New energy station multi-SVG reactive power coordination control method

Abstract

The invention relates to a multi-SVG reactive power coordination control method for a new energy station, and the method comprises the steps: firstly extracting a frequency spectrum of the new energy station, and carrying out the calculation to obtain a system frequency and a frequency change rate of frequency spectrum data; based on the detected system bus voltage, the system frequency and the frequency change rate, performing coordination control on the SVG; and acquiring the voltage at the co-coupling node, calculating the voltage deviation at the co-coupling node, and performing switching control on an overvoltage protection circuit in the generator set based on the voltage deviation so as to perform coordination control on the generator set and the SVG in the new energy station. According to the control method, timely switching of the overvoltage protection circuit can be achieved, the action duration time of the overvoltage protection circuit is shortened as far as possible, reactive power absorbed by the generator set from the system is reduced, the voltage transient amplitude can be reduced through coordinated control of the SVG and the generator set, the time consumed by voltage stabilization can be shortened, and the system stability can be improved. The voltage at the co-coupling node is stabilized within a desired range.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a method for coordinated reactive power control of multiple SVGs in a new energy station. Background Art

[0002] With the intensification of the fossil energy crisis and environmental pollution, the field of renewable energy power generation has received extensive attention and development, and large-scale grid connection of renewable energy power generation has become a major development trend of the power system. In this process, SVG (static var generator) can compensate for the reactive power of the system and stabilize the grid voltage during operation, and has been widely used. However, wind power generation has the characteristics of randomness and volatility, and it is difficult to ensure the stability of supply, which is not conducive to the dispatching of the power system; and because the uncertainty of wind energy resources will lead to unstable power output of wind farms, the large-scale grid connection of wind farms will greatly affect the voltage quality of the grid. The volatility of wind power generation is the main reason for the problems of reactive voltage, harmonics, voltage fluctuations and voltage flicker when large-scale wind power is connected to the grid.

[0003] At present, many studies have been conducted on how to apply SVG to new energy station systems to compensate for the reactive power of the system and stabilize the voltage of the power grid. However, the main content of the research is to use SVG in wind farms to support the voltage. For example, by measuring the voltage deviation of the grid connection point, the reactive power shortage of the system is calculated and then compared with the limit value of the reactive power generated by the wind turbine itself. First, the wind turbine is allowed to fully generate reactive power, and the excess is supplemented by SVG. This method can utilize the reactive power regulation ability of the wind farm, reduce the capacity of the reactive compensation device to a certain extent, and has certain economic benefits. However, in many cases, SVG is likely not fully utilized. When the SVG capacity has been determined and equipped, it is also a waste of resources, and the superior performance of SVG is not fully utilized. Summary of the invention

[0004] In response to the problems in the prior art, the present application proposes a method for coordinated reactive power control of multiple SVGs in a new energy station, which can not only realize timely switching of the overvoltage protection circuit, shorten the action duration of the overvoltage protection circuit as much as possible, and reduce the reactive power absorbed by the generator set from the system, but also reduce the voltage transient amplitude and the time consumed for voltage stabilization through coordinated control of SVG and the generator set, so that the voltage at the common coupling node is stabilized within the desired range.

[0005] The reactive power coordinated control method of multiple SVGs in a new energy station of the present invention comprises the following steps:

[0006] S1: Extract the spectrum of the new energy station and calculate the system frequency and frequency change rate of the spectrum data;

[0007] S2: Coordinated control of SVG based on the detected system bus voltage, system frequency, and frequency change rate;

[0008] S3: Collect the voltage at the common coupling node and calculate the voltage deviation there. Based on the voltage deviation, switch the overvoltage protection circuit in the generator set to coordinate the control of the generator set and SVG in the new energy station.

