Multi-harmonic injection flexible DC high-speed frequency scanning method and system

Abstract

The invention discloses a multi-harmonic injection flexible DC high-speed frequency scanning method. The method comprises the following steps: acquiring data information of a target power system; determining all frequencies to be scanned; grouping all frequencies; for the plurality of groups of grouped scanning frequencies, harmonic currents corresponding to the plurality of scanning frequencies are injected during one-time scanning of a disturbance injection point; measuring voltage signals of different frequencies at the disturbance injection point after the target power system is stabilized; calculating the impedance amplitude and phase under the corresponding frequency, and completing the current frequency scanning; and repeating the steps until all the to-be-scanned frequencies are scanned, thereby completing final high-speed frequency scanning. The invention also discloses a system for realizing the multi-harmonic injection flexible direct-current high-speed frequency scanning method. According to the invention, harmonic waves of multiple frequencies can be injected in one scanning process of frequency scanning, so that not only can frequency scanning be completed, but also the efficiency is higher on the basis of ensuring high reliability and accuracy.

Description

Technical Field

[0001] The invention belongs to the field of electrical automation, and in particular relates to a flexible direct current high-speed frequency scanning method and system with multi-harmonic injection. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring the stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] At present, as environmental problems become more and more serious, more and more new energy stations are being integrated into the power system and generating electricity. Before the new energy station is integrated into the power system, it is necessary to evaluate whether the new energy station can operate stably. At present, the commonly used evaluation scheme uses the frequency scanning method for evaluation. The frequency scanning method is to inject a specified harmonic current with a frequency that changes sequentially from the node to be studied, and calculate the harmonic voltage of the corresponding frequency at the node, so as to obtain the harmonic impedance of the system to be scanned, and finally obtain a set of amplitude and phase characteristic curves (amplitude-frequency / phase-frequency characteristic curves) that change according to the frequency change. The frequency scanning method can preliminarily determine the operating conditions under which subsynchronous oscillations may occur in the system.

[0004] However, the existing frequency scanning method can only inject one frequency harmonic in each measurement cycle. For complex systems or large-scale frequency scanning, hundreds of harmonics of specified frequencies need to be injected in sequence, which leads to a sharp increase in simulation time. For example, in a regional power grid, there are nearly 10,000 three-phase nodes that need to be fully electromagnetic transient simulated; in this case, the harmonic impedance scanning time of the existing frequency scanning method is even calculated in weeks; this situation greatly limits the application of the frequency scanning method. Summary of the invention

[0005] One of the purposes of the present invention is to provide a flexible direct current high-speed frequency scanning method with multi-harmonic injection having high reliability, good accuracy and higher efficiency.

[0006] A second object of the present invention is to provide a system for implementing the flexible direct current high-speed frequency scanning method for multi-harmonic injection.

[0007] The flexible direct current high-speed frequency scanning method with multi-harmonic injection provided by the present invention comprises the following steps:

[0008] S1. Obtain data information of the target power system;

[0009] S2. Determine all frequencies to be scanned according to the data information obtained in step S1;

[0010] S3. Group all frequencies to be scanned according to the set rules;

[0011] S4. For the grouped scanning frequencies, the harmonic currents corresponding to the scanning frequencies are injected into the disturbance injection point once during scanning;

[0012] S5. After the target power system is stabilized, measuring voltage signals of different frequencies at the disturbance injection point;

[0013] S6. According to the voltage signal obtained in step S5, the impedance amplitude and phase at the corresponding frequency are calculated to complete the current frequency scan;

[0014] S7. Repeat steps S4 to S6 until all frequencies to be scanned are scanned, completing the final high-speed frequency scan.

[0015] Step S3, grouping all frequencies to be scanned according to a set rule, specifically includes the following steps:

[0016] Group all frequencies to be scanned according to the rule of small to large;

[0017] There are n groups in total, each group includes m frequencies, expressed as {f 11 ,f 12 ,...,f 1m}、{f 21 ,f 22 ,...,f 2m}、…、{f i1 ,f i2 ,...,f im}、…、{f n1 ,f n2 ,...,f nm}; where f ij Indicates the jth frequency to be scanned in the i-th group.

