CN111900741B - Quick frequency adjustment device and method for power grid - Google Patents
Quick frequency adjustment device and method for power grid Download PDFInfo
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- CN111900741B CN111900741B CN202010547634.4A CN202010547634A CN111900741B CN 111900741 B CN111900741 B CN 111900741B CN 202010547634 A CN202010547634 A CN 202010547634A CN 111900741 B CN111900741 B CN 111900741B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
Abstract
The invention discloses a rapid frequency adjustment device and method for a power grid, which solve the problems of low response speed, low power adjustment accuracy and small adjustment range of the conventional device and method. The device comprises: the power grid frequency calculation module is used for calculating the instantaneous frequency of the power grid; the frequency average module calculates a short-time frequency average value and a long-time frequency average value; the frequency difference calculation module is used for obtaining a frequency difference value; the frequency difference filtering module is used for outputting a frequency difference filtering value; the frequency difference adjusting module is used for determining an adjusting coefficient, receiving the frequency difference filtering value and multiplying the adjusting coefficient to obtain a power adjusting value; the power adjustment control module is used for receiving the frequency difference value, and when the frequency difference value is larger than the fluctuation threshold, a reset signal is sent to the frequency difference filtering module, and then a starting instruction is sent; and the power adjustment module is used for receiving the power adjustment value and adjusting the output power of the power station by using the power adjustment value after receiving the starting instruction. The method is used for the device. The invention realizes the rapid frequency adjustment technology of the power grid.
Description
Technical Field
The invention relates to the field of power grids, in particular to a rapid frequency adjustment device and method for a power grid.
Background
In order to solve the problem of quick response of the frequency of the power grid, the national power grid provides a quick frequency adjustment problem for new energy grid connection, and a new energy power station requiring grid connection has a quick frequency adjustment technology, and the core of the technology is as follows: firstly, when a power station is in grid connection for power generation, 10% of power needs to be reserved; secondly, the power station can accurately detect the frequency of the power grid, and when the frequency is higher and lower by 0.1Hz, the power station automatically adjusts the output power. The existing rapid frequency modulation technology has the following defects: firstly, a certain generated energy must be reserved in a green energy power station, so that energy waste is caused; secondly, within the deviation of positive and negative frequency of 0.1Hz, the new energy power station cannot participate in the rapid adjustment, so that the phenomenon of unstable power grid frequency is caused; thirdly, the deviation is between plus and minus 0.1 and 0.2Hz, the output power of the new energy power station is in linear change, the adjustment form is single, and the power adjustment cannot be accurately carried out.
Disclosure of Invention
The invention provides a rapid frequency adjustment device and method for a power grid, which solve the problems of low response speed, low power adjustment accuracy and small adjustment range of the conventional device and method.
To solve the above problems, the present invention is achieved as follows:
the embodiment of the invention provides a rapid frequency adjustment device for a power grid, which comprises the following components: the power grid frequency calculation module is used for calculating the instantaneous frequency of the power grid; the frequency average module is used for receiving the instantaneous frequency of the power grid and calculating a short-time frequency average value and a long-time frequency average value; the frequency difference calculation module is used for receiving the long-time frequency average value and the short-time frequency average value and subtracting the long-time frequency average value and the short-time frequency average value to obtain a frequency difference value; the frequency difference filtering module is used for receiving the frequency difference value and outputting a frequency difference filtering value, receiving a reset signal sent by the power adjustment control module and resetting a time constant; the frequency difference adjusting module is used for receiving the frequency difference value, determining an adjusting coefficient according to the size of the frequency difference value and a time constant of the preset short-time frequency mean value, receiving the frequency difference filtering value and multiplying the adjusting coefficient to obtain a power adjusting value; the power adjustment control module is used for receiving the frequency difference value, and when the frequency difference value is larger than a fluctuation threshold, a reset signal is sent to the frequency difference filtering module, and then a starting instruction is sent to the power adjustment module; and the power adjustment module is used for receiving the power adjustment value, and adjusting the output power of the power station by using the power adjustment value after receiving the starting instruction.
