Power oscillation region self-damping control method and system based on time-delay measurement

Abstract

A power oscillation area self-damping control method and system based on time-delay measurement calculates the instantaneous active power of the interconnection line to be smoothed based on the spectrum analysis method; obtains the PMU data time stamp between two adjacent spectrum calculations, and calculates the instantaneous active power of the PMU data time stamp based on the cosine wave extrapolation method; the control instruction sent by the control master station to the control substation includes the PMU data time stamp and the corresponding instantaneous active power; the control substation calculates the execution time delay of the control instruction based on the PMU data time stamp, the time obtained from the local synchronous clock and the inherent time delay, and uses the execution time delay and the power distribution ratio of the power plant to correct the instantaneous active power corresponding to the PMU data time stamp, and obtains the power regulation amount when the power plant actually executes the control instruction. Each power plant smoothes the power oscillation according to the power regulation amount; solves the problem that the traditional oscillation suppression method cannot accurately adapt to the changing time delay and the changing oscillation frequency, and realizes oscillation suppression based on local information.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid stability control, and in particular to a method and system for self-damping control of power oscillation regions based on time-delay measurement. Background Art

[0002] Large-scale grid interconnection and renewable energy power generation systems make low-frequency oscillations and subsynchronous oscillations more likely to occur than before. Low-frequency oscillations and subsynchronous oscillations in power systems are both typical large-scale power oscillations.

[0003] In the prior art, low-frequency oscillations rely on the Power System Stabilizer (PSS) installed on-site by each generator set to suppress the oscillation of the power grid based on the detected machine-end power signal. However, the control parameters of the Power System Stabilizer are designed based on the expected power grid state and the expected oscillation mode. When the actual power grid operation mode and oscillation mode are different from the expected system during design, the control effect of the PSS will be greatly reduced. In recent years, the wide-area PSS based on the synchronous phasor measurement unit (PMU) can coordinate the oscillation of multiple units of the power grid, but it is still based on the expected oscillation mode for control; more importantly, for wide-area control, because it involves the delay generated by the wide-area communication system, delay compensation is a content that must be considered in the control program. The existing method usually estimates the system delay and then uses the transfer function delay compensation link to correct it (CN201711154870 A delay matching power system stabilizer and its design method). It does not mention how to obtain the specific delay or only mentions that the delay is obtained by estimation. However, since the real gap between the estimated phase delay and the actual phase delay is difficult to determine, the actual compensation effect is often not good, and it may even be compared with the same phase, exacerbating the oscillation. For subsynchronous oscillations, the current main method is to monitor the units participating in the subsynchronous oscillation on-site or at the dispatching center. When the oscillation power exceeds the limit, the unit that contributes a large amount to the oscillation power is removed, which has a great impact on the power generation of the power grid and is not conducive to the rapid recovery of power supply and load. Most of the traditional low-frequency oscillation or subsynchronous oscillation control technologies are based on local control. Although there are also wide-area oscillation control methods and the delay of measurement and control is considered, the existing delay compensation compensates for the expected oscillation mode through the transfer function, and cannot achieve accurate compensation for delay and phase, so it is impossible to accurately obtain reverse power, and the corresponding oscillation suppression effect often does not meet the requirements, especially for oscillation modes with large differences from the expected oscillation mode. The prior art (CN201310179845) is a PMU-based multi-DC coordinated wide-area damping control method. Although the time stamp is applied, it is applied at the control substation, and there is no mention of how to use the time stamp to calculate the delay and how to perform phase compensation. Moreover, the current time stamping method is performed at the substation, and the time difference between the power grid section represented by the decision data of the master station cannot be determined.

[0004] In addition, for traditional oscillation control methods, it is necessary to formulate the parameters of the power system stabilizer based on the information of all units participating in the oscillation; when the oscillating units within the monitoring range are only part of the units participating in the oscillation, there is currently no automatic continuous adjustment method except to cut off the corresponding units. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a regional self-damping control method and system for power oscillation based on time-delay measurement. Aiming at the deficiencies in the existing low-frequency oscillation and subsynchronous power oscillation technologies, a method for accurately calculating oscillation characteristic parameters in a long period is combined with a method for quickly calculating oscillation parameters in a short period to realize rapid calculation of future oscillation change characteristics; a method for including the measurement time scale of the power grid section on which the decision is based and the future oscillation change characteristic parameters in the control instruction of the master station is used, so that the control substation can accurately obtain the execution time delay and accurately compensate for the oscillation phase delay, thereby realizing effective reverse suppression of low-frequency or subsynchronous power oscillations; an oscillation coherent unit is used to reversely adjust the oscillation power of the regional external interconnection line, so as to realize regional self-damping control of power oscillations independent of the oscillation mechanism.

[0006] The present invention adopts the following technical solution.

[0007] The present invention proposes a power oscillation region self-damping control method based on time-delay measurement, comprising:

[0008] After starting the power oscillation suppression, the instantaneous active power on the tie line whose oscillation is to be suppressed is calculated based on the spectrum analysis method; between two adjacent spectrum analysis calculations, the measurement time of the PMU data of the tie line is obtained as the PMU data time stamp, and the instantaneous active power corresponding to the PMU data time stamp is calculated based on the cosine wave extrapolation method;

[0009] The control master station sends a control instruction to the control substation, and the control instruction includes the PMU data time stamp and the instantaneous active power corresponding to the PMU data time stamp; the control substation calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation, and uses the execution time delay and the adjustment power allocation ratio of the power plant to correct the instantaneous active power corresponding to the PMU data time stamp to obtain the power adjustment amount when the power plant actually executes the control instruction, and each power plant smoothes the power oscillation according to the power adjustment amount;

[0010] Among them, the calculation period of the spectrum analysis method is in the second level, and the calculation period of the cosine wave extrapolation method is in the millisecond level.

