Power station frequency modulation and peak regulation control method for preventing low-frequency oscillation diffusion of power grid

Abstract

The invention discloses a power station frequency modulation and peak regulation control method for preventing low-frequency oscillation diffusion of a power grid. The method comprises the following steps: step 1, determining a local station frequency deviation of a power station participating in power grid frequency regulation in a current state; 2, judging whether the calculated deviation value # imgabs0 # exceeds the determined deviation fixed value or not by using a high-low out-of-tolerance alarm module, and outputting a result; 3, superposing the output result of the switching module 1 at the # imgabs1 # and the output of the switching module 2 at the # imgabs2 # to obtain a deviation value out-of-tolerance integral value # imgabs3 #; step 4, updating the quantized oscillation unstable state # imgabs4 # in the step 3; 5, performing continuous conversion on the data in the step 4 to obtain frequency modulation and peak regulation control optimization parameters in an oscillation state; and step 6, multiplying the obtained intervention coefficient with the deviation value of the original power grid frequency or active power to realize function switching, and by modifying the control logic of the power station control system, preventing power grid oscillation diffusion caused by instability of the frequency modulation and peak regulation system.

Description

Technical Field

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

[0002] With the acceleration of global energy transformation, the structure of the power system is undergoing profound changes. In the new power system, the coexistence of multiple types of power sources such as "wind, light, water, fire, and storage" is becoming increasingly common, and the proportion of new energy in power supply is increasing. While this diversified power structure brings many advantages to the power system, it also brings a series of new challenges. The randomness and mutation of the power system energy are enhanced. In order to quickly respond to grid frequency fluctuations, the power generation unit needs to have the ability to quickly adjust the active power to compensate for the imbalance between power supply and power consumption.

[0003] When faced with low-frequency oscillations in the primary and secondary frequency regulation of the power grid, the attenuation of power oscillations can be accelerated by increasing damping by investing in a 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 the set deviation is exceeded. 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 flexible suppression from the two dimensions of amplitude and period.

[0004] Among them, the oscillation state is quantified by the number of times exceeding the set deviation, and 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 using the function correspondence. However, the accumulation of the number of oscillations in its core algorithm cannot reflect the state of the oscillation amplitude in time, and the suppression effect is poor when encountering an oscillation state with a large amplitude and a long oscillation period.

[0005] In summary, the existing control technology for low-frequency oscillation of power grid frequency has many problems such as insufficient optimization of control strategy, insufficient coordination between different power sources, and difficulty in effectively coping with complex working conditions when facing complex power systems with multiple types of power sources such as "wind, light, water, fire, and storage", especially in areas where low-frequency oscillations are prone to or have occurred, such as weak connection of the power system, the end of the grid, and a high proportion of new energy. Therefore, it is necessary to develop a new power station frequency regulation control technology during low-frequency oscillation of the power grid frequency, which can fully consider the power supply regulation characteristics, provide differentiated setting parameters for multiple power sources, optimize the control strategy of multiple types of power sources such as "wind, light, water, fire, and storage", and improve the stability and reliability of the power system under low-frequency oscillation. Summary of the invention

[0006] In order to overcome the above problems, the purpose of the present invention is to provide a power station 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 station 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 waits for the grid frequency damping to be normal before restoring the frequency support capacity, so as to suppress the low-frequency oscillation of the grid frequency, prevent the spread of grid oscillations due to excessive regulation of power supply frequency regulation and peak regulation, and improve the stability and reliability of the power system under low-frequency oscillation conditions.

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

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

[0009] Step 1: Determine the frequency deviation of the power station participating in the grid frequency regulation in the current state, and set the real-time grid frequency of the control unit of the power station participating in the grid frequency regulation and peak regulation With target value Subtract, or real-time active power The value and target value Subtract and 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 determined deviation value. If it does, the short-term output is a multiple of the absolute value of the above difference, generating data associated with the oscillation amplitude. If it does not exceed, 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 momentary switching module 2 is superimposed to obtain the deviation excess integral value , quantifying the oscillatory unstable state;

[0012] Step 4: Output the unstable state of oscillation in step 3 Its first-order inertial 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 fixed value C. If so, trigger a short pulse to clear the oscillation instability state. If not, keep cyclically superimposing the deviation calculated in step 1 and step 2 to update the quantized oscillation instability state in step 3. ;