Further, the power adjustment control module is further configured to send a stop instruction to the power adjustment module if an open loop condition is satisfied; if the monitoring office instruction is received, a stopping instruction and the monitoring office instruction are sent to the power adjustment module; the open loop condition is that the frequency difference value is kept stable when the calculation time is more than or equal to the first time; the power adjustment module is further used for stopping adjusting the output power of the power station by the power adjustment value when the stop instruction is received; and when the stop instruction and the monitoring office instruction are received, stopping adjusting the output power of the power station by using the power adjustment value, and adjusting the output power of the power station by using the monitoring office instruction.
Further, the power adjustment control module is further configured to send a power callback instruction when the output power of the power station is adjusted and no new monitoring office instruction is received at a time greater than or equal to a second time; the power adjustment module is further configured to receive the power callback instruction, and gradually adjust the output power of the power station to an original value.
Preferably, the sign of the adjustment coefficient is the same as the sign of the frequency difference, and the smaller the time constant of the preset short-time frequency mean value is, the larger the absolute value of the adjustment coefficient is.
Preferably, the time constant of the short-time frequency mean is not more than 1s, and the time constant of the long-time frequency mean is not less than 300s.
Preferably, the time constant of the frequency difference filtering module is less than or equal to 5s.
The embodiment of the invention also discloses a rapid frequency regulating method for a power grid, which is used for the device and comprises the following steps: calculating the instantaneous frequency, the short-time frequency average value and the long-time frequency average value of the power grid, and taking the difference between the long-time frequency average value and the short-time frequency average value as a frequency difference value; determining an adjustment coefficient according to the magnitude of the frequency difference value and the time constant of the short-time frequency average value; when the frequency difference is larger than a fluctuation threshold, filtering the frequency difference to obtain a frequency difference filtering value, and multiplying the frequency difference filtering value by the adjustment coefficient to obtain a power adjustment value; and adjusting the output power of the power station by using the power adjustment value.
Further, the method further comprises: stopping adjusting the output power of the power station if the open loop condition is met, and stopping adjusting the output power of the power station by using the power adjustment value if a monitoring office instruction is received, and adjusting the output power of the power station by using the monitoring office instruction; the open loop condition is that the frequency difference value is kept stable when the calculation time is larger than or equal to the first time.
Further, the method further comprises: and when the output power of the power station is adjusted and no new monitoring office instruction is received in the second time or more, gradually adjusting the output power of the power station to the original value.
The beneficial effects of the invention include: the device realizes closed-loop control on the frequency change of the power grid, and can accurately solve the frequency problem in a range which can be solved; in addition, the exit problem of the quick adjustment logic is explicitly provided, and preparation is made for the next quick adjustment; thirdly, the invention has high adjustment speed, does not limit the adjustment power, and aims to enable the frequency to return to a normal value within the capacity range.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
FIG. 1 is a diagram of an embodiment of a conventional frequency modulation method;
FIG. 2 is a schematic diagram of an embodiment of a fast frequency modulation device for a power grid;
FIG. 3 is a flowchart of a method for fast tuning a power grid;
fig. 4 is a flowchart of an embodiment of a method for fast frequency adjustment of a power grid including power adjustment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The power industry has strict requirements on indexes such as voltage, frequency and the like of a power grid, which is very important for guaranteeing the safe operation of the whole power grid. When the output power is changed within a certain range, the frequency and the voltage of the traditional main power plant can be kept unchanged through self adjustment. With the development of photovoltaic and wind power industries, the proportion of the emerging green energy sources in the power grid is larger and larger, and the adjustment of the frequency by the traditional dominant power plant is somewhat inexperienced.
