Method and system for setting parameters of large-capacity phase regulator in synchronous grid connection

Abstract

The present invention belongs to the field of grid connection technology, and specifically relates to a method and system for setting parameters of large-capacity phase regulator synchronous grid connection. The method comprises the following steps: 1) collecting the phase regulator synchronous grid connection slip rate δ and the synchronous relay closing action delay time T dq ;2) Get the maximum frequency difference setting value Δf allowed by the synchronization device mSet ; 3) construct the shortest grid connection time calculation function and constraint conditions; 4) according to step 2) Δf mSet , and the shortest grid connection time calculation function and constraint conditions determined in step 3), set the frequency difference setting value Δf of the synchronous device Set and phase angle difference setting value ΔA Set The present invention considers the influence of the action delay time of the synchronous relay on the synchronous grid connection of the phase regulator in actual engineering, calculates the setting value of the synchronous grid connection parameter, achieves the optimal grid connection time through parameter setting, and effectively solves the parameter setting problem of the synchronous grid connection of large-capacity phase regulator.

Description

Technical Field

[0001] The present invention belongs to the technical field of grid connection, and in particular relates to a method and system for setting parameters of synchronous grid connection of a large-capacity phase regulator. Background Art

[0002] As renewable energy sources increasingly contribute to the power system, the reactive power support capacity of these new power systems is declining, posing a serious threat to the safe and stable operation of the power grid. Large-capacity phase-shifting condensers are mechanical rotating equipment characterized by high reliability, large capacity, bidirectional reactive power absorption and generation, and strong instantaneous reactive power support capabilities. In the event of grid disturbances, they can provide large amounts of dynamic reactive power through forced excitation. Therefore, to ensure the safe and reliable operation of the power grid, large-capacity phase-shifting condensers have gained significant application within the grid.

[0003] The grid-connected parameter settings of large-capacity phase-shifting condensers are related to the successful grid connection of the condenser. If the parameters are set incorrectly, the failure of grid connection will cause a large amount of waste of electric power resources at the least, and the machine will be destroyed and people will die, causing a major safety accident at the worst. Therefore, the grid-connected parameter settings of the condenser are of great importance. When a large-capacity phase-shifting condenser is quickly connected to the grid, the static frequency converter (SFC) usually drags the condenser rotor from the cranking state to accelerate to a certain speed, and then the SFC exits. Due to the loss of driving force, the condenser rotor begins to inertially decelerate at a slip rate that changes in a certain regularity. During the inertial deceleration process, the synchronous grid-connected device establishes its terminal voltage at the excitation end and begins to look for a synchronization point that meets the grid connection conditions. After finding the synchronization point, the synchronous device sends a closing command to the synchronous relay to connect to the grid. Due to system sampling, measurement errors, and the time delay from the synchronous relay receiving the closing command to the action of the closing circuit, there is an action delay time constant T dq The duration of the synchronization point that meets the grid connection conditions should exceed T dq Grid connection is successful, so calculating the duration of the synchronization point is crucial. Existing methods for calculating the grid connection success rate use the frequency and phase angle differences between the phase regulator and the grid as the basis for calculating the grid connection success rate. This method lacks the calculation of the grid connection time period and does not consider the impact of synchronization relays, system sampling delays, and measurement errors on system operation time in real-world situations. Consequently, the calculation of the grid connection success rate is inaccurate, and grid connection parameter settings are not determined based on the calculation of the grid connection time point. Summary of the Invention

[0004] In order to overcome the above-mentioned defects, the purpose of the present invention is to provide a method and system for adjusting the synchronous grid-connected parameters of a large-capacity phase regulator, taking into account the influence of the delay time of the synchronization relay on the synchronous grid-connected phase regulator in actual projects, calculating the setting values ​​of the synchronous grid-connected parameters, achieving the optimal grid-connected time, and providing a method for adjusting the parameters of the synchronous grid-connected phase regulator, effectively solving the problem of grid-connected parameter setting.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for setting parameters of a large-capacity phase regulator for synchronous grid connection includes the following steps:

[0007] 1) Collect the slip rate δ of the synchronous phase-converter grid connection and the delay time T of the synchronous relay closing action dq ;

[0008] 2) Obtain the maximum frequency difference setting value Δf allowed by the synchronization device mSet ;

[0009] 3) Construct the calculation function and constraints for the shortest grid connection duration;

[0010] 4) According to the Δf in step 2) mSe , and step 3) determining the shortest grid connection time calculation function and constraint conditions, setting the frequency difference setting value Δf of the synchronous device Set and phase angle difference setting value ΔA Set .