[0013] Step 5: Continuously transform the data in step 4 to obtain the optimal parameters for frequency modulation and peak regulation control under oscillation. First, the output is passed through the first-order inertia link. , and the fixed value Add, then add the proportionality factor 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 on / off button. When the function is on, 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 achieve 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 the 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 after 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 , the low alarm setting is , is the grid frequency or active power deviation, then when or The output of the time deviation alarm module is 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 find 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 a true value, the output is the analog value of port 1, and when the selected port is a false value, 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 to 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, because steps 1-2 make the value have oscillation deviation amplitude correlation, so 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 quantified oscillation unstable state in step 3. , because after the periodic cycle superposition, the integral change rate of the amplitude is combined with the oscillation period to produce the combined amount of the 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, so that the above-mentioned oscillation unstable 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.

[0024] Beneficial effects of the present invention:

[0025] The present invention provides a power station frequency modulation and peak regulation control method for preventing the spread of low-frequency oscillations in a power grid. The control method modifies the control logic of primary frequency modulation and active power closed-loop regulation of a power station control system, optimizes 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 under low-frequency oscillation conditions.

[0026] The power station frequency modulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid of the present invention is superior to the traditional fixed accumulation method in steps 1-3. The multiples of the absolute value of the calculated deviation are used as the superposition target quantity, which 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.

[0027] The power station frequency modulation and peak regulation control method for preventing the spread of low-frequency oscillation in the power grid according to the present invention uses the deviation multiple and the upper cycle in the oscillation. The output of the Max selection module is not only proportional to the oscillation frequency, but also superimposed with 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 of the power grid according to the present invention, when it is judged in step 4 that the integral change rate is less than a fixed value, triggering 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 discloses a power station frequency modulation 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 station to achieve oscillation suppression. The implementation process is simple and convenient, and low-frequency oscillation transmission events caused by overshoot or uncoordinated active power between power station areas are prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the main control logic diagram of the power station frequency regulation and peak regulation control method for preventing the spread of low-frequency oscillation of the power grid proposed by the present invention;

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

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

[0033] The specific implementation of the present invention is described below in conjunction with 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 contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0035] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited 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 be used 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 modulation instruction will be transmitted to the speed regulator or other primary frequency modulation 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 modulation 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 that increases the damping of the power oscillation by investing in the power system stabilizer to accelerate the power oscillation, the method of exiting the frequency modulation and peak regulation control function can be adopted 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 modulation and peak regulation control, prevent the transmission of grid frequency or active power oscillations, and avoid the hidden danger of weak support of long-term withdrawal from frequency modulation and peak regulation due to oscillation risks.

[0039] Embodiment 1

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

[0041] Step 1: Determine the frequency deviation of the power station participating in the grid frequency regulation in the current state, and set the real-time grid frequency of the control unit of the power station participating in the grid frequency regulation and peak regulation With target value Subtract, or real-time active power The value and target value Subtract and 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 determined deviation value. If it does, the short-term output is a multiple of the absolute value of the above difference, generating data associated with the oscillation amplitude. If it does not exceed, 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 momentary switching module 2 is superimposed to obtain the deviation excess integral value , quantifying the oscillatory unstable state;

[0044] Step 4: Output the unstable state of oscillation in step 3 Its first-order inertial 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 fixed value C. If so, trigger a short pulse to clear the oscillation instability state. If not, keep cyclically superimposing the deviation calculated in step 1 and step 2 to update the quantized oscillation instability state in step 3. ;

[0045] Step 5: Continuously transform the data in step 4 to obtain the optimal parameters for frequency modulation and peak regulation control under oscillation. First, the output is passed through the first-order inertia link. , and the fixed value Add, then add the proportionality factor 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 on / off button. When the function is on, 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 achieve online monitoring and oscillation suppression.

[0047] In this embodiment, Figure 1 , Figure 2 As shown, the 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 early to suppress the low-frequency oscillation events 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 is not only proportional to the oscillation frequency, but also superimposed with 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 judged to be 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. A control strategy is added to the original control system of the power station to achieve oscillation suppression. The implementation process is simple and convenient, and it prevents low-frequency oscillation transmission events caused by active power overshoot or uncoordinated between power station areas.

