A closed loop primary frequency control method

Abstract

The application discloses a closed-loop primary frequency modulation control method, effectively improves the accuracy of processing power contribution index deviation, and comprises the following steps: step S1, system initialization and parameter setting; step S2, signal acquisition and processing; step S3, frequency modulation condition judgment; step S4, calculation; and step S5, adjustment, the basic valve position instruction and the contribution rate valve position compensation obtained in the step S4 are comprehensively adjusted to obtain a primary frequency modulation valve position instruction, which is sent to a steam turbine digital electro-hydraulic control system to control the opening degree of a steam turbine adjusting valve; the application is ingenious in design, simple and convenient to operate, effectively guarantees the accuracy and rapidity of signals, improves the regulation quality of the control system, reduces the occurrence probability of system oscillation or regulation fluctuation problems, reduces the internal disturbance of the control system, and improves the reliability and stability of the system.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology and relates to a closed-loop primary frequency regulation control method. Background Technology

[0002] The new version of the "Two Detailed Rules" for the Central China region officially came into effect on January 1, 2024. The new rules impose higher requirements on the primary frequency regulation of grid-connected generating units, with stricter requirements on key parameters such as control functions, calculation cycles, control accuracy, and power limiting. The assessment is also more rigorous. Traditional primary frequency regulation integrated management devices exhibit problems under the new rules, including unstable contribution rates, low frequency signal accuracy, and large fluctuations in active power. This results in a low primary frequency regulation pass rate, reducing the economic benefits for power generation companies and posing certain safety hazards to the safe and stable operation of the power grid.

[0003] The existing technology has the following drawbacks:

[0004] 1. Low frequency measurement accuracy: Existing technologies generally use turbine speed or generator frequency signals, which have the problem of large measurement range and low accuracy, which may lead to low accuracy of the control system;

[0005] 2. Safety Challenges: Traditional control strategies rely on high contribution rates, significantly altering the turbine regulating valve opening during primary frequency regulation to increase the primary frequency regulation contribution rate. High-frequency, large-amplitude regulation can easily cause system oscillations, leading to unsafe events such as valve position oscillations and power oscillations.

[0006] 3. Low pass rate: The new detailed rules have higher requirements for parameters such as adjustment accuracy and response time, and unqualified adjustments will result in economic assessment.

[0007] Therefore, a closed-loop primary frequency modulation control method is needed to solve the above problems and achieve high-precision measurement, rapid response, and high-precision adjustment. Summary of the Invention

[0008] To address the above problems, this invention proposes a closed-loop primary frequency modulation control method, which effectively solves the problems in the prior art.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A closed-loop primary frequency modulation control method includes the following steps:

[0011] Step S1: System initialization and parameter setting, manually setting the grid rated frequency f. n The values ​​of frequency modulation artificial dead zone Δfsq and grid-connected main body droop coefficient K are set, and the turbine digital electro-hydraulic control system and coordinated control system are self-tested and initialized for communication to ensure normal data transmission;

[0012] Step S2: Signal acquisition and processing. Obtain the real-time value f of the power grid frequency through the frequency signal acquisition module. t The real-time active power output value of the generator set is obtained through the active power signal acquisition module;

[0013] Step S3: Frequency regulation condition judgment, when the real-time value of the power grid frequency f t Exceeding the rated frequency f of the power grid n When the frequency modulation artificial dead zone Δfsq is ±, frequency modulation begins;

[0014] Step S4: Calculate the theoretical contribution power H of the first frequency modulation. e The actual power contribution of primary frequency regulation, the primary frequency regulation contribution rate K, the basic valve position command and the basic power command are used to finally obtain the contribution rate valve position compensation and the contribution rate power compensation.

[0015] Step S5: Adjustment. The basic valve position command and contribution rate valve position compensation obtained in step S4 are combined to obtain a primary frequency regulation valve position command, which is sent to the turbine digital electro-hydraulic control system to control the turbine to regulate the steam valve opening. The basic power command and contribution rate power compensation command are combined to obtain a primary frequency regulation power command, which is sent to the coordination control system to regulate the active power output of the generator set.

[0016] Preferably, in step S4, the theoretical contribution power H of primary frequency modulation is calculated. e Includes the following steps:

[0017] Step S41: Calculate the theoretical contribution power H of primary frequency regulation according to the following formula. e :

[0018]

[0019] Wherein: H e Theoretically, primary frequency modulation contributes electrical power.

