A comprehensive method for testing the correctness of the primary frequency modulation function

Abstract

The present invention relates to a method for comprehensively testing the correctness of the operation of a primary frequency regulation function. In view of the actual situation that a frequency step signal test method commonly used in the current industry cannot fully detect the correctness of the operation of the primary frequency regulation function, the method proposes that during the primary frequency regulation function test process, dynamic frequency information of the power grid within a specified time period is modulated in the input signal of the primary frequency regulation function module to replace the power grid frequency step test method commonly used in conventional frequency regulation tests, which simulates the power grid frequency step process using a single step signal. This solves the problem that a single step signal cannot truly simulate the dynamic process of the power grid frequency. By comparing the theoretical action of the primary frequency regulation function corresponding to a preset dynamic process of the power grid frequency with the actual primary frequency regulation action information of an on-site unit, the correctness of the operation of the primary frequency regulation function of the generator set is comprehensively analyzed, thereby achieving the purpose of fully detecting the correctness of the operation of the primary frequency regulation function in this process by truly simulating the dynamic continuous change process of the power grid frequency.

Description

Technical Field

[0001] The present invention belongs to the technical field of primary frequency regulation function on-site testing, and specifically relates to a method for comprehensively testing the correctness of the primary frequency regulation function operation, and more particularly to a comprehensive testing method that uses an AC voltage after modulating a grid frequency dynamic signal within a period of time as input during the primary frequency regulation function test of a conventional synchronous generator and a new energy generator set, and combines a frequency dynamic curve within a specified time period with primary frequency regulation function operation information. Background Art

[0002] Frequency is a key parameter in the quality of power supply provided by power grids to electricity users. To ensure safe and stable grid operation and improve the frequency and power supply quality of the grid, power grids both domestically and internationally currently require grid-connected power plants to possess a certain level of primary frequency regulation capability and to verify this capability through on-site testing. For example, relevant national and industry standards, such as GB / T30370-2013 "Guidelines for Primary Frequency Regulation Test and Performance Acceptance of Thermal Power Generator Sets," GB / T9652.1-2019 "Technical Conditions for Hydro-Turbine Speed Control Systems," DL / T 1245-2013 "Technical Conditions for Operation of Hydro-Turbine Regulation Systems," and the draft technical specifications for new energy frequency regulation currently being drafted by the National Energy Administration, all clarify the verification test methods for the frequency regulation capabilities of various grid-connected units. All require on-site verification of the primary frequency regulation capabilities of grid-connected units using a frequency step method, which is generally implemented on-site.

[0003] In conjunction with the "two detailed rules" issued by the various regional regulatory offices of the National Energy Administration in recent years, such as the "Implementation Rules for the Grid-Connected Operation Management of Power Plants in the Southern Region" and the "Implementation Rules for the Auxiliary Service Management of Remaining Grid-Connected Power Plants in the South" issued by the Southern Regulatory Bureau of the National Energy Administration in 2017, it is required that during the dynamic process of grid frequency, the correct operation rate of the unit's primary frequency regulation function be assessed based on the actual frequency dynamic process within a specified time period in accordance with relevant assessment management methods. However, based on the above-mentioned test and acceptance standards for the primary frequency regulation function, the frequency step test method recommended by the standard cannot fully verify the correct operation of the primary frequency regulation function. There is an urgent need to develop a test method that can fully simulate the time-domain frequency dynamic process of the grid to determine the correctness of the primary frequency regulation function within a specified time period.

[0004] As a dynamically changing physical quantity, the grid frequency is often subject to disturbances caused by a grid fault, which will cause the grid frequency to stabilize after multiple cycles of attenuated oscillation. According to the assessment method of the "Two Detailed Rules" promulgated by the National Energy Administration, it is necessary to evaluate each action of the entire attenuated oscillation process of the grid frequency and carry out relevant assessment work accordingly.

[0005] The test method of using a DC voltage step to simulate a step change in the same direction of the grid frequency, which is recommended by existing national standards and widely used within the industry, can accurately determine the correctness of the logic of a single-direction primary frequency regulation function action. However, it cannot truly determine the continuous change process of the primary frequency regulation function acting and resetting as the grid frequency attenuates and oscillates during multiple attenuation oscillations; then acting again and then resetting. The primary frequency regulation function program of the on-site unit often imposes restrictions on the number of continuous frequency regulation actions and the reset delay time that are not open to the public. As a result, conventional test methods cannot normally discover and eliminate this "defect", which brings invisible "assessment" pressure to the normal operation of the primary frequency regulation function of the generator set.

