generator sets and grid-connected inverters participating in frequency regulation in the power system.

[0013] Preferably, the frequency deviation correction factor for the i-th synchronous generator set is:

[0014]

[0015] in, Δf is the frequency deviation in the power system, f dead-i For the frequency regulation dead zone of synchronous generator set i, Δf lim-i The primary frequency regulation limit for the pre-set synchronous generator set i; S i Let be the droop coefficient of the speed governor in the i-th synchronous generator set.

[0016] Preferably, the frequency control method of the grid-connected inverter is droop control or PID control; the frequency deviation correction coefficient of the grid-connected inverter with droop control is...

[0017]

[0018] Among them, K Rj Let K be the frequency deviation correction coefficient for the j-th grid-connected inverter, and K is given by... Rj =K′ fj ·Δf,K′ fj P is the rated frequency deviation of the j-th grid-connected inverter. Rj The grid-connected power of the grid-connected inverter;

[0019] The frequency deviation correction coefficient for a PID-controlled grid-connected inverter is

[0020]

[0021] Among them, K PIh Let K be the frequency deviation correction coefficient for the h-th grid-connected inverter, and K is given by... RPh =K′ fh ·Δf,K′ fh The rated frequency deviation P of the h-th grid-connected inverter PIh This refers to the grid-connected power of the grid-connected inverter.

[0022] Preferably, the frequency regulation factor of the load in the power system is calculated based on the proportion of the load that is proportional to the zeroth, first, and second powers of the rotor angular velocity of the synchronous generator set.

[0023] Preferably, the frequency adjustment factor of the load is the sum of the frequency adjustment factor of the static load and the frequency adjustment factor of the dynamic load, i.e., K. L =K′ L [K0+K(A+2B)];

[0024] Where K0 is the proportion of the mechanical power of the synchronous generator set that is proportional to the zeroth power of the rotor angular velocity, K is the load rate of the synchronous generator set, A is the proportion of the mechanical power of the synchronous generator set that is proportional to the square of the rotor angular velocity, B is the proportion of the mechanical power of the synchronous generator set that is proportional to the first power of the rotor angular velocity, and K′ is the percentage of the mechanical power of the synchronous generator set that is proportional to the first power of the rotor angular velocity. L This is a correction factor.

[0025] Preferably, step 2 further includes correcting the load frequency adjustment factor using the load voltage deviation; wherein the correction coefficient is... U is the actual voltage of the load. N This refers to the rated voltage of the power system.

[0026] Preferably, the primary frequency regulation capability index of the power system is:

[0027]

[0028] Among them, f N P is the rated frequency of the power grid. L∑ denoted as the total power of the load, and e represents the number of synchronous generator sets or grid-connected inverters in the power system that serve as power sources, with a value ranging from 1 to s.

[0029] A second aspect of the present invention relates to a device for evaluating the primary frequency regulation capability in a power system, the device being implemented using the method described in the first part of the present invention.

[0030] The beneficial effects of this invention are that, compared with the prior art, the method and apparatus for evaluating the primary frequency regulation capability of a power system can comprehensively determine the primary frequency regulation capability of the power system by considering the operating status of synchronous generator sets, grid-connected inverters, and loads. The algorithm of this invention is simple, comprehensively considers the frequency regulation capabilities and participation of various different power system entities, and provides a reliable evaluation basis. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the steps of a method for evaluating the primary frequency regulation capability in a power system according to the present invention. Detailed Implementation

[0032] The present application will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be construed as limiting the scope of protection of the present application.

[0033] Figure 1 This is a schematic flowchart illustrating the steps of a method for evaluating the primary frequency regulation capability in a power system according to the present invention. Figure 1 As shown, the first aspect of the present invention relates to a method for evaluating the primary frequency regulation capability in a power system, the method comprising steps 1 to 3.

[0034] Step 1: Collect the equipment parameters of the synchronous generator sets and grid-connected inverters in the power system to calculate the frequency deviation coefficients of the synchronous generator sets and grid-connected inverters.

[0035] Specifically, the main power generation components in a power system include synchronous generator sets and various new energy power generation facilities connected to the grid via grid-connected inverters. In this invention, parameters of the aforementioned equipment are collected to obtain the frequency deviation coefficients of each device.

[0036] The frequency deviation coefficient in this invention is mainly used to describe the unit frequency deviation of the equipment during operation. The definition of this coefficient can be determined based on the definition in the prior art. Once the relevant parameters and operating indicators of the equipment are determined, this frequency deviation coefficient can be uniquely determined.