[0011] Preferably, step 3) of constructing the shortest grid connection duration calculation function and constraint conditions includes:

[0012] if Then Δf Set The value range is The calculation function of the shortest grid connection duration is:

[0013]

[0014] The constraints are:

[0015]

[0016]

[0017] Where, T min1 express The shortest grid connection time calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value.

[0018] Preferably, the frequency difference setting value Δf of the synchronization device is set in step 4). Set and phase angle difference setting value ΔA Set ,include:

[0019] if Then take

[0020] Preferably, step 3) of constructing the shortest grid connection duration calculation function and constraint conditions includes:

[0021] if Then Δf Se The value range is The calculation function of the shortest grid connection duration is:

[0022]

[0023] The constraints are:

[0024]

[0025]

[0026] Where, T min2 express The shortest grid connection time calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value.

[0027] Preferably, the frequency difference setting value Δf of the synchronization device is set in step 4). Set and phase angle difference setting value ΔA Set ,include:

[0028] if Then Δf Set =Δf mSet ,

[0029] A large-capacity phase-converter synchronous grid-connected parameter setting system, comprising:

[0030] The acquisition module collects the phase shifter synchronous grid-connected slip rate δ and the synchronous relay closing action delay time T dq The maximum frequency difference allowed by the synchronous device is Δf mSet ;

[0031] Modeling module, building the shortest grid connection time calculation function and constraint conditions;

[0032] Parameter setting module, set the frequency difference setting value Δf of the synchronization device Set and phase angle difference setting value ΔA Set .

[0033] Preferably, the modeling module constructs the shortest grid connection time calculation function and constraint conditions, including:

[0034] if Then Δf Se The value range is The calculation function of the shortest grid connection duration is:

[0035]

[0036] The constraints are:

[0037]

[0038]

[0039] if Then Δf Set The value range is The calculation function of the shortest grid connection duration is:

[0040]

[0041] The constraints are:

[0042]

[0043]

[0044] Where, T min1 、T min2 Respectively expressed in The shortest grid connection time calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value.

[0045] Preferably, the parameter setting module sets the frequency difference setting value Δf of the synchronization device Set and phase angle difference setting value ΔA Set ,include:

[0046] if Then take

[0047] if Then Δf Set =Δf mSe ,

[0048] The positive beneficial effects of the present invention are:

[0049] 1. Compared with the existing technology that only considers the influence of frequency difference and phase angle difference setting values ​​on the grid connection of the phase regulator, the present invention not only considers the influence of the synchronous relay action delay encountered in practice on the success of grid connection, but also calculates the grid connection time according to different situations. The grid connection time calculation function and constraint conditions are given through the relationship between the shortest grid connection time and the action delay, and the grid connection parameter setting method under different situations is given, which effectively solves the problem of grid connection parameter setting in the project.

[0050] 2. The existing technology calculates the grid connection success rate mainly with the frequency difference setting value and the phase angle difference setting value as an auxiliary. However, the present invention theoretically proves from the perspective of the grid connection time that the phase angle difference setting value is directly related to the grid connection time. In some cases, the frequency difference setting value has no direct relationship with the grid connection time. The frequency difference setting value indirectly affects the grid connection time by constraining the range of the phase angle difference setting value. The existing technology is not accurate in calculating the grid connection success rate. The present invention designs and optimizes the grid connection parameters with the phase angle difference setting value as the main and the frequency difference setting value as the auxiliary, so as to ensure the optimal grid connection time and reduce the impact of the phase-shifting phase on the power grid when it is connected to the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a diagram showing the total grid-connected duration under different initial phase angle differences of the present invention;

[0052] Figure 2 This is a diagram showing the grid-connected effect of a large-capacity phase regulator of the present invention when the phase angle difference is 342.45°. DETAILED DESCRIPTION

[0053] The present invention is further described below with reference to some specific embodiments.

