Method and device for detecting oscillations in an independent power system with pulsed loads

Abstract

The application provides an oscillation detection method and device for an independent power system containing a pulse load, wherein the method comprises the following steps: obtaining network-side voltage data and network-side current data of each grid-connected device in the independent power system; monitoring supplied energy of each synchronous motor, judging whether there is synchronous motor power oscillation caused by the pulse load based on the supplied energy, and determining an oscillation source; monitoring oscillation characteristic quantities of each power electronic converter, searching for a to-be-judged power electronic converter possibly participating in oscillation based on the oscillation characteristic quantities; determining an oscillation source power electronic converter according to Hamilton energy of a power electronic converter control system in which the to-be-judged power electronic converter is located; calculating a nonlinear characteristic index value of the oscillation source power electronic converter, comparing the nonlinear characteristic index value with a detection threshold, and determining an oscillation type of the oscillation source power electronic converter. The application improves the accuracy of oscillation detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power system analysis, in particular to an oscillation detection method and device for an independent power system with pulse load. BACKGROUND

[0002] Since the birth of power system, oscillation is one of the important contents of dynamic and stability problem research. In the independent power system with pulse load, in addition to the pulse load, there are usually other load devices such as traditional RLC (resistor, inductor, capacitor) load and ordinary rectifier type load, and multiple static var generators (SVG) are connected in different zones to compensate the excessive reactive power in the system for improving the system characteristics. However, the SVG device itself belongs to the system composed of power electronic converters, and its characteristics are related to the control of the power electronic converters. If the control is improper, the system oscillation may be excited.

[0003] In recent years, the power system oscillation problem caused by the control of power electronic converters has become a research hotspot in the field of power system stability. It can be seen that for the independent power system with pulse load, the system power oscillation may be caused by continuous pulse power impact, and the control oscillation may be caused by the connection of multiple SVG and other power electronic devices in the system. Therefore, when the independent power system with pulse load oscillates, the oscillation property needs to be judged and the oscillation source needs to be located in time, so as to further take control measures and maintain the safe and stable operation of the system.

[0004] Therefore, the oscillation property identification and the oscillation source location are the problems to be solved at present. SUMMARY

[0005] The present application provides an oscillation detection method and device for an independent power system with pulse load, which solves the defect of low accuracy of oscillation detection in the prior art, improves the accuracy of oscillation detection, and realizes the identification of oscillation property.

[0006] In a first aspect, the present application provides an oscillation detection method for an independent power system with pulse load, comprising:

[0007] Obtaining the grid-side voltage data and the grid-side current data of each grid-connected device in the independent power system, wherein the grid-connected device at least includes a synchronous motor, a pulse load and a power electronic converter;

[0008] Monitoring the supply energy of each synchronous motor through the grid-side voltage data and the grid-side current data of each synchronous motor, and judging whether there is synchronous motor power oscillation caused by the pulse load and determining the oscillation source based on the supply energy;

[0009] In the absence of synchronous motor power oscillation caused by pulse load, the oscillation characteristic quantity of each power electronic converter is monitored through the grid-side voltage data and the grid-side current data of each power electronic converter, and the to-be-discriminated power electronic converter possibly participating in the oscillation is searched based on the oscillation characteristic quantity;

[0010] The oscillation source power electronic converter is determined according to the Hamilton energy of the power electronic converter control system in which the to-be-discriminated power electronic converter is located;

[0011] The nonlinear characteristic index value of the oscillation source power electronic converter is calculated, the nonlinear characteristic index value is compared with a detection threshold value, and the oscillation type of the oscillation source power electronic converter is determined;

[0012] The detection threshold value is the nonlinear characteristic index value of the power electronic converter calculated under a normal background harmonic working condition, and the nonlinear characteristic index value is determined based on the bicoherence coefficient of the time sequence signal of the power electronic converter, the time sequence signal being obtained based on the grid-side current data.

[0013] Optionally, the grid-side voltage data of the grid-connected device includes grid-side instantaneous voltage data of the synchronous motor, and the grid-side current data of the grid-connected device includes grid-side instantaneous current data of the synchronous motor.