[0020] Δf(t): The frequency of the power grid exceeds f at time t. n The value of ±Δfsq;

[0021] f n Rated frequency of the power grid;

[0022] f t : The power grid frequency (Hz) at time t;

[0023] K c : Adjustment coefficient of the grid-connected entity.

[0024] Preferably, in step S4, calculating the actual power contribution of primary frequency regulation includes the following steps:

[0025] Step S42: Using the actual power generation P0 at the primary frequency regulation dead zone of the generator set as the base point, integrate the change in active power backward until the system frequency recovers to within the operating dead zone to obtain the actual power contribution of primary frequency regulation.

[0026] Preferably, in step S4, calculating the primary frequency contribution rate K includes the following steps:

[0027] Step S43: Calculate the first frequency contribution rate K:

[0028] The primary frequency modulation contribution rate K = (actual contribution of primary frequency modulation / theoretical contribution of primary frequency modulation) × 100%.

[0029] Preferably, in step S4, calculating the basic valve position command and the basic power command includes the following steps:

[0030] Step S44: Generate a basic valve position command based on the function F1(x) of the frequency deviation Δf combined with the valve opening increment, and generate a basic power command based on the function F2(x) of the frequency deviation Δf combined with the active power command increment.

[0031] Preferably, in step S4, calculating the contribution rate valve position compensation and contribution rate power compensation includes the following steps:

[0032] Step S45: Based on the primary frequency contribution rate K, calculate the contribution rate threshold compensation and contribution rate power compensation using functions F3(x) and F4(x) constructed based on experimental data.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. This invention provides a new signal processing algorithm for different applications of the measured signal, ensuring the accuracy and speed of the signal and meeting the control requirements of the frequency modulation system.

[0035] 2. This invention improves the control quality by refining the primary frequency regulation control strategy, thereby meeting the power grid's requirements for data such as frequency regulation accuracy and response time of the primary frequency regulation system.

[0036] 3. This invention features a closed-loop primary frequency regulation control method based on power contribution compensation, which effectively improves the regulation quality of the control system and avoids system oscillations or regulation fluctuations. This architecture design reduces internal disturbances in the control system and improves its reliability and stability. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall process of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The following is in conjunction with the appendix Figure 1 The specific embodiments of the present invention will be described in further detail below.

[0040] Depend on Figure 1 As shown, the present invention includes the following steps:

[0041] Step S1: System initialization and parameter setting, manually setting the grid rated frequency f. n Frequency modulation artificial dead zone Δfsq, and droop coefficient K of the grid-connected main body. c The values ​​are set, and the turbine digital electro-hydraulic control system and the coordination control system are self-tested and initialized to ensure that the data can be transmitted normally.

[0042] In this step:

[0043] Set the rated frequency f of the power grid n =50Hz, the frequency modulation artificial dead zone Δfsq is ±0.033Hz (can be adjusted according to actual power grid requirements);

[0044] Adjustment coefficient K c The value is set to 0.05 based on the characteristics of the grid-connected unit (different units may have different values);

[0045] The turbine digital electro-hydraulic control system (DEH) and coordinated control system (CCS) in the system perform self-tests and initial communication to ensure normal data transmission.

[0046] Step S2: Signal acquisition and processing. Obtain the real-time value f of the power grid frequency through the frequency signal acquisition module. t The real-time active power output value of the generator set is obtained through the active power signal acquisition module;

[0047] In this step:

[0048] The frequency signal module and active power signal acquisition module begin operation. The frequency signal acquisition uses a high-precision sensor to directly obtain the real-time value f of the power grid frequency. tThe frequency signal acquisition sensor is existing technology, such as the WBF152H25 frequency sensor, which will not be described in detail here. The active power signal is also obtained by using a high-precision measuring device to obtain the real-time active power output value of the generator set. The high-precision measuring device used to detect the active power signal is also existing technology, such as the YRGFP active power meter, which will not be described in detail here.

[0049] It should be noted that the real-time value of the power grid frequency f t The real-time active power output value of the generator set is directly transmitted to the core processing unit of the control system without going through inertial or lag processing.