[0009] As a further limitation of the present invention, the specific steps of extracting the spectrum of the new energy station and calculating the frequency change rate of the spectrum data are:

[0010] S11: extract the spectrum of the new energy station, construct the Hankel matrix, perform singular value decomposition, and reconstruct the Hankel matrix to achieve noise reduction based on the number of frequency components in the spectrum signal of the new energy station;

[0011] S12: Using the matrix bundle constructed by two Hankel matrices, solve the generalized eigenvalues ​​to obtain the pole information of the signal, and then obtain the fundamental frequency measurement value;

[0012] S13: Perform a second-order Taylor expansion on the phasor function of the frequency component of the spectrum data of the new energy station, ignore the high-order terms, use the signal poles obtained in step S12 to construct a least squares equation system, bring the filtered and denoised data into it to solve the polynomial coefficients, and then obtain the amplitude and phase angle measurement values ​​of the phasor of the frequency component;

[0013] S14: Taking the calculation time as the center, select five consecutive frequency measurement values ​​before and after to perform quadratic polynomial fitting to obtain the frequency change rate.

[0014] As a further limitation of the present invention, the method for obtaining the number of frequency components in step S11 is:

[0015] Extract the spectrum of the new energy station, perform windowing on the spectrum data, and add a certain number of integer powers from 0 to 2 to the end of the windowed data to make the highest spectrum line after zero padding closer to the true value;

[0016] Perform curve fitting on multiple interpolated spectra, and then calculate the peak value of the curve and the number of frequency components in the spectrum signal of the new energy station.

[0017] As a further limitation of the present invention, step S2 specifically includes:

[0018] S21: Determine whether the system frequency and frequency change rate are within the normal range. If they are normal, return to step S21, otherwise go to step S22;

[0019] S22: Determine whether the system frequency is greater than 51 Hz and whether the frequency change rate is greater than 3%. If so, proceed to step S23; otherwise, proceed to step S24.

[0020] S23: Determine whether the load node voltage is less than the threshold value and whether the active power output of the generator set has reached the limit. If so, the generator set and SVG are coordinated to increase reactive power, increase the load node voltage, and perform auxiliary frequency regulation. If not, proceed to S25.

[0021] S24: Determine whether the load node voltage is greater than a threshold value and whether the active power output of the generator set has reached a limit. If so, the generator set and SVG are coordinated to reduce reactive power and load node voltage, and perform auxiliary frequency modulation. If not, proceed to step S25.

[0022] S25: Frequency support is provided by generator sets only.

[0023] As a further limitation of the present invention, the specific method of collecting the voltage at the common coupling node in step S3, calculating the voltage deviation ΔV at the common coupling node, judging whether the absolute value of 1-ΔV exceeds the threshold, and switching the overvoltage protection circuit in the generator set is:

[0024] Detecting a voltage deviation ΔV at the common coupling node, and determining whether an absolute value of 1-ΔV is less than 5%;

[0025] When the absolute value of 1-ΔV is less than or equal to 5%, the generator units in the new energy station are kept operating in the maximum power point tracking mode, and the SVG smoothes the voltage fluctuations at the common coupling node;

[0026] When the absolute value of 1-ΔV is greater than 5%, an overvoltage protection circuit control method is used to determine whether the overvoltage protection circuit is activated, and the activation signal of the overvoltage protection circuit of each generator set is detected in real time.

[0027] As a further limitation of the present invention, the overvoltage protection circuit control method is specifically:

[0028] When the three-phase voltage drops and the instantaneous value of the rotor current exceeds the threshold, the overvoltage protection circuit is immediately activated to protect the rotor-side converter from being damaged by the rotor surge current;

[0029] During the operation of the overvoltage protection circuit, the rotor current amplitude |i r |, when the rotor current amplitude |i r |Less than the action threshold i cth When the overvoltage protection circuit is not activated;

[0030] When the rotor current amplitude |i r|greater than or equal to the action threshold i cth When the system controls the overvoltage protection circuit and locks the rotor-side converter, it also calculates in real time the rotor current peak value that will appear if the overvoltage protection circuit is cut off at the current moment. r1 |; If the condition is met at a certain moment|i r |≤|i r1 |, the overvoltage protection circuit is immediately disconnected and the control of the rotor-side converter is restored. If the rotor current amplitude |i r |greater than the peak value of the rotor current|i r1 |, keep the overvoltage protection circuit engaged and continue to implement real-time monitoring of the rotor current peak value |i r1 |Perform calculations.