[0011] Preferably, the method comprises:

[0012] Step 1, the control master station calculates the power oscillation amplitude and oscillation duration period on the tie line based on the spectrum analysis method, and starts the suppression of power oscillation when it is detected that the power oscillation amplitude is greater than the amplitude threshold and the oscillation duration period is not less than the period threshold;

[0013] Step 2: Select the power plant with the largest output power oscillation amplitude from all the power plants participating in the power oscillation as the reference power plant, and determine the relative initial phases of other power plants based on the initial phase of the reference power plant; divide the power plants into a forward oscillation group and a reverse oscillation group according to the relative initial phases, and use the tie line connecting the forward oscillation group and the reverse oscillation group as the tie line to be smoothed;

[0014] Perform spectrum analysis on the active power of the tie line to be smoothed to obtain the power oscillation phasor, determine the power oscillation phasor of each power plant participating in the oscillation based on the power oscillation phasor of the tie line to be smoothed, take the ratio of the power oscillation phasor of each power plant to the power oscillation phasor of the tie line to be smoothed as the contribution factor, and select the power plant with a contribution factor greater than the set value to participate in the suppression of power oscillation;

[0015] Step 3, using the first time threshold as a period, based on the spectrum analysis method, calculate the instantaneous active power on the tie line whose oscillation is to be smoothed; between two adjacent spectrum analysis method calculations, obtain the measurement time of the PMU data of the tie line as the PMU data time stamp, and use the second time threshold as a period, and calculate the instantaneous active power corresponding to the PMU data time stamp based on the cosine wave extrapolation method;

[0016] Step 4, the control instruction formed by the control master station includes: control type, power plant station identification, PMU data time stamp based on which the decision is made, instantaneous active power corresponding to the PMU data time stamp, and the adjustment power distribution ratio of the power plant; when the difference between the PMU data time stamp in the current control instruction and the PMU data time stamp in the previous control instruction exceeds the second time threshold, the control master station synchronously sends the control instruction to each power plant control substation participating in power oscillation suppression in a multicast manner;

[0017] Step 5: Each power plant control substation participating in power oscillation suppression calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation, and uses the execution time delay and the adjustment power allocation ratio of the power plant to correct the instantaneous active power corresponding to the PMU data time stamp to obtain the power adjustment amount when the power plant actually executes the control instruction;

[0018] Step 6, using the power adjustment distribution ratio and power adjustment amount of each unit in the power plant, determine the power adjustment amount of each unit, and the sum of the power adjustment amount of the unit and the output power of the unit is used as the target active power of the unit; when the current time and the time when the control substation last issued a power control instruction exceed the third time threshold, the control substation sends the target active power to each unit in a multicast manner as the power control instruction of each unit.

[0019] Preferably, step 1 comprises:

[0020] Step 1.1, the control master station performs spectrum analysis on the active power on each tie line in the monitoring area with 30 seconds as the calculation time window and 1 second as the moving step of the calculation time window, and obtains multiple power oscillations with a frequency range of 0.1 Hz to 40 Hz;

[0021] Step 1.2: From the various power oscillations, select the power oscillation whose amplitude is greater than the amplitude threshold A. osc , and the continuous oscillation period is not less than the period threshold N osc The power oscillation of osc is 5MW, the cycle threshold N osc 3 times;

[0022] Step 1.3, start the power oscillation suppression, and obtain the frequency F corresponding to the maximum oscillation amplitude among the screened power oscillations. osc , with frequency F osc The lower power oscillation is used as the object of suppression.

[0023] Preferably, step 2 comprises:

[0024] Step 2.1: Spectrum analysis is performed on the output power of each power plant in the power plant group to obtain the power spectrum at 0.9F. osc to 1.1F osc Between and with frequency F osc The nearest oscillation frequency is used as the participating frequency F of each power plant osc The actual frequency of the power oscillation is the actual frequency, the actual amplitude of the power oscillation corresponding to the actual frequency, and the initial phase constitute the participating frequency F osc The power oscillation characteristic parameters of each power plant under power oscillation;

[0025] Step 2.2, from the participating frequency F osc Among all the power plants with power oscillation, the power plant corresponding to the maximum actual amplitude of power oscillation is selected as the reference power plant and the initial phase of the reference power plant is set to 0; the relative initial phases of other power plants are calculated based on the initial phase of the reference power plant, and the power plants with the absolute value of the relative initial phase less than 90° are classified into the forward oscillation group, and the power plants with the absolute value of the relative initial phase greater than 90° are classified into the reverse oscillation group; the tie line connecting the areas where the power plants in the forward oscillation group and the reverse oscillation group are located is used as the tie line to be smoothed;

[0026] Step 2.3: Perform spectrum analysis on the active power of the tie line to be smoothed and obtain the frequency at 0.9F osc to 1.1F osc The power oscillation component corresponding to the maximum power oscillation amplitude is taken as the reference phase, and the power oscillation phasor of each power plant at the actual frequency is determined by the following relationship:

[0027] P g_i cos(2πf osc t+θ)

[0028] In the formula,

[0029] P g_i is the power amplitude of the power oscillation phasor of power plant i,

[0030] f osc The frequency F of each power plant osc The actual frequency of the lower power oscillation,

[0031] θ is the angle between the power oscillation phasor and the power oscillation component at the actual frequency of the power plant;

[0032] Step 2.4, calculate the contribution factor of the power amplitude of the power oscillation phasor of the power plant at the actual frequency to the power amplitude of the power oscillation component on the tie line to be smoothed by the following relationship:

[0033] h i =P g_i cosθ / P tie

[0034] In the formula,

[0035] h i is the contribution factor of power plant i,

[0036] P tie is the power amplitude of the power oscillation component in the tie line to be smoothed;

[0037] Step 2.5, select the contribution factor h i The power plants with a value greater than the set value H participate in power oscillation suppression, where H is 0.05; and the units with a value greater than or equal to 90° are defined as positively correlated power plants, and the units with a value less than 90° are defined as negatively correlated power plants.

[0038] Preferably, step 3 comprises:

[0039] Step 3.1, obtain the PMU data time stamp between two adjacent spectrum analysis calculations; take the time period of length NT before the PMU data time stamp as the spectrum analysis time window, where N is an integer greater than or equal to 5, where T is the oscillation period, satisfying T = 1 / F osc ; or take the PMU data time stamp to frequency F osc The time period between the starting moments of the lower power oscillation is taken as the spectrum analysis time window;

[0040] Step 3.2, within the spectrum analysis time window, the instantaneous active power p of the oscillation at the actual frequency is as follows:

[0041]

[0042] In the formula,

[0043] P A is the power amplitude of oscillation at the actual frequency,

[0044] For the first time difference, meet Where T 0 T is the starting time of the first spectrum analysis calculation cycle in two consecutive spectrum analysis calculations. C-0 is the PMU data time stamp,

[0045] Φ 0 is the initial phase, which is the starting time T 0 The corresponding phase;

[0046] Step 3.3, within 50 consecutive oscillation periods T, when the power amplitude P A Less than 10% A osc If yes, return to step 1; otherwise, go to step 3.4;

[0047] Step 3.4: If the first time difference exceeds the first time threshold, return to step 3.1; wherein the first time threshold T 1 is 0.5s; otherwise, go to step 3.5;

[0048] Step 3.5, use PMU data time stamp T c-0 Among the oscillation characteristic parameters of the initial phase, the instantaneous active power p of the oscillation at the actual frequency is calculated based on the cosine wave extrapolation method. c As shown below:

[0049] p c =P A cos(2πf osc t c +Φ c-0 )

[0050] In the formula, Φ c-0 is the PMU data time stamp T c-0 The corresponding phase satisfies:

[0051] Φ c-0 =Φ 0 +2πf osc (T c-0 -T 0 )

[0052] t c is the second time difference, satisfying t c =TT c-0 .