[0054] Example 1

[0055] After the condenser is driven to a certain speed by the static frequency converter SFC, the SFC exits and the condenser starts to coast at a slip rate δ. The slip rate represents the rate at which the condenser speed decreases when the condenser is coasting. The initial time is defined as the time when the condenser frequency and the grid frequency first meet the grid frequency difference setting value, that is, at this time t = 0, Δf = Δf Set , the relationship between the frequency difference on the machine-network side and time can be expressed as:

[0056] Δf=f s -f N =Δf Set -δt (1)

[0057] Where: Δf is the frequency difference between the machine and the network, f s is the phase modulator frequency, f N is the grid frequency, Δf Set is the grid-connected frequency difference setting value of the synchronous device, t is the time, and δ is the slip rate.

[0058] When the phase regulator is idling, the phase regulator frequency decreases with time. Under the premise of a constant grid frequency, it can be seen from (1) that the frequency difference between the machine and the grid Δf decreases with time. When Δf=-Δf Set , after which the frequency difference between the generator and the grid no longer meets the grid connection conditions. Since the slip rate changes little within the frequency difference range, δ can be approximated as a constant, and the grid connection period exists in within the range.

[0059] At t = 0, assuming that the initial phase angle difference between the phase regulator and the grid voltage is ΔA0, then in the process of the synchronization device capturing the grid synchronization within the fixed frequency difference range, the relationship between the phase angle difference and time is:

[0060] ΔA=A s -A N =ΔA0+360∫Δfdt (2)

[0061] Where: ΔA is the phase angle difference of the voltage on the machine-grid side; A s A is the phase angle of the phase shifter voltage; N is the grid voltage phase angle.

[0062] Substituting equation (1) into equation (2), we can get the relationship between the phase angle difference and time:

[0063] ΔA=ΔA0+360Δf Set t-180δt 2 (3)

[0064] When the frequency difference Δf and phase angle difference ΔA on the machine-grid side meet the set value conditions at the same time, the synchronization device sends a closing command to the synchronization relay. After receiving the command, the synchronization relay delays a certain time to close the switch. After the synchronization relay closes successfully, the phase regulator is connected to the grid. According to the definition, the grid connection frequency difference condition is met at time t = 0. The synchronization device starts to judge the phase angle difference condition on the machine-grid side. If condition (4) is met, the system starts to connect to the grid.

[0065] -ΔA Set ≤mod 360 (ΔA)≤ΔA Set (4)

[0066] Since the phase angle changes in a 360° cycle, mod 360 (·) represents the remainder of 360, ΔA Set Represents the phase angle difference setting value. From formula (4), we can get

[0067] -ΔA Set ≤mod 360 (ΔA0+360Δf Set t-180δt2 )≤ΔA Set (5)

[0068] Solving the left half of equation (5) yields:

[0069] -180δt 2 +360Δf Set t+ΔA0+ΔA Set -360n≥0 (6)

[0070] Where n=0, 1, 2, ... is an integer. The time to meet the conditions is

[0071] t∈[T1(n),T4(n)] (7)

[0072] Where, T1(n), T4(n) respectively represent The possible start and end points of grid connection within the time period, represents the definition of mathematical symbols, and λ1(n) is a mathematical symbol defined to simplify the expression. In order to ensure the existence of the solution in formula (7), λ1(n) ≥ 0, that is:

[0073] (360Δf Set ) 2 +720δ(ΔA0+ΔA Set )≥720δ(360n) (8)

[0074] From formula (8), we can get the condition that the integer n must satisfy:

[0075]

[0076] Where, Indicates rounding down. It represents the maximum integer that can be obtained when λ1(n)≥0.

