Power plant frequency and peak regulation control method to prevent the spread of low-frequency oscillation in the power grid

Abstract

The present invention discloses a power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillations in the power grid, comprising the following steps: Step 1: determining the frequency deviation of the power station participating in the power grid frequency regulation in the current state; Step 2: using a high and low deviation alarm module to judge whether the calculated deviation value #imgabs0# exceeds a determined deviation constant value and output the result; Step 3: superimposing the output result of the #imgabs1# moment switching module 1 with the output of the #imgabs2# moment switching module 2 to obtain a deviation deviation integral value #imgabs3#; Step 4: updating the oscillation instability state #imgabs4# quantified in Step 3; Step 5: continuously transforming the data of Step 4 to obtain frequency regulation and peak regulation control optimization parameters under the oscillation state; Step 6: obtaining an intervention coefficient and multiplying it by the deviation value of the original power grid frequency or active power to realize function switching. The method prevents the spread and propagation of power grid oscillations caused by the instability of the frequency regulation and peak regulation system by modifying the control logic of the power station control system.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid low-frequency oscillation frequency modulation and peak regulation control, and in particular to a power station frequency modulation and peak regulation control method for preventing the spread of power grid low-frequency oscillation. Background Art

[0002] With the acceleration of global energy transformation, the structure of the power system is undergoing profound changes. In new power systems, the coexistence of multiple power sources—wind, solar, hydro, thermal, and storage—is becoming increasingly common, and the proportion of renewable energy in power supply continues to increase. While this diversified power structure brings many advantages to the power system, it also brings a series of new challenges. The increased randomness and mutation of power system energy require that power generation units possess the ability to rapidly adjust active power to compensate for imbalances between power supply and consumption in order to quickly respond to grid frequency fluctuations.

[0003] When facing low-frequency oscillations in the primary and secondary frequency regulation of the power grid, the attenuation of power oscillations can be accelerated by increasing the damping by investing in the power system stabilizer, or the oscillation source can be checked after the low-frequency oscillation occurs and selectively invested or removed according to the oscillation source to effectively reduce the oscillation, or the oscillation state can be quantified by the number of times exceeding the set deviation. The quantified value corresponds to the weakened regulation effect, but the oscillation amplitude and oscillation period are not integrated. Either the amplitude is used to exit the frequency regulation effect, or the period frequency is used to weaken the active regulation support. Neither of them coordinates the flexible suppression from the two dimensions of amplitude and period.

[0004] Among them, the oscillation state is quantified by the number of times the set deviation is exceeded. The quantified value corresponds to the weakened regulation effect, which solves most of the problems. The oscillation state is calculated based on the cumulative differential of the number of times the active power and grid frequency oscillations exceed the fixed value area, and the frequency regulation effect is weakened by using the function correspondence. However, the accumulation of the number of oscillations in its core algorithm cannot timely reflect the state of the oscillation amplitude, and the suppression effect is poor when encountering an oscillation state with a large amplitude and a long oscillation period.

[0005] In summary, existing control technologies for low-frequency oscillations in the power grid suffer from numerous problems, including suboptimal control strategies, insufficient coordination between different power sources, and difficulty effectively responding to complex operating conditions, when faced with complex power systems where multiple power sources, including wind, solar, hydro, thermal, and storage, coexist. This is particularly true in areas prone to or experiencing low-frequency oscillations, such as weak power system connections, the end of the grid, and areas with a high proportion of renewable energy. Therefore, it is necessary to develop a new power plant frequency regulation control technology for periods of low-frequency oscillations in the power grid that fully considers the power source regulation characteristics, provides differentiated setting parameters for multiple power sources, optimizes the control strategy for multiple power sources, and improves the stability and reliability of the power system during low-frequency oscillations. Summary of the Invention

[0006] In order to overcome the above problems, the purpose of the present invention is to provide a power plant frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillations in the power grid. The control method modifies the control logic of the primary frequency regulation and active power closed-loop regulation of the power plant control system, optimizes the primary and secondary frequency regulation control strategies, automatically intervenes in the regulation performance of the unit supporting the grid frequency when the grid frequency oscillates, and restores the frequency support capability when the grid frequency damping is normal, thereby suppressing the low-frequency oscillation of the grid frequency, preventing the spread of grid oscillations due to excessive regulation of power supply frequency regulation and peak regulation, and improving the stability and reliability of the power system under low-frequency oscillation conditions.