[0031] As a further limitation of the present invention, step S3 further includes the following steps:

[0032] S31: Based on the collected voltage at the common coupling node, determine whether the voltage measurement value at the common coupling node is consistent with the voltage reference value U ref The difference ΔU ref Is it zero? If ΔU ref is not zero, then proceed to step S32. If ΔU ref is zero, proceed to step S33;

[0033] S32: Perform reactive power compensation and determine the state of the SVG. If the reactive power margin of the SVG is sufficient, the SVG is used first to compensate the voltage. If the reactive power margin of the SVG is insufficient, the generator set is used to perform reactive power compensation so that the voltage is adjusted, and the process goes to step S31 to cyclically detect the voltage at the common coupling node.

[0034] S33: Determine whether the voltage remains stable. If the voltage remains stable, proceed to step S34 to evaluate the reactive power distribution. If the voltage does not remain stable, proceed to step S31.

[0035] S34: Determine the reactive power distribution between the SVG and the generator set. If the distribution result needs to be adjusted, proceed to step S35 for reactive power redistribution. If the distribution result is reasonable, it indicates that there is no unnecessary reactive power flow between the generator set and the SVG, and the coordination and adjustment process ends.

[0036] S35: Re-determine the voltage dead zone of the reactive power distribution process, the SVG outputs reactive power to maintain voltage stability, and then proceeds to step S34 to repeat the detection of reactive power distribution.

[0037] As a further limitation of the present invention, the method for determining the reactive power distribution between the SVG and the generator set in step S34 is:

[0038] Determine the voltage stability. If ΔUref=0 for Δt time from t1, then at t2=t1+Δt, the voltage is stable. At this time, set U a =1; and at any time when ΔUref(t)≠0, it means the voltage is stable, at this time, set U a =0;

[0039] And detect the reactive absorption or generation state of SVG and generator set. If it is detected that one of SVG and generator set is in reactive absorption state and the other is in reactive generation state, then set U b =1, if not, then set U b =0;

[0040] If U a =1 and U b =1, it means that reactive power needs to be redistributed and the reactive power reference value of the generator set needs to be reset. At the same time, SVG adjusts its own reactive power output according to the voltage change.

[0041] As a further limitation of the present invention, the method for redetermining the voltage dead zone of the reactive power redistribution process in step S35 is:

[0042] Set the voltage reference value U of the distribution process r-1 =0.7U R +0.3U ref ;

[0043] Set the voltage offset range U of the distribution process r-1-dev =0.1U ref-dev ;

[0044] Among them, U R The voltage value of the monitoring point when reactive redistribution is started, U ref is the voltage reference value at the common coupling node, U ref-dev is the offset range;

[0045] Calculate the voltage deviation ΔU r-1 =UU r-1 , if ΔU r-1 ≠0, control SVG to perform reactive power compensation to smooth voltage fluctuations until U b =0, the reactive power redistribution operation ends.

[0046] In another aspect of the present invention, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, any one of the above-mentioned methods for coordinated reactive power control of multiple SVGs in a new energy station is implemented.

[0047] The present invention also provides a non-transitory computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the method for coordinated reactive power control of multiple SVGs in a new energy station as described in any one of the above is implemented.

[0048] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned methods for coordinated reactive power control of multiple SVGs in a new energy station.

[0049] Compared with the prior art, the beneficial effects are:

[0050] 1. The control method of the present invention can realize coordinated control of the generator set and SVG to enhance the frequency regulation capability of the power grid when the system wind power and photovoltaic power fluctuate greatly and the system frequency may deviate too much.

[0051] 2. The present invention can realize timely switching of the overvoltage protection circuit, shortening the action duration of the overvoltage protection circuit as much as possible, thereby reducing the reactive power absorbed by the generator set from the system, and can also effectively reduce the impact of the alternating switching of the overvoltage protection circuit on the safety of the power generation equipment (such as photovoltaic power generation equipment, wind power generation equipment) and its control device in the new energy station.