[0077] Similarly, solve the right half of equation (5), that is,

[0078] ΔA0+360°Δf Set t-180°δt 2 -ΔA Set -360n≤0 (10)

[0079] The time to meet the conditions is

[0080] t∈{[0, T2(n)]∪[T3(n),∞]} (11)

[0081] Where, T2(n), T3(n) respectively represent The possible grid connection end and start time within the time period, λ2(n) is a mathematical symbol defined to simplify the expression. From λ2(n)≥0, it can be obtained that the integer n needs to meet the following conditions:

[0082]

[0083] Where, represents the maximum integer that can be obtained when λ2(n)≥0. From equations (7) and (11), the possible grid-connected time period is:

[0084] t∈{[T1(n), T2(n)]∪[T3(n), T4(n)]} (13)

[0085] From formula (9) and (12), we can know that Therefore, the range of integer n is

[0086]

[0087] From formula (13), we can see that The following is the calculation of the grid connection time starting point, end point and grid connection time period for different situations. In order to determine the starting point and end point of the grid connection time, it is necessary to determine the relationship between T1(0), T2(0) and time 0 to determine the grid connection time starting point, and through T3(0), T4(0) and The grid connection end point is determined based on the relationship between the time.

[0088] (1) When and hour, Therefore, the grid-connected period is

[0089]

[0090] Where: ∪ represents the union of sets, Indicates n = 1 to Cumulative union operation of various sets.

[0091] (2) When And ΔA0+ΔA Set <360 and ΔA0-ΔA Set >0, Therefore, the grid-connected period is

[0092]

[0093] Where: ∪ represents the union of sets, Indicates n = 1 to Cumulative union operation of various sets.

[0094] (3) When And ΔA0+ΔA Set ≥360 and ΔA0-ΔA Set >0, Therefore, the grid-connected period is

[0095]

[0096] Where: ∪ represents the union of sets, Indicates n = 2 to Cumulative union operation of various sets.

[0097] (4) When and hour, Therefore, the grid connection period is:

[0098]

[0099] Where: ∪ represents the union of sets, Indicates n = 1 to Cumulative union operation of various sets.

[0100] (5) When And ΔA0+ΔA Set <360 and ΔA0-ΔA Set >0, Therefore, the grid-connected period is

[0101]

[0102] Where: ∪ represents the union of sets, Indicates n = 1 to Cumulative union operation of various sets.

[0103] (6) When And ΔA0+ΔA Set ≥360 and ΔA0-ΔA Set >0, Therefore, the grid-connected period is

[0104]

[0105] Where: ∪ represents the union of sets, Indicates n = 2 to Cumulative union operation of various sets.

[0106] (7) When When , there is no grid-connected period, so grid connection cannot be successful. In order to ensure that grid connection can be achieved for any initial phase angle difference, we can get:

[0107]

[0108] Since ΔA0 varies in [0, 360), ΔA0-360<0, and since ΔA Set >0, so ΔA0-ΔA Set -360<0, when calculating the time starting point, if there is a grid-connected period, T2(1)>0 for any case, indicating that the total time starting point will not exceed T2(1), so there is no need to judge whether the time point after T2(1) is the total time starting point of the grid-connected period. Similarly, in any case, This indicates that the total end point of the grid connection time is always after T3(1).

[0109] Example 2 Total Grid Connection Duration

[0110] The total grid connection duration under various conditions can be obtained by accumulating each segment:

[0111] (1) When and When the total grid-connected time is

[0112]

[0113] (2) When And ΔA0-ΔA Set When >0, the total grid-connected time is

[0114]

[0115] (3) When and When the total grid-connected time is

[0116]

[0117] (4) When And ΔA0-ΔA Set When >0, the total grid-connected time is:

[0118]

[0119] Example 3 Calculation of the shortest grid connection time

[0120] For phase-shifting ... In the two cases, namely, Equations (22) and (23), the total grid-connected duration is differentiated with respect to the initial phase angle difference ΔA0, and we can obtain:

[0121]

[0122] Since ΔA0+ΔA Set >ΔA0-ΔA Set ,therefore It can be seen that Therefore, during this time period, the total time it can be connected to the grid decreases as ΔA0 increases.

