Method, system and equipment for determining standby expected value of fan power load shedding

Abstract

The invention discloses a method, a system and equipment for determining a standby expected value of fan power load shedding. The method comprises the following steps: establishing an index of frequency modulation confidence coefficient based on primary frequency modulation participated by a wind turbine generator; the wind speed is partitioned based on an active power-wind speed characteristic curve of the wind turbine generator, and power reserve expected values under corresponding partitions are established; in each partition, according to the demand of the frequency modulation confidence of the wind turbine generator, calculating the variable load shedding coefficient of the wind turbine generator participating in the frequency modulation in each partition; and determining a standby expected value of fan power load shedding based on the variable load shedding coefficient of the wind turbine generator participating in frequency modulation in each partition. According to the frequency deviation and the frequency modulation requirement of the power grid, the variable load shedding coefficient can be flexibly adjusted, and quick response and accurate control of power output of the wind turbine generator are achieved.

Description

Technical Field

[0001] This invention relates to the field of wind power grid connection and power system operation control technology, specifically to a method, system, and equipment for determining the expected value of wind turbine power load shedding reserve. Background Technology

[0002] The stator windings of the wind turbine are directly connected to the power grid, while the rotor side achieves a flexible connection to the grid through a power electronic converter. This structure enables the wind turbine to react earlier than conventional synchronous generators when the system frequency fluctuates, thanks to its rapid response control capabilities. This provides timely active power support to the grid frequency and effectively enhances the transient stability of the system.

[0003] To ensure wind turbines can continuously provide effective power support during frequency regulation, they are typically required to operate in a reduced-load state, meaning they actively reserve a portion of their active capacity as a frequency regulation backup. Common reduced-load operation methods include fixed-power reduced-load and fixed-reduction-factor reduced-load. However, both methods have significant limitations: under low wind speed conditions, the available reduced-load space is limited, often failing to reserve sufficient backup capacity; while during high wind speeds, excessive reduced-load can easily lead to excess reserved capacity, resulting in a waste of wind energy resources. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a method, system, and device for determining the expected value of wind turbine power load shedding reserve, which can flexibly adjust the variable load shedding coefficient to achieve rapid response and precise control of wind turbine power output.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] The method for determining the expected value of wind turbine power load shedding reserve of the present invention includes:

[0007] Indicators for establishing frequency regulation confidence based on wind turbine units participating in primary frequency regulation;

[0008] Based on the active power-wind speed characteristic curve of the wind turbine, the wind speed is divided into zones, and the expected power reserve value under the corresponding zone is established.

[0009] Under each zone, the variable load factor for wind turbines to participate in frequency regulation is calculated based on the frequency regulation confidence requirements of the wind turbines.

[0010] Based on the variable load reduction coefficient of wind turbine units participating in frequency regulation in each zone, the reserve expectation value of wind turbine power load reduction is determined.

[0011] A further improvement of this invention is that the expression for the frequency modulation confidence index is:

[0012] ;

[0013] ;

[0014] In the formula: In terms of output power Does the wind turbine meet the frequency regulation requirements? For wind turbine units The power available at all times is standby. For wind turbines Expected power reserve during rated operation at any given time. The number of segments for dividing time. This represents the frequency regulation confidence level of the wind turbine.

[0015] A further improvement of this invention lies in: dividing wind speed into zones based on the active power-wind speed characteristic curve of the wind turbine, and establishing the expected power reserve value for each zone, specifically including:

[0016] Based on the active power-wind speed characteristic curve of the wind turbine, the wind speed is divided into four variable load shedding coefficient zones according to the cut-in and cut-out.

[0017] Based on the power upper limit of each variable load factor zone and the expected power reserve of the wind turbine during rated operation, the expected power reserve value of the corresponding variable load factor zone is determined.

[0018] A further improvement of the present invention is that, under each zone, based on the frequency regulation confidence requirements of the wind turbine units, the variable load reduction factor for wind turbine units participating in frequency regulation under each zone is calculated, including:

[0019] The power reserve of a wind turbine at any wind speed is expressed as:

[0020] ;

[0021] ;

[0022] In the formula: This represents the output power of the wind turbine at any wind speed. air density, For the area swept by the wind turbine, The wind energy utilization factor represents the efficiency of a wind turbine in converting wind energy into mechanical energy. The current wind speed, Reserve power available at the current wind speed. For variable load reduction factor;

[0023] Based on the expected power reserve for each variable load factor zone and the available power reserve at the current wind speed. Calculate the frequency modulation confidence level for each variable load factor zone;

[0024] Select the variable load factor corresponding to different zones based on the frequency modulation confidence requirements.