[0052] 3. The present invention can preferentially use SVG to compensate reactive power to quickly respond to voltage changes, and the voltage stabilization effect is good. When the load is large and the SVG or the generator set cannot supply enough reactive power alone, the coordinated control of the SVG and the generator set can reduce the voltage transient amplitude, shorten the time consumed for voltage stabilization, and stabilize the voltage at the common coupling node within the desired range. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 It is a flow chart of a method for coordinated reactive power control of multiple SVGs in a new energy station of the present invention;

[0055] Figure 2 It is a control flow chart of an SVG coordinated generator set in a multi-SVG reactive power coordinated control method for a new energy station of the present invention. DETAILED DESCRIPTION

[0056] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0057] In the description of the present invention, it should be noted that the terms “first”, “second” and “third” are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0058] like Figure 1 As shown, the multi-SVG reactive power coordinated control method for a new energy station designed by the present invention comprises the following steps:

[0059] S1: Extract the spectrum of the new energy station and calculate the system frequency and frequency change rate of the spectrum data;

[0060] S2: Coordinated control of SVG based on the detected system bus voltage, system frequency, and frequency change rate;

[0061] S3: Collect the voltage at the common coupling node and calculate the voltage deviation there. Based on the voltage deviation, switch the overvoltage protection circuit in the generator set to coordinate the control of the generator set and SVG in the new energy station.

[0062] It should be noted that, at present, a large amount of power electronic equipment is required for the generation and grid connection of new energy. As the proportion of new energy continues to increase, power electronic equipment may introduce interharmonics into the electrical signal. If its frequency is complementary to the natural oscillation frequency of the generator shaft system, it will further cause the unit to oscillate. In addition, when the wind power and photovoltaic power fluctuations of the power generation system are large, the system frequency may have a problem of excessive deviation.

[0063] Based on the above considerations, when performing reactive coordinated control on SVG, it is first necessary to enable the system to maintain a stable frequency and effectively control excessive frequency deviation.

[0064] The specific steps for extracting the spectrum of the new energy station and calculating the frequency change rate of the spectrum data are as follows:

[0065] S11: extract the spectrum of the new energy station, construct the Hankel matrix, perform singular value decomposition, and reconstruct the Hankel matrix to achieve noise reduction based on the number of frequency components in the spectrum signal of the new energy station;

[0066] S12: Use the matrix bundle constructed by two Hankel matrices to solve the generalized eigenvalues ​​and obtain the pole information of the signal, and then obtain the fundamental frequency measurement value:

[0067] S13: Perform a second-order Taylor expansion on the phasor function of the frequency component of the spectrum data of the new energy station, ignore the high-order terms, use the signal poles obtained in step 12 to construct a least squares equation system, bring the filtered and denoised data into it to solve the polynomial coefficients, and then obtain the amplitude and phase angle measurement values ​​of the phasor of the frequency component;

[0068] S14: Taking the calculation time as the center, select five consecutive frequency measurement values ​​before and after to perform quadratic polynomial fitting to obtain the frequency change rate.

[0069] Specifically, the method for obtaining the number of frequency components mentioned in the above solution is:

[0070] Extract the spectrum of the new energy station, perform windowing on the spectrum data, and add a certain number of integer powers from 0 to 2 to the end of the windowed data to make the highest spectrum line after zero padding closer to the true value;

[0071] Perform curve fitting on multiple interpolated spectra, and then calculate the peak value of the curve and the number of frequency components in the spectrum signal of the new energy station.

[0072] When the wind power and photovoltaic power of the system fluctuate greatly, the system frequency may deviate too much. The following method is used to coordinate the control of the generator set and SVG to enhance the frequency regulation capability of the power grid.

[0073] The specific method is as follows:

[0074] S21: Determine whether the system frequency and frequency change rate are within the normal range. If they are normal, return to step S21, otherwise go to step S22;

[0075] S22: Determine whether the system frequency is greater than 51 Hz and whether the frequency change rate is greater than 3%. If so, proceed to step S23; otherwise, proceed to step S24.

[0076] S23: Determine whether the load node voltage is less than the threshold value and whether the active power output of the generator set has reached the limit. If so, the generator set and SVG are coordinated to increase reactive power, increase the load node voltage, and perform auxiliary frequency regulation. If not, proceed to S25.