[0014] The supply energy of each synchronous motor is monitored through the grid-side voltage data and the grid-side current data of each synchronous motor, including:

[0015] The grid-side instantaneous voltage data of each synchronous motor is subjected to Fourier transform to obtain the working frequency of each synchronous motor.

[0016] The average value of the single-phase power of each synchronous motor is calculated according to the grid-side instantaneous voltage data and the grid-side instantaneous current data of each synchronous motor.

[0017] The supply energy of each synchronous motor is calculated based on a supply energy model.

[0018] The supply energy model is:

[0019]

[0020] wherein E geni represents the supply energy of the i Gi represents the grid-side instantaneous current data of the i Gi represents the grid-side instantaneous voltage data of the i represents the average value of the single-phase power of the i Gi represents the working frequency of the i

[0021] Optionally, the judging whether the synchronous motor power oscillation caused by the pulse load exists and determining the oscillation source based on the supply energy comprises:

[0022] If the supply energy of the i-th synchronous motor continuously increases, the synchronous motor power oscillation caused by the pulse load exists and the i-th synchronous motor is the oscillation source.

[0023] Otherwise, the synchronous motor power oscillation caused by the pulse load does not exist.

[0024] Optionally, the grid-side voltage data of the grid-connected device comprises three-phase instantaneous voltage data of the power electronic converter, and the grid-side current data of the grid-connected device comprises three-phase instantaneous current data of the power electronic converter.

[0025] The monitoring of the oscillation characteristic quantity of each power electronic converter through the grid-side voltage data and the grid-side current data of each power electronic converter comprises:

[0026] The oscillation characteristic quantity of the power electronic converter is calculated based on the following formula:

[0027] p ac = u a i a + u b i b + u c i c ;

[0028]

[0029]

[0030] Wherein, p ac represents the three-phase alternating current instantaneous power of the power electronic converter, u a , u b , u c represent the three-phase instantaneous voltage data of the power electronic converter, i a , i b , i c represent the three-phase instantaneous current data of the power electronic converter, TEF ac represents the transient energy flow on the alternating current network port of the power electronic converter, ΔESP ac represents the oscillation characteristic quantity of the power electronic converter, represents the average value of the three-phase alternating current instantaneous power of the power electronic converter; τ represents a period.

[0031] Optionally, the determining the oscillation source power electronic converter according to the Hamilton energy of the power electronic converter control system in which the power electronic converter to be judged is located comprises:

[0032] substitute the predetermined control parameters and the corresponding three-phase instantaneous current data, DC voltage and three-phase instantaneous voltage data of the power electronic converter control system into the Hamilton energy model to obtain Hamilton energy;

[0033] if the Hamilton energy is abnormal, the power electronic converter to be judged is an oscillation source power electronic converter.

[0034] Optionally, the nonlinear characteristic index value is obtained based on the following formula:

[0035]

[0036] wherein, represents the maximum estimation of the square of the bicoherence coefficient, represents the average value of the square of the bicoherence coefficient, represents the variance of the square of the bicoherence coefficient.

[0037] Optionally, the comparison of the nonlinear characteristic index value with the detection threshold value determines the oscillation type of the oscillation source power electronic converter, including:

[0038] if the nonlinear characteristic index value is greater than the detection threshold value, the oscillation type is nonlinear oscillation;

[0039] otherwise, the oscillation type is linear oscillation.

[0040] In a second aspect, the present application further provides an oscillation detection device for an independent power system with pulse loads, comprising:

[0041] a measurement unit configured to acquire grid-side voltage data and grid-side current data of each grid-connected device in the independent power system, wherein the grid-connected device at least includes a synchronous motor, a pulse load and a power electronic converter;

[0042] a first detection and analysis unit configured to monitor supply energy of each synchronous motor through the grid-side voltage data and the grid-side current data of each synchronous motor, and determine whether there is synchronous motor power oscillation caused by the pulse load and determine an oscillation source based on the supply energy;