[0050] Step S3: Frequency regulation condition judgment, when the real-time value of the power grid frequency f t Exceeding the rated frequency f of the power grid n In this embodiment, when the frequency modulation artificial dead zone Δfsq is ±1, Δfsq = 0.033Hz, that is, when the grid frequency f t Frequency modulation begins when the frequency exceeds 50Hz ± 0.033Hz.

[0051] Step S4: Calculate the theoretical contribution power H of the first frequency modulation. e The actual power contribution of primary frequency regulation, the primary frequency regulation contribution rate K, the basic valve position command and the basic power command are used to finally obtain the contribution rate valve position compensation and the contribution rate power compensation.

[0052] Step S41: Calculate the theoretical contribution power H of primary frequency regulation according to the following formula. e :

[0053]

[0054] Wherein: H e Theoretically, primary frequency modulation contributes electrical power.

[0055] Δf(t): The frequency of the power grid exceeds f at time t. n The value of ±Δfsq;

[0056] f n Rated frequency of the power grid;

[0057] f t : The power grid frequency (Hz) at time t;

[0058] K c : Adjustment coefficient of the grid-connected entity;

[0059] In this step of the embodiment, at a certain moment, when the real-time value of the power grid frequency f... t =50.05Hz, then Δf(t) = 50.05 - 50 = 0.05Hz (exceeding the frequency modulation dead zone), the rated power of the generator set Pn =600MW, according to the formula

[0060]

[0061] where ΔP(Δf,t)=-Δf(t) / f nn *P n Therefore, ΔP(Δf,t) = -0.05 / 50*600 = -0.6MW;

[0062] Simultaneously, step S42 is performed, taking the actual power generation P0 at the primary frequency regulation dead zone of the generator set as the base point (taking the average active power output of the first 3 seconds, P0 = 598MW in this embodiment), integrating the change in active power backward until the system frequency recovers to within the operating dead zone, and obtaining the actual power contribution of the primary frequency regulation.

[0063] Furthermore, by Figure 1 As shown, step S43, calculate the primary frequency contribution rate K:

[0064] The contribution rate of primary frequency modulation (K) is calculated as follows: (Actual contribution of primary frequency modulation / Theoretical contribution of primary frequency modulation) × 100%.

[0065] In this embodiment, the actual power contribution of the primary frequency regulation calculated by integration in step 42 is 0.5MW, so K = (-0.5) / (-0.6) × 100% ≈ 83.3%.

[0066] Furthermore, by Figure 1 As shown, step S4, calculating the basic valve position command and the basic power command includes the following steps:

[0067] Step S44: Generate a basic valve position command based on the function F1(x) of the frequency deviation Δf combined with the valve opening increment, and generate a basic power command based on the function F2(x) of the frequency deviation Δf combined with the active power command increment; where F1(x) and F2(x) are piecewise linear functions generated by the frequency difference.

[0068] In this embodiment, F1(x) is:

[0069]

[0070] Wherein, k1, k2, and c are parameters calibrated through experiments, reflecting the influence of different frequency difference ranges on the valve position;

[0071] F2(x) is:

[0072]

[0073] Where m1, m2, and n are experimentally determined coefficients used to match the power response characteristics;

[0074] F3(x) is:

[0075]

[0076] Where α is a compensation coefficient optimized through experiments, used to enhance regulation when the contribution rate is insufficient;

[0077] F4(x) is:

[0078]

[0079] Wherein, β is the power compensation coefficient, which ensures that the actual contribution approaches the theoretical value;

[0080] In this embodiment, when the frequency deviation Δf = 0.05Hz, the opening of the regulating valve should be increased by 5% (the specific value is determined according to the function relationship) by using the pre-set function F1(x) constructed based on experimental data; similarly, when the frequency deviation Δf = 0.05Hz, the active power command should be increased by 4MW (the specific value is determined according to the function relationship) by using the pre-set function F2(x) constructed based on experimental data.

[0081] Furthermore, by Figure 1 As shown, in step S45, based on the primary frequency contribution rate K = 83.8%, the contribution rate valve position compensation and contribution rate power compensation are calculated using functions F3(x) and F4(x) constructed based on experimental data. In this embodiment, the contribution rate valve position compensation obtained through F3(x) is an increase of 2% in the regulating valve opening, and the contribution rate power compensation obtained through F4(x) is an increase of 1MW in the active power command. F3(x) and F4(x) are piecewise linear functions generated by the contribution rate.

