Sagoe new energy base based on amplitude and phase coefficient of longitudinal protection method of gathering system

Abstract

The application discloses a kind of based on amplitude-phase coefficient's Shaguo Huang new energy base collection system longitudinal protection method, comprising the following steps: based on Shaguo Huang new energy base collection system, in first sampling window, obtain the setting current of new energy side of collection line and the setting current of high-voltage direct-current side of collection line to obtain amplitude-phase coefficient setting value, in second sampling window, obtain the current of new energy side of collection line and the current of high-voltage direct-current side of collection line to calculate amplitude-phase coefficient;According to amplitude-phase coefficient and amplitude-phase coefficient setting value, obtain the longitudinal protection criterion of collection system;According to longitudinal protection criterion, identify the fault type of Shaguo Huang new energy base collection system;According to fault type, enable protection measure.The amplitude-phase coefficient based on the longitudinal protection method of Shaguo Huang new energy base collection system provided by the application is reliable in fault identification, full-line quick action when fault occurs, strong in transition resistance and noise resistance, and wide in application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy power grid connection protection, in particular to a longitudinal protection method for Shagehuang new energy base collection system based on amplitude-phase coefficient. BACKGROUND

[0002] The existing Shagehuang new energy base sending-out system mainly adopts the grid connection mode of alternating current collection and extra-high voltage direct current sending-out. In the alternating current collection outgoing line of new energy unit connected to the power grid line commutated converter (LCC), both sides are power electronic power sources, so the fault characteristics have fundamentally changed, resulting in the decrease of the sensitivity of traditional differential protection, and even the refusal to act, so it is urgent to study a new protection principle suitable for the Shagehuang new energy base collection system.

[0003] At present, there are many research results on the new protection principle of time-domain short-circuit current waveform similarity of sending-out line, but the reliability of this kind of protection in the Shagehuang new energy base collection system has not been determined. The measurement of waveform similarity mainly includes similarity measurement method and distance measurement method. The commonly used similarity measurement methods at present mainly include Pearson correlation coefficient and cosine similarity. However, the above two protection principles cannot distinguish faults in the scene of weak power output on the new energy side or coinciding with permanent faults. The commonly used distance measurement methods at present mainly include Canberra distance and improved Euclidean distance. However, when high resistance faults occur, the short-circuit current waveforms on both sides are very close, and the distance measurement method will refuse to act. At the same time, the improved Euclidean distance needs to be re-set in different systems, which has a certain degree of difficulty. In summary, it is urgent to study a new protection principle suitable for the Shagehuang new energy base collection system. SUMMARY

[0004] In order to solve the problems in the prior art, the present application provides a longitudinal protection method for Shagehuang new energy base collection system based on amplitude-phase coefficient, which has reliable fault identification, fast action when faults occur, strong noise resistance and wide application range.

[0005] In order to achieve the above-mentioned purpose, the present application provides a longitudinal protection method for Shagehuang new energy base collection system based on amplitude-phase coefficient, which includes the following steps:

[0006] Based on the Shagehuang new energy base collection system, the set current of the new energy side of the collection line and the set current of the high-voltage direct current side of the collection line are obtained in a first sampling window at a first sampling frequency, and the current of the new energy side of the collection line and the current of the high-voltage direct current side of the collection line are obtained in a second sampling window at a second sampling frequency. The time length of the first sampling window is the same as that of the second sampling window, and the first sampling frequency is the same as the second sampling frequency.

[0007] According to the new energy side setting current of the collection line and the high voltage direct current side setting current of the collection line, the amplitude and phase coefficient setting value of the Shagexuan new energy base collection system is obtained.

[0008] According to the new energy side current of the collection line and the high voltage direct current side current of the collection line, the amplitude and phase coefficient is calculated; the amplitude and phase coefficient is:

[0009]

[0010] In the formula, F φ is the amplitude and phase coefficient of φ phase, φ is the phase in three-phase electricity, φ respectively takes A phase, B phase and C phase in three-phase electricity, x φk is the kth current sampling value of φ phase on the new energy side of the collection line, y φk is the kth current sampling value of φ phase on the high voltage direct current side of the collection line, and k is the sampling point serial number in the second sampling window, and n is the total number of sampling points in the second sampling window.