[0043] a second detection and analysis unit configured to monitor oscillation characteristic quantities of each power electronic converter through the grid-side voltage data and the grid-side current data of each power electronic converter in the case that there is no synchronous motor power oscillation caused by the pulse load, and search for a power electronic converter to be judged which is likely to participate in oscillation based on the oscillation characteristic quantities;

[0044] a third detection analysis unit determines the oscillation source power electronic converter according to Hamilton energy of a power electronic converter control system in which the power electronic converter to be identified is located;

[0045] a fourth detection analysis unit calculates a nonlinear characteristic index value of the oscillation source power electronic converter, compares the nonlinear characteristic index value with a detection threshold value, and determines an oscillation type of the oscillation source power electronic converter;

[0046] The detection threshold value is a nonlinear characteristic index value of the power electronic converter calculated under a normal background harmonic working condition, and the nonlinear characteristic index value is determined based on a bicoherence coefficient of a time sequence signal of the power electronic converter, the time sequence signal being obtained based on the grid-side current data.

[0047] In a third aspect, the present application further provides an electronic device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the oscillation detection method for the independent power system with the pulse load when executing the program.

[0048] In a fourth aspect, the present application further provides a non-transitory computer readable storage medium, which stores a computer program executable by a processor to implement the oscillation detection method for the independent power system with the pulse load.

[0049] The oscillation detection method and device for the independent power system with the pulse load provided by the embodiments of the present application can identify the power oscillation of the synchronous motor caused by the pulse load impact by monitoring the supply energy of the grid-side port of the synchronous motor. As known from the pulse load characteristics, the pulse load acts on the DC side of the system and mainly causes the active power impact on the synchronous motor. If the system oscillation is caused by the power impact, the synchronous motor is the main oscillation energy source. Therefore, the supply energy of the synchronous motor port is used as a characteristic quantity for judging the oscillation caused by the pulse load, and whether the pulse load access causes the power oscillation of the synchronous motor is monitored, so that the influence of the background harmonic on the judgment and positioning of the oscillation caused by the pulse load is overcome, and the accuracy of the oscillation detection and the oscillation source positioning caused by the pulse load is improved. On the other hand, the embodiments of the present application consider the system background harmonic caused by the pulse load access, obtain the nonlinear characteristic index value of the power electronic converter of the independent power system with the pulse load under the normal background harmonic working condition as the detection threshold value, overcome the influence of the background harmonic on the oscillation source positioning, identify the nonlinear characteristics of the oscillation caused by the power electronic converter control limiting, and make the oscillation source positioning result of the independent power system after the pulse load connection more objective and accurate. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0051] Figure 1 is one of the flowcharts of the oscillation detection method of the independent power system with pulse load provided by the embodiments of the present application;

[0052] Figure 2 is an electrical structure schematic diagram of the independent power system with pulse load provided by the embodiments of the present application;

[0053] Figure 3 is the second flowchart of the oscillation detection method of the independent power system with pulse load provided by the embodiments of the present application;

[0054] Figure 4 is a structural schematic diagram of the oscillation detection device of the independent power system with pulse load provided by the embodiments of the present application;

[0055] Figure 5 is a structural schematic diagram of the electronic device provided by the embodiments of the present application. DETAILED DESCRIPTION

[0056] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0057] The following will introduce the technical terms related to the present application:

[0058] Power system oscillation: Modern power system is essentially an electric energy system working at 50 / 60Hz (AC) and 0Hz (DC) by force; power system oscillation phenomenon usually refers to the reciprocating energy exchange of parasitic or mechanical, or electromagnetic or coupling outside the working frequency, which will cause stability or power quality problems when the energy exchange endangers the normal operation of the power system.

[0059] Independent power system: refers to the power system isolated from the large power grid and running independently, commonly used in electric vehicles, electric propulsion ships, etc.; the independent power system has limited capacity, and the integration degree of power electronic conversion devices in the system is high.

[0060] Pulse load: refers to a kind of power electronic equipment which shows low average power, high peak power, random duty cycle and continuous pulse power impact characteristics in load characteristics.

