Closed-loop primary frequency modulation control method

Abstract

The invention discloses a closed-loop primary frequency modulation control method, which effectively improves the accuracy of processing electric quantity contribution index deviation, and comprises the following steps of: S1, initializing a system and setting parameters; s2, signal acquisition and processing; s3, judging frequency modulation conditions; step S4, performing calculation; s5, adjustment is conducted, specifically, the basic valve position instruction obtained in the step S4 and contribution rate valve position compensation are synthesized to obtain a primary frequency modulation valve position instruction, the primary frequency modulation valve position instruction is sent to a steam turbine digital electro-hydraulic control system, and the steam turbine is controlled to adjust the valve opening degree; the method is ingenious in conception and easy and convenient to operate, the accuracy and rapidity of signals are effectively guaranteed, the adjusting quality of a control system is improved, the occurrence probability of system oscillation or adjusting fluctuation problems is reduced, internal disturbance of the control system is reduced, and the reliability and stability of the system are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power generation and relates to a closed-loop primary frequency modulation control method. Background Art

[0002] The new version of the "Two Regulations" for the Central China region will be officially implemented on January 1, 2024. The new regulations have higher requirements for the primary frequency regulation of grid-connected generators, stricter requirements for key parameters such as control functions, operation cycles, control accuracy, and power limits, and stricter assessments. In the assessment of the new regulations, traditional primary frequency regulation comprehensive management devices have problems such as unstable contribution rate, low frequency signal accuracy, and large active power fluctuations. The primary frequency regulation pass rate is not high, which reduces the economic benefits of power generation companies and brings certain safety risks to the safe and stable operation of the power grid;

[0003] The prior art has the following defects:

[0004] 1. Low frequency measurement accuracy: The existing technology generally uses turbine speed or generator frequency signals, which have the problems of large measurement range and low accuracy, which may lead to low accuracy of the regulation system;

[0005] 2. Safety Challenge: The traditional control strategy is based on high contribution rate. During the primary frequency modulation action, the steam turbine valve opening is greatly changed to improve the primary frequency modulation contribution rate. High-frequency and large-scale regulation is prone to system oscillation, valve position oscillation, power oscillation and other unsafe events;

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

[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 regulation. Summary of the invention

[0008] In view of the above problems, the present invention proposes a closed-loop primary frequency modulation control method, which effectively solves the problems in the prior art.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

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

[0011] Step S1: System initialization and parameter setting, manually set the grid rated frequency f n , artificial dead zone Δfsq of frequency regulation, and differential coefficient K of the grid-connected entity. The digital electro-hydraulic control system of the steam turbine and the coordinated control system are self-checked and initialized for communication, so that data can be transmitted normally;

[0012] Step S2: signal acquisition and processing, obtaining the real-time value of the power grid frequency f through the frequency signal acquisition module t , obtain the real-time active power output value of the generator set through the active power signal acquisition module;

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

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

[0015] Step S5, adjustment, combining the basic valve position instruction and the contribution rate valve position compensation obtained in step S4 to obtain a primary frequency modulation valve position instruction, which is sent to the digital electro-hydraulic control system of the steam turbine to control the steam turbine to adjust the valve opening; combining the basic power instruction and the contribution rate power compensation instruction to obtain a primary frequency modulation power instruction, which is sent to the coordinated control system to adjust the active power output of the generator set.

[0016] Preferably, in step S4, the theoretical contribution of frequency modulation is calculated as e The following steps are involved:

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

[0018]

[0019] Where: H e : Theoretical contribution of primary frequency modulation;

[0020] Δf(t): corresponds to the time t when the grid frequency exceeds f n ±Δfsq value;

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

[0022] f t : The grid frequency corresponding to time t (Hz);

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

[0024] Preferably, in step S4, calculating the actual power contribution of a frequency modulation comprises the following steps:

[0025] Step S42: Taking the actual power generation P0 of the primary frequency regulation dead zone as the base point, integrate the active power change backward until the system frequency recovers to within the action dead zone, and obtain the actual power contribution of the primary frequency regulation.