[0007] The technical solution adopted in the present invention is:

[0008] A power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillations in a power grid includes the following steps:

[0009] Step 1: Determine the frequency deviation of the power station in the current state of the grid frequency regulation, and set the real-time grid frequency of the control unit of the power station participating in the grid frequency regulation and peak regulation and target value Subtract, or real-time active power The value and target value Subtract to find the deviation value ;

[0010] Step 2: Use the high and low tolerance alarm module to determine the calculated deviation value Whether it exceeds the specified deviation value. If so, the short-term output is a multiple of the absolute value of the above difference, generating data associated with the oscillation amplitude. If not, the output is 0.

[0011] Step 3: Be in the present moment At this moment, the output result of switching module 1 is combined with The output of the moment switching module 2 is superimposed to obtain the deviation excess integral value , quantifying the oscillatory unstable state;

[0012] Step 4: Output of the unstable oscillation state in step 3 Its first-order inertia link Calculate the difference, limit the lower limit to 0, calculate the integral change rate in the accumulation direction, and determine whether the change rate is less than the constant value C. If so, trigger a short pulse to clear the oscillation instability state. Otherwise, keep cyclically superimposing the deviations calculated in steps 1 and 2 to update the quantized oscillation instability state in step 3. ;

[0013] Step 5: Continuously transform the data of step 4 to obtain the frequency modulation and peak regulation control optimization parameters under the oscillation state. First, the output is passed through the first-order inertia link. , and the fixed value Add, then add the proportional coefficient Multiply and input to the exponential function , and finally the exponential function The output and 1 are minimized and output, the upper limit is limited, and the intervention coefficient is generated. ;

[0014] Step 6: Set the function activation / exit button. When the function is activated, the obtained intervention coefficient is multiplied by the deviation value of the original grid frequency or active power to obtain a result value. The result value is the controlled parameter deviation with suppression capability. If there is an abnormality, the function exit button can be manually selected to exit. At this point, a calculation cycle ends. The method cyclically executes the above steps to realize online monitoring and oscillation suppression.

[0015] As a further description of the present invention, in step 1, when there is a risk of low-frequency oscillation caused by frequency and peak regulation in the power station, the control unit of the power station participating in the frequency and peak regulation of the power grid is used as the main body of the control implementation of the method to complete The deviation of the grid frequency or active power from the target value at each moment is calculated. When optimizing the power plant frequency regulation control strategy, the grid frequency is selected as the data source of this method. When optimizing the power plant peak regulation control strategy, the active power is selected as the data source of this method.

[0016] As a further description of the present invention, in step 2, the grid frequency or active power deviation obtained in step 1 is divided into two data streams, and the specific process is as follows:

[0017] One of the paths passes through the deviation alarm module, and the high value alarm setting is set to , low alarm setting value is , is the grid frequency or active power deviation, then when or The time deviation alarm module outputs a true value, i.e., TRUE, otherwise it outputs a false value, i.e., FALSE. After judgment, if it is a true value, the pulse outputs a true value, otherwise it is a false value, and then inputs it to the control selection port of the switching module 1;

[0018] Another way to get the absolute value of the deviation , and multiply by , and get the absolute error value , the absolute error value is input to port 1 of switch module 1, and the input to port 2 of switch module 1 is 0;

[0019] The control logic of the switching module is: when the selected port is true, the output is the analog value of port 1; when the selected port is false, the output is the analog value of port 2. That is, the logic of this step is that when the grid frequency or active power deviation exceeds the limit, the output is a multiple of the absolute error, and the current oscillation amplitude is recorded. When the grid frequency or active power does not exceed the limit, the output is 0.

[0020] As a further description of the present invention, in step 3, the deviation excess integral value obtained is It is an evaluation index based on the absolute error integral criterion, which can be used to evaluate the performance index of the control system and express the oscillation state during oscillation.

[0021] As a further description of the present invention, in step 4, the cumulative direction integral change rate obtained in step 3 has an oscillation deviation amplitude correlation because steps 1-2 make the value have an oscillation deviation amplitude correlation. Therefore, if the value increases, it indicates that the oscillation amplitude of the active power control loop is large;

[0022] Determine whether the rate of change is less than the set value C. If it is less than the set value C, a short pulse is triggered to make the switching module 2 output Clear to zero. This step can prevent the overflow of the superposition state quantity data and cause the control system to be abnormal. Otherwise, keep the deviation calculated by the cyclic superposition step 1-2 to update the oscillation unstable state quantified in step 3. , because after the periodic cycle superposition, the integral change rate of the amplitude is combined with the oscillation period, producing the combined amount of coupled amplitude and period, that is, the oscillation instability state .