[0051] In this embodiment, Figure 3 As shown, setting the function input / exit button of the control method can ensure timely exit of the function and play a regulating role in emergency frequency and peak regulation. The function button is activated and the control logic of steps 1-5 is executed to achieve the purpose of intervening frequency and peak regulation control, that is, the obtained intervention coefficient The result of multiplying the original grid frequency or active power deviation is used to obtain a controlled parameter deviation with suppression capability. The function exit button of this control method can be manually exited when an abnormal situation occurs to avoid causing 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 the 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 , the low alarm setting is , is the grid frequency or active power deviation, then when or The output of the time deviation alarm module is 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 find 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 a true value, the output is the analog value of port 1, and when the selected port is a false value, 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, through the description of the above 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 to 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 inertial link Calculate the difference, and calculate the maximum value output with 0, and calculate the integral change rate in the cumulative direction. The integral change rate in the cumulative direction obtained in step 3, because steps 1-2 make the value have the correlation of the oscillation deviation amplitude, so if the 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 quantified oscillation unstable state in step 3. , because after the periodic cycle superposition, the integral change rate of the amplitude is combined with the oscillation period to produce the combined amount of the coupled amplitude and period, that is, the oscillation instability state .

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

[0063] First, output After the first-order inertia link Then smooth the output to prevent the suppression effect from causing new disturbances to the frequency modulation and peak regulation, and the fixed value Add, then add the proportionality factor 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] Embodiment 2

[0065] Based on the control method of the first embodiment above, in an actual power station, taking a 350MW thermal power unit as an example, when the grid frequency is selected as the data source of the 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] Embodiment 3

[0085] Based on the control method of the first embodiment described above, a 50MW hydropower unit is taken as an example in 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 is 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] Embodiment 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 modulation 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 the above-mentioned Embodiment 2, Embodiment 3, and Embodiment 4 need to be set according to the on-site unit status, regional power grid frequency inertia time, active power regulation response time and other parameters. The parameters need to be determined after thermal engineering professional debugging and electrical system setting and verification to ensure that the normal frequency modulation is not affected and the characteristics described in the manual are possessed. The logic function and performance can be verified by simulating the frequency and power disturbances of the oscillation. At present, no targeted standards have been formulated, and the relevant regulations for closed-loop control of active power disturbances of various types of power supplies can be referred to for acceptance.

[0125] In summary, the control method modifies the control logic of 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 capacity, so as to suppress the low-frequency oscillation of the grid frequency, prevent the spread of grid oscillation due to excessive regulation of power supply frequency and peak regulation, and improve the stability and reliability of the power system under low-frequency oscillation.

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

[0127] Many other changes and modifications may be made without departing from the concept 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 oscillation in the power grid, characterized in that: The following steps are involved: Step 1: Determine the frequency deviation of the power station participating in the grid frequency regulation in the current state, and set the real-time grid frequency of the control unit of the power station participating in the grid frequency regulation and peak regulation With target value Subtract, or real-time active power The value and target value Subtract and find the deviation value ; Step 2: Use the high and low tolerance alarm module to determine the calculated deviation value Whether it exceeds the determined 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 momentary switching module 2 is superimposed to obtain the deviation excess integral value , quantifying the oscillatory unstable state; Step 4: Output the unstable state of oscillation in step 3 Its first-order inertial 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 fixed value C. If so, trigger a short pulse to clear the oscillation instability state. If not, keep cyclically superimposing the deviation calculated in step 1 and step 2 to update the quantized oscillation instability state in step 3. ; Step 5: Continuously transform the data in step 4 to obtain the optimal parameters for frequency modulation and peak regulation control under oscillation. First, the output is passed through the first-order inertia link. , and the fixed value Add, then add the proportionality factor 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 on / off button. When the function is on, 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 achieve online monitoring and oscillation suppression.

2. The power station frequency modulation 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 the 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 modulation 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 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 , the low alarm setting is , is the grid frequency or active power deviation, then when or The output of the time deviation alarm module is 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 find 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 a true value, the output is the analog value of port 1, and when the selected port is a false value, 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 modulation 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 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 to express the oscillation state during oscillation.

5. The power station frequency modulation 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, so if the value increases, it indicates that the oscillation amplitude of the active power control loop is large; Determine whether the change rate is less than the fixed value C. If it is less than the fixed 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 quantified oscillation unstable state in step 3. , because after the periodic cycle superposition, the integral change rate of the amplitude is combined with the oscillation period to produce the combined amount of the coupled amplitude and period, that is, the oscillation instability state .

6. The power station frequency modulation 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 the 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.

Images