[0082] In this embodiment,

[0083] Step S5: Adjustment. The basic valve position command and contribution rate valve position compensation obtained in step S4 are combined to obtain a primary frequency regulation valve position command, which is sent to the turbine digital electro-hydraulic control system to control the turbine to regulate the steam valve opening. The basic power command and contribution rate power compensation command are combined to obtain a primary frequency regulation power command, which is sent to the coordination control system to regulate the active power output of the generator set.

[0084] In this embodiment: the initial regulating valve opening is 30%, and after the basic valve position command increases by 5% and the contribution rate valve position compensation increases by 2%, the final regulating valve opening is adjusted to 37%; the initial active power output is 598MW, and after the basic power command increases by 4MW and the contribution rate power compensation increases by 1MW, the final active power output is adjusted to 603MW.

[0085] This invention features a novel structure, ingenious design, and simple and convenient operation. Through this design, the accuracy of processing the deviation of the power contribution index is effectively improved, ensuring the accuracy and speed of the signal, improving the regulation quality of the control system, reducing the probability of system oscillation or regulation fluctuation problems, reducing the internal disturbance of the control system, and improving the reliability and stability of the system.

[0086] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 closed loop, primary frequency control method, characterized by: The method comprises the following steps: Step S1, system initialization and parameter setting, manual to the rated frequency of the power grid f n , frequency modulation artificial dead zone Δfsq, and the difference coefficient K of the grid main body c The value is set, and the steam turbine digital electro-hydraulic control system and the coordinated control system are self-checked and initialized communication, so that the data can be normally transmitted; Step S2, signal acquisition and processing, obtaining the real-time value f of the power grid frequency through the frequency signal acquisition module t obtaining the real-time active power output value of the generator set through the active power signal acquisition module; Step S3, frequency modulation condition judgment, when the grid frequency real-time value f t When the grid rated frequency f n ± frequency modulation artificial dead zone Δfsq, start frequency modulation; Step S4, calculating, sequentially calculating the primary frequency modulation theoretical contribution electric quantity H e , the primary frequency modulation actual contribution electric quantity, the primary frequency modulation contribution rate K, the basic valve position instruction and the basic power instruction, finally obtaining the contribution rate valve position compensation and the contribution rate power compensation; Step S5, adjustment, the basic valve position instruction and the contribution rate valve position compensation obtained in step S4 are integrated to obtain a primary frequency regulation valve position instruction, which is sent to a turbine digital electro-hydraulic control system to control the turbine governing valve opening; the basic power instruction and the contribution rate power compensation instruction are integrated to obtain a primary frequency regulation power instruction, which is sent to a coordinated control system to adjust the active power output of the generator set; In the step S4, the theoretical contribution of frequency modulation is calculated H e comprising the steps of: Step S41, calculate the primary frequency modulation theoretical contribution electric quantity H according to the following formula e : wherein: H e : one-time frequency adjustment theoretical contribution power Δf(t): the grid frequency exceeds f at time t n the value of ±Δfsq; f n : grid nominal frequency; f t : the grid frequency at time t; K c : the correction factor of the grid-connected main body; In the step S4, the calculation of the primary frequency contribution rate K comprises the following steps: Step S43, calculation of the primary frequency contribution rate K: The primary frequency contribution rate K=(primary frequency actual contribution amount / theoretical contribution amount)×100%; In the step S4, the calculation of the basic valve position instruction and the basic power instruction comprises the following steps: Step S44, the basic valve position instruction is generated according to the frequency deviation Δf combined with the function F1(x) of the regulating valve opening increment, and the basic power instruction is generated according to the frequency deviation Δf combined with the function F2(x) of the active power instruction increment.

2. The closed loop frequency modulation control method of claim 1, wherein: In the step S4, the calculation of the primary frequency actual contribution electric quantity comprises the following steps: Step S42, taking the actual power generation P0 of the primary frequency regulation dead zone point of the generator set as a base point, the active power change amount is integrated backward until the system frequency is restored to within the action dead zone to obtain the primary frequency actual contribution electric quantity.

3. The closed loop frequency modulation control method of claim 1, wherein: In the step S4, the calculation of the contribution rate valve position compensation and the contribution rate power compensation comprises the following steps: Step S45, according to the primary frequency contribution rate K, the contribution rate valve position compensation and the contribution rate power compensation are calculated through the functions F3(x) and F4(x) constructed based on experimental data.

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