Accurate primary frequency modulation method and device for inertia-free power of grid-connected unit

Abstract

The invention relates to the technical field of power grid unit frequency modulation control, in particular to a grid-connected unit inertia-free power precise primary frequency modulation method and device. If a grid-connected unit is a thermal generator unit, after active disturbance occurs, primary frequency modulation is carried out through the frequency difference of an electric power system; after the frequency of the power system is stable, a precise frequency modulation instruction is superposed on the basis of primary frequency modulation, and precise frequency modulation is carried out; and if the grid-connected unit is not a thermal generator set, performing primary frequency modulation by using the frequency change rate of the power system after active disturbance occurs, and superposing a precise frequency modulation instruction on the basis of the primary frequency modulation after the frequency of the power system is stable to perform precise frequency modulation. After the frequency of the power system is stabilized by implementing primary frequency modulation, the precise frequency modulation instruction is superposed on the basis of the primary frequency modulation, so that the frequency of the power system can be recovered to the rated frequency, and support is provided for stable operation of the power system.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency regulation control of power grid units, and is a method and device for precise primary frequency regulation of grid-connected units without inertia power. Background Art

[0002] The primary frequency regulation of the unit refers to the automatic control process in which the control system of the grid-connected unit automatically controls the increase or decrease of the unit's active power to prevent the grid frequency from changing and maintain a stable grid frequency when the power system is disturbed by active power and the grid frequency changes once it deviates from the rated value. DO Remains constant and is always equal to the unit inertia power ΔP GX , Unit frequency modulation power ΔP Y , load regulation power ΔP D and load inertia power ΔP DX The sum of the four is:

[0003] ΔP DO =ΔP G +ΔP F =ΔP GX +ΔP Y +ΔP DX +ΔP D

[0004] Attached Figure 2 It shows the change curve of the dynamic frequency characteristics of the power system when the power system is disturbed and controlled by the existing primary frequency regulation method that only uses the frequency difference as the input. The horizontal axis represents time and the vertical axis intuitively shows the most influential characteristics of the 7 dynamic frequency characteristics of the power system.

[0005] At the beginning of the system frequency change, the maximum load inertia power is equal to the system disturbance power, and the load regulation power, unit inertia power and unit primary frequency regulation power are all zero. As the system frequency decreases, the unit primary frequency regulation power increases and the load inertia power decreases. When the sum of the unit primary frequency regulation power and the load regulation power is equal to the system disturbance power, the unit inertia power and the load inertia power are both "0", the system frequency stops changing and an inflection point appears, and the system frequency is in a stable state.

[0006] After the system frequency stops changing and an inflection point appears, it enters the frequency regulation stage. The unit's primary frequency regulation valve stops opening and starts to close, and the primary frequency regulation method used is the same as in the frequency stabilization stage. The unit's primary frequency regulation power continues to increase, but this part of the surge and fall energy is used to partially restore the system inertia energy storage, which is not enough to restore the system frequency to the rated frequency of the power system, 50Hz. Summary of the invention

[0007] The present invention provides a method and device for accurate primary frequency regulation of grid-connected units without inertia power, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problem that the existing primary frequency regulation method cannot restore the power system frequency to the rated frequency of the power system.

[0008] One of the technical solutions of the present invention is achieved by the following measures: a method for accurate primary frequency regulation of grid-connected units without inertia power, comprising:

[0009] Determine the type of grid-connected units;

[0010] If the grid-connected unit is a thermal power generating unit, after an active disturbance occurs, the frequency difference of the power system is used to perform a primary frequency modulation, and after the power system frequency is stabilized, a precise frequency modulation instruction is superimposed on the primary frequency modulation to perform precise frequency modulation;

[0011] If the grid-connected unit is not a thermal power generating unit, after an active disturbance occurs, a frequency adjustment is performed using the frequency change rate of the power system, and after the power system frequency stabilizes, a precise frequency adjustment instruction is superimposed on the primary frequency adjustment to perform precise frequency adjustment.