[0037] Preferably, the equipment parameters of the synchronous generator set include the synchronous generator set number participating in frequency regulation in the power system, the frequency regulation dead zone, the operating power, and the rated power; the equipment parameters of the grid-connected inverter include the grid-connected inverter number participating in frequency regulation in the power system, the frequency regulation dead zone, the operating power, the rated power, and the frequency control mode.

[0038] Using the above parameters, the power generation and frequency regulation of various power sources connected to the grid by synchronous generator sets or inverters can be calculated effectively and accurately.

[0039] Preferably, the frequency deviation coefficient of the synchronous generator set is

[0040]

[0041] Where i is the number of the synchronous generator unit participating in frequency regulation in the power system, and its value ranges from 1 to I, K Gi P is the frequency deviation correction factor for the i-th synchronous generator set. Gi Let P be the operating power of the i-th synchronous generator unit. G∑ It is the sum of the rated power of all synchronous generator sets and grid-connected inverters participating in frequency regulation in the power system.

[0042] It is understandable that in a power system, the total synchronous generator frequency deviation coefficient can be obtained by weighting the frequency deviation coefficients of multiple generator sets. In addition, this weight can be obtained by the power weight of each synchronous generator set.

[0043] Preferably, the frequency deviation correction factor for the i-th synchronous generator set is:

[0044]

[0045] in, Δf represents the frequency deviation in the power system, which is the difference between the actual operating frequency of the power grid where the synchronous generator unit is located and the rated frequency of the power grid. dead-i For the frequency regulation dead zone of synchronous generator set i, Δf lim The primary frequency regulation limit for the pre-set synchronous generator set i; S i Let be the droop coefficient of the speed governor in the i-th synchronous generator set.

[0046] To obtain the frequency deviation coefficient of the synchronous generator set more accurately, this invention modifies this coefficient. The specific modification process involves eliminating this frequency regulation effect, considering that the synchronous generator set does not provide actual frequency regulation within the frequency regulation dead zone. Additionally, a frequency regulation threshold can be preset, which limits the primary frequency regulation amplitude of the synchronous generator set.

[0047] Specifically, the frequency regulation threshold involved in this invention should ensure that the value of the frequency regulation threshold is equal to the value of the frequency dead zone when the primary frequency regulation adjustable capacity of the generator set is reduced to 0, and when the adjustable capacity is not 0, its value should be greater than the value of the frequency dead zone.

[0048] Preferably, the frequency control method of the grid-connected inverter is droop control or PID control;

[0049] The frequency deviation correction factor for a droop-controlled grid-connected inverter is

[0050]

[0051] Among them, K Rj Let K be the frequency deviation correction coefficient for the j-th grid-connected inverter, and K is given by... Rj =K′ fj ·Δf,K′ fj P is the rated frequency deviation of the j-th grid-connected inverter. Rj The grid-connected power of the grid-connected inverter;

[0052] The frequency deviation correction coefficient for a PID-controlled grid-connected inverter is

[0053]

[0054] Among them, K PIh Let K be the frequency deviation correction coefficient for the h-th grid-connected inverter, and K is given by... RPh =K′ fh ·Δf,K′ fh P is the rated frequency deviation of the h-th grid-connected inverter. PIh This refers to the grid-connected power of the grid-connected inverter.

[0055] Similarly, depending on the type of grid-connected inverter, the frequency deviation coefficient of the power supply corresponding to the grid-connected inverter can also be solved separately.

[0056] Step 2: Collect the frequency regulation characteristics of static and dynamic loads in the power system to obtain the frequency regulation factor of the load.

[0057] This invention also considers the impact of load on frequency regulation. Therefore, by integrating multiple frequency regulation methods, an accurate assessment of regulation capability indicators can be achieved.

[0058] Preferably, the frequency regulation factor of the load in the power system is calculated based on the proportion of the load that is proportional to the zeroth, first, and second powers of the rotor angular velocity of the synchronous generator set.

[0059] It is understandable that, depending on the load characteristics in the power system, the load magnitude changes with the generator set angular velocity. However, some loads do not change accordingly; these are referred to as static loads in this invention. Other loads change proportionally to the first power of the rotor angular velocity, some to the square of the rotor angular velocity, and still others to higher powers of the rotor angular velocity. This invention does not consider overly complex issues, but simply extracts the proportion of loads that change proportionally to the first power of the rotor angular velocity within the total load. The proportion that changes proportionally to the square of the rotor angular velocity is extracted similarly. By increasing the adjustment coefficient to 2, the total frequency regulation factor of the load can be finally obtained.