[0011] According to the amplitude and phase coefficient and the amplitude and phase coefficient setting value, the longitudinal protection criterion of the collection system is obtained.

[0012] According to the longitudinal protection criterion, the fault type of the Shagexuan new energy base collection system is identified.

[0013] According to the fault type, the protection measure is enabled.

[0014] Further, the longitudinal protection criterion of the collection system is:

[0015] F φ F φset ;

[0016] In the formula, F φset is the amplitude and phase coefficient setting value of φ phase.

[0017] Further, the step of obtaining the amplitude and phase coefficient setting value is:

[0018] The new energy side setting current of the collection line is obtained, and the high voltage direct current side setting current of the collection line is obtained.

[0019] The new energy side setting current of the collection line and the high voltage direct current side setting current of the collection line are substituted into formula one; the formula one is:

[0020] F φset =λF φ ' set , 0.88≤λ≤0.98;

[0021]

[0022] In the formula, F φset is the φ-phase amplitude-phase coefficient setting value, λ is the total margin coefficient, F φ set is the amplitude-phase coefficient value of the setting current, I 1φi is the φ-phase i-th setting current on the new energy side of the collection line, I 2φi is the φ-phase i-th setting current on the HVDC side of the collection line, i is the sampling point serial number in the first sampling window, and m is the total number of sampling points in the first sampling window.

[0023] The amplitude-phase coefficient setting value is obtained by solving the formula.

[0024] Further, the setting current on the new energy side of the collection line is:

[0025]

[0026] In the formula, I 1φ is the φ-phase setting current on the new energy side of the collection line, I m is the current amplitude, ω is the power frequency angular frequency, t is the sampling time, is the φ-phase current initial phase angle, and θ1 is the phase angle error.

[0027] Further, the setting current on the HVDC side of the collection line is:

[0028]

[0029] In the formula, I 2φ is the φ-phase setting current on the new energy side of the collection line, I m is the current amplitude, ω is the power frequency angular frequency, t is the sampling time, is the φ-phase current initial phase angle, and ε is the amplitude error.

[0030] Further, the phase angle error is in the range of -16°≤θ1≤16°.

[0031] Further, the amplitude error is in the range of ε≤10%.

[0032] Further, the duration of the first sampling window is 10ms-20ms.

[0033] Further, if the collection system pilot protection criterion is not established, it is determined that the φ-phase of the Shagehuang new energy base collection system is not faulty.

[0034] If the collection system pilot protection criterion is established, it is determined that the φ-phase of the Shagehuang new energy base collection system is faulty.

[0035] Further, the enabling of the protection measure includes:

[0036] ​If a single-phase fault occurs, the fault phase is disconnected, and the non-fault phase is normally operated.

[0037] If a two-phase or three-phase fault occurs, the three phases are disconnected.

[0038] The beneficial effects of the present application are:

[0039] 1. The present application can quickly and reliably identify faults when a fault occurs in the gathering line area, and can achieve full-line speed operation.

[0040] 2. The present application has strong resistance to transition resistance and noise.

[0041] 3. The present application is not affected by the capacity and operation mode of the new energy station, and can still reliably identify faults when the new energy station has weak output or coincides with permanent faults. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The flowchart of the present application is shown in the figure.

[0043] Figure 2 The topology diagram of the Shaguo Huang new energy base gathering system of the present application is shown in the figure.

[0044] Figure 3 The amplitude and phase coefficient calculation value diagram of the setting current considering 16° phase angle error and 10% amplitude error of the present application is shown in the figure.

[0045] Figure 4 The amplitude and phase coefficient diagram when different faults occur at the midpoint of the gathering line in the embodiment of the present application is shown in the figure: (a) is a single-phase short-circuit ground fault, (b) is a two-phase interphase short-circuit fault, (c) is a two-phase short-circuit ground fault, and (d) is a three-phase short-circuit fault.

[0046] Figure 5 The action performance of different protection methods when A-phase high-resistance ground fault occurs at the midpoint K3 of the gathering line: (a) is the cosine similarity protection method, (b) is the Canberra distance protection method, (c) is the improved Euclidean distance protection method, and (d) is the amplitude and phase coefficient-based Shaguo Huang new energy base gathering system pilot protection method. DETAILED DESCRIPTION

[0047] To clearly illustrate the technical features of the present scheme, the present scheme will be described below through specific embodiments.