[0006] Therefore, how to overcome the shortcomings of the existing technology is an urgent problem to be solved in the field of primary frequency modulation function field test technology. Summary of the Invention

[0007] The purpose of the present invention is to address the deficiencies of the prior art and provide a method for comprehensively testing the correctness of the primary frequency regulation function. This method is applicable to the primary frequency regulation function test of conventional synchronous generators and new energy generators. To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A comprehensive method for testing the correctness of the primary frequency regulation function is proposed. This method modulates a preset grid frequency dynamic curve into the input signal of the primary frequency regulation module to replace the single step signal simulation grid frequency step test method commonly used in conventional frequency regulation tests. The correctness of the frequency regulation function is analyzed based on the operation of each sampling time point under the preset grid frequency dynamic curve.

[0009] The specific steps include:

[0010] Assume that the preset grid frequency dynamic curve is expressed as f grid (t), the dead zone of the primary frequency modulation function is ±f dead , then the frequency modulation action signal is ACT n ACT n When it is 1, it indicates that the frequency modulation function is in effect, and when it is 0, it indicates that the frequency modulation function is not in effect; ACT n Judge by formula (1):

[0011]

[0012] In formula (1), abs means taking the absolute value of the result in the brackets; ±f dead The known frequency regulation power frequency action dead zone value specified by the local power grid;

[0013] In the process of the dynamic curve of the power grid frequency in the preset time period, the theoretical action information of the frequency regulation function of each frequency sampling point on the preset curve can be accurately determined according to formula (1) for each sampling point;

[0014] The time series is used as the link between the theoretical action information and the actual action information under the dynamic frequency curve of the power grid in the preset time period. Assuming that the time corresponding to the Nth theoretical frequency regulation action signal of the frequency regulation function in the time series is T N_th The actual frequency modulation action signal in the field test corresponds to the time T in the time series. N_act The maximum delay time allowed for the frequency regulation function specified by the local power grid is T max , then for any preset power grid dynamic frequency process, compare the time range corresponding to the Nth frequency regulation action in the theoretical frequency regulation action information with the corresponding frequency regulation action information within the maximum allowed delay time range, then the Nth frequency regulation action time index S N Judge by formula (2):

[0015]

[0016] In formula (2), abs means taking the absolute value of the result in the brackets;

[0017] When S N When it is 1, it means that within the range of the power grid frequency dynamic curve in the preset time period, the Nth theoretical frequency regulation time index information is consistent with the actual frequency regulation information, and the frequency regulation function operates correctly; when S N When it is 0, it means that within the range of the grid frequency dynamic curve in the preset time period, the Nth theoretical frequency regulation action information and the actual frequency regulation information do not meet the delay time requirements, and the frequency regulation function action is incorrect.

[0018] Furthermore, preferably, the frequency-modulated power frequency action dead zone value is ±0.1 Hz.

[0019] Furthermore, preferably, T max The value is 3 seconds, but is not limited to this. It can be set according to actual needs.

[0020] The present invention modulates the dynamic frequency information of the power grid within a specified time period in the input signal of the primary frequency modulation function module to replace the single step signal simulation power grid frequency step test method commonly used in conventional frequency modulation tests, and analyzes its correctness based on the operation of the frequency modulation function under the preset dynamic continuous change of the power grid frequency;

[0021] The present invention comprehensively analyzes the correctness of the primary frequency regulation function on site based on the theoretical action of the primary frequency regulation function corresponding to the preset grid frequency dynamic process and the actual primary frequency regulation action on site, in combination with relevant frequency regulation index parameters at the same time coordinate, and with the theoretical action behavior of the frequency regulation function in the same time period as a reference.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In view of the actual situation that the frequency step signal test method commonly used in the current industry cannot fully detect the correctness of the primary frequency regulation function, the method of the present invention proposes to modulate the dynamic frequency information of the power grid within a specified time period in the input signal of the primary frequency regulation function module during the primary frequency regulation function test to replace the power grid frequency step test method simulated by the single step signal commonly used in conventional frequency regulation tests. This solves the problem that the single step signal cannot truly simulate the dynamic process of the power grid frequency, especially the frequency attenuation oscillation process after the disturbance caused by the power grid fault. By comparing the theoretical action of the primary frequency regulation function corresponding to the preset dynamic process of the power grid frequency and the actual primary frequency regulation action information of the on-site unit, the correctness of the primary frequency regulation function of the generator set is comprehensively analyzed, so as to achieve the purpose of fully detecting the correctness of the action of the primary frequency regulation function in this process by truly simulating the dynamic continuous change process of the power grid frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a comparison chart of the actual power grid frequency dynamic process and the frequency dynamic process simulated by the conventional test method; the horizontal axis is time, in seconds; the vertical axis is frequency, in Hertz;