[0060] Preferably, the frequency adjustment factor of the load is the sum of the frequency adjustment factor of the static load and the frequency adjustment factor of the dynamic load, i.e., K′ L [K0+K(A+2B)];

[0061] Where K0 is the proportion of the mechanical power of the synchronous generator set that is proportional to the zeroth power of the rotor angular velocity, K is the load rate of the synchronous generator set, A and B are the proportions of the load power of the synchronous generator set that are proportional to the first and second powers of the rotor angular velocity, respectively, and K′ L This is a correction factor.

[0062] In this way, the overall frequency regulation of loads that are more affected by frequency and loads that are less affected by frequency can be accurately obtained.

[0063] Preferably, step 2 further includes correcting the load frequency adjustment factor using the load voltage deviation; wherein the correction coefficient is... U is the actual voltage of the load, that is, the sum of the voltages at each load connection point. N This refers to the rated voltage of the power system.

[0064] It is understood that the loads in this invention may receive inaccurate power. For example, some loads are expected to receive active power at the rated voltage, but in reality, the power they receive varies with the actual voltage of the power grid. Therefore, in order to more accurately assess the frequency regulation capability of the power grid, the above-mentioned correction factor is added here.

[0065] Step 3: Obtain the operating power of the synchronous generator set, grid-connected inverter and load, and the frequency deviation in the power system. Based on the calculation results of Step 1 and Step 2, solve for the primary frequency regulation capability index of the power system, thereby evaluating the primary frequency regulation capability of the power system.

[0066] Preferably, the primary frequency regulation capability index of the power system is:

[0067]

[0068] Among them, f N P is the rated frequency of the power grid. L∑ denoted as the total power of the load, and e represents the number of synchronous generator sets or grid-connected inverters in the power system that serve as power sources, with a value ranging from 1 to s.

[0069] Understandably, based on the frequency regulation capability mentioned above, the overall frequency regulation capability index of the power grid can be obtained. This index is similar to the frequency regulation capability index in existing technologies, and both can characterize the frequency regulation capability of the power grid. They can also further guide the development and construction of the power grid or actual frequency regulation, so as to prevent operational failures and improve the safety and reliability of the power grid.

[0070] A second aspect of the present invention relates to a device for evaluating the primary frequency regulation capability in a power system, which is implemented using the method described in the first aspect of the present invention.

[0071] It is understood that, in order to implement the various functions in the methods provided in the embodiments of this application, the primary frequency modulation capability evaluation device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the algorithm steps of the examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0072] This application embodiment can divide the primary frequency modulation capability evaluation device into functional modules according to the above method example. For example, each function can be divided into its own functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0073] The device includes at least one processor, a bus system, and at least one communication interface.

[0074] The processor can be a central processing unit (CPU), or it can be replaced by a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or other hardware. Alternatively, an FPGA or other hardware can be used together with a CPU as a processor.

[0075] The memory can be read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed discs, laser discs, optical discs, universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited to these. The memory can exist independently and be connected to the processor via a bus. The memory can also be integrated with the processor.

[0076] The hard drive can be a mechanical hard drive or a solid-state drive (SSD), etc. The interface card can be a host bus adapter (HBA), a redundant array of independent disks (RID), an expander card, or a network interface controller (NIC), etc., and this embodiment of the invention is not limited to any particular type. The interface card in the hard drive module communicates with the hard drive. The storage node communicates with the interface card of the hard drive module to access the hard drive in the hard drive module.

[0077] The hard drive interface can be Serial Attached Small Computer System Interface (SAS), Serial Advanced Technology Attachment (SATA), or Peripheral Component Interconnect Express (PCIe), etc.

[0078] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software programs, implementation can be, in whole or in part, in the form of a computer program product. This computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device containing one or more servers, data centers, etc., that can be integrated with the medium. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state disks (SSDs)).

[0079] The beneficial effects of this invention are that, compared with the prior art, the method and apparatus for evaluating the primary frequency regulation capability of a power system can comprehensively determine the primary frequency regulation capability of the power system by considering the operating status of synchronous generator sets, grid-connected inverters, and loads. The algorithm of this invention is simple, comprehensively considers the frequency regulation capabilities and participation of various different power system entities, and provides a reliable evaluation basis.