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

[0027] Step S43, calculate the primary 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 instruction and the basic power instruction includes the following steps:

[0030] Step S44, generate a basic valve position instruction according to the frequency deviation Δf combined with the function F1(x) of the regulating valve opening increment, and generate a basic power instruction according to the frequency deviation Δf combined with the function F2(x) of the active power instruction increment.

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

[0032] Step S45, according to the primary frequency contribution rate K, by using functions F3(x) and F4(x) constructed based on experimental data, calculate the contribution rate valve position compensation and the contribution rate power compensation.

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

[0034] 1. The present invention has a new signal processing algorithm for different uses of measurement signals, which ensures the accuracy and speed of the signal and meets the control requirements of the frequency modulation system.

[0035] 2. The present invention improves the control quality by improving 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. The present invention has a closed-loop primary frequency modulation control method based on power contribution compensation, which effectively improves the regulation quality of the control system and avoids the problem of system oscillation or regulation fluctuation. This architecture design reduces the internal disturbance of the control system and improves the reliability and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The following is combined with Figure 1 The specific implementation modes of the present invention are described in further detail.

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

[0041] Step S1: System initialization and parameter setting, manually set the grid rated frequency f n , artificial dead zone of frequency regulation Δfsq, differential coefficient K of the main grid connection c The value is set, and the steam turbine digital electro-hydraulic control system and the coordinated control system are self-checked and initialized for communication, so that data can be transmitted normally;

[0042] In this step:

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

[0044] Adjustment coefficient K c It is set to 0.05 according to the characteristics of the grid-connected entity (different units may have different values);

[0045] The steam turbine digital electro-hydraulic control system (DEH) and coordinated control system (CCS) in the system perform self-checks and initialize communications to ensure normal data transmission;

[0046] Step S2: signal acquisition and processing, obtaining the real-time value of the power grid frequency f through the frequency signal acquisition module t , obtain the real-time active power output value of the generator set through the active power signal acquisition module;

[0047] In this step:

[0048] The frequency signal module and active power signal acquisition module start working. The frequency signal acquisition uses a high-precision sensor to directly obtain the real-time value of the power grid frequency. tThe frequency signal acquisition sensor is a prior art, such as the frequency sensor of model WBF152H25, which will not be described in detail here; the active power signal also uses a high-precision measuring device to obtain the real-time active power output value of the generator set, and the high-precision measuring device for detecting the active power signal is also a prior art, such as the active power meter of model YRGFP, 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 being processed by inertia and lag links;

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

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

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

[0053]

[0054] Where: H e : Theoretical contribution of primary frequency modulation;

[0055] Δf(t): corresponds to the time t when the grid frequency exceeds f n ±Δfsq value;

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

[0057] f t : The grid frequency corresponding to time t (Hz);

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

[0059] In this step of the present 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 (outside the artificial dead zone of frequency regulation), 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 , we can get ΔP(Δf,t)=-0.05 / 50*600=-0.6MW;

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

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

[0064] Primary frequency modulation contribution rate K = (actual contribution of primary frequency modulation / theoretical contribution of primary frequency modulation) × 100%;

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

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

[0067] Step S44, generating a basic valve position instruction according to the frequency deviation Δf combined with the function F1(x) of the regulating valve opening increment, and generating a basic power instruction according to the function F2(x) of the frequency deviation Δf combined with the active power instruction increment; wherein F1(x) and F2(x) are broken line functions generated by the frequency difference;

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

[0069]

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

[0071] F2(x) is:

[0072]

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

[0074] F3(x) is:

[0075]

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

[0077] F4(x) is:

[0078]

[0079] Among them, β is the power compensation coefficient, which ensures that the actual contribution is close to the theoretical value;

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

[0081] Further, by Figure 1 As shown, step S45, according to the primary frequency contribution rate K=83.8%, the contribution rate valve position compensation and the contribution rate power compensation are calculated by using the functions F3(x) and F4(x) constructed based on the experimental data. In this embodiment, the contribution rate valve position compensation obtained by F3(x) is the regulating valve opening increased by 2%, and the contribution rate power compensation obtained by F4(x) is the active power instruction increased by 1MW; F3(x) and F4(x) are broken line functions generated by the contribution rate;

[0082] In this embodiment,

[0083] Step S5, regulation, combining the basic valve position instruction and the contribution rate valve position compensation obtained in step S4 to obtain a primary frequency modulation valve position instruction, which is sent to the steam turbine digital electro-hydraulic control system to control the steam turbine to adjust the valve opening; combining the basic power instruction and the contribution rate power compensation instruction to obtain a primary frequency modulation power instruction, which is sent to the coordinated control system to adjust 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 instruction 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 instruction increases by 4MW and the contribution rate power compensation increases by 1MW, the final active power output is adjusted to 603MW.