[0077] S24: Determine whether the load node voltage is greater than a threshold value and whether the active power output of the generator set has reached a limit. If so, the generator set and SVG are coordinated to reduce reactive power and load node voltage, and perform auxiliary frequency modulation. If not, proceed to step S25.

[0078] S25: Frequency support is provided by generator sets only.

[0079] It should be further explained that, under normal operation, the sum of the absolute values ​​of the positive and negative deviations of the voltage at the common coupling node of the new energy station does not exceed 10% of the nominal value, so the threshold for judging whether the voltage at the common coupling node of the new energy station exceeds the limit is selected as 5%.

[0080] like Figure 2 As shown, first, the voltage fluctuation at the bus at the common coupling node is monitored in real time, and the voltage deviation ΔV at the location is calculated to determine whether the absolute value of 1-ΔV is less than 5%;

[0081] When the absolute value of 1-ΔV is less than or equal to 5%, the generator units in the new energy station are kept operating in the maximum power point tracking mode, and the SVG smoothes the voltage fluctuations at the common coupling node;

[0082] When the absolute value of 1-ΔV is greater than 5%, an overvoltage protection circuit control method is used to determine whether the overvoltage protection circuit is activated, and the activation signal of the overvoltage protection circuit of each generator set is detected in real time.

[0083] It should be further explained that the overvoltage protection circuit control method in the above scheme is specifically as follows:

[0084] When the three-phase voltage drops and the instantaneous value of the rotor current exceeds the threshold, the overvoltage protection circuit is immediately activated to protect the rotor-side converter from being damaged by the rotor surge current;

[0085] During the operation of the overvoltage protection circuit, the rotor current amplitude |i r |, when the rotor current amplitude |i r |Less than the action threshold i cth When the overvoltage protection circuit is not activated;

[0086] When the rotor current amplitude |i r |greater than or equal to the action threshold i cth When the system controls the overvoltage protection circuit and locks the rotor-side converter, it also calculates in real time the rotor current peak value that will appear if the overvoltage protection circuit is cut off at the current moment. r1 |; If the condition is met at a certain moment|i r |≤|i r1 |, the overvoltage protection circuit is immediately disconnected and the control of the rotor-side converter is restored. If the rotor current amplitude |i r |greater than the peak value of the rotor current|i r1 |, keep the overvoltage protection circuit engaged and continue to implement real-time monitoring of the rotor current peak value |i r1 |Perform calculations.

[0087] It should be noted that, since the real-time value of the rotor current is not used but the possible maximum current is used to compare with the threshold action current of the overvoltage protection circuit, compared with the traditional scheme, the adaptive removal strategy in this paper greatly reduces the possibility of alternating input of the overvoltage protection circuit. When a serious voltage drop occurs in the power grid, the minimum input time of the overvoltage protection circuit can be accurately found by calculating the rotor current peak value |ir1| in real time, so that the overvoltage protection circuit can be removed as soon as possible and the unit can be controlled to generate reactive power to support the voltage.

[0088] In addition, the traditional overvoltage protection circuit control scheme is to immediately activate the overvoltage protection circuit when the instantaneous value of the rotor current exceeds the action threshold of the overvoltage protection circuit; when the instantaneous value of the rotor current is less than the action threshold, the overvoltage protection circuit is cut off after a delay of one synchronization cycle (such as 120ms).

[0089] However, if the overvoltage protection circuit is not disconnected in time after the rotor current has been suppressed, the time for the generator set to be put into operation and absorb system reactive power will be increased.

[0090] The above-mentioned control strategy of the present invention can realize timely switching of the overvoltage protection circuit, shorten the action duration of the overvoltage protection circuit as much as possible, thereby reducing the reactive power absorbed by the generator set from the system, and can also effectively reduce the impact of the alternating switching of the overvoltage protection circuit on the safety of the power generation equipment (such as photovoltaic power generation equipment, wind power generation equipment) and its control device in the new energy station.