[0053] Preferably, the second time threshold T 2 It is 10ms level, and the value is 30ms or 40ms;

[0054] The third time threshold T 3 The value is less than T 2 / 2, the value is 10ms.

[0055] Preferably, step 5 comprises:

[0056] Step 5.1, calculate the execution time delay △t of the control command in the control substation of power plant i using the following relationship: osc-i :

[0057] △t osc-i =T osc-s-i -T osc-m-i +T exc-i

[0058] In the formula,

[0059] T osc-s-i is the time obtained by the control substation of power plant i from the local synchronous clock,

[0060] T osc-m-i is the PMU data time stamp in the control command received by the control substation of power plant i,

[0061] T exc-i is the inherent time delay of the control substation of power plant i;

[0062] Step 5.2, calculate the time T obtained from the local synchronous clock based on the execution time delay osc-s-i The power regulation quantity P of power plant i osc-i-r (T osc-s-i ),as follows:

[0063] P osc-i-r (T osc-s-i )=-k i P A cos(2πf osc Δt osc-i +Φ c-0 )

[0064] In the formula,

[0065] k i is the regulation power allocation ratio of power plant i,

[0066] The negative sign indicates that the power regulation is the active power in the opposite direction to the oscillating power on the tie line.

[0067] P Ais the power amplitude of oscillation at the actual frequency,

[0068] f osc is the actual frequency,

[0069] Φ c-0 is the PMU data time stamp T c-0 The corresponding phase.

[0070] Preferably, in the forward oscillation group under the PMU data time scale, the regulating power allocation ratio of the power plant is the ratio of the power regulation margin of each power plant in the forward oscillation group to the total forward power regulation margin; in the reverse oscillation group under the PMU data time scale, the regulating power allocation ratio of the power plant is the ratio of the power regulation margin of each power plant in the reverse oscillation group to the total reverse power regulation margin.

[0071] Preferably, in step 6, the target active power P of unit j of power plant i is calculated osc-ij (T osc-s-i ),as follows:

[0072] P osc-ij (T osc-s-i )=P osc-ij-PMU (T osc-s-i )+k ij P osc-i-r (T osc-s-i )

[0073] In the formula,

[0074] P osc-ij-PMU (T osc-s-i ) is the unit j of power plant i at time T osc-s-i The PMU measured value of the unit's output power,

[0075] k ij is the regulation power allocation ratio of unit j in power plant i, which is the ratio of the power regulation margin of unit j to the power regulation margin of the power plant.

[0076] The present invention also proposes a power oscillation region self-damping control system based on time-delay measurement, comprising:

[0077] Start-up module, oscillation parameter calculation module, master station instruction issuing module, instruction compensation module, instruction execution module;

[0078] A start-up module is used to control the master station to calculate the power oscillation amplitude and oscillation duration period on the interconnection line based on the spectrum analysis method, and start the suppression of power oscillation when it is detected that the power oscillation amplitude is greater than the amplitude threshold and the oscillation duration period is not less than the period threshold; select the power plant with the largest output power oscillation amplitude from all the power plants participating in the power oscillation as the reference power plant, and determine the relative initial phases of other power plants based on the initial phase of the reference power plant; divide the power plants into forward oscillation groups and reverse oscillation groups according to the relative initial phases, and use the interconnection line connecting the forward oscillation group and the reverse oscillation group as the interconnection line to be smoothed; perform spectrum analysis on the active power of the interconnection line to be smoothed to obtain the power oscillation phasor, and determine the power oscillation phasor of each power plant participating in the oscillation based on the power oscillation phasor of the interconnection line to be smoothed, and use the ratio of the power oscillation phasor of each power plant to the power oscillation phasor of the interconnection line to be smoothed as the contribution factor, and select the power plant with a contribution factor greater than the set value to participate in the suppression of power oscillation;

[0079] The oscillation parameter calculation module calculates the instantaneous active power on the tie line whose oscillation is to be suppressed based on the spectrum analysis method, taking the first time threshold as the period; between two adjacent spectrum analysis method calculations, obtaining the measurement time of the PMU data of the tie line as the PMU data time stamp, and calculating the instantaneous active power corresponding to the PMU data time stamp based on the cosine wave extrapolation method, taking the second time threshold as the period;

[0080] The master station instruction issuing module is used to control the control instructions formed by the master station, including: control type, power plant station identification, PMU data time stamp based on which the decision is made, instantaneous active power corresponding to the PMU data time stamp, and the adjustment power distribution ratio of the power plant; when the difference between the PMU data time stamp in the current control instruction and the PMU data time stamp in the previous control instruction exceeds the second time threshold, the control master station synchronously issues the control instruction to each power plant control substation participating in power oscillation suppression in a multicast manner;

[0081] The instruction compensation module is used for each power plant control substation participating in power oscillation suppression. It calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation. The instantaneous active power corresponding to the PMU data time stamp is corrected by using the execution time delay and the adjustment power allocation ratio of the power plant to obtain the power adjustment amount when the power plant actually executes the control instruction.

[0082] The instruction execution module is used to determine the power adjustment amount of each unit by using the adjustment power distribution ratio and power adjustment amount of each unit in the power plant, and the sum of the power adjustment amount of the unit and the output power of the unit is used as the target active power of the unit; when the current time and the time when the control substation last issued a power control instruction exceed the third time threshold, the control substation sends the target active power to each unit in a multicast manner as the power control instruction of each unit.

[0083] The beneficial effects of the present invention are as follows:

[0084] 1. When the frequency F is detected osc When power oscillation occurs, the spectrum analysis algorithm is used to accurately calculate the oscillation parameters in a long period of seconds, and the cosine wave extrapolation algorithm is used to quickly and roughly estimate the oscillation parameters in a short period of milliseconds, i.e., the control period, so as to avoid affecting the real-time performance of millisecond-level period control due to calling the time-consuming spectrum analysis algorithm in each control period;

[0085] 2. By including the time stamp of the PMU data at the time of measurement and the characteristic parameters of the future power oscillation in the control instructions of the master station, the control substation can accurately obtain the execution time delay and accurately compensate for the oscillation phase delay, thereby achieving effective reverse suppression of low-frequency or subsynchronous power oscillations. This solves the problem that traditional oscillation suppression methods cannot accurately adapt to changing delays and changing oscillation frequencies.