[0023] As a further description of the present invention, in step 5, the data of step 4 is continuously transformed, which can feed back the above-mentioned oscillation instability state to the regulation control link to achieve oscillation suppression and obtain the intervention depth of the frequency modulation and peak regulation control effect under the oscillation state.

[0024] Beneficial effects of the present invention:

[0025] The present invention provides a power plant frequency modulation and peak regulation control method for preventing the spread of low-frequency oscillations in the power grid. The control method modifies the control logic of the primary frequency modulation and active power closed-loop regulation of the power plant control system, optimizes the primary and secondary frequency regulation control strategies, automatically intervenes in the regulation performance of the unit supporting the grid frequency when the grid frequency oscillates, and restores the frequency support capability when the grid frequency damping is normal, thereby suppressing the low-frequency oscillations of the grid frequency, preventing the spread of grid oscillations due to excessive regulation of power supply frequency modulation and peak regulation, and improving the stability and reliability of the power system operation under low-frequency oscillations.

[0026] The power station frequency modulation and peak regulation control method for preventing the spread of low-frequency oscillations in the power grid of the present invention is superior to the traditional fixed accumulation method in steps 1-3. The multiples of the calculated absolute value of the deviation are used as the superposition target quantity, which can effectively provide feedback information on the low-frequency oscillation amplitude to the subsequent system. When the oscillation amplitude is large and the frequency is low, the suppression mode is quickly activated, and the frequency modulation and peak regulation control link is intervened early to suppress low-frequency oscillation events caused by active power regulation.

[0027] The present invention prevents the spread of low-frequency oscillation in the power grid. The power station frequency regulation and peak regulation control method of the present invention prevents the spread of low-frequency oscillation in the power grid. In the steps 3-4, the deviation multiple and the upper cycle are used during oscillation. The output of the Max selection module not only maintains a positive proportional relationship with the oscillation frequency, but also superimposes the oscillation amplitude and the deviation integral to obtain a comprehensive evaluation quantization value that takes into account the oscillation frequency, amplitude and integral.

[0028] The power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid of the present invention, when it is judged in step 4 that the integral change rate is less than a fixed value, trigger Clear to prevent module overflow, and the max election logic can prevent the rate of change from negative overshoot and instability when clearing.

[0029] The present invention provides a power plant frequency and peak regulation control method for preventing the spread of low-frequency oscillations in the power grid. The control method is implemented based on the original control system strategy. A control strategy is added to the original control system of the power plant to achieve oscillation suppression. The implementation process is simple and convenient, and prevents low-frequency oscillation transmission events caused by active power overshoot or uncoordinated between power plant areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the main control logic diagram of the power station frequency and peak regulation control method proposed by the present invention to prevent the spread of low-frequency oscillations in the power grid;

[0031] Figure 2 This is a flow chart of the power station frequency and peak regulation control method proposed by the present invention to prevent the spread of low-frequency oscillations in the power grid;

[0032] Figure 3 This is a functional switching control logic diagram of the power station frequency and peak regulation control method proposed by the present invention to prevent the spread of low-frequency oscillations in the power grid. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention is described below with reference to the accompanying drawings and embodiments:

[0034] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0035] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0036] like Figures 1 to 3 As shown, it shows a specific embodiment of the present invention:

[0037] In the power system, thermal, hydro, nuclear, wind and photovoltaic power stations can all serve as power sources participating in the primary frequency regulation of the power grid. The control systems of these power stations will monitor the grid connection point frequency or the grid connection speed of the prime mover in real time. When the relevant parameters deviate from the nominal value and exceed the primary frequency regulation dead zone, such as the grid frequency of the thermal power generating unit deviates from 50±0.033Hz, the hydropower generating unit deviates from 50±0.05Hz, and other power sources have similar situations, the power station controller will start the frequency regulation action to prevent the frequency from dropping or overshooting.