[0091] It should be further explained that since reactive power compensation equipment is used in the new energy station system to meet the system's requirements for reactive power, if the reactive power compensation equipment is not configured with sufficient capacity, it is easy to affect the stability of the system voltage. The use of SVG with superior reactive power control capability and the generator units in the new energy station for reactive power compensation can well achieve reactive power and voltage control. In the case of sufficient reactive power capacity, if only the SVG and the generator units are allowed to perform reactive power compensation operations separately, voltage instability may occur due to different compensation characteristics.

[0092] Therefore, the present invention also designs the following method to realize the coordinated control of the generator sets in the SVG and the new energy station. The details are as follows:

[0093] S31: Based on the collected voltage at the common coupling node, determine whether the voltage measurement value at the common coupling node is consistent with the voltage reference value U ref Is the difference ΔUref zero? If ΔU ref is not zero, then proceed to step S32. If ΔU ref is zero, proceed to step S33;

[0094] S32: Perform reactive power compensation and determine the state of the SVG. If the reactive power margin of the SVG is sufficient, the SVG is used first to compensate the voltage. If the reactive power margin of the SVG is insufficient, the generator set is used to perform reactive power compensation so that the voltage is adjusted, and the process goes to step S31 to cyclically detect the voltage at the common coupling node.

[0095] S33: Determine whether the voltage remains stable. If the voltage remains stable, proceed to step S34 to evaluate the reactive power distribution. If the voltage does not remain stable, proceed to step S31.

[0096] S34: Determine the reactive power distribution between the SVG and the generator set. If the distribution result needs to be adjusted, proceed to step S35 for reactive power redistribution. If the distribution result is reasonable, it indicates that there is no unnecessary reactive power flow between the generator set and the SVG, and the coordination and adjustment process ends.

[0097] S35: Re-determine the voltage dead zone of the reactive power distribution process, the SVG outputs reactive power to maintain voltage stability, and then proceeds to step S34 to repeat the detection of reactive power distribution.

[0098] The technical purpose that the present invention expects to achieve is to quickly put SVG into use to compensate for reactive power, and then control the generator set to participate in reactive power regulation after the SVG is fully loaded; in this process, the real-time voltage U is constantly approaching the set voltage reference value, and the SVG and the generator set are gradually tending to a stable output, and finally the voltage at the common coupling node is stabilized within the set dead zone.

[0099] When the voltage is stable, the reactive power distribution is checked again, and the reactive power is redistributed through the reactive power coordination module in the hope of eliminating unnecessary reactive power flow.

[0100] It should be further explained that the method for determining the reactive power distribution between the SVG and the generator set in the above scheme is:

[0101] Determine the voltage stability. If ΔUref=0 for Δt time from t1, then at t2=t1+Δt, the voltage is stable. At this time, set U a =1; and at any time when ΔUref(t)≠0, it means the voltage is stable, at this time, set U a =0;

[0102] And detect the reactive absorption or generation state of SVG and generator set. If it is detected that one of SVG and generator set is in reactive absorption state and the other is in reactive generation state, then set U b =1, if not, then set U b =0;

[0103] If U a=1 and U b =1, it means that reactive power needs to be redistributed and the reactive power reference value of the generator set needs to be reset. At the same time, SVG adjusts its own reactive power output according to the voltage change.

[0104] It should be further explained that the method for redetermining the voltage dead zone in the reactive power redistribution process in the above solution is:

[0105] Set the voltage reference value U of the distribution process r-1 =0.7U R +0.3U ref ;

[0106] Set the voltage offset range U of the distribution process r-1-dev =0.1U ref-dev ;

[0107] Among them, U R The voltage value of the monitoring point when reactive redistribution is started, U ref is the voltage reference value at the common coupling node, U ref-dev is the offset range;

[0108] Calculate the voltage deviation ΔU r-1 =UU r-1 , if ΔU r-1 ≠0, control SVG to perform reactive power compensation to smooth voltage fluctuations until U b =0, the reactive power redistribution operation ends.

[0109] It should be noted that, through the above scheme, the present invention can preferentially use SVG to compensate reactive power, so as to quickly respond to voltage changes and achieve good voltage stabilization effect; when the load is large and the SVG or the generator set cannot supply sufficient reactive power alone, the coordinated control of the SVG and the generator set can reduce the voltage transient amplitude, shorten the time consumed for voltage stabilization, and stabilize the voltage at the common coupling node within the desired range.