[0025] Figure 2 This is a comparison chart of the primary frequency modulation function operation under the comprehensive test method and the conventional test method; the horizontal axis is time, in seconds; the vertical axis is the frequency modulation action signal S n ;

[0026] Figure 3 This is a comparison chart of the theoretical operation of the frequency regulation function during the dynamic process of the preset grid frequency and the frequency exceeding the dead zone; where the horizontal axis is time, unit is seconds; the vertical axis is frequency, unit is Hertz;

[0027] Figure 4 This is a comparison chart of the theoretical and actual operation of the frequency modulation function based on time coordinates; where the horizontal axis is time, in seconds; the vertical axis is the frequency modulation action signal S n . DETAILED DESCRIPTION

[0028] The present invention is described in further detail below with reference to the embodiments.

[0029] Those skilled in the art will understand that the following examples are intended to illustrate the present invention only and should not be construed as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in the product specifications were used. Materials or equipment used without manufacturer identification are commercially available conventional products.

[0030] A comprehensive method for testing the correctness of the primary frequency regulation function is proposed. This method modulates a preset grid frequency dynamic curve into the input signal of the primary frequency regulation module to replace the single step signal simulation grid frequency step test method commonly used in conventional frequency regulation tests. The correctness of the frequency regulation function is analyzed based on the operation of each sampling time point under the preset grid frequency dynamic curve.

[0031] The specific steps include:

[0032] Assume that the preset grid frequency dynamic curve is expressed as f grid (t), the dead zone of the primary frequency modulation function is ±f dead , then the frequency modulation action signal is ACT n ACT n When it is 1, it indicates that the frequency modulation function is in effect, and when it is 0, it indicates that the frequency modulation function is not in effect; ACT n Judge by formula (1):

[0033]

[0034] In formula (1), abs means taking the absolute value of the result in the brackets; ±f dead The known frequency regulation power frequency action dead zone value specified by the local power grid;

[0035] In the process of the dynamic curve of the power grid frequency in the preset time period, the theoretical action information of the frequency regulation function of each frequency sampling point on the preset curve can be accurately determined according to formula (1) for each sampling point;

[0036] The time series is used as the link between the theoretical action information and the actual action information under the dynamic frequency curve of the power grid in the preset time period. Assuming that the time corresponding to the Nth theoretical frequency regulation action signal of the frequency regulation function in the time series is T N_th The actual frequency modulation action signal in the field test corresponds to the time T in the time series. N_act The maximum delay time allowed for the frequency regulation function specified by the local power grid is T max, then for any preset power grid dynamic frequency process, compare the time range corresponding to the Nth frequency regulation action in the theoretical frequency regulation action information with the corresponding frequency regulation action information within the maximum allowed delay time range, then the Nth frequency regulation action time index S N Judge by formula (2):

[0037]

[0038] In formula (2), abs means taking the absolute value of the result in the brackets;

[0039] When S N When it is 1, it means that within the range of the power grid frequency dynamic curve in the preset time period, the Nth theoretical frequency regulation time index information is consistent with the actual frequency regulation information, and the frequency regulation function operates correctly; when S N When it is 0, it means that within the range of the grid frequency dynamic curve in the preset time period, the Nth theoretical frequency regulation action information and the actual frequency regulation information do not meet the delay time requirements, and the frequency regulation function action is incorrect.

[0040] Preferably, the frequency modulation power frequency action dead zone value is ±0.1 Hz.

[0041] Optimum, T max The value is 3 seconds.

[0042] Application Examples

[0043] The time domain dynamic curve of the power grid frequency usually involves a time range of up to 200-200 seconds, and the sampling rate of the power grid frequency time domain dynamic curve is usually 200 points per second. Calculation shows that a complete set of sampling point data of the power grid frequency time domain dynamic curve will reach 40,000 to 60,000 points (rows). In order to save space, the present invention provides two application cases. The first case illustrates the use of the present invention with a smaller number of sampling points; the second case takes the frequency time domain dynamic curve of the entire provincial power grid after a power grid failure on November 20, 2019 as an example to illustrate the effect of comprehensively testing the correctness of the frequency regulation function according to the present invention.