[0123] for For the two cases, namely, Equation (24) and (25), the total grid connection time is derived with respect to the initial phase angle difference ΔA0, and we can get

[0124]

[0125] because Right now Right now Right now Therefore,

[0126] therefore, according to Define, if So

[0127] therefore, so, This shows that f2(ΔA0) increases as ΔA0 increases.

[0128] In summary, when Its grid-connected time decreases as ΔA0 increases; when The grid-connected duration increases as ΔA0 increases.

[0129] ΔA0 varies periodically from 0 to 360°, so the grid connection duration also varies periodically with the change of ΔA0. Therefore, if and only if at this time When , the grid connection time is the shortest, without loss of generality, take

[0130]

[0131] When the grid connection time is the shortest, the corresponding initial phase angle difference is

[0132]

[0133] ΔA * It is the initial phase angle difference corresponding to the shortest grid-connected time.

[0134] To calculate ΔA0=ΔA *The shortest grid connection time is calculated by simply calculating the starting and ending points of the grid connection time. The symmetric axis is symmetrical, and the duration of the symmetrical grid-connected periods is equal. In order to calculate the grid-connected duration of each grid-connected period, it is necessary to calculate the starting point and end point of each grid-connected period. In order to calculate the starting point of the grid-connected time, it is necessary to compare T1(0, ΔA * ) and 0, that is,

[0135]

[0136] When n=0,

[0137] When n=1, This shows that: 1) Only T1(0, ΔA * ) is likely to be less than 0; 2) T1(1, ΔA * ) has reached the time symmetry axis. At this time, there is only one grid-connected period, and the end point is T2(0, ΔA * ).

[0138] The following discusses the starting point of the grid connection period in different situations. Since each synchronization device has a maximum frequency difference setting value Δf provided by the manufacturer mSet , that is, there exists Δf Set ≤Δf mSet .

[0139] The first case: When When Δf Se The value range is At this time, T1(0, ΔA * )≥0.

[0140] Because the phase angle difference changes in a 360° cycle, ΔA Set ≤180°, so the shortest grid-connected duration is

[0141]

[0142] If the shortest grid-connected time is greater than or equal to the action delay T dq k times, the conditions that need to be met are:

[0143]

[0144] Where k represents the action delay T dq The magnification factor is

[0145]

[0146] We can get:

[0147]

[0148] From the grid connection condition (21), we know that In summary

[0149]

[0150] In order to make T min1 Greater than or equal to action delay T dq k times, ΔA Set It is necessary to satisfy formula (33), and ΔA Set The upper limit is also affected by and 180° limit, obviously, in this case, just take Established, at this time it can guarantee ΔA Set Can take values ​​within a larger range.

[0151] In summary, the grid-connected parameter settings At this time, the initial phase angle difference corresponding to the shortest grid connection time is substituted into formula (29): ΔA * <0 is because the value of formula (28) is 1. Since the initial phase angle difference changes periodically and the agreed initial phase angle difference is in the range of 0 to 360°, the initial phase angle difference corresponding to the shortest grid connection time is ΔA * =-ΔA Set +360, that is, when the value of formula (28) is 2, the initial phase angle difference within these agreed ranges can be obtained.

[0152] In summary, the calculation function for the shortest grid connection duration is:

[0153]

[0154] The constraints are:

[0155]

[0156]

[0157] The second case: When Then Δf Set The value range is Then T1(ΔA * )<0, then the shortest grid connection time is

[0158]

[0159] If the shortest grid-connected time is required to be greater than or equal to k times T dq ,

[0160]

[0161] Right now

[0162]

[0163] Available

[0164]

[0165] Based on the above grid connection conditions (21), we can get

[0166]

[0167] Similarly, in order to achieve T min2 Greater than or equal to k times T dq , just choose Δf as large as possible Set , to ensure ΔA Set It can take values ​​in a larger range, that is, it is necessary to set Δf Set =Δf mSet ,