[0038] Subsequently, the frequency regulation instruction will be transmitted to the speed regulator or other primary frequency regulation actuator, and the active power will be regulated by a specific unequal rate or differential rate to meet the various requirements of the primary frequency regulation control performance. However, the power supply has nonlinear and weak damping links, which have caused low-frequency oscillation events in recent years. After on-site analysis and typical experience accumulation, for the low-frequency oscillation link that cannot be suppressed by the attenuation system of increasing damping to accelerate the power oscillation by investing in the power system stabilizer, the frequency regulation and peak regulation control function can be exited to suppress it. However, there is a vacuum period in the link where the power supply supports the grid frequency. Therefore, this method can solve the above problems at the same time and improve the suppression function performance, so as to achieve the ability of the power supply to suppress low-frequency oscillations through the optimization of the power supply frequency regulation and peak regulation control, prevent the transmission of grid frequency or active power oscillations, and avoid the hidden danger of weak support caused by long-term exit of frequency regulation and peak regulation due to oscillation risks.

[0039] Example 1

[0040] A power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillations in a power grid includes the following steps:

[0041] Step 1: Determine the frequency deviation of the power station in the current state of the grid frequency regulation, and set the real-time grid frequency of the control unit of the power station participating in the grid frequency regulation and peak regulation and target value Subtract, or real-time active power The value and target value Subtract to find the deviation value ;

[0042] Step 2: Use the high and low tolerance alarm module to determine the calculated deviation value Whether it exceeds the specified deviation value. If so, the short-term output is a multiple of the absolute value of the above difference, generating data associated with the oscillation amplitude. If not, the output is 0.

[0043] Step 3: Be in the present moment At this moment, the output result of switching module 1 is combined with The output of the moment switching module 2 is superimposed to obtain the deviation excess integral value , quantifying the oscillatory unstable state;

[0044] Step 4: Output of the unstable oscillation state in step 3 Its first-order inertia link Calculate the difference, limit the lower limit to 0, calculate the integral change rate in the accumulation direction, and determine whether the change rate is less than the constant value C. If so, trigger a short pulse to clear the oscillation instability state. Otherwise, keep cyclically superimposing the deviations calculated in steps 1 and 2 to update the quantized oscillation instability state in step 3. ;

[0045] Step 5: Continuously transform the data of step 4 to obtain the frequency modulation and peak regulation control optimization parameters under the oscillation state. First, the output is passed through the first-order inertia link. , and the fixed value Add, then add the proportional coefficient Multiply and input to the exponential function , and finally the exponential function The output and 1 are minimized and output, the upper limit is limited, and the intervention coefficient is generated. ;

[0046] Step 6: Set the function activation / exit button. When the function is activated, the obtained intervention coefficient is multiplied by the deviation value of the original grid frequency or active power to obtain a result value. The result value is the controlled parameter deviation with suppression capability. If there is an abnormality, the function exit button can be manually selected to exit. At this point, a calculation cycle ends. The method cyclically executes the above steps to realize online monitoring and oscillation suppression.

[0047] In this embodiment, Figure 1 、 Figure 2 As shown, steps 1-3 are superior to the traditional fixed accumulation method. Taking the multiple of the absolute value of the calculated deviation as the superposition target quantity can effectively provide feedback information of the low-frequency oscillation amplitude to the subsequent system. When the oscillation amplitude is large and the frequency is low, the suppression mode is quickly started, and the frequency modulation and peak regulation control link is intervened in advance to suppress the low-frequency oscillation event caused by active power regulation.

[0048] In the steps 3-4, the deviation multiple and the upper cycle are used during oscillation. The output of the Max selection module not only maintains a positive proportional relationship with the oscillation frequency, but also superimposes the oscillation amplitude and the deviation integral to obtain a comprehensive evaluation quantization value that takes into account the oscillation frequency, amplitude and integral.

[0049] When the integral change rate is less than the set value in step 4, the trigger Clear to prevent module overflow, and the max election logic can prevent the rate of change from negative overshoot and instability when clearing.

[0050] The implementation of this control method is based on the original control system strategy. On the basis of the original control system of the power plant, a control strategy is added to achieve oscillation suppression. Its implementation process is simple and convenient, and it prevents low-frequency oscillation transmission events caused by active power overshoot or uncoordinated between power plant areas.