[0012] The following are further optimizations and / or improvements to the above technical solutions:

[0013] The above process of generating precise frequency modulation instructions includes:

[0014] After the power system frequency is stabilized, the current power system stable frequency difference is obtained;

[0015] The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed;

[0016] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

[0017] The above-mentioned frequency regulation using the frequency change rate of the power system includes:

[0018] The power given value is corrected by using the frequency change rate, and the corresponding valve instruction is obtained according to the corrected power given value;

[0019] The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism;

[0020] Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0021] The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions;

[0022] The boiler master controller controls the boiler to respond to boiler related instructions.

[0023] The above-mentioned frequency regulation using the frequency difference of the power system includes:

[0024] Obtaining a speed difference exceeding a speed difference dead zone according to the frequency difference of the current power system, wherein the speed difference is a difference between an operating speed of the synchronous unit and a rated speed;

[0025] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value;

[0026] The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism;

[0027] Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0028] The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions;

[0029] The boiler master controller controls the boiler to respond to boiler related instructions.

[0030] The above-mentioned use of the electro-hydraulic servo mechanism to convert the valve command into the corresponding throttle opening signal includes: amplifying the valve command, electro-hydraulic conversion, rate limiting, and position limiting in sequence, and then outputting the throttle opening signal.

[0031] The above also includes feeding back the oil motor stroke signal after the valve opening signal acts on the oil motor of the synchronous unit, and using the oil motor stroke signal to correct the valve instruction.

[0032] The above process of obtaining the frequency change rate of the power system after the active power disturbance occurs includes:

[0033] After an active disturbance occurs, when the power system frequency changes and the duration is longer than the set time, obtain the current frequency;

[0034] Taking the derivative of this frequency, we get the corresponding frequency change rate.

[0035] The second technical solution of the present invention is achieved by the following measures: a non-inertia power accurate primary frequency regulation device for a grid-connected unit, comprising:

[0036] Determine the trigger unit and the type of grid-connected unit;

[0037] The first precise primary frequency regulation unit, if the grid-connected unit is a thermal or hydroelectric generating unit, performs primary frequency regulation using the frequency difference of the power system after an active disturbance occurs, and superimposes precise frequency regulation instructions on the basis of the primary frequency regulation after the power system frequency stabilizes, to perform precise frequency regulation;

[0038] The second precise frequency regulation unit, if the grid-connected unit is not a thermal or hydropower generating unit, will perform a primary frequency regulation using the frequency change rate of the power system after an active disturbance occurs, and will superimpose precise frequency regulation instructions on the basis of the primary frequency regulation after the power system frequency stabilizes.

[0039] The following are further optimizations and / or improvements to the above technical solutions:

[0040] The first precise frequency modulation unit comprises:

[0041] The primary frequency modulation module uses the frequency difference of the power system to perform primary frequency modulation after an active disturbance occurs, including:

[0042] Obtaining a speed difference exceeding a speed difference dead zone according to the frequency difference of the current power system, wherein the speed difference is a difference between an operating speed of the synchronous unit and a rated speed;

[0043] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value;

[0044] The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism;

[0045] Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0046] The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions;

[0047] The boiler master controller controls the boiler to respond to boiler-related instructions;

[0048] The precise frequency modulation module adds precise frequency modulation instructions on the basis of primary frequency modulation after the power system frequency is stable, and performs precise frequency modulation, including:

[0049] After the power system frequency is stabilized, the current power system stable frequency difference is obtained;

[0050] The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed;

[0051] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

[0052] The second precise frequency modulation unit comprises:

[0053] The primary frequency modulation module uses the frequency change rate of the power system to perform primary frequency modulation after an active disturbance occurs, including:

[0054] The power given value is corrected by using the frequency change rate, and the corresponding valve instruction is obtained according to the corrected power given value;

[0055] The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism;

[0056] Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0057] The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions;

[0058] The boiler master controller controls the boiler to respond to boiler-related instructions;

[0059] The precise frequency modulation module adds precise frequency modulation instructions on the basis of primary frequency modulation after the power system frequency is stable, and performs precise frequency modulation, including:

[0060] After the power system frequency is stabilized, the current power system stable frequency difference is obtained;

[0061] The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed;

[0062] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

[0063] After implementing primary frequency modulation to stabilize the frequency of the power system, the present invention superimposes precise frequency modulation instructions on the basis of the primary frequency modulation, so that the frequency of the power system can be restored to the rated frequency, providing support for the stable operation of the power system. At the same time, the primary frequency modulation input of other generator sets other than thermal power generator sets is modified to the frequency change rate of the power system to avoid excessive decrease in the frequency of the power system, providing a basis for precise frequency modulation, so that the frequency of the power system can be more accurately adjusted back to the rated frequency after a disturbance occurs in the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Attached Figure 1 A schematic flow chart of a method for precise primary frequency regulation of grid-connected units without inertia power provided in one embodiment of the present invention.