[0061] For an independent power system containing a pulse load, due to the continuous impact of the pulse load, the system frequency and voltage fluctuate, if the frequency and voltage fluctuation period is strongly related to the working period of the pulse load, the generated reciprocating energy exchange is a normal system phenomenon, and therefore is not considered as an oscillation problem. However, if the system under the action of the pulse load, appears the reciprocating energy exchange which is not related to the characteristics of the pulse load, and interferes with the normal operation of the independent power system, it is considered that the system has an oscillation problem.

[0062] For the system oscillation problem, such as the system oscillation problem caused by the power electronic device, the traditional energy method or the harmonic method is usually used to locate the oscillation source in the related art.

[0063] However, the traditional energy method is essentially not suitable for the power system oscillation phenomenon in the harmonic background based on the energy flow definition of the phasor representation. In the traditional power system, all are sinusoidal signals, which can be represented by a single phasor method, but in the power system involving power electronic devices or pulse loads, there are harmonics, and the current is no longer a single sinusoidal signal. In this case, the single phasor method is not applicable, and the single phasor method cannot accurately determine the oscillation source.

[0064] On the other hand, the accuracy of locating the oscillation source by the harmonic method is easily affected by the system background harmonics, and since the linear LC oscillation and the nonlinear control amplitude limiting oscillation are both represented as harmonic currents, the harmonic method cannot distinguish between the linear LC oscillation and the nonlinear control amplitude limiting oscillation, and cannot accurately attribute the system oscillation to the control link of the power electronic device.

[0065] In view of this, the present application proposes an identification method of the power electronic converter participating in the system oscillation based on the energy structure of the power electronic converter (such as voltage source converter) and combined with the nonlinear detection means, and applies it to the oscillation analysis of the independent power system containing the pulse load, and the following Figure 1 Figure 3 The present application provides an oscillation detection method for an independent power system containing a pulse load.

[0066] Figure 1 is one of the flowcharts of the oscillation detection method for the independent power system containing the pulse load provided by the embodiments of the present application, as shown in Figure 1 The oscillation detection method for the independent power system containing the pulse load provided by the embodiments of the present application comprises:

[0067] ​Step 110: Obtain grid-side voltage data and grid-side current data of each grid-connected device in the independent power system. The grid-connected devices include at least synchronous motors, pulse loads, and power electronic converters.

[0068] Specifically, an independent power system is an independent power system containing pulse loads. Figure 2 This is an electrical structure schematic diagram of an independent power system with pulse load provided by an embodiment of the present invention, such as... Figure 2 As shown, the independent power system provided in this embodiment of the invention may include pulse loads, rectifier loads, RLC loads, static var generators (SVG), and generator sets. Figure 2 A medium-sized generator set is a diesel generator set that includes an excitation system, a diesel engine, and a speed control system. This should be understood. Figure 2 Examples provided for the purpose of understanding the present invention are not limited to generator sets used in independent power systems and may include photovoltaic generator sets, energy storage systems, and standby diesel generator sets, etc.

[0069] The power electronic converter in this embodiment of the invention can be a DC-AC converter. Based on this embodiment, those skilled in the art can extend the above solution to other types of converters, which should also fall within the scope of protection of this invention. This embodiment of the invention does not limit the number of various grid-connected devices; there can be one or more.

[0070] Step 120: Monitor the power supply of each synchronous motor by using the grid-side voltage data and grid-side current data of each synchronous motor, and determine whether there is synchronous motor power oscillation caused by pulse load and identify the oscillation source based on the power supply.

[0071] Specifically, the energy supplied by each synchronous motor is calculated based on the grid-side voltage data and grid-side current data of each synchronous motor.

[0072] For example, if the energy supplied to a synchronous motor is abnormal, such as continuously increasing, then the synchronous motor will experience power oscillations caused by pulse load impacts. If the energy supply is normal, then there will be no power oscillations caused by pulse load impacts.

[0073] Step 130: In the absence of synchronous motor power oscillation caused by pulse load, monitor the oscillation characteristic of each power electronic converter by using grid-side voltage data and grid-side current data of each power electronic converter, and search for power electronic converters that may participate in the oscillation based on the oscillation characteristic.