[0086] 3. Use the oscillation synchronization unit to reversely regulate the oscillation power of the regional external interconnection line to achieve regional self-damping control of power oscillations that is independent of the oscillation mechanism; solve the problem that the traditional oscillation control method needs to formulate the parameters of the power system stabilizer based on the information of all units participating in the oscillation, resulting in the lack of automatic continuous adjustment method when the oscillating units within the monitoring range are only part of the units participating in the oscillation, except for cutting off the corresponding units. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 It is a flow chart of the power oscillation region self-damping control method based on time-delay measurement in the present invention. DETAILED DESCRIPTION

[0088] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0089] The present invention proposes a power oscillation area self-damping control method based on time-delay measurement. After starting power oscillation suppression, the instantaneous active power on the interconnection line to be suppressed is calculated based on the spectrum analysis method. Between two adjacent spectrum analysis calculations, the measurement time of the PMU data of the interconnection line is obtained as the PMU data time stamp, and the instantaneous active power corresponding to the PMU data time stamp is calculated based on the cosine wave extrapolation method. The control main station sends a control instruction to the control substation, and the control instruction includes the PMU data time stamp and the instantaneous active power corresponding to the PMU data time stamp. The control substation calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock and the inherent time delay of the control substation, and uses the execution time delay and the adjustment power allocation ratio of the power plant to correct the instantaneous active power corresponding to the PMU data time stamp, so as to obtain the power regulation amount when the power plant actually executes the control instruction, and each power plant suppresses the power oscillation according to the power regulation amount. Among them, the calculation cycle of the spectrum analysis method is in the second level, and the calculation cycle of the cosine wave extrapolation method is in the millisecond level.

[0090] The present invention proposes a method for controlling power oscillation region self-damping based on actual measurement of control delay, such as Figure 1 As shown, including:

[0091] Step 1: The control master station calculates the power oscillation amplitude and oscillation duration period on the tie line based on the spectrum analysis method. When it is detected that the power oscillation amplitude is greater than the amplitude threshold A osc And the oscillation duration period is not less than the period threshold N osc When , the suppression of power oscillations is started.

[0092] Specifically, based on real-time spectrum analysis, the control master detects the presence of frequency F osc The oscillation amplitude is greater than the oscillation threshold A osc , and the oscillation lasts N osc When the starting frequency is F osc Suppression of lower power oscillations.

[0093] Specifically, step 1 includes:

[0094] Step 1.1, the control master station uses 30 seconds as the calculation time window and 1 second as the moving step of the calculation time window to perform spectrum analysis on the active power on each interconnection line in the monitoring area, and obtains multiple power oscillations with a frequency range of 0.1 Hz to 40 Hz; the multiple power oscillations include low-frequency power oscillations and sub-synchronous power oscillations.

[0095] Step 1.2: From the various power oscillations, select the power oscillation whose amplitude is greater than the amplitude threshold A. osc , and the continuous oscillation period is not less than the period threshold N oscPower oscillations;

[0096] In a non-limiting preferred embodiment, the amplitude threshold A osc is 5MW, the cycle threshold N osc For 3 times.

[0097] Step 1.3, start the power oscillation suppression, and obtain the frequency F corresponding to the maximum oscillation amplitude among the screened power oscillations. osc , with frequency F osc The lower power oscillation is used as the object of suppression.

[0098] Step 2: Select the power plant with the largest output power oscillation amplitude from all the power plants participating in the power oscillation as the reference power plant, and determine the relative initial phases of other power plants based on the initial phase of the reference power plant; divide the power plants into a forward oscillation group and a reverse oscillation group according to the relative initial phases, and use the tie line connecting the forward oscillation group and the reverse oscillation group as the tie line to be smoothed;

[0099] The active power of the tie-line to be smoothed is subjected to spectrum analysis to obtain the power oscillation phasor. The power oscillation phasor of each power plant participating in the oscillation is determined based on the power oscillation phasor of the tie-line to be smoothed. The ratio of the power oscillation phasor of each power plant to the power oscillation phasor of the tie-line to be smoothed is used as the contribution factor. The power plants with contribution factors greater than the set value are selected to participate in the suppression of power oscillation.

[0100] Specifically, step 2 includes:

[0101] Step 2.1: Spectrum analysis is performed on the output power of each power plant in the power plant group to obtain the power spectrum at 0.9F. osc to 1.1F osc Between and with frequency F osc The nearest oscillation frequency is used as the participating frequency F of each power plant osc The actual frequency f of the power oscillation osc , with the actual frequency f osc , actual frequency f osc The corresponding actual amplitude of power oscillation is A fosc and initial phase Constitute participation frequency F osc The power oscillation characteristic parameters of each power plant under power oscillation.

[0102] Step 2.2, from the participating frequency F osc Among all power plants with power oscillation, select the actual power oscillation amplitude A foscThe power plant corresponding to the maximum value is used as the reference power plant and the initial phase of the reference power plant is set to 0; the relative initial phases of other power plants are calculated based on the initial phase of the reference power plant, and the power plants with the absolute value of the relative initial phase less than 90° are classified into the forward oscillation group, and the power plants with the absolute value of the relative initial phase greater than 90° are classified into the reverse oscillation group; the tie line connecting the areas where the power plants in the forward oscillation group and the reverse oscillation group are located is used as the tie line to be smoothed

[0103] When all power plants belong to the positive oscillation group, the external interconnection lines in the area where the power plant group is located are used as the interconnection lines to be smoothed, and the area where the power plant group flows out is taken as the positive direction of power.

[0104] Step 2.3: Perform spectrum analysis on the active power of the tie line to be smoothed and obtain the frequency at 0.9F osc to 1.1F osc The power oscillation component corresponding to the maximum power oscillation amplitude is taken as the reference phase, and the power oscillation phasor of each power plant at the actual frequency is determined by the following relationship:

[0105] P g_i cos(2πf osc t+θ)

[0106] In the formula,

[0107] P g_i is the power amplitude of the power oscillation phasor of power plant i,

[0108] f osc The frequency F of each power plant osc The actual frequency of the lower power oscillation,

[0109] θ is the angle between the power oscillation phasor and the power oscillation component at the actual frequency of the power plant.

[0110] Step 2.4, calculate the contribution factor of the power amplitude of the power oscillation phasor of the power plant at the actual frequency to the power amplitude of the power oscillation component on the tie line to be smoothed by the following relationship:

[0111] h i =P g_i cosθ / P tie

[0112] In the formula,

[0113] h i is the contribution factor of power plant i,

[0114] P tie is the power amplitude of the power oscillation component in the interconnection line to be smoothed.

[0115] Step 2.5, select the contribution factor h i The power plants with a value greater than the set value H participate in power oscillation suppression, where H is 0.05; and the units with a value greater than or equal to 90° are defined as positively correlated power plants, and the units with a value less than 90° are defined as negatively correlated power plants.

[0116] Step 3: Take the first time threshold T 1 The instantaneous active power of the tie line whose oscillation is to be suppressed is calculated based on the spectrum analysis method. Between two adjacent spectrum analysis calculations, the measurement time of the PMU data of the tie line is obtained as the PMU data time mark T c-0 , with the second time threshold T 2 The PMU data time stamp T is calculated based on the cosine wave extrapolation method. c-0 The corresponding instantaneous active power.