[0048] For the Shaguo Huang new energy base gathering system, the fault characteristics of new energy power supply and high-voltage direct-current transmission are analyzed.

[0049] The new energy power supply fault current analytical expression is:

[0050]

[0051]

[0052]

[0053] where i φ is the fault current provided by the φ-phase new energy power supply, is the reference value of the d-axis current, is the reference value of the q-axis current, is the initial phase angle of the φ-phase current, ω is the PLL angular frequency, and ω d is the damping oscillation frequency, ω n is the natural oscillation angular frequency, ξ is the damping ratio, and i d0 is the d-axis current reference value before the fault, and β is the damping angle;

[0054] According to the fault current analytical expression of the new energy power supply, considering the response time of the phase-locked loop, the short-circuit current frequency may deviate from the power frequency, and the fault current of the new energy power supply presents the fault characteristics of amplitude limitation and frequency deviation, which is limited by the current resistance of the converter;

[0055] The current analytical expression of the HVDC power feeding into the AC system is:

[0056] I rec = (k D A Di +k Y A Ym )∫U nr dt+(k D B Di +k Y B Ym )i d ;

[0057] where I rec is the current feeding into the AC system, k D is the transformation ratio of the D-bridge converter transformer, k Y is the transformation ratio of the Y-bridge converter transformer, A Di , A Ym , B Di , and B Ym are the conduction coefficients of the converter bridge arms, U nr is the three-phase voltage of the converter bus, and i d is the DC current;

[0058] From the current analytical expression of the DC feeder into the AC system, it can be known that, when a fault occurs, if the commutation failure of the converter valve is not considered, due to the low-voltage current limiting control strategy, the fault current provided by the high-voltage direct current (HVDC) converter presents the frequency fault characteristic with limited amplitude. If the commutation failure occurs, the equivalent frequency current characteristic of the HVDC feeder is distorted, and the fault current of the HVDC presents the fault characteristic with limited amplitude and serious distortion;

[0059] From the above analysis, it can be known that there is a difference between the fault current waveform at the new energy side of the collection line and the fault current waveform at the HVDC side of the collection line: the fault current at the new energy side of the collection line presents the fault characteristic with limited amplitude and frequency deviation, while the fault current at the HVDC side of the collection line presents the frequency fault characteristic with limited amplitude or the fault characteristic with limited amplitude and serious distortion.

[0060] If the differential protection is used, the risk of refusal to act may occur. Specifically:

[0061] The protection action criterion of the differential protection is:

[0062]

[0063] In the formula, is the differential current, is the braking current, wherein is the current at the installation place of the new energy side protection of the collection line, is the current at the installation place of the HVDC side protection of the collection line, and the same phase, K rel is the ratio braking coefficient, and a typical value is 0.5-0.8, I op0 is the starting value;

[0064] Supposing that the current amplitude ratio k of the collection line is the current amplitude of the HVDC side of the collection line / the current amplitude of the new energy side of the collection line, and the absolute value of the phase angle difference of the collection line is θ, the differential current and the braking current are obtained and substituted into the protection action criterion of the differential protection, the action boundary of the differential protection can be obtained as:

[0065]

[0066] The ratio braking coefficient K rel is 0.8. From the differential protection action boundary, it can be known that when the current phase angle difference of the two sides is less than 102.7°, the differential protection can reliably act, and when the current phase angle difference of the two sides exceeds 102.7°, the ratio of the differential current to the braking current may be less than the ratio braking coefficient, at this time, the differential protection faces the risk of refusal to act. For example:

[0067] For three-phase short-circuit fault, when three-phase short-circuit fault occurs in the collection line, the fault sequence network diagram can be decoupled into two sub-networks. Since the three-phase short-circuit fault occurs, only the positive sequence current is provided on both sides of the collection line, i.e. the HVDC side of the collection line and the new energy side of the collection line, and under the condition of not considering the phase-locked loop error, the fault current on both sides of the collection line tends to be in phase, so the phase angle difference will not exceed 102.7° when the three-phase short-circuit fault occurs, and the differential protection can reliably act.