[0018] The step S4 of injecting harmonic currents corresponding to the plurality of scanning frequencies at a disturbance injection point during one scanning for the plurality of grouped scanning frequencies specifically includes the following steps:

[0019] For the kth scan, the value of k ranges from 1 to m:

[0020] The harmonic current source is set to be the sum of the fundamental current at the disturbance injection point and the harmonic current of the kth frequency to be scanned in each group, expressed as

[0021] I k =I0sin(ω0t+θ0)+I 1k sin(ω 1k t+θ 1k )+I2k sin(ω 2k t+θ 2k )+…+I nk sin(ω nk t+θ nk )

[0022] =I0sin(2πf0t+θ0)+I 1k sin(2πf 1k t+θ 1k )+I 2k sin(2πf 2k t+θ 2k )+…I nk sin(2πf nk t+θ nk ) where I k is the harmonic current injected during the kth scan; I0 is the fundamental current amplitude at the disturbance injection point; ω0 is the fundamental angular frequency; θ0 is the fundamental current phase at the disturbance injection point; I nk is the disturbance amplitude corresponding to the kth frequency to be scanned in the nth group; ω nk is the angular frequency corresponding to the kth frequency to be scanned in the nth group; θ nk is the disturbance phase corresponding to the kth frequency to be scanned in the nth group; f0 is the fundamental frequency; f nk is the kth frequency to be scanned in the nth group;

[0023] In the kth scan, the harmonic current I is injected at the disturbance injection point k .

[0024] After the target power system is stabilized, the voltage signals of different frequencies are measured at the disturbance injection point in step S5, which specifically includes the following steps:

[0025] After the target power system is stable, the corresponding voltage signals V0 and V 1k 、V 2k , ..., V nk ; Where V0 is the fundamental voltage, V nk is the voltage corresponding to the kth frequency to be scanned in the nth group.

[0026] The calculation of the impedance amplitude and phase at the corresponding frequency described in step S6 specifically includes the following steps:

[0027] The impedance at each frequency is calculated using the following formula:

[0028]

[0029] Where Z nkis the impedance corresponding to the kth frequency to be scanned in the nth group; R nk is the resistance value of the impedance corresponding to the kth frequency to be scanned in the nth group; X nk is the reactance value in the impedance corresponding to the kth frequency to be scanned in the nth group;

[0030] According to the impedance at each frequency, the impedance amplitude and phase are calculated using the following formula:

[0031]

[0032] Where |Z nk | is the impedance amplitude corresponding to the kth frequency to be scanned in the nth group; is the phase corresponding to the kth frequency to be scanned in the nth group.

[0033] Step S7 repeats steps S4 to S6 until all frequencies to be scanned are scanned, which specifically includes the following steps:

[0034] Repeat steps S4 to S6 m times in total until all frequencies to be scanned are scanned.

[0035] The present invention also provides a system for implementing the flexible direct current high-speed frequency scanning method for multi-harmonic injection, comprising a data acquisition module, a frequency determination module, a frequency grouping module, a frequency injection module, a voltage measurement module, a frequency scanning module and a high-speed scanning module; the data acquisition module, the frequency determination module, the frequency grouping module, the frequency injection module, the voltage measurement module and the frequency scanning module are connected in series in sequence; the input end of the high-speed scanning module is connected to the output end of the frequency scanning module, and the output end of the high-speed scanning module is connected to the input end of the frequency injection module; the data acquisition module is used to acquire data information of the target power system and upload the data information to the frequency determination module; the frequency determination module is used to determine all frequencies to be scanned according to the received data information and the acquired data information, and upload the data information to the frequency grouping module; the frequency grouping module is used to group all frequencies to be scanned according to the received data information according to the set rules The data are grouped and the data information is uploaded to the frequency injection module; the frequency injection module is used to inject harmonic currents corresponding to several scanning frequencies when scanning the disturbance injection point once for several groups of scanning frequencies after grouping according to the received data information, and upload the data information to the voltage measurement module; the voltage measurement module is used to measure voltage signals of different frequencies at the disturbance injection point after the target power system is stable according to the received data information, and upload the data information to the frequency scanning module; the frequency scanning module is used to calculate the impedance amplitude and phase at the corresponding frequency according to the received data information and the obtained voltage signal, complete the current frequency scan, and upload the data information to the high-speed scanning module; the high-speed scanning module is used to control the frequency injection module, the voltage measurement module and the frequency scanning module to work repeatedly according to the received data information, until all frequencies to be scanned are scanned, and the final high-speed frequency scan is completed.