[0051] In this embodiment, Figure 3 As shown, the function input / exit button of this control method is set to ensure timely exit of the function and play a regulating role in emergency frequency and peak regulation. When the function button is turned on, the control logic of steps 1-5 is executed to achieve the purpose of intervening frequency and peak regulation control, that is, the intervention coefficient is obtained. The result of multiplying the deviation with the original grid frequency or active power is used to obtain the controlled parameter deviation with suppression capability. The function exit button of this control method can be manually exited in the event of an abnormal situation to avoid greater impact on the grid.

[0052] Specifically, in step 1, when there is a risk of low-frequency oscillation caused by frequency and peak regulation in the power station, the control unit of the power station participating in the frequency and peak regulation of the power grid is used as the main body of the control implementation of the method to complete The deviation of the grid frequency or active power from the target value at each moment is calculated. When optimizing the power plant frequency regulation control strategy, the grid frequency is selected as the data source of this method. When optimizing the power plant peak regulation control strategy, the active power is selected as the data source of this method.

[0053] In this embodiment, the control method can not only realize the regulation of grid frequency, but also realize the regulation of grid peak. Different parameters are selected as the data source for deviation calculation in different situations. In actual grid operation, this solution can be given priority for power stations that have experienced low-frequency oscillations. The implementation of this control method is based on the original control system strategy. On the basis of the original control system of the power station, a control strategy is added to realize oscillation suppression. The implementation process is simple and convenient, and can avoid the low-frequency oscillation of the power station caused by abnormal frequency and peak control parameters to stimulate greater disturbances in the power grid, thereby ensuring stable and safe operation of the power grid.

[0054] Specifically, in step 2, the grid frequency or active power deviation obtained in step 1 is divided into two data streams, and the specific process is as follows:

[0055] One of the paths passes through the deviation alarm module, and the high value alarm setting is set to , low alarm setting value is , is the grid frequency or active power deviation, then when or The time deviation alarm module outputs a true value, i.e., TRUE, otherwise it outputs a false value, i.e., FALSE. After judgment, if it is a true value, the pulse outputs a true value, otherwise it is a false value, and then inputs it to the control selection port of the switching module 1;

[0056] Another way to get the absolute value of the deviation , and multiply by , and get the absolute error value , the absolute error value is input to port 1 of switch module 1, and the input to port 2 of switch module 1 is 0;

[0057] The control logic of the switching module is: when the selected port is true, the output is the analog value of port 1; when the selected port is false, the output is the analog value of port 2. That is, the logic of this step is that when the grid frequency or active power deviation exceeds the limit, the output is a multiple of the absolute error, and the current oscillation amplitude is recorded. When the grid frequency or active power does not exceed the limit, the output is 0.

[0058] In this embodiment, Figure 1 As shown in the above description of the specific process, the control logic of step 2 is that when the grid frequency or active power deviation exceeds the limit, the output is the absolute error multiple and the current oscillation amplitude is recorded.

[0059] Specifically, in step 3, the deviation excess integral value obtained is It is an evaluation index based on the absolute error integral criterion, which can be used to evaluate the performance index of the control system and express the oscillation state during oscillation.

[0060] Specifically, in step 4, the output of the unstable oscillation state in step 3 is Its first-order inertia link Calculate the difference, and calculate the maximum output from 0 to obtain the cumulative direction integral change rate. The cumulative direction integral change rate obtained in step 3 has the correlation with the oscillation deviation amplitude because steps 1-2 make the value have the oscillation deviation amplitude. Therefore, if this value increases, it indicates that the oscillation amplitude of the active power control loop is large.

[0061] Determine whether the rate of change is less than the set value C. If it is less than the set value C, a short pulse is triggered to make the switching module 2 output Clear to zero. This step can prevent the overflow of the superposition state quantity data and cause the control system to be abnormal. Otherwise, keep the deviation calculated by the cyclic superposition step 1-2 to update the oscillation unstable state quantified in step 3. , because after the periodic cycle superposition, the integral change rate of the amplitude is combined with the oscillation period, producing the combined amount of coupled amplitude and period, that is, the oscillation instability state .