[0110] The electronic device provided by the present invention may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus. The processor may call the logic instructions in the memory to execute the above-mentioned multi-SVG reactive power coordinated control method of the new energy station.

[0111] The logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0112] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the multi-SVG reactive coordination control method for new energy stations provided by the above methods.

[0113] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the multi-SVG reactive power coordinated control method for a new energy station provided by the above-mentioned methods.

[0114] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0115] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for coordinated reactive power control of multiple SVGs in a new energy station, characterized in that: The following steps are involved: S1: Extract the spectrum of the new energy station and calculate the system frequency and frequency change rate of the spectrum data; S2: Coordinated control of the SVG based on the detected system bus voltage, the system frequency, and the frequency change rate; S3: Collect the voltage at the common coupling node and calculate the voltage deviation there, and switch the overvoltage protection circuit in the generator set based on the voltage deviation to coordinate the generator set and SVG in the new energy station.

2. The method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 1 is characterized in that: In step S1, the specific steps of extracting the spectrum of the new energy station and calculating the frequency change rate of the spectrum data are as follows: S11: extract the spectrum of the new energy station, construct the Hankel matrix, perform singular value decomposition, and reconstruct the Hankel matrix to achieve noise reduction based on the number of frequency components in the spectrum signal of the new energy station; S12: Using the matrix bundle constructed by two Hankel matrices, solve the generalized eigenvalues ​​to obtain the pole information of the signal, and then obtain the fundamental frequency measurement value; S13: Perform a second-order Taylor expansion on the phasor function of the frequency component of the spectrum data of the new energy station, ignore the high-order terms, use the signal poles obtained in step S12 to construct a least squares equation system, bring the filtered and denoised data into it to solve the polynomial coefficients, and then obtain the amplitude and phase angle measurement values ​​of the phasor of the frequency component; S14: Taking the calculation time as the center, select five consecutive frequency measurement values ​​before and after to perform quadratic polynomial fitting to obtain the frequency change rate.

3. The method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 2 is characterized in that: The method for obtaining the number of frequency components in step S11 is: Extract the spectrum of the new energy station, perform windowing on the spectrum data, and add a certain number of integer powers from 0 to 2 to the end of the windowed data to make the highest spectrum line after zero padding closer to the true value; Curve fitting is performed on the multiple interpolated frequency spectra, and then the peak value of the curve and the number of frequency components in the frequency spectrum signal of the new energy station are calculated.

4. A method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 1 or 3, characterized in that: Step S2 specifically includes: S21: Determine whether the system frequency and the frequency change rate are within a normal range. If they are normal, return to step S21; otherwise, proceed to step S22; S22: Determine whether the system frequency is greater than 51 Hz and whether the frequency change rate is greater than 3%. If so, proceed to step S23; otherwise, proceed to step S24. S23: Determine whether the load node voltage is less than the threshold value and whether the active power output of the generator set has reached the limit. If so, the generator set and SVG are coordinated to increase reactive power, increase the load node voltage, and perform auxiliary frequency regulation. If not, proceed to S25. S24: Determine whether the load node voltage is greater than a threshold value and whether the active power output of the generator set has reached a limit. If so, the generator set and SVG are coordinated to reduce reactive power and load node voltage, and perform auxiliary frequency modulation. If not, proceed to step S25. S25: Frequency support is provided by generator sets only.

5. The method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 1 is characterized in that: In step S3, the voltage at the common coupling node is collected, and the voltage deviation ΔV at the node is calculated to determine whether the absolute value of 1-ΔV exceeds the threshold. The specific method for switching the overvoltage protection circuit in the generator set is as follows: Detecting a voltage deviation ΔV at the common coupling node, and determining whether an absolute value of 1-ΔV is less than 5%; When the absolute value of 1-ΔV is less than or equal to 5%, the generator units in the new energy station are kept operating in the maximum power point tracking mode, and the SVG smoothes the voltage fluctuations at the common coupling node; When the absolute value of 1-ΔV is greater than 5%, an overvoltage protection circuit control method is used to determine whether the overvoltage protection circuit is activated, and the activation signal of the overvoltage protection circuit of each generator set is detected in real time.