[0068] For asymmetric ground fault, when asymmetric short-circuit ground fault occurs, since the fault current amplitude of the new energy side of the collection line is limited, the fault current is mainly in the zero sequence current, and the zero sequence currents on both sides of the collection line are in phase, thereby reducing the phase angle difference of the fault phase current on both sides of the collection line. Without considering high-resistance faults, the phase angle difference of the fault phase current on both sides of the collection line will not exceed 102.7° when the asymmetric short-circuit ground fault occurs, and the differential protection will not refuse to act.

[0069] For two-phase inter-phase short-circuit fault, since the converter on the new energy side of the collection line adopts a control strategy to suppress the negative sequence current, only the negative sequence path is provided by the HVDC side of the collection line after the fault occurs. Taking the BC phase inter-phase short-circuit fault as an example, the currents on both sides of the collection line are expressed using sequence components, and are converted into using the positive and negative sequence currents on the HVDC side of the collection line, which can be expressed as:

[0070]

[0071]

[0072]

[0073] In the formula, is the A-phase current on the new energy side of the collection line, is the A-phase current on the HVDC side of the collection line, is the positive sequence current on the HVDC side of the collection line, is the negative sequence current on the HVDC side of the collection line, is the B-phase current on the new energy side of the collection line, and j is the imaginary unit, is the B-phase current on the HVDC side of the collection line, is the C-phase current on the new energy side of the collection line, is the C-phase current on the HVDC side of the collection line.

[0074] Since the positive and negative sequence equivalent impedances on the HVDC side of the collection line are equal, the positive and negative sequence current amplitudes on the system side are almost equal when two-phase inter-phase fault occurs. Since and Therefore and The phase angle difference of B phase is almost equal to 60°, and the phase angle difference of C phase is almost equal to 120°. According to the action boundary of differential protection, when the phase-to-phase short circuit fault occurs, the B-phase differential protection can reliably act, and the C-phase differential protection may refuse to act.

[0075] Referring to Figure 1 The application provides a longitudinal protection method for a Shagehuang new energy base collection system based on amplitude-phase coefficients, and comprises the following steps:

[0076] Based on the Shagehuang new energy base collection system, the set current of the new energy side of the collection line and the set current of the high-voltage direct current side of the collection line are obtained in a first sampling window at a first sampling frequency, and the current of the new energy side of the collection line and the current of the high-voltage direct current side of the collection line are obtained in a second sampling window at a second sampling frequency; the time length of the first sampling window is the same as that of the second sampling window, and the first sampling frequency is the same as the second sampling frequency; preferably, the time length of the first sampling window and the time length of the second sampling window are respectively 10ms-20ms, and the first sampling frequency and the second sampling frequency are both 1kHz.

[0077] The amplitude-phase coefficient set value of the Shagehuang new energy base collection system is obtained according to the set current of the new energy side of the collection line and the set current of the high-voltage direct current side of the collection line.

[0078] The amplitude-phase coefficient is calculated according to the current of the new energy side of the collection line and the current of the high-voltage direct current side of the collection line; the amplitude-phase coefficient is:

[0079]

[0080] In the formula, F φ is the amplitude-phase coefficient of φ phase, φ is a phase in three-phase electricity, φ respectively takes A phase, B phase and C phase in three-phase electricity, x φk is the kth current sampling value of the new energy side of the collection line, y φk is the kth current sampling value of the high-voltage direct current side of the collection line, k is the sampling point serial number in the second sampling window, and n is the total number of sampling points in the second sampling window.

[0081] The amplitude-phase coefficient set value is obtained.

[0082] The collection system longitudinal protection criterion is obtained according to the amplitude-phase coefficient and the amplitude-phase coefficient set value.

[0083] The fault type of the Shagehuang new energy base collection system is identified according to the longitudinal protection criterion.

[0084] The protection measures are enabled according to the fault type.