[0065] Attached Figure 2An embodiment of the present invention provides a corresponding curve of dynamic characteristic change of power system frequency when controlling by using the existing primary frequency modulation method which only uses the frequency difference as the input quantity.

[0066] Attached Figure 3 An embodiment of the present invention provides a corresponding power system frequency dynamic characteristic change curve when the method disclosed in the present invention is used for control.

[0067] Attached Figure 4 A schematic flow chart of a method for performing primary frequency modulation using the frequency change rate of an electric power system provided in accordance with an embodiment of the present invention.

[0068] Attached Figure 5 A schematic flow chart of a method for performing primary frequency modulation using a frequency difference of an electric power system provided in accordance with an embodiment of the present invention.

[0069] Attached Figure 6 A flowchart of a method for generating precise frequency modulation instructions provided by one embodiment of the present invention.

[0070] Attached Figure 7 A schematic diagram of the structure of a grid-connected unit non-inertia power precise primary frequency regulation device provided in one embodiment of the present invention.

[0071] Attached Figure 8 A schematic diagram of a primary frequency modulation control structure using a frequency difference as an input quantity provided by an embodiment of the present invention.

[0072] Attached Fig. 9 A schematic diagram of a primary frequency modulation control structure using a frequency change rate as an input quantity provided by an embodiment of the present invention.

[0073] Attached Fig.10 A schematic diagram of the CCS coordination process structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0074] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0075] In the embodiments of the present invention, the term "module" or "unit" refers to a computer program or a part of a computer program with a predetermined function, and works together with other related parts to achieve a predetermined goal, and can be implemented in whole or in part by using software, hardware (such as processing circuits or memories) or a combination thereof. Similarly, a processor (or multiple processors or memories) can be used to implement one or more modules or units. In addition, each module or unit can be a part of an overall module or unit that includes the function of the module or unit.

[0076] In addition, the term "plurality" in the embodiments of the present invention refers to two or more than two. The terms "first" and "second" in the embodiments of the present invention are used for distinguishing descriptions and should not be understood as implying relative importance.

[0077] The technical solution of the present invention will be introduced and explained below with reference to several examples.

[0078] Embodiment 1: As attached Figure 1 As shown, the embodiment of the present invention discloses a method for accurate primary frequency regulation of grid-connected units without inertia power, including:

[0079] Step S110, determining the type of the grid-connected unit.

[0080] Step S120: If the grid-connected unit is a thermal or hydroelectric generating unit, after an active disturbance occurs, a frequency adjustment is performed using the frequency difference of the power system, and after the power system frequency stabilizes, a precise frequency adjustment instruction is superimposed on the primary frequency adjustment to perform precise frequency adjustment.

[0081] Step S130, if the grid-connected unit is not a thermal power generating unit, after an active disturbance occurs, a frequency modulation is performed using the frequency change rate of the power system, and after the power system frequency stabilizes, a precise frequency modulation instruction is superimposed on the basis of the primary frequency modulation to perform precise frequency modulation.

[0082] Attached Figure 2 It shows the change curve of the dynamic frequency characteristics of the power system when the power system is disturbed and controlled by the existing primary frequency regulation method that only uses the frequency difference as the input. The horizontal axis represents time and the vertical axis intuitively shows the most influential characteristics of the 7 dynamic frequency characteristics of the power system.

[0083] At the beginning of the system frequency change, the maximum load inertia power is equal to the system disturbance power, and the load regulation power, unit inertia power and unit primary frequency regulation power are all zero. As the system frequency decreases, the unit primary frequency regulation power increases and the load inertia power decreases. When the sum of the unit primary frequency regulation power and the load regulation power is equal to the system disturbance power, the unit inertia power and the load inertia power are both "0", the system frequency stops changing and an inflection point appears, and the system frequency is in a stable state.