[0168] In summary, the calculation function for the shortest grid connection duration is:

[0169]

[0170] The constraints are:

[0171]

[0172]

[0173] Example 4 Grid-connected parameter setting process

[0174] A method for setting parameters of a large-capacity phase regulator for synchronous grid connection includes the following steps:

[0175] 1) Collect the slip rate δ of the synchronous phase-converter grid connection and the delay time T of the synchronous relay closing action dq ;

[0176] 2) Based on the frequency difference setting value allowable range provided in the synchronization device instruction manual, obtain the maximum frequency difference setting value Δf allowed by the synchronization device mSet ;

[0177] 3) Construct the calculation function and constraints for the shortest grid connection duration;

[0178] 4) According to the Δf in step 2) mSet, and step 3) determining the shortest grid connection time calculation function and constraint conditions, setting the frequency difference setting value Δf of the synchronous device Set and phase angle difference setting value ΔA Set .

[0179] Furthermore, step 3) of constructing the shortest grid connection duration calculation function and constraint conditions includes:

[0180] if Then Δf Set The value range is At this time, the calculation function of the shortest grid-connected duration is:

[0181]

[0182] The constraints are:

[0183]

[0184]

[0185] Where, T min1 express The shortest grid connection time calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value.

[0186] Furthermore, the frequency difference setting value Δf of the synchronization device is set in step 4). Set and phase angle difference setting value ΔA Set ,include:

[0187] if Then take

[0188] Furthermore, step 3) of constructing the shortest grid connection duration objective function and constraint conditions includes:

[0189] if Then Δf Set The value range is At this time, the calculation function of the shortest grid-connected duration is:

[0190]

[0191] The constraints are:

[0192]

[0193]

[0194] Where, T min2 express The shortest grid connection time calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value.

[0195] Furthermore, the frequency difference setting value Δf of the synchronization device is set in step 4). Set and phase angle difference setting value ΔA Set ,include:

[0196] if Then Δf Set =Δf mSet ,

[0197] Example 5 Grid-connected parameter setting system

[0198] A large-capacity phase-converter synchronous grid-connected parameter setting system, comprising:

[0199] The acquisition module collects the phase shifter synchronous grid-connected slip rate δ and the synchronous relay closing action delay time T dq The maximum frequency difference allowed by the synchronous device is Δf mSet ;

[0200] Modeling module, building the shortest grid connection time calculation function and constraint conditions;

[0201] Parameter setting module, set the frequency difference setting value Δf of the synchronization device Set and phase angle difference setting value ΔA Set .

[0202] Furthermore, the modeling module constructs a calculation function and constraint conditions for the shortest grid connection time, including:

[0203] if Then Δf Se The value range is The calculation function of the shortest grid connection duration is:

[0204]

[0205] The constraints are:

[0206]

[0207]

[0208] if Then Δf Set The value range is The calculation function of the shortest grid connection duration is:

[0209]

[0210] The constraints are:

[0211]

[0212]

[0213] Where, T min1 、T min2 Respectively expressed in The shortest grid connection time calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value.

[0214] Furthermore, the parameter setting module sets the frequency difference setting value Δf of the synchronization device. Set and phase angle difference setting value ΔA Set ,include:

[0215] if Then take

[0216] if So

[0217] Example 7 Simulation Verification

[0218] Set the phase shifter slip rate to δ = 0.125Hz / s, and the system action delay is T dq =0.1s, the maximum frequency difference setting value Δf allowed by the synchronization device mSet is 0.6Hz. According to the tuning process, its parameters are set as:

[0219] because Frequency difference setting value

[0220] Get the phase angle difference setting value Where k = 2, which means that the grid-connected time is twice the system delay;

[0221] The initial phase angle difference corresponding to the shortest grid-connected time is

[0222]

[0223] Because the initial phase difference range is defined within 0-360°, when the initial phase angle difference is ΔA * =-17.55+360=342.45° when the grid connection time is the shortest.