[0025] The wind turbine power load reduction reserve expectation value determination system of the present invention includes:

[0026] The index establishment module is used to establish an index for frequency regulation confidence based on wind turbine units participating in primary frequency regulation;

[0027] The power reserve expectation value establishment module is used to partition wind speed based on the active power-wind speed characteristic curve of wind turbine and establish the power reserve expectation value of the corresponding partition.

[0028] The variable load factor calculation module is used to calculate the variable load factor for wind turbines participating in frequency regulation in each zone, based on the frequency regulation confidence requirements of the wind turbines.

[0029] The determination module is used to determine the reserve expectation value of wind turbine power load reduction based on the variable load reduction coefficient of wind turbine units participating in frequency regulation in each zone.

[0030] The electronic device of the present invention 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, it implements the steps of the method for determining the expected value of wind turbine power load reduction reserve described above.

[0031] The present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method for determining the expected value of wind turbine power load reduction reserve.

[0032] The beneficial effects of this invention are as follows: This invention proposes a power reserve method with variable load shedding coefficients under different zoning conditions, corresponding to variable load shedding frequency regulation under different operating conditions, so as to achieve the goal of meeting frequency regulation requirements without wasting wind energy. This invention can flexibly adjust the variable load shedding coefficients according to the frequency deviation of the power grid and the frequency regulation requirements, so as to achieve rapid response and precise control of wind turbine power output. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method in an embodiment of the present invention; Figure 2 This is a schematic diagram of the active power-wind speed characteristic curve of the doubly fed wind turbine in an embodiment of the present invention; Figure 3 This is a schematic diagram of the four variable load reduction factor partitions in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the relationship between the load reduction coefficient and frequency modulation confidence level under different wind speed zones in this embodiment of the invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0035] like Figure 1 As shown, this embodiment is a method for determining the expected value of wind turbine power load reduction reserve, including:

[0036] Step 1: Establish an index for frequency regulation confidence based on the participation of wind turbine units in primary frequency regulation, in order to evaluate the frequency regulation reliability of wind turbine units.

[0037] Step 2: Based on the active power-wind speed characteristic curve of the wind turbine, divide the wind speed into zones and establish the expected reserve value of wind turbine power in the corresponding zone.

[0038] Step 3: Under each zone, calculate the variable load reduction factor for wind turbines participating in frequency regulation based on the frequency regulation confidence requirements of the wind turbines.

[0039] Step 4: Based on the variable load reduction coefficient of wind turbine units participating in frequency regulation in each zone, determine the reserve expected value of wind turbine power load reduction.

[0040] To objectively evaluate the frequency regulation performance of wind turbines, this embodiment uses the statistical concept of confidence level to measure the degree to which load shedding capacity meets the frequency regulation requirements of the power system. In this embodiment, the frequency regulation confidence level refers to the probability or reliability that, under specific environmental conditions and operating states, the wind turbine will reliably and fully provide the promised frequency regulation capability after receiving a frequency regulation command. During the wind turbine's participation in power system frequency regulation, if the power reserve provided by the wind turbine is greater than the expected power reserve during rated operation, then the wind turbine's reserve capacity during that period meets the frequency regulation requirements.

[0041] Wind speed at any time Wind turbine The active power output at any time is The criteria for determining whether frequency modulation requirements can be met are as follows:

[0042] (1);

[0043] (2);

[0044] In the formula, variables In terms of output power The value is 1 if the wind turbine meets the frequency regulation requirements, and 0 otherwise. For wind turbine units The power available at all times is standby. For wind turbines Expected power reserve during rated operation at any given time. The number of segments for dividing time. This represents the frequency regulation confidence level of the wind turbine.

[0045] In step 2, the wind speed is divided into four variable load factor zones according to the active power-wind speed characteristic curve of the wind turbine, and the wind turbine power reserve expectation value of the corresponding variable load factor zone is determined based on the power upper limit of each variable load factor zone and the power reserve expectation value of the wind turbine during rated operation.

[0046] When wind turbines participate in power system frequency regulation, in order to fully leverage the role of wind power in supporting the power system frequency, the unit regulation power of wind turbines is amplified, and the expression is:

[0047] (3);

[0048] In the formula: This refers to the unit regulating power of the wind turbine. The proportional coefficient for the unit regulating power of the wind turbine is set to reference the unit regulating power of the synchronous generator, and , For the unit regulating power of the synchronous generator, This represents the per-unit value of the power system frequency deviation. This represents the per-unit value of the change in output power of the synchronous generator. For variable load reduction factor, For frequency deviation, This is the standard frequency.