[0084] After the system frequency stops changing and an inflection point appears, it enters the frequency regulation stage. The unit's primary frequency regulation valve stops opening and starts to close, and the primary frequency regulation method used is the same as in the frequency stabilization stage. The unit's primary frequency regulation power continues to increase, but this part of the surge and fall energy is used to partially restore the system inertia energy storage, which is not enough to restore the system frequency to the rated frequency of the power system, 50Hz.

[0085] Therefore, after the embodiment of the present invention implements the primary frequency modulation to stabilize the power system frequency, a precise frequency modulation instruction is superimposed on the basis of the primary frequency modulation. It should be noted that the precise frequency modulation instruction is independent of the primary frequency modulation part and can be added in an external manner, and the specific value of the precise frequency modulation instruction can be set according to the difference between the power system frequency after stabilization and the rated frequency of the power system.

[0086] Attached Figure 3 The figure shows the change curve of the dynamic characteristics of the power system frequency when a disturbance occurs in the power system and the control is performed using the method disclosed in the embodiment of the present invention. The horizontal axis represents time and the vertical axis intuitively shows the most influential characteristics of the 7 dynamic characteristics of the power system frequency.

[0087] When the sum of the unit's primary frequency regulation power and the load regulation power is equal to the system disturbance power, the unit's inertia power and the load's inertia power are both "0", the system frequency stops changing and an inflection point appears. After the system frequency is in a stable state, the precise frequency regulation command is superimposed on the basis of the primary frequency regulation to perform precise frequency regulation, which can be one or more times. Compared with the attached Figure 2 , the power system frequency can be restored to the rated frequency.

[0088] Furthermore, when an active disturbance occurs in the power system, the frequency of the power system changes. Currently, all types of grid-connected units use the power system frequency difference as the primary frequency modulation input for primary frequency modulation. The process of using the power system frequency difference as the primary frequency modulation input for primary frequency modulation requires waiting for a certain period of time when an active disturbance occurs to obtain the power system frequency difference. During this period of time, the power system frequency will change dramatically. In order to avoid excessive changes in the power system frequency, resulting in the problem that the system frequency is not enough to restore to 50Hz during the frequency modulation stage, it is necessary to consider the frequency change rate at a certain point in time as the input of the unit's inertia power primary frequency modulation control. The frequency change rate is a point value, so it can respond in time when an active disturbance occurs in the power system. However, since the primary frequency modulation input of thermal power generation and hydropower units is not easy to modify, the present invention modifies the primary frequency modulation input of other generator sets other than thermal power and hydropower generator sets to the frequency change rate of the power system to avoid excessive decrease in the power system frequency, providing a basis for precise frequency modulation, so that the frequency of the power system can be more accurately adjusted back to the rated frequency after a disturbance occurs in the power system.

[0089] Step S110 of obtaining the acquisition frequency change rate at a certain time point includes:

[0090] (1) After an active disturbance occurs, when the power system frequency changes and the duration is greater than the set time, the frequency at the current moment is obtained; the time is set here to determine whether the active disturbance actually occurs.

[0091] (2) Derivative the frequency to obtain the corresponding frequency change rate.

[0092] The embodiment of the present invention discloses a method for precise primary frequency regulation of inertia-free power of a grid-connected unit. After the primary frequency regulation is implemented to stabilize the frequency of a power system, a precise frequency regulation instruction is superimposed on the primary frequency regulation to enable the frequency of the power system to be restored to the rated frequency, thereby providing support for the stable operation of the power system. At the same time, the primary frequency regulation input of other generator sets other than thermal and hydroelectric generator sets is modified to the frequency change rate of the power system to avoid excessive decrease in the frequency of the power system, thereby providing a basis for precise frequency regulation, so that the frequency of the power system can be more accurately adjusted back to the rated frequency after a disturbance occurs in the power system.