[0085] When the zone fault occurs in the aggregation line, the short-circuit current waveforms on both sides of the aggregation line are quite different, and the amplitude-phase coefficient is far less than 1; when the normal operation or the zone fault occurs, the short-circuit current waveforms on both sides of the aggregation line are opposite, and the current waveforms on both sides of the aggregation line are basically consistent after the anti-phase processing, and the amplitude-phase coefficient is close to 1; when the weak power output occurs on the new energy side of the aggregation line, the current sampling value on the new energy side of the aggregation line is 0, and the amplitude-phase coefficient is 0.

[0086] Therefore, the amplitude-phase coefficient can reliably identify the zone fault and is suitable for the scenario of weak power output on the new energy side of the aggregation line.

[0087] The longitudinal protection criterion of the aggregation system is:

[0088] F φ <F φset ;

[0089] In the formula, F φset is the φ-phase amplitude-phase coefficient setting value.

[0090] The steps of obtaining the amplitude-phase coefficient setting value are:

[0091] Obtaining the new energy side setting current of the aggregation line and obtaining the high-voltage direct current side setting current of the aggregation line;

[0092] Substituting the new energy side setting current of the aggregation line and the high-voltage direct current side setting current of the aggregation line into formula one; formula one is:

[0093] F φset =λF φ ' set , 0.88≤λ≤0.98;

[0094]

[0095] In the formula, F φset is the φ-phase amplitude-phase coefficient setting value, λ is a total margin coefficient, F φ ' set is the amplitude-phase coefficient value of the setting current, I 1φi is the φ-phase i-th setting current on the new energy side of the aggregation line, I 2φi is the φ-phase i-th setting current on the high-voltage direct current side of the aggregation line, i is the sampling point serial number in the first sampling window, and m is the total number of sampling points in the first sampling window; since the time length of the first sampling window is the same as the time length of the second sampling window and the first sampling frequency is the same as the second sampling frequency, m=n;

[0096] The amplitude-phase coefficient setting value is obtained by solving formula one.

[0097] The new energy side setting current of the aggregation line is:

[0098]

[0099] The setting current of the high-voltage DC side of the gathering line is:

[0100]

[0101] In the formula, I 1φ is the φ-phase setting current of the new energy side of the gathering line, I 2φ is the φ-phase setting current of the new energy side of the gathering line, I m is the current amplitude, ω is the power frequency angular frequency, and t is the sampling time, is the initial phase angle of the φ-phase current, θ1 is the phase angle error, and ε is the amplitude error.

[0102] Data synchronization and CT transformation may cause errors in the amplitude and phase coefficients during normal operation or external fault. Therefore, the amplitude error ε and the phase angle error θ1 need to be considered when setting the protection value. Preferably, the value range of the phase angle error is -16°≤θ1≤16°, and the value range of the amplitude error is ε≤10%.

[0103] Preferably, the phase angle error θ1 is 16°, the amplitude error ε is 10%, the time length of the first sampling window is 10 ms, and the amplitude and phase coefficient value F φ ' set is 0.917384. Considering a margin of 0.95, while considering that other factors may affect the calculation of the amplitude and phase coefficient, a certain margin is also left, so the total margin coefficient λ is 0.92-0.93, and the amplitude and phase coefficient setting value F φset is 0.85, that is, the criterion of the longitudinal protection of the gathering system is:

[0104] F φ <0.85;

[0105] By comparing the size between the calculated values of the amplitude and phase coefficients of each phase on both sides of the gathering line and the amplitude and phase coefficient setting value, the fault type is identified and the corresponding protection measures are enabled, as follows:

[0106] If the criterion of the longitudinal protection of the gathering system is not established, it is determined that the φ-phase of the Shagehuang new energy base gathering system is not faulty;

[0107] If the criterion of the longitudinal protection of the gathering system is established, it is determined that the φ-phase of the Shagehuang new energy base gathering system is faulty.

[0108] The protection measures include:

[0109] If a single-phase fault occurs, the faulty phase is disconnected, and the non-faulty phase is normally operated;

[0110] If a two-phase or three-phase fault occurs, the three phases are disconnected.