[0036] The flexible direct current high-speed frequency scanning method and system with multi-harmonic injection provided by the present invention can inject harmonics of multiple frequencies during one scanning process of frequency scanning. Therefore, the present invention can not only complete the frequency scanning, but also has higher efficiency while ensuring high reliability and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a schematic diagram of the method flow of the present invention.

[0038] Figure 2 A schematic diagram of the simulation duration of an embodiment of the method of the present invention using a non-accelerated frequency scanning algorithm.

[0039] Figure 3 A schematic diagram of the simulation duration of the method of the present invention is shown in FIG.

[0040] Figure 4 Schematic diagram of an RLC series circuit of an embodiment of the method of the present invention.

[0041] Figure 5 Schematic diagram of the amplitude-frequency characteristic curve of the system to be scanned in an embodiment of the method of the present invention.

[0042] Figure 6 Schematic diagram of the phase-frequency characteristic curve of the system to be scanned according to the method embodiment of the present invention.

[0043] Figure 7 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0044] like Figure 1 The method flow chart of the method of the present invention is shown as follows: the flexible direct current high-speed frequency scanning method with multi-harmonic injection disclosed in the present invention comprises the following steps:

[0045] S1. Obtain data information of the target power system;

[0046] S2. Determine all frequencies to be scanned according to the data information obtained in step S1;

[0047] S3. Group all frequencies to be scanned according to the set rules; specifically including the following steps:

[0048] Group all frequencies to be scanned according to the rule of small to large;

[0049] There are n groups in total, each group includes m frequencies, expressed as {f 11 ,f 12 ,...,f 1m}、{f 21 ,f 22 ,...,f 2m}, …, {f i1 ,f i2 ,...,f im}、…、{f n1 ,f n2 ,...,f nm}; where f ij represents the jth frequency to be scanned in the i-th group;

[0050] S4. For the grouped scanning frequencies, injecting harmonic currents corresponding to the scanning frequencies at the disturbance injection point during one scanning; specifically comprising the following steps:

[0051] For the kth scan, the value of k ranges from 1 to m:

[0052] The harmonic current source is set to be the sum of the fundamental current at the disturbance injection point and the harmonic current of the kth frequency to be scanned in each group, expressed as

[0053] I k =I0sin(ω0t+θ0)+I 1k sin(ω 1k t+θ 1k )+I 2k sin(ω 2k t+θ 2k )+…+I nk sin(ω nk t+θ nk )

[0054] =I0sin(2πf0t+θ0)+I 1k sin(2πf 1k t+θ 1k )+I 2k sin(2πf 2k t+θ 2k )+…I nk sin(2πf nk t+θ nk ) where I k is the harmonic current injected during the kth scan; I0 is the fundamental current amplitude at the disturbance injection point; ω0 is the fundamental angular frequency; θ0 is the fundamental current phase at the disturbance injection point; I nk is the disturbance amplitude corresponding to the kth frequency to be scanned in the nth group; ω nk is the angular frequency corresponding to the kth frequency to be scanned in the nth group; θ nk is the disturbance phase corresponding to the kth frequency to be scanned in the nth group; f0 is the fundamental frequency; f nk is the kth frequency to be scanned in the nth group;

[0055] In the kth scan, the harmonic current I is injected at the disturbance injection point k ;

[0056] S5. After the target power system is stable, measuring voltage signals of different frequencies at the disturbance injection point; specifically comprising the following steps:

[0057] After the target power system is stable, the corresponding voltage signals V0 and V 1k 、V 2k , ..., V nk ; Where V0 is the fundamental voltage, V nk is the voltage corresponding to the kth frequency to be scanned in the nth group;

[0058] S6. According to the voltage signal obtained in step S5, the impedance amplitude and phase at the corresponding frequency are calculated to complete the current frequency scan; specifically, the steps include:

[0059] The impedance at each frequency is calculated using the following formula:

[0060]

[0061] Where Z nk is the impedance corresponding to the kth frequency to be scanned in the nth group; R nk is the resistance value of the impedance corresponding to the kth frequency to be scanned in the nth group; X nk is the reactance value in the impedance corresponding to the kth frequency to be scanned in the nth group;

[0062] According to the impedance at each frequency, the impedance amplitude and phase are calculated using the following formula:

[0063]

[0064] Where |Z nk | is the impedance amplitude corresponding to the kth frequency to be scanned in the nth group; is the phase corresponding to the kth frequency to be scanned in the nth group;

[0065] S7. Repeat steps S4 to S6 until all frequencies to be scanned are scanned, completing the final high-speed frequency scan; specifically, the following steps are included:

[0066] Repeat steps S4 to S6 m times in total until all frequencies to be scanned are scanned;

[0067] In specific implementation, a preferred solution is: start the value of k from 1, and increase the value of k by 1 each cycle. At this time, repeat steps S4 to S6 m times, and the value of k increases from 1 to m in sequence, which can ensure that all frequencies are scanned.

[0068] The effect of the method of the present invention is described below:

[0069] By comparing the simulation time required by the traditional non-accelerated frequency scanning algorithm and the accelerated algorithm, the improvement effect of the multi-harmonic injection accelerated frequency scanning algorithm proposed in the present invention is illustrated. The simulation time required by the two algorithms is shown in Figure 2. Figure 2 and Figure 3 As shown in the figure, after the simulation starts, it takes T0 to wait for the system to reach a steady state before the first harmonic injection can begin. In each frequency scan, after the harmonic injection, it takes T1 to wait for the system to stabilize before the measurement can begin. The measurement duration is T2.

[0070] Therefore, for the unaccelerated algorithm, the simulation time required for n*m frequencies is T freq T freq =T0+n*m*(T1+T2); and the simulation time required by the solution of the present invention is T acc_freq Tacc_freq =T0+m*(T1+T2); As we can see, T freq ≈nT acc_freq ;

[0071] Since the method of the present invention injects multiple harmonics of different frequencies in one scan, a large amount of time for waiting for the system to stabilize and measure after the harmonic injection is saved; at the same time, since the frequencies of the harmonics injected together are greatly different, the mutual interference is small; therefore, the scheme of the present invention can greatly improve the speed of frequency scanning in electromagnetic transient simulation without affecting the scanning results, and increase the practicality of this function in large power grid simulation.

[0072] The method of the present invention is further described below in conjunction with an embodiment:

[0073] Figure 4 The system to be scanned is a simple RLC series circuit, where R = 20Ω, L = 0.1H, C = 100μF; the harmonic current source is connected to the system from the disturbance injection point, and the harmonic current with the specified frequency changing in sequence is injected. The frequency scanning parameter settings are shown in Table 1. The harmonic current disturbance size of each frequency is set to 0.5% of the fundamental current amplitude; in each scanning cycle, after the harmonic source is injected, wait for T1 = 2s for the system to run stably before starting the measurement, so the simulation time of each scanning cycle is T1 + T2 = 3s;

[0074] Table 1 Frequency scanning parameters

[0075]

[0076] It can be seen from the scanning frequency range shown in Table 1 that a total of 200 frequency points need to be scanned. The parallel group number n=20 of multi-harmonic injection set based on the method of the present invention, that is, all frequencies to be scanned are divided into 20 groups from small to large, and 20 harmonics of different frequencies are injected each time. After 10 frequency scans, the harmonic impedance of the system to be scanned at all frequencies can be obtained. The harmonic frequency distribution of each scan injected is shown in Table 2.