[0093] Embodiment 2: As attached Figure 4 As shown, the embodiment of the present invention is a further optimization of the above embodiment, wherein the frequency change rate of the power system is used to perform a frequency modulation, including:

[0094] Step S210, using the frequency change rate to correct the power given value, and obtaining a corresponding valve instruction according to the corrected power given value;

[0095] In this embodiment, a power set value is preset, and the power set value is corrected once using the frequency change rate. Combined with the conversion function or comparison table between the power and valve instructions in the synchronous unit turbine provided by the manufacturer, the corresponding valve instruction is obtained, wherein the valve instruction is the regulating valve position instruction.

[0096] Step S220, using the electro-hydraulic servo mechanism to convert the valve command into a corresponding valve opening signal;

[0097] In this embodiment, the process performed by the electro-hydraulic servo mechanism includes amplifying the valve command, electro-hydraulic conversion, rate limiting, and position limiting in sequence, and then outputting the valve opening signal. The rate limiting is completed according to the maximum valve opening speed and the maximum valve closing speed, and the position limiting is completed according to the minimum output power of the oil motor and the maximum output power of the oil motor.

[0098] Step S230, obtaining the main steam flow at the current moment, and determining the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0099] Step S240, using the variation to obtain corresponding boiler-related instructions, and after amplifying and adjusting the boiler-related instructions, outputting them to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions, and feed water instructions;

[0100] Step S250: the boiler main controller controls the boiler to respond to boiler-related instructions.

[0101] Here, steps 230 to 250 implement the CCS coordination process, which is applicable to thermal power units. When applied in thermal power units, the CCS coordination process and the primary frequency modulation process of steps 210 to 220 are used simultaneously, but they are independent of each other. Steps 230 to 250 adopt the "furnace following machine" mode, changing from following power to following the main steam flow of the steam turbine. When the main steam flow at the boiler outlet changes, the boiler fuel, air volume, feed water, and steam temperature are coordinated and controlled to keep the superheated steam temperature and pressure at the boiler outlet continuously stable, so as to achieve the continuous stability of the primary frequency modulation power.

[0102] Embodiment 3: As attached Figure 5 As shown, the embodiment of the present invention is a further optimization of the above embodiment, wherein the frequency difference of the power system is used to perform a frequency modulation, including:

[0103] Step S310, obtaining a speed difference exceeding a speed difference dead zone according to the frequency difference of the current power system, wherein the speed difference is a difference between an operating speed of the synchronous unit and a rated speed;

[0104] In this embodiment, when an active disturbance occurs in the power system, a difference occurs between the speed setting value and the actual speed value, namely, the speed difference. The embodiment of the present invention utilizes the speed difference exceeding the speed difference dead zone as the input quantity of the primary frequency regulation control process of the synchronous unit.

[0105] The above-mentioned obtaining the speed difference exceeding the speed difference dead zone according to the frequency difference of the current power system specifically includes:

[0106] (1) Convert the frequency difference of the current power system into a speed difference;

[0107] (2) obtaining a speed difference, wherein the speed difference is a difference between a given speed value and an actual speed value;

[0108] (3) determining whether the speed difference exceeds the speed difference dead zone, and in response, outputting the speed difference;

[0109] (4) The speed difference is amplified using the speed difference amplification factor.

[0110] Step S320, using the speed difference to correct the power given value, and obtaining a corresponding valve instruction according to the corrected power given value;

[0111] In this embodiment, a power set value is preset, and the power set value is corrected once using the speed difference. Combined with the conversion function or comparison table between the power and valve instructions in the synchronous unit turbine provided by the manufacturer, the corresponding valve instruction is obtained, wherein the valve instruction is the regulating valve position instruction.

[0112] Step S330, using the electro-hydraulic servo mechanism to convert the valve command into a corresponding valve opening signal;

[0113] In this embodiment, the process performed by the electro-hydraulic servo mechanism includes amplifying the valve command, electro-hydraulic conversion, rate limiting, and position limiting in sequence, and then outputting the valve opening signal. The rate limiting is completed according to the maximum valve opening speed and the maximum valve closing speed, and the position limiting is completed according to the minimum output power of the oil motor and the maximum output power of the oil motor.