The frequency of the mechanical generator depends on the rotation speed of the rotor, and considering a simple monopole single-phase generator, the rotor rotates once a circle to cut the magnetic lines of force N once and once S, so that the number of rotations per second is the frequency of the generated electricity, and if the frequency is required to be 50Hz, the rotation speed per minute is 3000. The generator outputs electric power to the outside, and when the load suddenly increases, the electromagnetic resistance of the generator rotor suddenly increases, which tends to slow down the rotation speed. The mechanical inertia of the generator rotor can ensure that the frequency does not change suddenly, which is important for stabilizing the frequency, and then the problem is solved substantially, so that work needs to be added. Sudden load decreases also have frequency instability problems, which are not described in detail. At present, the grid connection condition of green energy is that, taking a photovoltaic power station as an example, the generated electricity is firstly regulated to be high-voltage direct current, then sine wave current is fed into a power grid according to the phase of the power grid by 180 DEG, the product of the current and the voltage is the power output to the power grid, and an electric power monitoring department can send some instructions to the photovoltaic power station according to the requirement of the power grid, wherein the instructions comprise power control, power factor control and the like. Observing this grid-connected mode, the photovoltaic power station cannot quickly compensate for the frequency change, because the essence of compensation is to adjust the power output, and the adjustment of the power output of the photovoltaic power station needs to wait for an instruction, and after a few minutes of waiting for the instruction, the quick frequency change can occur within tens of seconds. Under the condition that no new energy is added into the power grid, when the load changes by 30% (an assumption here), the frequency of the generator is only changed by 0.1Hz under the conditions of inertia frequency stabilization and self rapid adjustment, the generator can be adjusted back in a short period of 30 seconds, but as the proportion of the green power supply in the power grid increases, the mechanical inertia of the traditional generator does not play a good role in frequency stabilization, and the self power generation power adjustment cannot enable the frequency to be recovered in a short time, so that the generator needs to issue instructions to each grid-connected green energy power plant, and the time consumption is often from a few minutes to more than 10 minutes.
The innovation points of the invention are as follows: firstly, the existing power adjustment mode adopts open-loop control adjustment, the change of the power grid frequency is responded in time in a closed-loop control mode, the output power of the power station is adjusted according to the size and the speed of the frequency change, and the closed-loop control mode has the advantages of stability and timeliness; secondly, in order to prevent unstable factors caused by frequency difference mutation in the control loop, the invention changes the adjustment coefficient of the loop in real time according to the frequency difference (including symbols) and the speed dynamics of the frequency difference, and has better and more accurate adjustment effect; thirdly, the power adjustment control module introduces an exit mechanism, namely the loop is in a power stable state for a long time, performs power callback, can be prepared for the next quick control, reduces manual operation, and has stronger practicability.
The following describes in detail the technical solutions provided by the embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of an embodiment of a conventional frequency modulation method, which is a conventional fast frequency modulation technique, and illustrates the drawbacks of the prior art.
In order to solve the problem of quick response of the power grid frequency, a new energy power station requiring grid connection has a quick frequency adjustment technology, and the core of the technology comprises: firstly, when a power station is connected to a grid for power generation, 10% of power needs to be reserved, for example, the power station has the capacity of generating 1000W, but only 900W can be output outwards, so that the energy utilization rate is low; secondly, the power station can accurately detect the frequency of the power grid, when the frequency is higher or lower than 0.1Hz, the power station automatically adjusts the output power, the adjustment mode is shown in figure 1, the abscissa is frequency and unit Hz, the ordinate is power, and the unit MW and Pn represent the maximum output power of the power station.
In the embodiment of the present invention, the green energy power station (new energy power station) must retain a certain amount of power generation, for example, 10% pn, that is, 10% of the maximum output power of the power station.
In the embodiment of the invention, taking the alternating current frequency as an example, when the frequency variation range is within plus or minus 0.1Hz, the power output by the new energy power station is kept unchanged, that is to say, the frequency is between 49.9Hz and 50.1Hz, and the new energy power station cannot participate in the rapid frequency adjustment. Therefore, when the new energy power station in the power grid is dominant and the frequency deviation is within +/-0.1 Hz, the power can be adjusted by waiting for the instruction of the power grid monitoring bureau, and the power station cannot be adjusted in a self-adaptive manner, so that the unstable phenomenon of the power grid frequency is more and more serious.
In the embodiment of the invention, when the frequency deviation is between 0.1Hz and 0.2Hz or between-0.2 Hz and-0.1 Hz, the output power of the new energy power station changes linearly with the frequency, and the linear change cannot be used for indicating that the adjustment of the output power adapts to the change of the frequency, and because the output power is possibly in a nonlinear relation, whether the adjustment of the output power of the new energy power station is correct or not cannot be indicated when the frequency is between 49.8Hz and 49.9Hz or between 50.1Hz and 50.2 Hz.