[0117] Specifically, high-precision spectrum analysis algorithms include but are not limited to the Prony method and the empirical mode decomposition (EMD) method.

[0118] Specifically, step 3 includes:

[0119] Step 3.1, obtain the PMU data time stamp between two adjacent spectrum analysis calculations; take the time period of length NT before the PMU data time stamp as the spectrum analysis time window, where T is the oscillation period, satisfying T = 1 / F osc ; or take the PMU data time stamp to frequency F osc The time period between the start and end times of the upper and lower power oscillations is taken as the spectrum analysis time window.

[0120] In a non-limiting preferred embodiment, N is an integer greater than or equal to 5.

[0121] Step 3.2, within the spectrum analysis time window, the instantaneous active power p of the oscillation at the actual frequency is as follows:

[0122]

[0123] In the formula,

[0124] P A is the power amplitude of oscillation at the actual frequency,

[0125] t is the first time difference, satisfying Where T 0 T is the starting time of the first spectrum analysis calculation cycle in two consecutive spectrum analysis calculations. C-0 is the PMU data time stamp,

[0126] Φ 0 is the initial phase, which is the starting time T 0 The corresponding phase.

[0127] Step 3.3, within 50 consecutive oscillation periods T, when the power amplitude P A Less than 10% A osc If yes, return to step 1; otherwise go to step 3.4.

[0128] Step 3.4: If the first time difference exceeds the first time threshold, return to step 3.1; wherein the first time threshold T 1 is 0.5s; otherwise go to step 3.5;.

[0129] Step 3.5, use PMU data time stamp T c-0 Among the oscillation characteristic parameters of the initial phase, the instantaneous active power p of the oscillation at the actual frequency is calculated based on the cosine wave extrapolation method. c As shown below:

[0130] p c =P A cos(2πf osc t c +Φ c-0 )

[0131] In the formula, Φ c-0 is the PMU data time stamp T c-0 The corresponding phase satisfies:

[0132] Φ c-0 =Φ 0 +2πf osc (T c-0 -T 0 )

[0133] t c is the second time difference, satisfying t c =TT c-0 .

[0134] In the method proposed by the present invention, when the frequency F is detected osc When power oscillation occurs, the spectrum analysis algorithm is used to accurately calculate the oscillation parameters with a long period of seconds, and the cosine wave extrapolation algorithm is used to quickly and roughly estimate the oscillation parameters in a short period of milliseconds, i.e., the control period, thereby avoiding the real-time performance of millisecond-level period control being affected by calling the time-consuming spectrum analysis algorithm in each control period.

[0135] Step 4: The control command generated by the control master station includes: control type, power plant station identification, PMU data time stamp T based on which the decision is based c-0 、PMU data time stamp T c-0The corresponding instantaneous active power and the regulated power distribution ratio of the power plant; when the difference between the PMU data time stamp in the current control instruction and the PMU data time stamp in the previous control instruction exceeds the second time threshold T 2 When the control master station sends control instructions to the control substations of each power plant participating in power oscillation suppression in a multicast manner,

[0136] Specifically, in step 4, the PMU data time stamp T c-0 In the positive oscillation group under i is the ratio of the power regulation margin of each power plant in the forward oscillation group to the total forward power regulation margin; PMU data time scale T c-0 In the reverse oscillation group under i is the ratio of the power regulation margin of each power plant in the reverse oscillation group to the total reverse power regulation margin

[0137] In a non-limiting preferred embodiment, the second time threshold T 2 It is at the 10ms level and the value can be 30ms or 40ms.

[0138] Step 5: Each power plant control substation participating in power oscillation suppression calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation. The instantaneous active power corresponding to the PMU data time stamp is corrected using the execution time delay and the power regulation allocation ratio of the power plant to obtain the power regulation amount P when the power plant actually executes the control instruction. osc-i-r .

[0139] Step 5 includes:

[0140] Step 5.1, calculate the execution time delay △t of the control command in the control substation of power plant i using the following relationship: osc-i :

[0141] △t osc-i =T osc-s-i -T osc-m-i +T exc-i

[0142] In the formula,

[0143] T osc-s-i is the time obtained by the control substation of power plant i from the local synchronous clock,

[0144] T osc-m-i is the PMU data time stamp in the control command received by the control substation of power plant i,

[0145] T exc-iis the inherent time delay of the control substation of power plant i.

[0146] Step 5.2, calculate the time T obtained from the local synchronous clock based on the execution time delay osc-s-i The power regulation quantity P of power plant i osc-i-r (T osc-s-i ),as follows:

[0147] P osc-i-r (T osc-s-i )=-k i P A cos(2πf osc Δt osc-i +Φ c-0 )

[0148] In the formula,

[0149] k i is the regulation power allocation ratio of power plant i,

[0150] The negative sign indicates that the power regulation is the active power in the opposite direction to the oscillating power on the tie line.

[0151] P A is the power amplitude of oscillation at the actual frequency,

[0152] f osc is the actual frequency,

[0153] Φ c-0 is the PMU data time stamp T c-0 The corresponding phase.

[0154] Step 6: Use the power distribution ratio k of each unit in the power plant ij And power regulation P osc-i-r , determine the power regulation of each unit, and the sum of the power regulation of the unit and the output power of the unit is taken as the target active power P of the unit osc-ij (T osc-s-i ); The current time and the time when the control substation last issued a power control instruction exceed the third time threshold T 3 When the target active power is set to the power control command of each unit, the control substation sends the target active power to each unit in a multicast manner as the power control command of each unit.

[0155] In step 6, the target active power P of unit j of power plant i is calculated. osc-ij (T osc-s-i ),as follows:

[0156] P osc-ij (T osc-s-i )=P osc-ij-PMU (T osc-s-i )+k ij Posc-i-r (T osc-s-i )

[0157] In the formula,

[0158] P osc-ij-PMU (T osc-s-i ) is the unit j of power plant i at time T osc-s-i The PMU measured value of the unit’s output power.

[0159] k ij is the regulation power allocation ratio of unit j in power plant i, which is the ratio of the power regulation margin of unit j to the power regulation margin of the power plant.

[0160] In a non-limiting preferred embodiment, the third time threshold T 3 The value is less than T 2 / 2, the value is 10ms.