[0085] The present invention has a novel structure, ingenious conception, and simple and convenient operation. Through this design, the accuracy of processing the deviation of the power contribution index is effectively improved, the accuracy and rapidity of the signal are guaranteed, the regulation quality of the control system is improved, the probability of occurrence of system oscillation or regulation fluctuation problems is reduced, the internal disturbance of the control system is reduced, and the reliability and stability of the system are improved.

[0086] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A closed-loop primary frequency modulation control method, characterized in that: The following steps are involved: Step S1: System initialization and parameter setting, manually set the grid rated frequency f n , artificial dead zone of frequency regulation Δfsq, differential coefficient K of the main grid connection c The value is set, and the steam turbine digital electro-hydraulic control system and the coordinated control system are self-checked and initialized for communication, so that data can be transmitted normally; Step S2, signal acquisition and processing, obtaining the real-time value of the grid frequency ft through the frequency signal acquisition module, and 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 real-time value of the grid frequency is f t Exceeding the rated frequency of the power grid f n ±Frequency modulation artificial dead zone Δfsq, frequency modulation starts; Step S4: Calculate the theoretical contribution of frequency modulation H e , the actual contribution of primary frequency regulation, the primary frequency regulation contribution rate K, the basic valve position command and the basic power command, and finally obtain the contribution rate valve position compensation and contribution rate power compensation; Step S5, adjustment, combining the basic valve position instruction and the contribution rate valve position compensation obtained in step S4 to obtain a primary frequency modulation valve position instruction, which is sent to the digital electro-hydraulic control system of the steam turbine to control the steam turbine to adjust the valve opening; combining the basic power instruction and the contribution rate power compensation instruction to obtain a primary frequency modulation power instruction, which is sent to the coordinated control system to adjust the active power output of the generator set.

2. A closed-loop primary frequency modulation control method according to claim 1, characterized in that: In step S4, the theoretical contribution of primary frequency modulation is calculated. e The following steps are involved: Step S41: Calculate the theoretical contribution of primary frequency modulation H according to the following formula: e : Where: H e : Theoretical contribution of primary frequency modulation; Δf(t): corresponds to the time t when the grid frequency exceeds f n ±Δfsq value; f n : Rated frequency of the power grid; f t : corresponds to the grid frequency at time t; K c : The adjustment coefficient of the grid-connected entity.

3. A closed-loop primary frequency modulation control method according to claim 1, characterized in that: In step S4, calculating the actual power contribution of a frequency modulation comprises the following steps: Step S42: Taking the actual power generation P0 of the primary frequency regulation dead zone as the base point, integrate the active power change backward until the system frequency recovers to within the action dead zone, and obtain the actual power contribution of the primary frequency regulation.

4. A closed-loop primary frequency modulation control method according to claim 1, characterized in that: In step S4, calculating the primary frequency contribution rate K includes the following steps: Step S43, calculate the primary frequency contribution rate K: The primary frequency modulation contribution rate K = (actual contribution of primary frequency modulation / theoretical contribution of primary frequency modulation) × 100%.

5. A closed-loop primary frequency modulation control method according to claim 1, characterized in that: In step S4, calculating the basic valve position instruction and the basic power instruction includes the following steps: Step S44, generate a basic valve position instruction according to the frequency deviation Δf combined with the function F1(x) of the regulating valve opening increment, and generate a basic power instruction according to the frequency deviation Δf combined with the function F2(x) of the active power instruction increment.

6. A closed-loop primary frequency modulation control method according to claim 1, characterized in that: In step S4, calculating the contribution rate valve position compensation and the contribution rate power compensation includes the following steps: Step S45, according to the primary frequency contribution rate K, by using functions F3(x) and F4(x) constructed based on experimental data, calculate the contribution rate valve position compensation and the contribution rate power compensation.

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