[0114] Step S340, obtaining the main steam flow at the current moment, and determining the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0115] Step S350, using the variation to obtain corresponding boiler-related instructions, and after amplifying and adjusting the boiler-related instructions, outputting them to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions, and feed water instructions;

[0116] Step S360: the boiler main controller controls the boiler to respond to boiler-related instructions.

[0117] In this embodiment, steps 340 to 360 implement the CCS coordination process, which is applicable to thermal power units. When applied in thermal power units, they are used simultaneously with the primary frequency modulation process of steps 310 to 330, but are independent of each other, that is, steps 310 to 330 adopt the "furnace following machine" mode, changing from following power to following the main steam flow of the steam turbine. When the main steam flow at the boiler outlet changes, the boiler fuel, air volume, feed water, and steam temperature are coordinated and controlled to keep the superheated steam temperature and pressure at the boiler outlet continuously stable, so that the primary frequency modulation power implemented by steps 310 to 330 is continuously stable.

[0118] Embodiment 4: As attached Figure 6 As shown, the embodiment of the present invention is a further optimization of the above embodiment, wherein the process of generating a precise frequency modulation instruction includes:

[0119] Step S410, after the power system frequency is stabilized, obtaining the current power system stable frequency difference;

[0120] Step S420, obtaining a corresponding speed difference according to the current stable frequency difference of the power system, wherein the speed difference is the difference between the operating speed of the unit and the rated speed;

[0121] Step S430, using the speed difference to correct the power set value, and obtaining the corresponding valve instruction according to the corrected power set value, which is the precise frequency modulation instruction.

[0122] In this embodiment, the process of generating precise frequency modulation instructions is independent of the sequential frequency modulation process, and the precise frequency modulation instructions can be connected to the single frequency modulation in the form of a plug-in.

[0123] It should also be noted that after the power system frequency is stabilized, the precise frequency modulation command is superimposed on the primary frequency modulation to perform precise frequency modulation, that is, after obtaining the corresponding valve command according to the corrected power given value in the primary frequency modulation, the precise frequency modulation command is superimposed on the valve command to obtain the final valve command and input it into the electro-hydraulic servo mechanism. As a result, the valve opening signal output by the primary frequency modulation is increased on the original basis, which facilitates the power system frequency to recover to the rated frequency. At the same time, the precise frequency modulation command can also be manually set as needed to avoid over-modulation.

[0124] Embodiment 5: The embodiment of the present invention is a further optimization of the above embodiment, in which an electro-hydraulic servo mechanism is used to convert the valve command into a corresponding throttle opening signal, including: amplifying the valve command, electro-hydraulic conversion, rate limiting, and position limiting in sequence, and then outputting the throttle opening signal.

[0125] Embodiment 6: The embodiment of the present invention is a further optimization of the above embodiment, which also includes feeding back the oil motor stroke signal after the valve opening signal acts on the oil motor of the synchronous unit, and using the oil motor stroke signal to correct the valve instruction.

[0126] Embodiment 7: As attached Figure 7 As shown, the embodiment of the present invention discloses a non-inertia power precise primary frequency regulation device for a grid-connected unit, comprising:

[0127] Determine the trigger unit and the type of grid-connected unit;

[0128] The first precise primary frequency regulation unit, if the grid-connected unit is a thermal power generating unit, uses the frequency difference of the power system to regulate the frequency after an active disturbance occurs, and superimposes precise frequency regulation instructions on the basis of primary frequency regulation to perform precise frequency regulation after the power system frequency stabilizes;

[0129] The second precise primary frequency regulation unit, if the grid-connected unit is not a thermal power generating unit, will perform primary frequency regulation using the frequency change rate of the power system after an active disturbance occurs, and will perform precise frequency regulation by superimposing precise frequency regulation instructions on the basis of the primary frequency regulation after the power system frequency stabilizes.