[0044] Case 1:

[0045] Assume that the point-by-point frequency sampling results of the preset grid frequency dynamic curve are as shown in Table 1 “Grid frequency sampling value (Hz)”.

[0046] Table 1

[0047]

[0048] 10 0.05 50.11 1 1 11 0.055 50.04 0 1 12 0.06 50.04 0 0 13 0.065 50.03 0 0 14 0.07 49.98 0 0 15 0.075 49.96 0 0 16 0.08 49.94 0 0 17 0.085 49.96 0 0 18 0.09 49.94 0 0 19 0.095 49.96 0 0 20 0.1 49.97 0 0

[0049] Step 1: Point-by-point theoretical frequency modulation action signal ACTn Calculate the frequency of the action signal ACT according to the formula (1) of the present invention for each sampling point. n Judge and set the dead zone parameter f dead =0.1Hz, such as: the frequency signal of the first sampling point is calculated, f grid (t) Take the frequency corresponding to the first sampling point as 49.967Hz, and get abs(49.967-50)=0.033, which is less than the set dead zone of 0.1Hz. Therefore, the corresponding frequency modulation action signal S n The value 0 corresponds to the frequency modulation function not being activated. The calculation method is used for each sampling point, and the calculation results are shown in the table above as "Theoretical Frequency Modulation Action Signal ACT n " column.

[0050] Step 2: Successive frequency modulation action time index S N Action behavior analysis. Combined with the analysis results of step 1, the frequency modulation action signal ACT is analyzed point by point. n When there is a position where 0 changes to 1 or 1 changes to 0, the time difference between the theoretical action and the actual action of each frequency modulation action is analyzed. As shown in Table 1, ACT n When it changes from 0 to 1 for the first time, it corresponds to the 5th sampling point sequence, the time is 0.025 seconds, and the actual frequency modulation action time recorded on site is the 8th sampling point sequence, the corresponding time is 0.04 seconds. Therefore, the actual frequency modulation action lags behind the theoretical frequency modulation action by 0.04-0.025=0.015 seconds. The maximum time allowed for the frequency modulation function action delay is T max Within the allowed 3 seconds, it indicates the frequency modulation action time index S N After calculation by formula (2), the result is 1, so it is judged that the theoretical action and actual action of the first frequency modulation function in the above table meet the requirements; ACT n When it changes from 1 to 0 for the first time, it indicates that the frequency modulation action returns. The calculation method and judgment method of the time difference between the theoretical action and the actual action are similar to those mentioned above and will not be repeated here.

[0051] Step 3: Repeat steps 1 and 2 to calculate the frequency of each sampling point and frequency modulation action signal ACT in the preset grid frequency dynamic curve. n The calculation of the displacement is completed, which completes the comprehensive analysis of all frequency sampling points of the preset power grid frequency dynamic curve. The frequency regulation action time indicator correct action number of 100% is used as the judgment basis. If one incorrect action occurs, it is judged that the on-site frequency regulation function does not meet the requirements. If the frequency regulation action and return in the above table are correct, and there is no incorrect action within the entire preset power grid frequency dynamic curve time range, it is judged that the on-site frequency regulation function under the preset power grid frequency dynamic curve is correct.

[0052] Case 2:

[0053] The time domain dynamic curve of the whole network frequency after a power grid failure occurred on November 20, 2019 in a provincial power grid is used as the preset power grid frequency dynamic curve in the content of this invention. In order to compare with the conventional test method, the attached Figure 1 The frequency step signal in the conventional test method is also added, as shown in the attached Figure 1 shown.

[0054] The preset grid dynamic frequency information is modulated as the input signal of the generator frequency modulation module. Compared with the conventional frequency step test signal, the frequency modulation function action signal is Figure 2 It can be seen that the conventional frequency step signal can only reflect the single action information of the frequency modulation function, while the test method of using the preset grid dynamic frequency curve as the input signal provided by the present invention can continuously reflect the multiple action information of the frequency modulation function, and can more realistically reflect the actual action status of the frequency modulation function on site.