[0077] Table 2 Schematic diagram of multi-harmonic injection in each scan

[0078] First scan <![CDATA[f 11 =1Hz,f 21 =11Hz,f 31 =21Hz,…,f 19_1 =910Hz,f 20_1 =1010Hz]]> Second scan <![CDATA[f 12 =2Hz,f 22 =12Hz,f 32 =22Hz,…,f 19_2 =920Hz,f 20_2 =1020Hz]]> Scan 3 <![CDATA[f 13 =3Hz,f 23 =13Hz,f 33 =23Hz,…,f 19_3 =930Hz,f 20_3 =1030Hz]]> Scan 4 <![CDATA[f 14 =4Hz,f 24 =14Hz,f 34 =24Hz,…,f 19_4 =940Hz,f 20_4 =1040Hz]]> Scan 5 <![CDATA[f 15 =5Hz,f 25 =15Hz,f 35 =25Hz,…,f 19_5 =950Hz,f 20_5 =1050Hz]]> Scan 6 <![CDATA[f 16 =6Hz,f 26 =16Hz,f 36 =26Hz,…,f 19_6 =960Hz,f 20_6 =1060Hz]]> Scan 7 <![CDATA[f 17 =7Hz,f 27 =17Hz,f 37 =27Hz,…,f 19_7 =970Hz,f 20_7 =1070Hz]]> Scan 8 <![CDATA[f 18 =8Hz,f 28 =18Hz,f 38 =28Hz,…,f 19_8 =980Hz,f 20_8 =1080Hz]]> Scan No. 9 <![CDATA[f 19 =9Hz,f 29 =19Hz,f 39 =29Hz,…,f 19_9 =990Hz,f 20_9 =1090Hz]]> 10th Scan <![CDATA[f 1_10 =10Hz,f 2_10 =20Hz,f 3_10 =30Hz,…,f 19_10 =1000Hz,f 20_10 =1100Hz]]>

[0079] Taking the first scan as an example, the injected harmonic current source I1 is:

[0080] I1=I0sin(2πf0t+θ0)+I 11 sin(2πf 11 t+θ 11 )+I 21 sin(2πf 21 t+θ 21)+…I 20_1 sin(2πf 20_1 t+θ 20_1 )

[0081] Among them I 11 ,I 21 ,…I 20_1 All are 0.005I0, and the values ​​of I0, f0, and θ0 are shown in Table 1. 11 、f 21 ,…f 20_1 The values ​​are shown in Table 2. 11 ,θ 21 ,…θ 20_1 f 11 、f 21 ,…f 20_1 The phase of the current source at the frequency can be staggered. Then measure the voltage V at different injection frequencies at the disturbance injection point. 11 、V 21 …V 20_1 , the resulting impedance Z k1 =V k1 / I k1 =R k1 +jX k1 (1≤k≤20) is the system to be scanned at different frequencies f 11 、f 21 ,…f 20_1 The harmonic impedance of the

[0082] Perform 10 scans according to the above method, and you can get the amplitude and phase characteristic curves of the system to be scanned from 1 to 1100 Hz. Figure 5 , Figure 6 As shown in the figure, the amplitude-frequency and phase-frequency characteristic curves of the system to be scanned are compared using the traditional non-accelerated algorithm and the method of the present invention. As can be seen from the figure below, the results obtained by the two algorithms are completely consistent, and the method proposed by the present invention does not affect the scanning results.

[0083] As can be seen from Table 1, the simulation time for each scan cycle is 3s, and 200 frequency points need to be scanned. The traditional non-accelerated algorithm only injects harmonics of one frequency in one scan cycle, so the simulation time is 4+3*200=604s, and the actual test simulation takes 27s. The method of the present invention injects 20 harmonics in one scan cycle, and only needs to scan 10 times, so the simulation time is 4+3*10=34s, and the actual test simulation takes 3s.