[0049] Under a certain frequency deviation, the expected power reserve of wind turbine units operating at rated power in a power system is:

[0050] (4);

[0051] In the formula, This is the baseline value for active power.

[0052] The output of wind turbines fluctuates with wind speed, resulting in significant power loss. Under different wind speeds, the expected value of the power system's response to changes in wind turbine power output varies with wind speed; therefore, the expected power reserve also changes with wind speed. However, the variation in the expected power reserve with wind speed increases the difficulty of wind turbine control. Therefore, this embodiment divides the wind turbine operating wind speed into four zones, setting corresponding expected power reserve values ​​for each zone, such as... Figure 2 As shown, Figure 2In the diagram, AB represents the starting zone, BC represents the MPPT zone, CD represents the constant speed zone, and DE represents the constant power zone. For example... Figure 3 As shown, in this embodiment, according to Figure 2 The operating range of the doubly fed wind turbine is divided into four variable load factor zones (wind speed zones) based on the total wind speed. Wind speed zones Wind speed zones Wind speed zones . Figure 3 Five points (A, B, C, D, E) in the graph correspond to the active power-wind speed characteristic curve. After dividing the total wind speed into four wind speed zones, the wind speed range and power range of the four wind speed zones are determined, as shown in Table 1. To cut in wind speed; For cutting off the wind speed; , , The boundaries of the four wind speed zones; , , , , The per-unit value of the output power at the corresponding wind speed:

[0053] Table 1: Wind speed zone data

[0054] ;

[0055] Combination Figure 2 , Figure 3 As shown in Table 1, when the wind speed is low in the MPPT zone, the active power output is low. If power is reserved, the reserve capacity is small and it is difficult to achieve a good frequency regulation effect, and it is easy to affect the stability of wind turbine operation. Therefore, wind speed distribution points and Non-overlapping, wind speed is Power reserve is not activated at times. Wind speed zones. Wind speed zones All are part of the MPPT zone, wind speed zone This refers to the constant speed and constant power operating ranges of wind turbine units.

[0056] Based on the power limit of each wind speed zone and the expected power reserve of the wind turbine during rated operation, the expected power reserve value of the corresponding zone is determined.

[0057] When the wind speed is within the wind speed zone When the wind turbine reaches the minimum wind speed for grid connection, its active power output is low, and the expected power reserve is:

[0058] (5);

[0059] When the wind speed is within the wind speed zone At that time, the expected power reserve value is:

[0060] (6);

[0061] When the wind speed is within the wind speed zone At that time, the expected power reserve value is:

[0062] (7);

[0063] When the wind speed is within the wind speed zone At that time, the expected power reserve value is:

[0064] (8);

[0065] In the formula, This refers to the droop coefficient of the wind turbine unit. , , and Wind speed zones Wind speed zones Wind speed zones Wind speed zones The expected value of power reserve.

[0066] The zoning is set up to correspond to different operating conditions. The expected power reserve value under different zoning is calculated to determine the power reserve of the wind turbine for primary frequency regulation, thereby determining the variable load factor.

[0067] In step 3, under the four wind speed zones, based on the frequency regulation confidence requirements of the wind turbine units, the power reserve of the wind turbine units in each wind speed zone is calculated, and the variable load factor for the wind turbine units to participate in frequency regulation is set to meet the requirements for participating in the power system frequency regulation.

[0068] To meet frequency regulation requirements, the power reserve of wind turbines should not be less than the expected power reserve value. The power reserve of wind turbines at any wind speed is expressed as:

[0069] (9);

[0070] In the formula, air density, For the area swept by the wind turbine, The wind energy utilization factor represents the efficiency of a wind turbine in converting wind energy into mechanical energy. The current wind speed, As a reserve of power available at the current wind speed, when When the power reserve is greater than the expected value within the wind speed range, the wind turbine unit meets the frequency regulation requirements of the current power system.

[0071] From expressions (5) to (8), we can know the expected power reserve values ​​corresponding to the four wind speed zones. , , and From formula (9), it can be seen that the power reserve of the wind turbine at any wind speed is... The power reserve is determined by the variable load factor. As can be seen from expressions (1) and (2), the frequency modulation confidence is obtained by power reserve and the expected value of power reserve.

[0072] Wind speed zones No power reserve is provided, and wind turbines are not required to participate in frequency regulation; therefore, wind speed zoning is not considered. Frequency modulation confidence Wind speed zones The optimal variable load reduction factor Set to 0.