[0055] Figure 3 Given Figure 1 As the preset grid frequency dynamic curve, in the case of frequency modulation action dead zone ±0.1Hz, the frequency modulation action signal S is calculated according to formula (1) of the present invention. N The comparison diagram of the calculated frequency dynamic curve and the frequency modulation function action signal is shown in the figure. The theoretical frequency modulation action signal S N It can accurately act when the preset grid frequency dynamic curve is higher than 50.1 Hz or lower than 49.9 Hz (S N From 0 to 1), and accurately returns when the preset grid frequency dynamic curve returns to the frequency regulation dead zone range (S N From 1 to 0).

[0056] Figure 4 Given Figure 1 As the preset grid frequency dynamic curve, the conclusion of the frequency regulation function theoretical action and actual action situation, according to formula (2) to calculate the frequency regulation action time index parameter S N , we can see that the actual action of the on-site frequency modulation function is consistent with the theoretical action situation in the initial time period of the frequency dead zone, and the actual frequency modulation action time lags slightly behind the theoretical frequency modulation action time, but within the specified maximum allowable time for the frequency modulation function action delay of T max Within the range (set to 3 seconds); in the latter part of the preset grid frequency dynamic curve, due to the small deviation of the system frequency from the frequency regulation action dead zone, the on-site frequency regulation function basically does not act or the action lag time exceeds T max In other words, the accuracy of the on-site frequency modulation function cannot reach 100%, which cannot meet the engineering requirement of 100% accuracy of the frequency modulation function.

[0057] This example also indirectly illustrates the actual situation that the traditional frequency modulation function test method can only verify the correctness of the action within a certain period of time during the frequency dynamic process, but is unable to analyze and judge the correctness of the action in the later period.

[0058] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for comprehensively testing the correctness of a primary frequency modulation function, characterized in that: A preset grid frequency dynamic curve is modulated in the input signal of the primary frequency modulation function module to replace the grid frequency step test method commonly used in conventional frequency modulation tests, which is simulated by a single step signal. The correctness of the frequency modulation function is analyzed based on the operation of each sampling time point under the preset grid frequency dynamic curve. The specific method is: Assume that the preset grid frequency dynamic curve is expressed as , the action dead zone of the primary frequency modulation function is , then the frequency modulation action signal is ; When it is 1, it indicates that the frequency modulation function is in effect, and when it is 0, it indicates that the frequency modulation function is not in effect; Judge by formula (1): (1) In formula (1), abs means taking the absolute value of the result in the brackets; The known frequency regulation power frequency action dead zone value specified by the local power grid; In the process of the dynamic curve of the power grid frequency in the preset time period, the theoretical action information of the frequency regulation function of each frequency sampling point on the preset curve can be accurately determined according to formula (1) for each sampling point; Using the time series as the link between the theoretical action information and the actual action information under the dynamic frequency curve of the power grid in the preset time period, it is assumed that the time corresponding to the Nth theoretical frequency regulation action signal of the frequency regulation function in the time series is , the actual frequency modulation action signal in the field test process corresponds to the time series The maximum delay time allowed for the frequency regulation function action stipulated by the local power grid is , then for any preset power grid dynamic frequency process, compare whether there is corresponding frequency regulation action information in the time range corresponding to the Nth frequency regulation action in the theoretical frequency regulation action information within the maximum allowable delay time range. If the Nth theoretical frequency regulation time index information is consistent with the actual frequency regulation information, the frequency regulation function is correct; if the Nth theoretical frequency regulation action information and the actual frequency regulation information do not meet the delay time requirements, the frequency regulation function is incorrect.

2. The method for comprehensively testing the correctness of the primary frequency modulation function according to claim 1, characterized in that: The Nth frequency modulation action time indicator Judge by formula (2): ； In formula (2), abs means taking the absolute value of the result in the brackets; when When it is 1, it means that within the range of the power grid frequency dynamic curve in the preset time period, the Nth theoretical frequency regulation time index information is consistent with the actual frequency regulation information, and the frequency regulation function operates correctly; when When it is 0, it means that within the range of the grid frequency dynamic curve in the preset time period, the Nth theoretical frequency regulation action information and the actual frequency regulation information do not meet the delay time requirements, and the frequency regulation function action is incorrect.

3. The method for comprehensively testing the correctness of the primary frequency modulation function according to claim 1, characterized in that: The dead zone value of FM power frequency action is Hz.

4. The method for comprehensively testing the correctness of the primary frequency modulation function according to claim 2, characterized in that: The value is 3 seconds.

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