[0161] The present invention also proposes a power oscillation region self-damping control system based on time-delay measurement, comprising:

[0162] Start-up module, oscillation parameter calculation module, master station instruction issuing module, instruction compensation module, instruction execution module;

[0163] A start-up module is used to control the master station to calculate the power oscillation amplitude and oscillation duration period on the interconnection line based on the spectrum analysis method, and start the suppression of power oscillation when it is detected that the power oscillation amplitude is greater than the amplitude threshold and the oscillation duration period is not less than the period threshold; select the power plant with the largest output power oscillation amplitude from all the power plants participating in the power oscillation as the reference power plant, and determine the relative initial phases of other power plants based on the initial phase of the reference power plant; divide the power plants into forward oscillation groups and reverse oscillation groups according to the relative initial phases, and use the interconnection line connecting the forward oscillation group and the reverse oscillation group as the interconnection line to be smoothed; perform spectrum analysis on the active power of the interconnection line to be smoothed to obtain the power oscillation phasor, and determine the power oscillation phasor of each power plant participating in the oscillation based on the power oscillation phasor of the interconnection line to be smoothed, and use the ratio of the power oscillation phasor of each power plant to the power oscillation phasor of the interconnection line to be smoothed as the contribution factor, and select the power plant with a contribution factor greater than the set value to participate in the suppression of power oscillation;

[0164] The oscillation parameter calculation module calculates the instantaneous active power on the tie line whose oscillation is to be suppressed based on the spectrum analysis method, taking the first time threshold as the period; between two adjacent spectrum analysis method calculations, obtaining the measurement time of the PMU data of the tie line as the PMU data time stamp, and calculating the instantaneous active power corresponding to the PMU data time stamp based on the cosine wave extrapolation method, taking the second time threshold as the period;

[0165] The master station instruction issuing module is used to control the control instructions formed by the master station, including: control type, power plant station identification, PMU data time stamp based on which the decision is made, instantaneous active power corresponding to the PMU data time stamp, and the adjustment power distribution ratio of the power plant; when the difference between the PMU data time stamp in the current control instruction and the PMU data time stamp in the previous control instruction exceeds the second time threshold, the control master station synchronously issues the control instruction to each power plant control substation participating in power oscillation suppression in a multicast manner;

[0166] The instruction compensation module is used for each power plant control substation participating in power oscillation suppression. It calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation. The instantaneous active power corresponding to the PMU data time stamp is corrected by using the execution time delay and the adjustment power allocation ratio of the power plant to obtain the power adjustment amount when the power plant actually executes the control instruction.

[0167] The instruction execution module is used to determine the power adjustment amount of each unit by using the adjustment power distribution ratio and power adjustment amount of each unit in the power plant, and the sum of the power adjustment amount of the unit and the output power of the unit is used as the target active power of the unit; when the current time and the time when the control substation last issued a power control instruction exceed the third time threshold, the control substation sends the target active power to each unit in a multicast manner as the power control instruction of each unit.

[0168] Among them, the startup module, oscillation parameter calculation module and master station instruction issuing module are all located in the control main station; the instruction compensation module and instruction execution module are located in the control substation.

[0169] The present invention proposes a power oscillation self-damping control method based on control delay measurement, and constructs a control master station and a substation in a local power grid for suppressing low-frequency oscillation or subsynchronous power oscillation, so as to realize that the local power grid does not participate in the power oscillation of the external power grid or the global power grid, thereby helping to suppress the power oscillation of the external power grid or the global power grid. The minimum period of the power oscillation to be suppressed is 25ms, and the maximum period can be more than 10s. In order to realize the timely tracking of the power oscillation within the above oscillation period range, the PMU device is required to use a dedicated independent port to send 100 frames / s of data to the power smoothing control master station, that is, the monitoring of the key power section and the unit in the controlled power station uses PMU data with a 10ms sending period to replace the conventional PMU data with a 20ms sending period. For the communication network used for data acquisition and control, in order to ensure the reliability of oscillation control, it is recommended to use a control dedicated network, for example, for high-performance thermal power plants, energy storage stations, photovoltaic stations, and wind farms with large capacity and fast response speed, a 2M dedicated line is used as the communication network for acquisition and control.

[0170] In addition, the present invention limits the power oscillations to be suppressed to low-frequency power oscillations or subsynchronous power oscillations because the periods of these power oscillations are longer than 25ms, while the shortest control period of the currently achievable AC power grid wide-area control system is 10ms. Therefore, it is possible to directly suppress this frequency band by constructing anti-phase oscillation power. For higher-frequency power oscillations in the power system, the current main method is to control the parameters of the power grid or control system and then indirectly suppress the power oscillations.

[0171] To suppress the oscillation in the opposite phase, it is necessary to know the phase delay caused by the time delay of the control instruction. The spectrum analysis algorithm for calculating the phase of the oscillation curve, such as the Prony algorithm, is usually large in calculation and very time-consuming, and it is difficult to achieve continuous calculation every 10ms. Therefore, there is currently no method for oscillation suppression based on delay measurement in oscillation suppression. The present invention combines the method of accurately calculating the oscillation characteristic parameters in a long period with the method of quickly calculating the oscillation parameters in a short period to achieve rapid calculation of the future change characteristics of the oscillation, that is, using a long period of seconds to use an accurate and complex spectrum analysis algorithm (such as the Prony or EMD algorithm) to perform accurate spectrum analysis to obtain the accurate phase at a certain moment; then, in the phase between the two accurate phase calculations, a fast algorithm with a fixed frequency is used to estimate the phase using a millisecond short period, thereby achieving a more accurate calculation of the 10ms control cycle phase, so that the method of marking the time is applied in oscillation suppression. In addition, the instruction time stamp at the master station is not obtained at the master station, but the time stamp of the PMU data used for the current control decision of the master station at the measurement time.

[0172] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0173] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0174] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0175] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0176] 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 above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for self-damping control of power oscillation region based on time-delay measurement, characterized in that: include: After starting the power oscillation suppression, the instantaneous active power on the tie line whose oscillation is to be suppressed is calculated based on the spectrum analysis method; between two adjacent spectrum analysis calculations, the measurement time of the PMU data of the tie line is obtained as the PMU data time stamp, and the instantaneous active power corresponding to the PMU data time stamp is calculated based on the cosine wave extrapolation method; within the spectrum analysis time window, the instantaneous active power p oscillating at the actual frequency is shown in the following formula: Where P A is the power amplitude of the oscillation at the actual frequency, f osc The frequency F of each power plant osc The actual frequency of the power oscillation, F osc is the frequency corresponding to the maximum oscillation amplitude, For the first time difference, meet T0 is the starting time of the first spectrum analysis calculation cycle in two consecutive spectrum analysis calculations, T C-0 is the PMU data time stamp, Φ0 is the initial phase, which is the phase corresponding to the starting time T0; The instantaneous active power p calculated based on the cosine wave extrapolation method c As shown below: p c =P A cos(2πf osc t c +F c-0 ) Where, t c is the second time difference, satisfying t c =TT c-0 , T is the oscillation period; Φ c-0 is the PMU data time stamp T c-0 The corresponding phase satisfies: Φ c-0 =Φ0+2πf osc (T c-0 -T0); The control master station sends a control instruction to the control substation, and the control instruction includes the PMU data time stamp and the instantaneous active power corresponding to the PMU data time stamp; the control substation calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation, and uses the execution time delay and the adjustment power allocation ratio of the power plant to correct the instantaneous active power corresponding to the PMU data time stamp to obtain the power adjustment amount when the power plant actually executes the control instruction, and each power plant smoothes the power oscillation according to the power adjustment amount; Among them, the calculation period of the spectrum analysis method is in the second level, and the calculation period of the cosine wave extrapolation method is in the millisecond level.