[0074] Specifically, the oscillation characteristic quantity refers to an electric power parameter capable of reflecting the oscillation characteristic, which can be supply energy, transient energy, etc. of the power electronic converter. The power electronic converter is judged for device-level power electronic oscillation through the oscillation characteristic quantity.

[0075] Exemplarily, the power electronic converters in the power system are searched, the oscillation characteristic quantities of the respective power electronic converters are calculated, and if the oscillation characteristic quantity of the power electronic converter is abnormal, such as continuously increasing, the power electronic converter is a to-be-judged power electronic converter, which refers to a power electronic converter that can cause an independent power system oscillation phenomenon due to power electronic converter control clipping. There can be one or more to-be-judged power electronic converters.

[0076] It should be understood that the oscillation phenomenon caused by the pulse load and the oscillation phenomenon caused by the power electronic converter do not exist at the same time in engineering, and once they exist at the same time, the system will not be able to run. Generally, the probability of oscillation of the pulse load is greater than the probability of oscillation of the power electronic converter.

[0077] Step 140, determining the oscillation source power electronic converter according to the Hamilton energy of the power electronic converter control system in which the to-be-judged power electronic converter is located.

[0078] Specifically, the to-be-judged power electronic converter is judged one by one to determine whether the to-be-judged power electronic converter causes an independent power system oscillation phenomenon due to power electronic converter control clipping. If the Hamilton energy of the power electronic converter control system (such as SVG) in which the to-be-judged power electronic converter is located is abnormal, the to-be-judged power electronic converter is an oscillation source power electronic converter, which refers to a power electronic converter that causes an independent power system oscillation due to power electronic converter control (such as improper control, control clipping). It should be understood that the Hamilton energy is used to judge the device control-level oscillation.

[0079] Step 150, calculating the nonlinear characteristic index value of the oscillation source power electronic converter, comparing the nonlinear characteristic index value with a detection threshold value, and determining the oscillation type of the oscillation source power electronic converter;

[0080] The detection threshold value is the nonlinear characteristic index value of the oscillation source power electronic converter calculated under a normal background harmonic working condition of the independent power system containing the pulse load. The nonlinear characteristic index value is determined based on a bicoherence coefficient of a timing signal of the power electronic converter, and the timing signal is obtained based on the grid-side current data.

[0081] Specifically, the nonlinear characteristic index value is used to represent the degree of nonlinear oscillation of the power electronic converter. The oscillation type can include linear oscillation and nonlinear oscillation caused by power electronic converter control.

[0082] Exemplarily, the nonlinear characteristic index value is compared with a detection threshold value, if the nonlinear characteristic index value is greater than the detection threshold value, it is determined that the power electronic converter of the oscillation source occurs nonlinear oscillation, otherwise, it is determined that the power electronic converter of the oscillation source occurs linear oscillation.

[0083] The normal background harmonic working condition can refer to a harmonic injected current under a maximum operating working condition as a benchmark, and a voltage harmonic distortion rate meeting a national standard as a limit. It should be understood that the nonlinear characteristic index value for comparison with the detection threshold value is obtained by calculation on an independent power system under a working condition (such as a current state) to be detected.

[0084] The oscillation detection method of the independent power system with the pulse load provided by the embodiment of the present application can identify the power oscillation of the synchronous motor caused by the pulse load impact by monitoring the supply energy of the grid-side port of the synchronous motor. As known from the pulse load characteristics, the pulse load acts on the DC side of the system, mainly showing active power impact on the synchronous motor. If the system oscillation is caused by the power impact, the synchronous motor is the main source of oscillation energy. Therefore, the supply energy of the synchronous motor port is taken as a characteristic quantity for judging the oscillation caused by the pulse load, and whether the pulse load access causes the power oscillation of the synchronous motor is monitored, so as to overcome the influence of the background harmonic on the judgment and positioning of the oscillation caused by the pulse load, and improve the accuracy of the oscillation detection and the oscillation source positioning after the pulse load is connected to the independent power system. On the other hand, the embodiment of the present application considers the system background harmonic caused by the pulse load access, takes the nonlinear characteristic index value of the power electronic converter of the independent power system with the pulse load under the normal background harmonic working condition as the detection threshold value, overcomes the influence of the background harmonic on the oscillation source positioning, and can identify the nonlinear characteristics of the oscillation caused by the control amplitude limiting of the power electronic converter, so that the oscillation source positioning result after the pulse load is connected to the independent power system is more objective and accurate.