6. A method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 5, characterized in that: The overvoltage protection circuit control method is specifically as follows: When the three-phase voltage drops and the instantaneous value of the rotor current exceeds the threshold, the overvoltage protection circuit is immediately activated to protect the rotor-side converter from being damaged by the rotor surge current; During the operation of the overvoltage protection circuit, the rotor current amplitude |i r |, when the rotor current amplitude |i r |Less than the action threshold i cth When the overvoltage protection circuit is not activated; When the rotor current amplitude |i r |greater than or equal to the action threshold i cth When the system controls the overvoltage protection circuit and locks the rotor-side converter, it also calculates in real time the rotor current peak value that will appear if the overvoltage protection circuit is cut off at the current moment. r1 |; If the condition is met at a certain moment|i r |≤|i r1 |, the overvoltage protection circuit is immediately disconnected and the control of the rotor-side converter is restored. If the rotor current amplitude |i r |greater than the peak value of the rotor current|i r1 |, keep the overvoltage protection circuit engaged and continue to implement real-time monitoring of the rotor current peak value |i r1 |Perform calculations.

7. The method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 5 is characterized in that: Step S3 also includes the following steps: S31: Based on the collected voltage at the common coupling node, determine whether the voltage measurement value at the common coupling node is consistent with the voltage reference value U ref Is the difference ΔUref zero? If ΔU ref is not zero, then proceed to step S32. If ΔU ref is zero, proceed to step S33; S32: Perform reactive power compensation and determine the state of the SVG. If the reactive power margin of the SVG is sufficient, the SVG is used first to compensate the voltage. If the reactive power margin of the SVG is insufficient, the generator set is used to perform reactive power compensation so that the voltage is adjusted, and the process goes to step S31 to cyclically detect the voltage at the common coupling node. S33: Determine whether the voltage remains stable. If the voltage remains stable, proceed to step S34 to evaluate the reactive power distribution. If the voltage does not remain stable, proceed to step S31. S34: Determine the reactive power distribution between the SVG and the generator set. If the distribution result needs to be adjusted, proceed to step S35 for reactive power redistribution. If the distribution result is reasonable, it indicates that there is no unnecessary reactive power flow between the generator set and the SVG, and the coordination and adjustment process ends. S35: Re-determine the voltage dead zone of the reactive power distribution process, the SVG outputs reactive power to maintain voltage stability, and then proceeds to step S34 to repeat the detection of reactive power distribution.

8. The method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 7 is characterized in that: The method for determining the reactive power distribution between the SVG and the generator set in step S34 is: Determine the voltage stability. If ΔUref=0 for Δt time from t1, then at t2=t1+Δt, the voltage is stable. At this time, set U a =1; and at any time when ΔUref(t)≠0, it means the voltage is stable, at this time, set U a =0; And detect the reactive absorption or generation state of SVG and generator set. If it is detected that one of SVG and generator set is in reactive absorption state and the other is in reactive generation state, then set U b =1, if not, then set U b =0; If U a =1 and U b =1, it means that reactive power needs to be redistributed and the reactive power reference value of the generator set needs to be reset. At the same time, SVG adjusts its own reactive power output according to the voltage change.

9. A method for coordinated reactive power control of multiple SVGs in a new energy station according to claim 8, characterized in that: The method for redetermining the voltage dead zone of the reactive power redistribution process in step S35 is: Set the voltage reference value U of the distribution process r-1 =0.7U R +0.3U ref ; Set the voltage offset range U of the distribution process r-1-dev =0.1U ref-dev ; Among them, U R The voltage value of the monitoring point when reactive redistribution is started, U ref is the voltage reference value at the common coupling node, U ref-dev is the offset range; Calculate the voltage deviation ΔU r-1 =UU r-1 , if ΔU r-1 ≠0, control SVG to perform reactive power compensation to smooth voltage fluctuations until U b =0, the reactive power redistribution operation ends.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, any one of the above-mentioned methods for coordinated reactive power control of multiple SVGs in a new energy station is implemented.

Images