[0073] , and Indicates wind speed zones , and Frequency modulation confidence level is affected by varying load reduction coefficients under different wind speed zones. , and The impact. Figure 4 To determine the relationship between the load reduction factor and frequency modulation confidence level under different wind speed zones, combined with Figure 4 By calculating the frequency regulation confidence level corresponding to different variable load shedding factors in the three zones, the correlation between frequency regulation confidence level and variable load shedding factor can be obtained. Considering the effects of wind curtailment and frequency regulation, when the frequency regulation confidence level reaches 90%, it is determined that the variable load shedding factor has met the frequency regulation requirements. Therefore, the variable load shedding factor corresponding to a confidence level of 90% is selected in each zone.

[0074] This invention sets different variable load shedding coefficients under different wind speed zones according to the frequency regulation confidence requirements, ensuring that the system has appropriate power reserves to meet the expected reserve value requirements of wind turbine power load shedding. It realizes rapid response and precise control of wind turbine power output by flexibly adjusting the variable load shedding coefficient according to the frequency deviation of the power grid and the frequency regulation requirements, so as to meet the frequency regulation requirements of the power system. By reducing power reserves, the economic efficiency of wind turbine participation in frequency regulation is guaranteed.

[0075] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0076] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining a desired value of a wind turbine power reduction backup period, characterized in that: The method comprises the following steps: an index of frequency modulation confidence is established based on participation of the wind turbine in primary frequency modulation; wind speed is divided into zones based on an active power-wind speed characteristic curve of the wind turbine, and an expected value of power reserve under the corresponding zone is established; under each zone, a variable load shedding coefficient of the wind turbine participating in frequency modulation under each zone is calculated according to a demand of the frequency modulation confidence of the wind turbine; an expected value of wind turbine power reserve is determined based on the variable load shedding coefficient of the wind turbine participating in frequency modulation under each zone.

2. The method of claim 1, wherein: The index expression of the frequency modulation confidence is as follows: ； ； In the formula: is an index indicating whether the wind turbine meets the frequency modulation requirement when the output power is an index indicating whether the wind turbine meets the frequency modulation requirement when the output power is the power reserve provided by the wind turbine at the time is the power reserve provided by the wind turbine at the time is the power reserve provided by the wind turbine at the time is the power reserve provided by the wind turbine at the time is the number of time segments, is the frequency modulation confidence of the wind turbine.

3. The method of claim 1, wherein: wind speed is divided into zones based on an active power-wind speed characteristic curve of the wind turbine, and an expected value of power reserve under the corresponding zone is established, which specifically comprises the following steps: wind speed is divided into four variable load shedding coefficient zones based on an active power-wind speed characteristic curve of the wind turbine; an expected value of power reserve of the corresponding variable load shedding coefficient zone is determined according to a power upper limit of each variable load shedding coefficient zone and an expected value of power reserve when the wind turbine is rated to operate.

4. The method of claim 3, wherein: under each zone, a variable load shedding coefficient of the wind turbine participating in frequency modulation under each zone is calculated according to a demand of the frequency modulation confidence of the wind turbine, which comprises the following steps: the power reserve of the wind turbine at any wind speed is expressed as: ； ； wherein: P is the output power of the wind turbine at any wind speed, is the air density, is the rotor swept area, is the wind energy utilization coefficient, is the current wind speed, is the power reserve available at the current wind speed, is the variable derating factor; a power reserve expectation value for each variable load factor partition and a power reserve available at a current wind speed a frequency modulation confidence is calculated for each variable load factor partition, respectively; a variable load shedding coefficient corresponding to different zones is selected according to a demand of the frequency modulation confidence.

5. A system for determining a desired value of a reserve period of a power reduction of a fan based on the method according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: an index establishment module is configured to establish an index of frequency modulation confidence based on participation of the wind turbine in primary frequency modulation; an expected value establishment module is configured to divide wind speed into zones based on an active power-wind speed characteristic curve of the wind turbine, and establish an expected value of power reserve under the corresponding zone; a variable load shedding coefficient calculation module is configured to, under each zone, calculate a variable load shedding coefficient of the wind turbine participating in frequency modulation under each zone according to a demand of the frequency modulation confidence of the wind turbine; a determination module is configured to determine an expected value of wind turbine power reserve based on the variable load shedding coefficient of the wind turbine participating in frequency modulation under each zone.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: The processor executes the computer program to realize the steps of the wind turbine power reserve expected value determination method according to any one of claims 1 to 4.

7. A computer readable storage medium storing a computer program, characterized in that: The computer program is executed by the processor to realize the steps of the wind turbine power reserve expected value determination method according to any one of claims 1 to 4.

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