[0085] Next, possible implementation manners of the above steps in specific embodiments are further described.

[0086] Optionally, the grid-side voltage data of the grid-connected device includes grid-side instantaneous voltage data of the synchronous motor, and the grid-side current data of the grid-connected device includes grid-side instantaneous current data of the synchronous motor.

[0087] Specifically, the grid-side instantaneous voltage data can be an instantaneous voltage waveform, and the grid-side instantaneous current data can be an instantaneous current waveform, that is, the grid-side instantaneous voltage data and the grid-side instantaneous current data both contain instantaneous voltages or instantaneous currents at multiple continuous time points (such as a period of time). The instantaneous data in this paper can all be waveform data, containing power data at multiple continuous time points (such as a period of time), which will not be described hereinafter.

[0088] The monitoring of the supply energy of each synchronous motor includes:

[0089] The grid-side instantaneous voltage data of each synchronous motor is subjected to Fourier transform to obtain the working frequency of each synchronous motor;

[0090] Specifically, according to the obtained grid-side (i.e. output port) instantaneous voltage u Gi of the i th synchronous motor in the independent power system, the Fourier transform method is used to detect the working frequency ω G i of the synchronous motor;

[0091] According to the grid-side instantaneous voltage data and the grid-side instantaneous current data of each synchronous motor, the average value of the single-phase power of each synchronous motor is calculated;

[0092] Specifically, according to the obtained grid-side (output) instantaneous current i Gi of the synchronous motor, and in combination with the instantaneous voltage u Gi , the average value of the single-phase instantaneous power P of the i th synchronous motor is calculated.

[0093] The supply energy of each synchronous motor is calculated based on a supply energy model;

[0094] The supply energy model is as follows:

[0095]

[0096] Wherein, E geni represents the supply energy of the i th synchronous motor, i Gi represents the grid-side instantaneous current data of the i th synchronous motor, u Gi represents the grid-side instantaneous voltage data of the i th synchronous motor, represents the average value of the single-phase power of the i th synchronous motor, ω Gi represents the working frequency of the i th synchronous motor.

[0097] The oscillation detection method for the independent power system with pulse load provided by the embodiment of the application, the process of obtaining the port supply energy of the synchronous motor in the independent power system, the port supply energy model is defined based on transient energy flow by instantaneous method, compared with the non-transient energy flow defined based on the traditional phasor method, is more suitable for analyzing the oscillation phenomenon under the condition that the pulse load participates in the independent power system, and can more accurately depict the synchronous motor power oscillation energy flow of the independent power system under the background harmonic working condition; the port supply energy model only depends on the measurement of the external port voltage and current of the synchronous motor, and is beneficial to the implementation in the engineering field.

[0098] Optionally, the judging whether the synchronous motor power oscillation caused by the pulse load exists and the oscillation source based on the supply energy comprises:

[0099] If the supply energy of the i-th synchronous motor continuously increases, the synchronous motor power oscillation caused by the pulse load exists and the i-th synchronous motor is the oscillation source;

[0100] Otherwise, the synchronous motor power oscillation caused by the pulse load does not exist.

[0101] Exemplarily, there are synchronous motors 1 and 2, the supply energy of the synchronous motor 1 continuously increases, and the supply energy of the synchronous motor 2 is stable, it can be determined that the synchronous motor 1 has the synchronous motor power oscillation caused by the pulse load, and the synchronous motor 1 is the oscillation source.