2. The power oscillation region self-damping control method based on time-delay measurement according to claim 1 is characterized in that: Step 1, the control master station calculates the power oscillation amplitude and oscillation duration period on the tie line based on the spectrum analysis method, and starts the suppression of power oscillation when it is detected that the power oscillation amplitude is greater than the amplitude threshold and the oscillation duration period is not less than the period threshold; Step 2: Select the power plant with the largest output power oscillation amplitude from all the power plants participating in the power oscillation as the reference power plant, and determine the relative initial phases of other power plants based on the initial phase of the reference power plant; divide the power plants into a forward oscillation group and a reverse oscillation group according to the relative initial phases, and use the tie line connecting the forward oscillation group and the reverse oscillation group as the tie line to be smoothed; Perform spectrum analysis on the active power of the tie line to be smoothed to obtain the power oscillation phasor, determine the power oscillation phasor of each power plant participating in the oscillation based on the power oscillation phasor of the tie line to be smoothed, take the ratio of the power oscillation phasor of each power plant to the power oscillation phasor of the tie line to be smoothed as the contribution factor, and select the power plant with a contribution factor greater than the set value to participate in the suppression of power oscillation; Step 3, using the first time threshold as a period, based on the spectrum analysis method, calculate the instantaneous active power on the tie line whose oscillation is to be smoothed; between two adjacent spectrum analysis method calculations, obtain the measurement time of the PMU data of the tie line as the PMU data time stamp, and use the second time threshold as a period, and calculate the instantaneous active power corresponding to the PMU data time stamp based on the cosine wave extrapolation method; Step 4, the control instruction formed by the control master station includes: control type, power plant station identification, PMU data time stamp based on which the decision is made, instantaneous active power corresponding to the PMU data time stamp, and the adjustment power distribution ratio of the power plant; when the difference between the PMU data time stamp in the current control instruction and the PMU data time stamp in the previous control instruction exceeds the second time threshold, the control master station synchronously sends the control instruction to each power plant control substation participating in power oscillation suppression in a multicast manner; Step 5: Each power plant control substation participating in power oscillation suppression calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation, and uses the execution time delay and the adjustment power allocation ratio of the power plant to correct the instantaneous active power corresponding to the PMU data time stamp to obtain the power adjustment amount when the power plant actually executes the control instruction; Step 6, using the adjustment power distribution ratio and power adjustment amount of each unit in the power plant, determine the power adjustment amount of each unit, and the sum of the power adjustment amount of the unit and the output power of the unit is used as the target active power of the unit; When the current time and the time when the control substation last sent the power control instruction exceed the third time threshold, the control substation sends the target active power to each unit in a multicast manner as the power control instruction of each unit.

3. The power oscillation region self-damping control method based on delayed measurement according to claim 2 is characterized in that: Step 1 includes: Step 1.1, the control master station performs spectrum analysis on the active power on each tie line in the monitoring area with 30 seconds as the calculation time window and 1 second as the moving step of the calculation time window, and obtains multiple power oscillations with a frequency range of 0.1 Hz to 40 Hz; Step 1.2: From the various power oscillations, select the power oscillation whose amplitude is greater than the amplitude threshold A. osc , and the continuous oscillation period is not less than the period threshold N osc The power oscillation of osc is 5MW, the cycle threshold N osc 3 times; Step 1.3, start the power oscillation suppression, and obtain the frequency F corresponding to the maximum oscillation amplitude among the screened power oscillations. osc , with frequency F osc The lower power oscillation is used as the object of suppression.

4. The power oscillation region self-damping control method based on delayed measurement according to claim 3 is characterized in that: Step 2 includes: Step 2.1: Spectrum analysis is performed on the output power of each power plant in the power plant group to obtain the power spectrum at 0.9F. osc to 1.1F osc Between and with frequency F osc The nearest oscillation frequency is used as the participating frequency F of each power plant osc The actual frequency of the power oscillation is the actual frequency, the actual amplitude of the power oscillation corresponding to the actual frequency, and the initial phase constitute the participating frequency F osc The power oscillation characteristic parameters of each power plant under power oscillation; Step 2.2, from the participating frequency F osc Among all the power plants with power oscillation, the power plant corresponding to the maximum actual amplitude of power oscillation is selected as the reference power plant and the initial phase of the reference power plant is set to 0; the relative initial phases of other power plants are calculated based on the initial phase of the reference power plant, and the power plants with the absolute value of the relative initial phase less than 90° are classified into the forward oscillation group, and the power plants with the absolute value of the relative initial phase greater than 90° are classified into the reverse oscillation group; the tie line connecting the areas where the power plants in the forward oscillation group and the reverse oscillation group are located is used as the tie line to be smoothed; Step 2.3: Perform spectrum analysis on the active power of the tie line to be smoothed and obtain the frequency at 0.9F osc to 1.1F osc The power oscillation component corresponding to the maximum power oscillation amplitude is taken as the reference phase, and the power oscillation phasor of each power plant at the actual frequency is determined by the following relationship: P g_i icos(2πf osc t+θ) In the formula, P g_i is the power amplitude of the power oscillation phasor of power plant i, f osc The frequency F of each power plant osc The actual frequency of the lower power oscillation, θ is the angle between the power oscillation phasor and the power oscillation component at the actual frequency of the power plant; Step 2.4, calculate the contribution factor of the power amplitude of the power oscillation phasor of the power plant at the actual frequency to the power amplitude of the power oscillation component on the tie line to be smoothed by the following relationship: h i =P g_i cosθ / P tie In the formula, h i is the contribution factor of power plant i, P tie is the power amplitude of the power oscillation component in the tie line to be smoothed; Step 2.5, select the contribution factor h i The power plants with a value greater than the set value H participate in power oscillation suppression, where H is 0.05; and the units with a value greater than or equal to 90° are defined as positively correlated power plants, and the units with a value less than 90° are defined as negatively correlated power plants.