[0130] Among them, the first precise primary frequency modulation unit includes:

[0131] The primary frequency modulation module uses the frequency difference of the power system to perform primary frequency modulation after an active disturbance occurs. The primary frequency modulation includes:

[0132] Obtaining a speed difference exceeding a speed difference dead zone according to the frequency difference of the current power system, wherein the speed difference is a difference between an operating speed of the synchronous unit and a rated speed;

[0133] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value;

[0134] The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism;

[0135] Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0136] The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions;

[0137] The boiler master controller controls the boiler to respond to boiler-related instructions;

[0138] The precise frequency modulation module adds precise frequency modulation instructions on the basis of primary frequency modulation after the power system frequency is stable, and performs precise frequency modulation, including:

[0139] After the power system frequency is stabilized, the current power system stable frequency difference is obtained;

[0140] The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed;

[0141] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

[0142] Among them, the second precise primary frequency modulation unit includes:

[0143] The primary frequency modulation module uses the frequency change rate of the power system to perform primary frequency modulation after an active disturbance occurs. The primary frequency modulation includes:

[0144] The power given value is corrected by using the frequency change rate, and the corresponding valve instruction is obtained according to the corrected power given value;

[0145] The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism;

[0146] Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment;

[0147] The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions;

[0148] The boiler master controller controls the boiler to respond to boiler-related instructions;

[0149] The precise frequency modulation module adds precise frequency modulation instructions on the basis of primary frequency modulation after the power system frequency is stable, and performs precise frequency modulation, including:

[0150] After the power system frequency is stabilized, the current power system stable frequency difference is obtained;

[0151] The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed;

[0152] The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

[0153] In this embodiment, the primary frequency modulation module structure of the first precise primary frequency modulation unit can be as shown in the attached figure. Figure 8 , 10 As shown, Δf is the speed difference, T1 is the time constant of the speed conversion link, K is the speed change coefficient, and the value is smaller than the initial frequency modulation. The amplitude of the reduction is dynamically changed as needed to avoid overmodulation. Here, the conversion function between the existing speed and power is used to obtain correction.

[0154] In this embodiment, the primary frequency modulation module structure of the second precise primary frequency modulation unit can be as shown in the attached figure. Fig. 9 , 10 As shown, is the frequency change rate, T1 is the time constant of the speed conversion link, K is the speed change coefficient, and the value can be increased by 3.5% to 4% during the first frequency modulation; here, the conversion function between the existing speed and power is used to obtain the correction.

[0155] Attached Figure 8 , 9 In the PID control part (K p , K d , K i PID proportional, differential, integral link multiples), time constant adjustment part (T SM is the time constant of the CV control valve servo mechanism, T SJ is the time constant of the IV control stop valve servo mechanism), rate limiting part (rate limiting is completed according to VELopen maximum valve opening speed and VELclose maximum valve closing speed), position limiting part (position limiting is completed according to PMIN minimum output power of the oil motor and PMAX maximum output power of the oil motor), feedback part (LVDT, where T2 is the time constant of the oil motor stroke feedback link).

[0156] The above content is only a specific implementation mode of the present invention, which has strong adaptability and implementation effect, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the protection scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present invention.

Claims

1. A method for accurate primary frequency modulation of grid-connected units without inertia power, characterized in that: include: Determine the type of grid-connected units; If the grid-connected unit is a thermal power generating unit, after an active disturbance occurs, the frequency difference of the power system is used to perform a primary frequency modulation, and after the power system frequency is stabilized, a precise frequency modulation instruction is superimposed on the primary frequency modulation to perform precise frequency modulation; If the grid-connected unit is not a thermal power generating unit, after an active disturbance occurs, a frequency adjustment is performed using the frequency change rate of the power system, and after the power system frequency stabilizes, a precise frequency adjustment instruction is superimposed on the primary frequency adjustment to perform precise frequency adjustment.

2. The method for accurate primary frequency modulation of grid-connected units without inertia power according to claim 1 is characterized in that: The process of generating precise frequency modulation instructions includes: After the power system frequency is stabilized, the current power system stable frequency difference is obtained; The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed; The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

3. The method for accurate primary frequency modulation of grid-connected units without inertia power according to claim 1 or 2, characterized in that: The frequency change rate of the power system is used to perform primary frequency regulation, including: The power given value is corrected by using the frequency change rate, and the corresponding valve instruction is obtained according to the corrected power given value; The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism; Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment; The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions; The boiler master controller controls the boiler to respond to boiler related instructions.