[0111] Figure 2 The topology diagram of the Shagehuang new energy base collection system is shown in the figure. The new energy stations in the figure are photovoltaic stations and permanent magnet wind power stations. Taking the permanent magnet wind power station as an example, the capacities are set to 400 MW, 500 MW and 500 MW respectively, the voltage level of the collection line is 220 kV, the line length is 40 km, the positive and negative sequence impedances are both (0.075+j0.335) Ω / km, and the zero sequence impedance is (0.285+j0.825) Ω / km. The rated capacity of the main transformer is 500 MVA, the transformer ratio is 220 kV / 35 kV, and the short-circuit impedance is 6%. According to the topology structure in the and the above parameters, the Shagehuang new energy base collection system model is built in the real-time digital simulator (RTDS) and the general protection platform to verify the effect of the protection method proposed in the application. Figure 2

[0112] The fault line is set to be a 500 MW permanent magnet wind farm 220 kV collection line, and five fault points are set, which are the external outlet of the new energy side of the collection line, the 10 km, 20 km and 30 km from the new energy side of the collection line in the area, and the external outlet of the high voltage direct current side of the collection line, which are respectively denoted as K1, K2, K3, K4 and K5. The fault types are set to be A-phase short circuit to ground, BC two-phase interphase short circuit, BC two-phase short circuit to ground and ABC three-phase short circuit, which are respectively denoted as AG, BC, BCG and ABC.

[0113] Figure 3 The amplitude-phase coefficient calculation value graph of the setting current considering the 16° phase angle error and the 10% amplitude error can be seen. The maximum value and the minimum value of the calculated setting current amplitude-phase coefficient differ by only 10 -15 , which indicates that the value of the amplitude-phase coefficient of the setting current is not affected by the calculation initial time and the initial phase angle, and has strong reliability. The amplitude-phase coefficient of the setting current at this time is selected to obtain the amplitude-phase coefficient setting value and realize protection.

[0114] Figure 4 The amplitude-phase coefficient schematic diagram when the midpoint of the collection line fails is shown in the figure. As can be seen from the figure, when the area fault occurs in the collection line, the amplitude-phase coefficient calculation value of the fault phase is less than the protection setting value 0.85 within 5 ms, the protection reliably acts, and the non-fault amplitude-phase coefficient calculation value is always higher than the protection setting value, and the protection reliably does not act.

[0115] To verify the performance of the Shagehuang new energy base collection system pilot protection method based on the amplitude-phase coefficient, a hardware-in-the-loop dynamic simulation experiment platform is constructed. According to the actual topology structure and parameters of the Kubqi large base station, the Figure 2 ​The shown sagoe new energy base collection system. In verifying the performance of the protection, a permanent magnet wind power station is taken as an example, the capacity is set to 400MW, 500MW, 500MW respectively, the voltage level of the collection line is 220kV, and the length of the line is 40km. In Figure 2 The simulation experiments of different fault positions in different fault types in the hardware-in-the-loop simulation experiment platform are carried out, and tables 1-4 give all simulation results. Table 1 gives the action performance of the proposed protection under different fault scenarios, wherein all coefficients are amplitude-phase coefficient calculation values; table 2 is the calculation value of the amplitude-phase coefficient under different transition resistances; table 3 is the calculation value of the amplitude-phase coefficient under different noise scenarios; and table 4 is the calculation value of the amplitude-phase coefficient under different capacity new energy stations.

[0116] Table 1 Action performance of simulation experiment under different fault scenarios

[0117]

[0118]

[0119] Table 2 Calculation value of amplitude-phase coefficient under different transition resistances

[0120]

[0121] Table 3 Calculation value of amplitude-phase coefficient under different noise scenarios

[0122]

[0123]

[0124] Table 4 Calculation value of amplitude-phase coefficient under different capacity new energy stations

[0125]

[0126] The simulation results show that the protection proposed in the application can reliably identify various intra-zone and external faults, and under various fault scenarios, when intra-zone fault occurs, the fault phase amplitude-phase coefficient is less than the protection setting value, and the protection can reliably act. Under different transition resistance scenarios, different noise scenarios and different station capacities, the proposed protection can reliably identify faults.

[0127] In order to further verify the action performance of the protection principle proposed in the application, the protection method proposed in the application is compared with the longitudinal protection principle based on cosine similarity protection method, Canberra distance protection method and improved Euclidean distance protection method. Among them Figure 5 The action performance of the above three similarity methods and the proposed protection when A-phase high resistance ground fault occurs at the midpoint K3 of the collection line is given.