[0102] Optionally, the grid-side voltage data of the grid-connected device comprises three-phase instantaneous voltage data of the power electronic converter, and the grid-side current data of the grid-connected device comprises three-phase instantaneous current data of the power electronic converter;

[0103] The monitoring of the oscillation characteristic quantity of each power electronic converter through the grid-side voltage data and the grid-side current data of each power electronic converter comprises:

[0104] The oscillation characteristic quantity of the power electronic converter is calculated based on the following formula:

[0105] p ac = u a i a + u b i b + u c i c ;

[0106]

[0107]

[0108] Wherein, p ac represents three-phase alternating current instantaneous power of the power electronic converter, u a , u b , u c represent three-phase instantaneous voltage data of the power electronic converter, i a , i b , i c represent three-phase instantaneous current data of the power electronic converter, TEF ac represents transient energy flow on the alternating current network port of the power electronic converter, ΔESP ac represents the oscillation characteristic quantity of the power electronic converter, τ represents the average value of the three-phase AC instantaneous power of the power electronic converter; τ represents the period.

[0109] Specifically, the oscillation characteristics of each power electronic converter can be determined based on the energy supplied to the grid-side port of each power electronic converter (i.e., the transient energy flow on the AC network port of the power electronic converter). Specific steps may include:

[0110] Step 1: Obtain the grid-side three-phase instantaneous voltage u of the power electronic converter a u b u c and three-phase instantaneous current i a i b i c According to the grid-side three-phase instantaneous voltage u of the power electronic converter a u b u c and three-phase instantaneous current i a i b i c Calculate the instantaneous power p of the three-phase AC circuit. ac ;

[0111] And define the transient energy flow on the AC network port of the power electronic converter:

[0112]

[0113] Step 2: Based on the obtained transient energy flow (TEF) at the power electronic converter network port ac Define the oscillation characteristic quantity used to detect (identify) whether a power electronic converter participates in independent power system oscillations:

[0114]

[0115] Optionally, if the oscillation characteristic ΔESP of the i-th power electronic converter ac If the value continues to increase, then the i-th power electronic converter is the power electronic converter to be determined.

[0116] Optionally, determining the oscillation source power electronic converter based on the Hamiltonian energy of the power electronic converter control system where the power electronic converter to be determined is located includes:

[0117] Substitute the predetermined control parameters and the corresponding three-phase instantaneous current data, DC voltage and three-phase instantaneous voltage data of the power electronic converter control system into the Hamiltonian energy model to obtain the Hamiltonian energy.

[0118] If the Hamiltonian energy is abnormal, then the power electronic converter to be identified is an oscillating source power electronic converter.

[0119] Specifically, the Hamilton energy of the power electronic converter control system in which the power electronic converter to be judged is located is monitored, and the Hamilton energy of the power electronic converter control system is taken as a characteristic quantity for judging whether the power electronic converter control participates in the independent power system oscillation. If the Hamilton energy of the power electronic converter control system is abnormal, such as continuously increasing, the power electronic converter to be judged in the power electronic converter control system is an oscillation source power electronic converter.

[0120] The Hamilton energy of the power electronic converter control system is obtained, including but not limited to the following steps:

[0121] Step 1: According to the known information, the control conditions of the power electronic converter are set (the determination method of the control conditions is referred to the related technology, which will not be repeated here), including the DC voltage control reference value u dcref , the grid-side voltage control reference value u dref , the integral control parameters K Iud , K Iuq and the proportional control parameters K Pud , K Puq of the voltage control loop (VL), and the integral control parameter K Ii of the current control loop (CL).

[0122] Step 2: According to the obtained DC voltage u dc of the power electronic converter, and the grid-side three-phase instantaneous voltage u a , u b , u c and the three-phase instantaneous current i a , i b , i c , the Hamilton energy model of the power electronic converter control system is established:

[0123]

[0124]

[0125] Wherein

[0126] x1=∫(u dcref -u dc )dt;

[0127] x2=∫(u dref -u d )dt;

[0128] x3=∫(i dref -i d )dt;

[0129] x4 = ∫(i qref -i q )dt;

[0130] i dref = K Pud (u dcref -u dc )+ K Iud x1;

[0131] i qref = K Puq (u dref -u d )+ K Iuq x1;

[0132] u d represents the voltage d-axis component, i d represents the current d-axis component, i q represents the q-axis component of the current,

[0133] Further, the Hamilton energy of the power electronic converter control system, including the voltage control loop Hamilton energy H VL and the current control loop Hamilton energy H CL , is taken as a characteristic quantity for judging whether the power electronic converter control participates in the independent power system oscillation.