Fig. 2 is an embodiment of a fast frequency adjustment device for a power grid, which can be used for a new energy power station to solve the problem of fast frequency fluctuation, specifically, a fast frequency adjustment device for a power grid, comprising: the device comprises a power grid frequency calculation module 11, a frequency average module 12, a frequency difference calculation module 13, a frequency difference filtering module 14, a frequency difference adjustment module 15, a power adjustment control module 17 and a power adjustment module 16.
The power grid frequency calculation module is used for calculating the instantaneous frequency of the power grid; the frequency average module is used for receiving the instantaneous frequency of the power grid and calculating a short-time frequency average value and a long-time frequency average value; the frequency difference calculation module is used for receiving the long-time frequency average value and the short-time frequency average value and subtracting the long-time frequency average value and the short-time frequency average value to obtain a frequency difference value; the frequency difference filtering module is used for receiving the frequency difference value and outputting a frequency difference filtering value, receiving a reset signal sent by the power adjustment control module and resetting a time constant; the frequency difference adjusting module is used for receiving the frequency difference value, determining an adjusting coefficient according to the size of the frequency difference value and the time of the preset short-time frequency average value, receiving the frequency difference filtering value and multiplying the adjusting coefficient to obtain a power adjusting value; the power adjustment control module is used for receiving the frequency difference value, and when the frequency difference value is larger than a fluctuation threshold, a reset signal is sent to the frequency difference filtering module, and then a starting instruction is sent to the power adjustment module; and the power adjustment module is used for receiving the power adjustment value, and adjusting the output power of the power station by using the power adjustment value after receiving the starting instruction.
In the embodiment of the invention, the power grid frequency calculation module has high requirement precision and short delay, and aims to quickly acquire the instantaneous frequency of the power grid.
In the embodiment of the present invention, the frequency averaging module may further include a short-time frequency averaging module, configured to calculate a short-time frequency average value; and the long-time frequency average module is used for calculating the long-time frequency average value. For the short-time frequency average, the instantaneous frequency average is obtained in order to obtain an instantaneous frequency value with sufficiently high accuracy, so that the time constant is small, and generally, the time constant of the short-time frequency average is not more than 1s; for the long-term frequency average, the purpose is to obtain a long-term average of the power grid, which is taken as a stable value of the power grid frequency, that is, a target value of frequency adjustment, and generally, the time constant of the long-term frequency average is not less than 300s.
In the embodiment of the invention, the time constant of the short-time frequency mean value is 1s, and the time constant of the long-time frequency mean value is 300s. The short-time frequency average value and the long-time frequency average value may be other values, and are not particularly limited herein.
In the embodiment of the present invention, the frequency difference value output by the frequency difference calculation module is the long-time frequency average value minus the short-time frequency average value, and is used as an error term of a control loop.
In the embodiment of the invention, the frequency difference filtering module realizes low-pass filtering of errors, namely low-pass filtering of the frequency difference, and considers the requirement of quick frequency modulation, and the time constant of the frequency difference filtering module is less than or equal to 5s, and in the embodiment of the invention, the time constant is 5s. The time constant 5s is a set time constant, and other time constants satisfying rapid frequency modulation may be set, and the present invention is not limited thereto.
In the embodiment of the invention, the adjustment coefficient can be used as adjustment control strength, the strength determines the stability of the whole control loop, the feedback is too strong, the loop cannot be quickly stabilized, and the feedback is weak, so that the adjustment effect is not realized. The feedback intensity of a general control loop is fixed by a proper value, and in the invention, the feedback intensity cannot be fixed, because a plurality of new energy power stations adopting the same control measures possibly exist in the power grid, so that the adjustment values of the new energy power stations are added together to form the whole adjustment value, the whole adjustment value influences the frequency of the main power station, that is, the control loop is not located at one place at all, the feedback of each place is only a part, the frequency difference adjustment module can calculate whether the feedback intensity is proper or not according to the change speed of the instantaneous frequency difference, the proper feedback intensity is quickly given, and the change speed can be determined by the time constant of the short-time frequency mean value and the size of the frequency difference.