[0080] The applicant of this invention has provided a detailed description of the embodiments of the invention in conjunction with the accompanying drawings. However, those skilled in the art should understand that the above embodiments are merely preferred embodiments of the invention. The detailed description is only intended to help readers better understand the spirit of the invention and is not intended to limit the scope of protection of the invention. On the contrary, any improvements or modifications made based on the inventive spirit of the invention should fall within the scope of protection of the invention.

Claims

1. A method for evaluating the primary frequency regulation capability in a power system, characterized in that, The method includes the following steps: Step 1: Collect the equipment parameters of the synchronous generator set and grid-connected inverter in the power system to calculate the frequency deviation coefficient of the synchronous generator set and grid-connected inverter. The frequency deviation coefficient of the synchronous generator set is in, The synchronous generator sets participating in frequency regulation in the power system are numbered, with values ​​ranging from 1 to... Natural numbers between For the first Frequency deviation correction factor for the aforementioned synchronous generator set. For the first The operating power of the aforementioned synchronous generator set It is the sum of the rated power of all synchronous generator sets participating in frequency regulation in the power system and the grid-connected inverter; The frequency control method of the grid-connected inverter is either droop control or PID control. The frequency deviation correction coefficient of the grid-connected inverter with droop control is in, For the first The frequency deviation correction coefficient of the grid-connected inverter, and has , For the first The rated frequency deviation of the grid-connected inverter is described above. The grid-connected power of the grid-connected inverter is... Frequency deviation in the power system; The frequency deviation correction coefficient of the grid-connected inverter under PID control is in, For the first The frequency deviation correction coefficient of the grid-connected inverter, and has , For the first The rated frequency deviation of the grid-connected inverter is described above. The grid-connected power of the grid-connected inverter; Step 2: Collect the frequency regulation characteristics of static and dynamic loads in the power system to obtain the frequency regulation factor of the load; The frequency adjustment factor of the load is the sum of the frequency adjustment factor of the static load and the frequency adjustment factor of the dynamic load, that is... K L = K L ' K 0 + K A + 2 B ; in, This refers to the proportion of the mechanical power of the synchronous generator set that is proportional to the zeroth power of the rotor angular velocity. Let A be the load rate of the synchronous generator set, A be the proportion of the mechanical power of the synchronous generator set that is proportional to the square of the rotor angular velocity, and B be the proportion of the mechanical power of the synchronous generator set that is proportional to the first power of the rotor angular velocity. This is a correction factor; Step 3: Obtain the operating power of the synchronous generator set, the grid-connected inverter, and the load, as well as the frequency deviation in the power system. Based on the calculation results of Step 1 and Step 2, solve for the primary frequency regulation capability index of the power system, thereby evaluating the primary frequency regulation capability of the power system. The primary frequency regulation capability index of the power system is: in, The rated frequency of the power grid. The total power of the load is given by , and the value of e ranges from 1 to s.

2. The method for evaluating the primary frequency regulation capability in a power system according to claim 1, characterized in that: The equipment parameters of the synchronous generator set include the synchronous generator set number participating in frequency regulation in the power system, frequency regulation dead zone, operating power, and rated power. The equipment parameters of the grid-connected inverter include the number of the grid-connected inverter participating in frequency regulation in the power system, the frequency regulation dead zone, the rated operating power, and the frequency control mode.

3. The method for evaluating the primary frequency regulation capability in a power system according to claim 2, characterized in that: No. The frequency deviation correction factor for each synchronous generator set is: in, , The frequency deviation in the power system, For the synchronous generator set FM dead zone For the pre-set synchronous generator set First frequency modulation limiting; For the first The droop coefficient of the speed governor in the aforementioned synchronous generator set.

4. The method for evaluating the primary frequency regulation capability in a power system according to claim 3, characterized in that: The frequency regulation factor of the load in the power system is calculated based on the proportion of the load that is proportional to the zeroth, first, and second powers of the rotor angular velocity of the synchronous generator set.

5. The method for evaluating the primary frequency regulation capability in a power system according to claim 4, characterized in that: Step 2 also includes correcting the frequency adjustment factor of the load using the load voltage deviation; Wherein, the correction coefficient is , The actual voltage of the load. The rated voltage of the power system is denoted as .

6. A device for evaluating the primary frequency regulation capability in a power system, characterized in that: The device is implemented using the method described in any one of claims 1-5.

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