[0128] Depend on Figure 5 It can be seen that when a high-resistance fault occurs, the fault phase current amplitudes on both sides of the line are relatively small, and the phase angle difference is close to 180°. All three similarity measurement methods fail to operate, while the proposed protection principle can still reliably identify the fault in the event of a high-resistance fault and has high sensitivity. Simulation results verify that the proposed protection has a strong ability to withstand high-resistance faults compared to other similarity measurement methods.

[0129] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0130] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0131] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficients, characterized in that: The following steps are involved: Based on the Shagohuang new energy base collection system, within a first sampling window, a set current on the new energy side of the collection line and a set current on the high-voltage direct current side of the collection line are obtained at a first sampling frequency; within a second sampling window, a current on the new energy side of the collection line and a current on the high-voltage direct current side of the collection line are obtained at a second sampling frequency; the duration of the first sampling window is the same as the duration of the second sampling window, and the first sampling frequency is the same as the second sampling frequency; Obtaining the amplitude and phase coefficient setting value of the Shagohuang New Energy Base collection system according to the new energy side setting current of the collection line and the high voltage DC side setting current of the collection line; The amplitude-phase coefficient is calculated based on the current on the new energy side of the collection line and the current on the high-voltage DC side of the collection line; the amplitude-phase coefficient is: ； Where, for Phase-amplitude coefficient, is the phase in three-phase electricity, Take the three-phase electricity A Mutually, B Mutually, C Mutually, To gather the new energy side of the line Xiangdi Current sampling value, To collect the high voltage DC side of the line Xiangdi The current sampling value is inverted. is the sampling point number in the second sampling window, is the total number of sampling points in the second sampling window; Obtaining a criterion for longitudinal protection of the collection system according to the amplitude-phase coefficient and the amplitude-phase coefficient setting value; Identify the fault type of the Shagohuang new energy base collection system according to the longitudinal protection criterion; Activate protection measures according to the fault type; The longitudinal protection criterion of the collection system is: ； Where, for Phase-amplitude coefficient setting value; The steps for obtaining the amplitude and phase coefficient setting values ​​are as follows: Substitute the set current on the new energy side of the collection line and the set current on the high-voltage DC side of the collection line into Formula 1; Formula 1 is: ， ； ； Where, for Phase-amplitude coefficient setting value, is the total margin coefficient, is the amplitude-phase coefficient value of the setting current, To gather the new energy side of the line Xiangdi A set current, To collect the high voltage DC side of the line Xiangdi A set current, is the sampling point number in the first sampling window, is the total number of sampling points in the first sampling window; Solving the formula 1 to obtain the amplitude-phase coefficient setting value; If the longitudinal protection criterion of the collection system is not established, it is determined that the collection system of the Shagohuang New Energy Base No phase fault; If the longitudinal protection criterion of the collection system is established, it is determined that the collection system of the Shagohuang New Energy Base Phase failure.

2. The longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficient according to claim 1 is characterized in that: The set current on the new energy side of the collection line is: ； Where, To gather the new energy side of the line Phase setting current, is the current amplitude, is the power frequency angular frequency, is the sampling time, for Phase current initial phase angle, is the phase angle error.

3. The longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficient according to claim 1 is characterized in that: The set current on the high-voltage DC side of the collection line is: ； Where, To gather the new energy side of the line Phase setting current, is the current amplitude, is the power frequency angular frequency, is the sampling time, for Phase current initial phase angle, is the amplitude error.

4. The longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficient according to claim 2 is characterized in that: The phase angle error range is: -16°≤ ≤16°.

5. The longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficient according to claim 3 is characterized in that: The amplitude error range is: ≤10%.

6. The longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficient according to claim 1 is characterized in that: The duration of the first sampling window is 10ms 20ms.

7. The longitudinal protection method for the Shagohuang new energy base collection system based on amplitude and phase coefficients according to any one of claims 1 to 6, characterized in that: The enabling protection measures include: If a single-phase fault occurs, the faulty phase will be disconnected and the non-faulty phase will operate normally; If a two-phase or three-phase fault occurs, the three phases are disconnected.

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