Further, the sign of the adjustment coefficient is the same as the sign of the frequency difference. Specifically, when the frequency difference is a negative number, that is, the short-time frequency average value is greater than the long-time frequency average value, the adjustment coefficient is smaller than zero, so that the power adjustment value is smaller than zero, and the power output by the power station is reduced; when the frequency difference is positive, namely the short-time frequency average value is smaller than the long-time frequency average value, the adjustment coefficient is larger than zero, so that the power adjustment value is larger than zero, and the power station output power is increased; when the frequency difference is 0, that is, the short-time frequency average value is equal to the long-time frequency average value, the adjustment coefficient is zero, so that the power adjustment value is zero, and the output power of the power station is not adjusted.
Further, the smaller the time of the preset short-time frequency mean value, the larger the absolute value of the adjustment coefficient, that is, the smaller the time constant of the short-time frequency mean value is a preset value, which indicates the faster the frequency change speed, and the larger the absolute value of the adjustment coefficient, and thus the larger the power adjustment value, in order to enable the output power to respond to such rapid adjustment.
It should be noted that, the magnitude of the adjustment coefficient determines the magnitude of the power adjustment value, that is, the magnitude of the power adjusted by the control loop at each time, for example, if the adjustment coefficient is 10, the power adjustment value is 1MW when the frequency difference is 0.1Hz for the first 1s, and the frequency difference is still 0.1Hz for the second 1s, and the power adjustment value is 1MW.
In the embodiment of the invention, when the frequency difference value is larger than the fluctuation threshold, power adjustment is needed, a reset signal is sent to the frequency difference filtering module, and then a starting instruction is sent to the power adjustment module, namely, the frequency difference filtering module is restarted, the frequency difference filtering value is recalculated, and the power adjustment module is used for next power adjustment.
In the embodiment of the invention, the power adjustment control module is further configured to send a stop instruction to the power adjustment module if an open loop condition is satisfied; if the monitoring office instruction is received, a stopping instruction and the monitoring office instruction are sent to the power adjustment module; the open loop condition is that the frequency difference value is kept stable when the calculation time is more than or equal to the first time; the power adjustment module is further used for stopping adjusting the output power of the power station by the power adjustment value when the stop instruction is received; and when the stop instruction and the monitoring office instruction are received, stopping adjusting the output power of the power station by using the power adjustment value, and adjusting the output power of the power station by using the monitoring office instruction.
Further, the power adjustment control module is further configured to send a power callback instruction when the output power of the power station is adjusted and no new monitoring office instruction is received at a time greater than or equal to a second time; the power adjustment module is further configured to receive the power callback instruction, and gradually adjust the output power of the power station to an original value.
Specifically, the power adjustment control module controls whether or not the power needs to be adjusted and how to adjust the power. Aiming at the requirement of rapid adjustment of power, the logic observes the output frequency difference value of the frequency difference calculation module in real time according to a preset fluctuation threshold, and when the value is larger than the fluctuation threshold, the logic resets the frequency difference filtering module once, and then starts the power adjustment module to realize power adjustment. The fast power adjustment logic may enter the second phase when at least one of the following conditions is met: 1) The frequency difference value of the frequency difference calculation module meets a preset threshold for a long time, and a control loop is disconnected at the moment, namely the frequency difference value is kept stable when the calculation time is more than or equal to the first time, and the power adjustment module is forbidden to start; 2) And when the new energy power station receives the monitoring office clear adjustment instruction, the control loop is disconnected, and the new energy power station is adjusted according to the instruction, namely, when the new energy power station receives the monitoring office instruction, the new energy power station sends a stop instruction and the monitoring office instruction to the power adjustment module, and the power adjustment module directly adjusts the output power according to the monitoring office instruction. If the control logic does not receive the command of the monitoring office in the second stage for a period of time (more than or equal to the second time), the output power is adjusted in steps in the opposite direction until the original set value (original value), namely, the output power is adjusted back to the original value, which is prepared for the next rapid adjustment.
The power of the power station is gradually adjusted to the original value, the power can be gradually adjusted according to the adjusted output power and the original value, and if the output power is smaller than the original value, the output power of the power station can be adjusted to the original value at one time, and the original value of the value can be adjusted step by step for multiple times; if the output power is larger than the original value, the output power of the power station can be adjusted to the original value step by step for a plurality of times.
In the present invention, the fluctuation threshold, the first time, and the second time are all set values, and are not particularly limited.