[0084] In summary, it can be seen that the method of the present invention can greatly improve the speed of frequency scanning in electromagnetic transient simulation without affecting the scanning results, and increase the practicality of this function in large power grid simulation.

[0085] like Figure 7 The functional module schematic diagram of the system of the present invention is shown as follows: the system of the flexible direct current high-speed frequency scanning method for realizing the multi-harmonic injection disclosed in the present invention comprises a data acquisition module, a frequency determination module, a frequency grouping module, a frequency injection module, a voltage measurement module, a frequency scanning module and a high-speed scanning module; the data acquisition module, the frequency determination module, the frequency grouping module, the frequency injection module, the voltage measurement module and the frequency scanning module are connected in series in sequence; the input end of the high-speed scanning module is connected to the output end of the frequency scanning module, and the output end of the high-speed scanning module is connected to the input end of the frequency injection module; the data acquisition module is used to acquire data information of the target power system and upload the data information to the frequency determination module; the frequency determination module is used to determine all frequencies to be scanned according to the received data information and the acquired data information, and upload the data information to the frequency grouping module; the frequency grouping module is used to group all frequencies to be scanned according to the received data information rate, group them according to the set rules, and upload the data information to the frequency injection module; the frequency injection module is used to inject the harmonic currents corresponding to the several scanning frequencies when scanning the disturbance injection point once for the several groups of scanning frequencies after grouping according to the received data information, and upload the data information to the voltage measurement module; the voltage measurement module is used to measure the voltage signals of different frequencies at the disturbance injection point after the target power system is stable according to the received data information, and upload the data information to the frequency scanning module; the frequency scanning module is used to calculate the impedance amplitude and phase at the corresponding frequency according to the received data information and the obtained voltage signal, complete the current frequency scanning, and upload the data information to the high-speed scanning module; the high-speed scanning module is used to control the frequency injection module, the voltage measurement module and the frequency scanning module to work repeatedly according to the received data information, until all the frequencies to be scanned are scanned, and the final high-speed frequency scanning is completed.

Claims

1. A flexible direct current high-speed frequency scanning method with multi-harmonic injection, comprising the following steps: S1. Obtain data information of the target power system; S2. Determine all frequencies to be scanned according to the data information obtained in step S1; S3. Group all frequencies to be scanned according to the set rules; S4. For the grouped scanning frequencies, the harmonic currents corresponding to the scanning frequencies are injected into the disturbance injection point once during scanning; S5. After the target power system is stabilized, measuring voltage signals of different frequencies at the disturbance injection point; S6. According to the voltage signal obtained in step S5, the impedance amplitude and phase at the corresponding frequency are calculated to complete the current frequency scan; S7. Repeat steps S4 to S6 until all frequencies to be scanned are scanned, completing the final high-speed frequency scan.

2. The flexible direct current high-speed frequency scanning method with multi-harmonic injection according to claim 1, characterized in that Step S3, grouping all frequencies to be scanned according to a set rule, specifically includes the following steps: Group all frequencies to be scanned according to the rule of small to large; There are n groups in total, each group includes m frequencies, expressed as {f 11 ,f 12 ,...,f 1m }、{f 21 ,f 22 ,...,f 2m }、…、{f i1 ,f i2 ,...,f im }、…、{f n1 ,f n2 ,...,f nm }; where f ij Indicates the jth frequency to be scanned in the i-th group.