4. The method for accurate primary frequency modulation of grid-connected units without inertia power according to claim 1 or 2, characterized in that: The frequency difference of the power system is used for primary frequency regulation, including: Obtaining a speed difference exceeding a speed difference dead zone according to the frequency difference of the current power system, wherein the speed difference is a difference between an operating speed of the synchronous unit and a rated speed; The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value; The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism; Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment; The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions; The boiler master controller controls the boiler to respond to boiler related instructions.

5. The method for accurate primary frequency modulation of grid-connected units without inertia power according to claim 3 or 4, characterized in that: The valve command is converted into a corresponding throttle opening signal by using an electro-hydraulic servo mechanism, including: the valve command is amplified, electro-hydraulic converted, rate limited, and position limited in sequence, and then the throttle opening signal is output; or / and, after the throttle opening signal acts on the oil motor of the synchronous unit, the oil motor stroke signal is fed back, and the valve command is corrected by using the oil motor stroke signal.

6. The method for accurate primary frequency modulation of grid-connected units without inertia power according to any one of claims 1 to 5, characterized in that: The process of obtaining the frequency change rate of the power system after an active disturbance occurs includes: After an active disturbance occurs, when the power system frequency changes and the duration is longer than the set time, obtain the current frequency; Taking the derivative of this frequency, we get the corresponding frequency change rate.

7. A non-inertia power precise primary frequency modulation device for a grid-connected unit using the method as claimed in any one of claims 1 to 6, characterized in that: include: Determine the trigger unit and the type of grid-connected unit; The first precise primary frequency regulation unit, if the grid-connected unit is a thermal power generating unit, performs primary frequency regulation using the frequency difference of the power system after an active disturbance occurs, and superimposes precise frequency regulation instructions on the basis of the primary frequency regulation after the power system frequency stabilizes, to perform precise frequency regulation; The second precise primary frequency regulation unit, if the grid-connected unit is not a thermal power generating unit, will perform primary frequency regulation using the frequency change rate of the power system after an active disturbance occurs, and will perform precise frequency regulation by superimposing precise frequency regulation instructions on the basis of the primary frequency regulation after the power system frequency stabilizes.

8. The inertia-free power precise primary frequency modulation device for grid-connected units according to claim 7, characterized in that: The first precise primary frequency modulation unit comprises: The primary frequency modulation module uses the frequency difference of the power system to perform primary frequency modulation after an active disturbance occurs, including: Obtaining a speed difference exceeding a speed difference dead zone according to the frequency difference of the current power system, wherein the speed difference is a difference between an operating speed of the synchronous unit and a rated speed; The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value; The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism; Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment; The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions; The boiler master controller controls the boiler to respond to boiler-related instructions; The precise frequency modulation module adds precise frequency modulation instructions on the basis of primary frequency modulation after the power system frequency is stable, and performs precise frequency modulation, including: After the power system frequency is stabilized, the current power system stable frequency difference is obtained; The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed; The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

9. The inertia-free power precise primary frequency modulation device for grid-connected units according to claim 7 or 8, characterized in that: The second precise primary frequency modulation unit comprises: The primary frequency modulation module uses the frequency change rate of the power system to perform primary frequency modulation after an active disturbance occurs, including: The power given value is corrected by using the frequency change rate, and the corresponding valve instruction is obtained according to the corrected power given value; The valve command is converted into the corresponding valve opening signal by using the electro-hydraulic servo mechanism; Obtain the main steam flow at the current moment, and determine the change between the main steam flow at the current moment and the main steam flow at the previous moment; The corresponding boiler-related instructions are obtained by using the variation, and after amplifying and adjusting the boiler-related instructions, the instructions are output to the boiler main controller, wherein the boiler-related instructions include fuel instructions, air volume instructions and feed water instructions; The boiler master controller controls the boiler to respond to boiler-related instructions; The precise frequency modulation module adds precise frequency modulation instructions on the basis of primary frequency modulation after the power system frequency is stable, and performs precise frequency modulation, including: After the power system frequency is stabilized, the current power system stable frequency difference is obtained; The corresponding speed difference is obtained according to the current stable frequency difference of the power system, where the speed difference is the difference between the operating speed of the unit and the rated speed; The speed difference is used to correct the power given value, and the corresponding valve instruction is obtained according to the corrected power given value.

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