The power grid rapid frequency adjustment device provided by the embodiment of the invention adopts a closed-loop control mode, has smaller dead zone, can be set, has high response speed, can accurately solve the problem of rapid frequency change, and also has the advantages of clear exit problem of rapid adjustment logic, readiness for the next rapid adjustment, simple design and strong practicability.
Fig. 3 is a flowchart of a power grid rapid frequency adjustment method, which can be used in the power grid rapid frequency adjustment device of the present invention, as an embodiment of the present invention, a power grid rapid frequency adjustment method, comprising the following steps:
and 101, calculating the instantaneous frequency, the short-time frequency average value and the long-time frequency average value of the power grid, and taking the difference between the long-time frequency average value and the short-time frequency average value as a frequency difference value.
In step 101, the method of calculating the grid instantaneous frequency, the short-time frequency mean, the long-time frequency mean and the frequency difference is described in detail in the second embodiment, and the discussion is not repeated here.
And 102, determining an adjustment coefficient according to the magnitude of the frequency difference value and the time of the short-time frequency average value.
In step 102, the method of determining the adjustment coefficient has been discussed in detail in the second embodiment, and the discussion is not repeated here.
And step 103, when the frequency difference is larger than the fluctuation threshold, filtering the frequency difference to obtain a frequency difference filtering value, and multiplying the frequency difference filtering value by the adjustment coefficient to obtain a power adjustment value.
In step 103, the method of obtaining the power adjustment value is described in detail in the second embodiment, and the discussion is not repeated here.
And step 104, adjusting the output power of the power station by using the power adjustment value.
In step 104, the output power of the plant is adjusted to add the power adjustment value to the existing output power.
The embodiment of the invention provides a rapid frequency adjustment method for a power grid, which adopts a closed-loop control mode to adjust the output power of a power station according to the magnitude and the speed of the instantaneous frequency change of the power grid, and the self-adaptive adjustment mode can correct an adjustment coefficient in real time according to a frequency difference value, so that nonlinear adjustment is realized, and the accuracy is high and the practicability is strong.
Fig. 4 is a flowchart of a power grid rapid frequency adjustment method including power callback, in which an exit mechanism and power callback are added, as an embodiment of the present invention, a power grid rapid frequency adjustment method includes the following steps:
and 101, calculating the instantaneous frequency, the short-time frequency average value and the long-time frequency average value of the power grid, and taking the difference between the long-time frequency average value and the short-time frequency average value as a frequency difference value.
And 102, determining an adjustment coefficient according to the magnitude of the frequency difference value and the time of the short-time frequency average value.
And step 103, when the frequency difference is larger than the fluctuation threshold, filtering the frequency difference to obtain a frequency difference filtering value, and multiplying the frequency difference filtering value by the adjustment coefficient to obtain a power adjustment value.
And step 105, stopping adjusting the output power of the power station if the open loop condition is met, and stopping adjusting the output power of the power station by the power adjustment value if a monitoring office command is received, and adjusting the output power of the power station by the monitoring office command.
In step 105, the open loop condition is that the frequency difference remains stable when the calculation time is equal to or longer than the first time.
The term "the frequency difference remains stable" means that the frequency value is fixed near a certain value, for example, fixed at a certain value plus or minus 0.01Hz, and here, 0.01Hz is a preset value, and is not particularly limited.
In step 105, when the frequency difference is stable for a long time, the output power of the power station is not required to be adjusted, and the power grid is in a relatively stable power supply environment.
In step 105, when a monitoring office command is received, the monitoring office command has the highest priority, and the output power of the power station is adjusted according to the data in the command.
Step 106, when the output power of the power station is adjusted and no new monitoring office command is received in the second time or longer, the output power of the power station is adjusted to the original value step by step.
In step 106, when the output power of the power station is at the adjusted value for a long time, the monitoring office command is not received, and the new energy power station modulates the output power by a preset original value in consideration of the fact that the power station (such as a wind power station and a hydraulic power station) which is dominant in the power grid has completed power adjustment, so as to prepare for the next rapid frequency change.
The power grid rapid frequency regulation method provided by the embodiment of the invention has the functions of disconnecting loops and power callback, comprehensively considers the change condition of the output power of each power station in the power grid, has higher power regulation accuracy, and ensures that the whole power grid operates more stably.