3. The flexible DC high-speed frequency scanning method with multi-harmonic injection according to claim 2 is characterized in that The step S4 of injecting harmonic currents corresponding to the plurality of scanning frequencies at a disturbance injection point during one scanning for the plurality of grouped scanning frequencies specifically includes the following steps: For the kth scan, the value of k ranges from 1 to m: The harmonic current source is set to be the sum of the fundamental current at the disturbance injection point and the harmonic current of the kth frequency to be scanned in each group, expressed as I k =I0sin(ω0t+θ0)+I 1k sin(ω 1k t+θ 1k )+I 2k sin(ω 2k t+θ 2k )+…+I nk sin(ω nk t+θ nk ) =I0sin(2πf0t+θ0)+I 1k sin(2πf 1k t+θ 1k )+I 2k sin(2πf 2k t+θ 2k )+…I nk sin(2πf nk t+θ nk ) where I k is the harmonic current injected during the kth scan; I0 is the fundamental current amplitude at the disturbance injection point; ω0 is the fundamental angular frequency; θ0 is the fundamental current phase at the disturbance injection point; I nk is the disturbance amplitude corresponding to the kth frequency to be scanned in the nth group; ω nk is the angular frequency corresponding to the kth frequency to be scanned in the nth group; θ nk is the disturbance phase corresponding to the kth frequency to be scanned in the nth group; f0 is the fundamental frequency; f nk is the kth frequency to be scanned in the nth group; In the kth scan, the harmonic current I is injected at the disturbance injection point k .

4. The flexible direct current high-speed frequency scanning method with multi-harmonic injection according to claim 3 is characterized in that After the target power system is stabilized, the voltage signals of different frequencies are measured at the disturbance injection point in step S5, which specifically includes the following steps: After the target power system is stable, the corresponding voltage signals V0 and V 1k 、V 2k , ..., V nk ; Among them, V0 is the fundamental voltage, V nk is the voltage corresponding to the kth frequency to be scanned in the nth group.

5. The flexible direct current high-speed frequency scanning method with multi-harmonic injection according to claim 4 is characterized in that The calculation of the impedance amplitude and phase at the corresponding frequency described in step S6 specifically includes the following steps: The impedance at each frequency is calculated using the following formula: Where Z nk is the impedance corresponding to the kth frequency to be scanned in the nth group; R nk is the resistance value of the impedance corresponding to the kth frequency to be scanned in the nth group; X nk is the reactance value in the impedance corresponding to the kth frequency to be scanned in the nth group; According to the impedance at each frequency, the impedance amplitude and phase are calculated using the following formula: Where |Z nk | is the impedance amplitude corresponding to the kth frequency to be scanned in the nth group; is the phase corresponding to the kth frequency to be scanned in the nth group.

6. The flexible direct current high-speed frequency scanning method with multi-harmonic injection according to claim 5, characterized in that Step S7 repeats steps S4 to S6 until all frequencies to be scanned are scanned, which specifically includes the following steps: Repeat steps S4 to S6 m times in total until all frequencies to be scanned are scanned.

7. A system for implementing the flexible DC high-speed frequency scanning method for multi-harmonic injection according to any one of claims 1 to 6, characterized in that It includes a data acquisition module, a frequency determination module, a frequency grouping module, a frequency injection module, a voltage measurement module, a frequency scanning module and a high-speed scanning module; the data acquisition module, the frequency determination module, the frequency grouping module, the frequency injection module, the voltage measurement module and the frequency scanning module are connected in series in sequence; the input end of the high-speed scanning module is connected to the output end of the frequency scanning module, and the output end of the high-speed scanning module is connected to the input end of the frequency injection module; the data acquisition module is used to acquire data information of the target power system and upload the data information to the frequency determination module; The frequency determination module is used to determine all frequencies to be scanned based on the received data information and the acquired data information, and upload the data information to the frequency grouping module; The frequency grouping module is used to group all the frequencies to be scanned according to the set rules based on the received data information, and upload the data information to the frequency injection module; the frequency injection module is used to inject harmonic currents corresponding to several scanning frequencies when scanning the disturbance injection point once for several groups of scanning frequencies after grouping according to the received data information, and upload the data information to the voltage measurement module; the voltage measurement module is used to measure voltage signals of different frequencies at the disturbance injection point after the target power system is stable according to the received data information, and upload the data information to the frequency scanning module; the frequency scanning module is used to calculate the impedance amplitude and phase at the corresponding frequency according to the received data information and the obtained voltage signal, complete the current frequency scan, and upload the data information to the high-speed scanning module; the high-speed scanning module is used to control the frequency injection module, the voltage measurement module and the frequency scanning module to work repeatedly according to the received data information, until all the frequencies to be scanned are scanned, and the final high-speed frequency scan is completed.

Images