[0062] Specifically, in step 5, the data of step 4 is continuously transformed, and the unstable oscillation state can be fed back to the regulation control link to achieve oscillation suppression and obtain the intervention depth of the frequency modulation and peak regulation control effect under the oscillation state. The specific process is:

[0063] First, output After the first-order inertia link Then output it smoothly to prevent the suppression from causing new disturbance to the frequency modulation and peak regulation. Add, then add the proportional coefficient Multiply and input to the exponential function , and finally the exponential function The output and 1 are minimized and output, the upper limit is limited, and the intervention coefficient is generated. The curve characteristic of the exponential function that is infinitely close to 0 can be brought into play. By modifying the constant D and the proportional coefficient k2, the corresponding relationship between the unstable oscillation state and the intervention coefficient can be matched, and the control parameters of the frequency modulation and peak regulation after the oscillation exceeds the limit can be appropriately intervened, thereby suppressing the oscillation problem caused by the frequency modulation and peak regulation.

[0064] Example 2

[0065] Based on the control method of the first embodiment above, in an actual power plant, taking a 350MW thermal power unit as an example, when the grid frequency is selected as the data source of this method, the above parameters are set as follows:

[0066] ,

[0067] ,

[0068] ,

[0069] ,

[0070] ,

[0071] ,

[0072] ,

[0073] ,

[0074] If the grid frequency is replaced by the synchronous machine speed, the speed should be converted to the grid frequency according to the number of magnetic pole pairs and then the control logic is executed with the above parameters;

[0075] When active power is selected as the data source of this method, the above parameters are set as follows:

[0076] ,

[0077] ,

[0078] ,

[0079] ,

[0080] ,

[0081] ,

[0082] ,

[0083] .

[0084] Example 3

[0085] Based on the control method of the first embodiment above, a 50MW hydropower unit is taken as an example at an actual power station site.

[0086] When the grid frequency is selected as the data source of this method, the above parameters are set as follows:

[0087] ,

[0088] ,

[0089] ,

[0090] ,

[0091] ,

[0092] ,

[0093] ,

[0094] ,

[0095] If the grid frequency is replaced by the synchronous machine speed, the speed should be converted to the grid frequency according to the number of magnetic pole pairs, and then the control logic should be executed with the above parameters;

[0096] When active power is selected as the data source of this method, the above parameters are set as follows:

[0097] ,

[0098] ,

[0099] ,

[0100] ,

[0101] ,

[0102] ,

[0103] ,

[0104] .

[0105] Example 4

[0106] Based on the control method of the first embodiment above, at an actual power station site, a 100MW photovoltaic or wind power station with fast frequency response or primary frequency regulation is used, and the grid frequency is used as the data source of this method. The above parameters are set as follows:

[0107] ,

[0108] ,

[0109] ,

[0110] ,

[0111] ,

[0112] ,

[0113] ,

[0114] ,

[0115] When active power is selected as the data source of this method, the above parameters are set as follows:

[0116] ,

[0117] ,

[0118] ,

[0119] ,

[0120] ,

[0121] ,

[0122] ,

[0123] .

[0124] The parameters of Examples 2, 3, and 4 above need to be set based on parameters such as the on-site unit status, the regional grid frequency inertia time, and the active power regulation response time. These parameters must be determined after professional thermal engineering commissioning and electrical system calibration to ensure they do not affect normal frequency regulation while maintaining the characteristics described in the manual. The logic function and performance can be verified by simulating frequency and power disturbances caused by oscillation. Currently, no specific standards have been established; reference can be made to the relevant procedures for closed-loop control of active power disturbances for various types of power supplies for acceptance.

[0125] In summary, this control method modifies the control logic of the primary frequency regulation and active power closed-loop regulation of the power station control system, optimizes the primary and secondary frequency regulation control strategies, automatically intervenes in the regulation performance of the unit to support the grid frequency when the grid frequency oscillates, and waits for the grid frequency damping to return to normal before restoring the frequency support capability, thereby suppressing the low-frequency oscillation of the grid frequency, preventing the spread of grid oscillations due to excessive regulation of power supply frequency and peak regulation, and improving the stability and reliability of the power system under low-frequency oscillation conditions.