5. The power oscillation region self-damping control method based on time-delay measurement according to claim 4 is characterized in that: Step 3 includes: Step 3.1, obtain the PMU data time stamp between two adjacent spectrum analysis calculations; take the time period of length NT before the PMU data time stamp as the spectrum analysis time window, where N is an integer greater than or equal to 5, where T is the oscillation period, satisfying T = 1 / F osc ; or take the PMU data time stamp to frequency F osc The time period between the starting moments of the lower power oscillation is taken as the spectrum analysis time window; Step 3.2, within the spectrum analysis time window, the instantaneous active power p of the oscillation at the actual frequency is as follows: In the formula, P A is the power amplitude of oscillation at the actual frequency, For the first time difference, meet T0 is the starting time of the first spectrum analysis calculation cycle in two consecutive spectrum analysis calculations, T C-0 is the PMU data time stamp, Φ0 is the initial phase, which is the phase corresponding to the starting time T0; Step 3.3, within 50 consecutive oscillation periods T, when the power amplitude P A Less than 10% A osc If yes, return to step 1; otherwise, go to step 3.4; Step 3.4, if the first time difference exceeds the first time threshold, return to step 3.1; wherein the first time threshold T1 is 0.5s; otherwise, proceed to step 3.5; Step 3.5, use PMU data time stamp T c-0 Among the oscillation characteristic parameters of the initial phase, the instantaneous active power p of the oscillation at the actual frequency is calculated based on the cosine wave extrapolation method. c As shown below: p c =P A cos(2πf osc t c +F c-0 ) In the formula, Φ c-0 is the PMU data time stamp T c-0 The corresponding phase satisfies: F c-0 =Φ0+2πf osc (T c-0 -T0) t c is the second time difference, satisfying t c =TT c-0 .

6. The power oscillation region self-damping control method based on time-delay measurement according to claim 2 is characterized in that: The second time threshold T2 is at the 10ms level, and the value is 30ms or 40ms; The value of the third time threshold T3 is less than T2 / 2, and is 10 ms.

7. The power oscillation region self-damping control method based on delayed measurement according to claim 2 is characterized in that: Step 5 includes: Step 5.1, calculate the execution time delay △t of the control command in the control substation of power plant i using the following relationship: osc-i : △t osc-i =T osc-s-i -T osc-m-i +T exc-i In the formula, T osc-s-i is the time obtained by the control substation of power plant i from the local synchronous clock, T osc-m-i is the PMU data time stamp in the control command received by the control substation of power plant i, T exc-i is the inherent time delay of the control substation of power plant i; Step 5.2, calculate the time T obtained from the local synchronous clock based on the execution time delay osc-s-i The power regulation quantity P of power plant i osc-i-r (T osc-s-i ),as follows: P osc-i-r (T osc-s-i )=-k i P A cos(2πf osc Δt osc-i +F c-0 ) In the formula, k i is the regulation power allocation ratio of power plant i, The negative sign indicates that the power regulation is the active power in the opposite direction to the oscillating power on the tie line. P A is the power amplitude of oscillation at the actual frequency, f osc is the actual frequency, Φ c-0 is the PMU data time stamp T c-0 The corresponding phase.

8. The power oscillation region self-damping control method based on time-delay measurement according to claim 7 is characterized in that: In the forward oscillation group under the PMU data time scale, the regulating power allocation ratio of the power plant is the ratio of the power regulation margin of each power plant in the forward oscillation group to the total forward power regulation margin; in the reverse oscillation group under the PMU data time scale, the regulating power allocation ratio of the power plant is the ratio of the power regulation margin of each power plant in the reverse oscillation group to the total reverse power regulation margin.

9. The power oscillation region self-damping control method based on delayed measurement according to claim 8, characterized in that: In step 6, the target active power P of unit j of power plant i is calculated osc-ij (T osc-s-i ),as follows: P osc-ij (T osc-s-i )=P osc-ij-PMU (T osc-s-i )+k ij P osc-i-r (T osc-s-i ) In the formula, P osc-ij-PMU (T osc-s-i ) is the unit j of power plant i at time T osc-s-i The PMU measured value of the unit's output power, k ij is the regulation power allocation ratio of unit j in power plant i, which is the ratio of the power regulation margin of unit j to the power regulation margin of the power plant.

10. A power oscillation region self-damping control system based on time-delay measurement, used to implement the method described in any one of claims 1 to 9, characterized in that: The system includes: Start-up module, oscillation parameter calculation module, master station instruction issuing module, instruction compensation module, instruction execution module; A start-up module is used to control the master station to calculate the power oscillation amplitude and oscillation duration period on the interconnection line based on the spectrum analysis method, and start the suppression of power oscillation when it is detected that the power oscillation amplitude is greater than the amplitude threshold and the oscillation duration period is not less than the period threshold; select the power plant with the largest output power oscillation amplitude from all the power plants participating in the power oscillation as the reference power plant, and determine the relative initial phases of other power plants based on the initial phase of the reference power plant; divide the power plants into forward oscillation groups and reverse oscillation groups according to the relative initial phases, and use the interconnection line connecting the forward oscillation group and the reverse oscillation group as the interconnection line to be smoothed; perform spectrum analysis on the active power of the interconnection line to be smoothed to obtain the power oscillation phasor, and determine the power oscillation phasor of each power plant participating in the oscillation based on the power oscillation phasor of the interconnection line to be smoothed, and use the ratio of the power oscillation phasor of each power plant to the power oscillation phasor of the interconnection line to be smoothed as the contribution factor, and select the power plant with a contribution factor greater than the set value to participate in the suppression of power oscillation; The oscillation parameter calculation module calculates the instantaneous active power on the tie line whose oscillation is to be suppressed based on the spectrum analysis method, taking the first time threshold as the period; between two adjacent spectrum analysis method calculations, obtaining the measurement time of the PMU data of the tie line as the PMU data time stamp, and calculating the instantaneous active power corresponding to the PMU data time stamp based on the cosine wave extrapolation method, taking the second time threshold as the period; The master station instruction issuing module is used to control the control instructions formed by the master station, including: control type, power plant station identification, PMU data time stamp based on which the decision is made, instantaneous active power corresponding to the PMU data time stamp, and the adjustment power distribution ratio of the power plant; when the difference between the PMU data time stamp in the current control instruction and the PMU data time stamp in the previous control instruction exceeds the second time threshold, the control master station synchronously issues the control instruction to each power plant control substation participating in power oscillation suppression in a multicast manner; The instruction compensation module is used for each power plant control substation participating in power oscillation suppression. It calculates the execution time delay of the control instruction according to the PMU data time stamp in the control instruction, the time obtained by the control substation from the local synchronous clock, and the inherent time delay of the control substation. The instantaneous active power corresponding to the PMU data time stamp is corrected by using the execution time delay and the adjustment power allocation ratio of the power plant to obtain the power adjustment amount when the power plant actually executes the control instruction. The instruction execution module is used to determine the power adjustment amount of each unit by using the adjustment power distribution ratio and power adjustment amount of each unit in the power plant, and the sum of the power adjustment amount of the unit and the output power of the unit is used as the target active power of the unit; when the current time and the time when the control substation last issued a power control instruction exceed the third time threshold, the control substation sends the target active power to each unit in a multicast manner as the power control instruction of each unit.

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