[0224] The simulation results are as follows Figure 1 and Figure 2 By setting the grid-connected parameter Δf of the phase-converter system Set , ΔA Set , the total grid connection time corresponding to different initial phase angle differences can be obtained, such as Figure 1 As shown, the shortest duration occurs when ΔA0=342.45°, according to ΔA Set =17.55°, Δf Set =0.5Hz,δ=0.125Hz / s, we can see that at this time And ΔA0-ΔA Set > 0, the total grid-connected time can be calculated by formula (25), that is, the total grid-connected time is 0.4s, that is, Figure 1 The position indicated by the arrow is the same as the theoretical calculation result, which verifies the correctness of the theoretical calculation. The grid connection situation corresponding to ΔA0=342.45° is as follows Figure 2 As shown, by ΔA Set , Δf Set ,δ, It can be seen that the calculation of the starting and ending points of the grid connection time is based on formula (20). Therefore, at t = 0, the machine-grid frequency difference has reached the upper limit of the frequency difference setting value. At this time, the machine-grid phase angle difference also meets the grid connection conditions. Therefore, the grid connection starting point starts from t = 0 and at t = T2 (1, ΔA * )=0.2s later, although the frequency difference still meets the grid connection conditions, the phase angle difference no longer meets the grid connection conditions, so the grid connection period is [0, 0.2]s; as time goes by, t=T3(1, ΔA * )=7.8s, the system meets the grid connection conditions again until However, the frequency difference between the generator and the grid no longer meets the grid connection requirements. The grid connection period is now [7.8, 8] seconds. In summary, in this case, there are two possible grid connection periods, each lasting 0.2 seconds, or twice the delay. The simulation results validate the theoretical calculations and the effectiveness of the parameter tuning process.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for setting parameters of large-capacity phase-converter synchronous grid connection, characterized in that: The following steps are involved: 1) Collect the slip rate δ of the synchronous phase-converter grid connection and the delay time T of the synchronous relay closing action dq ; 2) Obtain the maximum frequency difference setting value Δf allowed by the synchronization device mSet ; 3) Construct the shortest grid connection duration calculation function and constraint conditions; 4) According to the Δf in step 2) mSet , and the shortest grid connection time calculation function and constraint conditions determined in step 3), set the frequency difference setting value Δf of the synchronous device Set and phase angle difference setting value ΔA Set ; Step 3) of constructing the shortest grid connection duration calculation function and constraint conditions includes: if Then Δf Set The value range is The calculation function of the shortest grid connection duration is: The constraints are: if Then Δf Set The value range is The calculation function of the shortest grid connection duration is: The constraints are: Where, T min1 、T min2 Respectively expressed in The shortest grid connection duration calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value; Step 4) Set the frequency difference setting value Δf of the synchronization device Set and phase angle difference setting value ΔA Set ,include: if Then take if Then Δf Set =Δf mSet , 2. A large-capacity phase-converter synchronous grid-connected parameter setting system, characterized in that: include: The acquisition module collects the phase shifter synchronous grid-connected slip rate δ and the synchronous relay closing action delay time T dq The maximum frequency difference setting value Δf allowed by the synchronization device mSet ; Modeling module, building the shortest grid connection time calculation function and constraint conditions; Parameter setting module, set the frequency difference setting value Δf of the synchronization device Set and phase angle difference setting value ΔA Set ; The modeling module constructs the shortest grid connection time calculation function and constraint conditions, including: if Then Δf Set The value range is The calculation function of the shortest grid connection duration is: The constraints are: if Then Δf Set The value range is The calculation function of the shortest grid connection duration is: The constraints are: Where, T min1 、T min2 Respectively expressed in The shortest grid connection duration calculation function under the situation, T dq Indicates the delay time of closing action of synchronous relay, k indicates the delay time of closing action of T dq The magnification factor, δ represents the slip rate, Δf Set Indicates the frequency difference setting value, ΔA Set Indicates the phase angle difference setting value; The parameter setting module sets the frequency difference setting value Δf of the synchronization device Set and phase angle difference setting value ΔA Set ,include: if Then take if Then Δf Set =Δf mSet ,

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