[0126] The preferred embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

[0127] Many other changes and modifications can be made without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillations in the power grid, characterized in that: The following steps are involved: Step 1: Determine the frequency deviation of the power station in the current state of the grid frequency regulation, and set the real-time grid frequency of the control unit of the power station participating in the grid frequency regulation and peak regulation and target value Subtract, or real-time active power The value and target value Subtract to find the deviation value ; Step 2: Use the high and low tolerance alarm module to determine the calculated deviation value Whether it exceeds the specified deviation value. If so, the short-term output is a multiple of the absolute value of the above difference, generating data associated with the oscillation amplitude. If not, the output is 0. Step 3: Be in the present moment At this moment, the output result of switching module 1 is combined with The output of the moment switching module 2 is superimposed to obtain the deviation excess integral value , quantifying the oscillatory unstable state; Step 4: Output of the unstable oscillation state in step 3 Its first-order inertia link Calculate the difference, limit the lower limit to 0, calculate the integral change rate in the accumulation direction, and determine whether the change rate is less than the constant value C. If so, trigger a short pulse to clear the oscillation instability state. Otherwise, keep cyclically superimposing the deviations calculated in steps 1 and 2 to update the quantized oscillation instability state in step 3. ; Step 5: Continuously transform the data of step 4 to obtain the frequency modulation and peak regulation control optimization parameters under the oscillation state. First, the output is passed through the first-order inertia link. , and the fixed value Add, then add the proportional coefficient Multiply and input to the exponential function , and finally the exponential function The output and 1 are minimized and output, the upper limit is limited, and the intervention coefficient is generated. ; Step 6: Set the function activation / exit button. When the function is activated, the obtained intervention coefficient is multiplied by the deviation value of the original grid frequency or active power to obtain a result value. The result value is the controlled parameter deviation with suppression capability. If there is an abnormality, the function exit button can be manually selected to exit. At this point, a calculation cycle ends. The method cyclically executes the above steps to realize online monitoring and oscillation suppression.

2. The power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid according to claim 1 is characterized in that: In step 1, when there is a risk of low-frequency oscillation caused by frequency and peak regulation in the power station, the control unit of the power station participating in the frequency and peak regulation of the power grid is used as the main body of the control implementation of the method to complete The deviation of the grid frequency or active power from the target value at each moment is calculated. When optimizing the power plant frequency regulation control strategy, the grid frequency is selected as the data source of this method. When optimizing the power plant peak regulation control strategy, the active power is selected as the data source of this method.

3. The power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid according to claim 1, characterized in that: In step 2, the grid frequency or active power deviation obtained in step 1 is divided into two data streams, and the specific process is as follows: One of the paths passes through the deviation alarm module, and the high value alarm setting is set to , low alarm setting value is , is the grid frequency or active power deviation, then when or The time deviation alarm module outputs a true value, i.e., TRUE, otherwise it outputs a false value, i.e., FALSE. After judgment, if it is a true value, the pulse outputs a true value, otherwise it is a false value, and then inputs it to the control selection port of the switching module 1; Another way to get the absolute value of the deviation , and multiply by , and get the absolute error value , the absolute error value is input to port 1 of switch module 1, and the input to port 2 of switch module 1 is 0; The control logic of the switching module is: when the selected port is true, the output is the analog value of port 1; when the selected port is false, the output is the analog value of port 2. That is, the logic of this step is that when the grid frequency or active power deviation exceeds the limit, the output is a multiple of the absolute error, and the current oscillation amplitude is recorded. When the grid frequency or active power does not exceed the limit, the output is 0.

4. The power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid according to claim 1 is characterized in that: In step 3, the deviation excess integral value obtained It is an evaluation index based on the absolute error integral criterion, which can be used to evaluate the performance index of the control system and express the oscillation state during oscillation.

5. The power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid according to claim 1 is characterized in that: In step 4, the cumulative direction integral change rate obtained in step 3 has a correlation with the oscillation deviation amplitude because steps 1-2 make the value have an oscillation deviation amplitude. Therefore, if the value increases, it indicates that the oscillation amplitude of the active power control loop is large; Determine whether the rate of change is less than the set value C. If it is less than the set value C, a short pulse is triggered to make the switching module 2 output Clear to zero. This step can prevent the overflow of the superposition state quantity data and cause the control system to be abnormal. Otherwise, keep the deviation calculated by the cyclic superposition step 1-2 to update the oscillation unstable state quantified in step 3. , because after the periodic cycle superposition, the integral change rate of the amplitude is combined with the oscillation period, producing the combined amount of coupled amplitude and period, that is, the oscillation instability state .

6. The power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid according to claim 1, characterized in that: In step 5, the data of step 4 is continuously transformed, so that the unstable oscillation state can be fed back to the regulation control link to achieve oscillation suppression and obtain the intervention depth of the frequency modulation and peak regulation control effect under the oscillation state.

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