It should be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
The foregoing is merely exemplary of the present invention and is not intended to limit the present invention. Various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are to be included in the scope of the claims of the present invention.
Claims (6)
1. A rapid frequency modulation device for an electrical network, comprising:
the power grid frequency calculation module is used for calculating the instantaneous frequency of the power grid;
the frequency average module is used for receiving the instantaneous frequency of the power grid and calculating a short-time frequency average value and a long-time frequency average value; the time constant of the short-time frequency mean value is not more than 1s, and the time constant of the long-time frequency mean value is not less than 300s;
the frequency difference calculation module is used for receiving the long-time frequency average value and the short-time frequency average value and subtracting the long-time frequency average value and the short-time frequency average value to obtain a frequency difference value;
the frequency difference filtering module is used for receiving the frequency difference value, carrying out low-pass filtering on the frequency difference value and outputting a frequency difference filtering value, and the time constant of the frequency difference filtering module is less than or equal to 5s;
the frequency difference adjusting module is used for receiving the frequency difference value, determining an adjusting coefficient according to the size of the frequency difference value and a preset time constant of the short-time frequency average value, wherein the sign of the adjusting coefficient is the same as that of the frequency difference value, and the smaller the time constant of the preset short-time frequency average value is, the larger the absolute value of the adjusting coefficient is; receiving the frequency difference filtering value, and multiplying the frequency difference filtering value by the adjustment coefficient to obtain a power adjustment value;
the power adjustment control module is used for receiving the frequency difference value, and when the frequency difference value is larger than a fluctuation threshold, a reset signal is sent to the frequency difference filtering module, and then a starting instruction is sent to the power adjustment module;
and the power adjustment module is used for receiving the power adjustment value, and adjusting the output power of the power station by using the power adjustment value after receiving the starting instruction.
2. A rapid frequency regulating device for an electrical network according to claim 1, wherein,
the power adjustment control module is also used for controlling the power adjustment control module,
if the open loop condition is met, a stop instruction is sent to the power adjustment module;
if the monitoring office instruction is received, a stopping instruction and the monitoring office instruction are sent to the power adjustment module;
the open loop condition is that the frequency difference value is kept stable when the calculation time is more than or equal to the first time;
the power adjustment module is also used for adjusting the power of the power supply,
when the stopping instruction is received, stopping adjusting the output power of the power station by using the power adjusting value;
and when the stop instruction and the monitoring office instruction are received, stopping adjusting the output power of the power station by using the power adjustment value, and adjusting the output power of the power station by using the monitoring office instruction.
3. A rapid frequency regulating device for an electrical network according to claim 1, wherein,
the power adjustment control module is further configured to send a power callback instruction when the output power of the power station is adjusted and no new monitoring office instruction is received in a second time or longer;
the power adjustment module is further configured to receive the power callback instruction, and gradually adjust the output power of the power station to an original value.
4. A rapid frequency modulation method for a power grid, which is used for the device of any one of claims 1 to 3, and is characterized by comprising the following steps:
calculating the instantaneous frequency, the short-time frequency average value and the long-time frequency average value of the power grid, and taking the difference between the long-time frequency average value and the short-time frequency average value as a frequency difference value;
determining an adjustment coefficient according to the magnitude of the frequency difference value and the time constant of the short-time frequency average value;
when the frequency difference is larger than a fluctuation threshold, filtering the frequency difference to obtain a frequency difference filtering value, and multiplying the frequency difference filtering value by the adjustment coefficient to obtain a power adjustment value;
and adjusting the output power of the power station by using the power adjustment value.
5. The rapid grid tuning method of claim 4, further comprising:
stopping adjusting the output power of the power station if the open loop condition is met, and stopping adjusting the output power of the power station by using the power adjustment value if a monitoring office instruction is received, and adjusting the output power of the power station by using the monitoring office instruction;
the open loop condition is that the frequency difference value is kept stable when the calculation time is larger than or equal to the first time.
6. The rapid grid tuning method of claim 5, further comprising:
and when the output power of the power station is adjusted and no new monitoring office instruction is received in the second time or more, gradually adjusting the output power of the power station to the original value.
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