[0134] The process of obtaining the energy supplied by each element (including synchronous motors, power electronic converters, etc.) in the independent power system is described in the embodiment. The port energy supply model is based on the transient energy flow defined by the instantaneous method. Compared with the traditional non-transient energy flow defined by the phasor method, it is more suitable for analyzing the oscillation phenomenon under the condition that the pulse load is connected to the independent power system, and can more accurately depict the synchronous motor power oscillation energy flow and the power electronic converter control limiting amplitude oscillation energy flow of the independent power system under the background harmonic working condition. The port energy supply model and the extraction process of its oscillation characteristic quantity only rely on the setting of the control parameters of the given independent power system (including the direct current voltage control reference value u dcref , the grid-side voltage control reference value u dref , the integral control parameters K Iud , K Iuq of the voltage control loop and the proportional control parameters K Pud , K Puq , the integral control parameters K Ii of the current control loop, etc.), as well as the grid-side (external port) voltage and the grid-side (external port) current of each grid-connected device (including the direct current voltage u dc of the power electronic converter, and the grid-side three-phase instantaneous voltage u a , u b , u cand three-phase instantaneous current i a b c The measurement of the amount of non-linear characteristic index is conducive to the realization of the engineering site.

[0135] Optionally, the non-linear characteristic index value is obtained based on the following formula:

[0136]

[0137] wherein, represents the maximum estimation of the square of the bicoherence coefficient, represents the average value of the square of the bicoherence coefficient, represents the variance of the square of the bicoherence coefficient.

[0138] Specifically, the grid-side current data of the grid-connected device includes grid-side instantaneous current data of the power electronic converter; the grid-side instantaneous current data can be a current instantaneous waveform.

[0139] The non-linear characteristic index value of the port current of each element (such as the power electronic converter) obtained includes but is not limited to the following steps:

[0140] Step 1: The obtained grid-side instantaneous current data of the port of each element (such as the power electronic converter) is arranged in the form of time sequence signal X(n) to obtain the time sequence signal X(n); that is, X(n) is sampled.

[0141] Step 2: Further, the bispectrum BX, the power spectrum PX and the bicoherence coefficient bic of the time sequence signal X(n) are obtained, wherein

[0142]

[0143]

[0144]

[0145]

[0146]

[0147] In the formula, f1 and f2 are two-dimensional Fourier transform frequencies; τ1 and τ2 are time sequence variables of two-dimensional Fourier transform.

[0148] Step 3: Further, the non-linear characteristic index value of the time sequence signal X(n) is calculated:

[0149]

[0150] ​​Optionally, the nonlinear characteristic index value μ obtained by the independent power system under normal background harmonic working condition is taken as a detection threshold value for judging whether the system oscillation is caused by the control amplitude limiting of the power electronic converter.

[0151] Optionally, the comparison of the nonlinear characteristic index value with the detection threshold value determines the oscillation type of the oscillation source power electronic converter, including:

[0152] If the nonlinear characteristic index value is greater than the detection threshold value, the oscillation type is nonlinear oscillation.

[0153] Otherwise, the oscillation type is linear oscillation.

[0154] Exemplarily, if the nonlinear characteristic index value of the oscillation source power electronic converter is greater than the detection threshold value, the oscillation of the oscillation source power electronic converter is nonlinear oscillation caused by the power electronic converter (such as VSC); if the nonlinear characteristic index value of the oscillation source power electronic converter is not greater than the detection threshold value, the oscillation of the oscillation source power electronic converter is linear oscillation.

[0155] It should be understood that the detection threshold value of each power electronic converter is calculated according to the grid-side current data of the port of each power electronic converter.

[0156] The oscillation detection method of the independent power system with pulse load provided by the embodiment of the present application, the process of obtaining the detection threshold value of the control amplitude limiting oscillation of the power electronic converter, only needs to measure and collect the port voltage or current instantaneous waveform of the power electronic converter, and the threshold value calculation can be implemented, and the above-mentioned detection threshold value can be updated in real time with the change of the system working condition, so as to realize more timely and accurate identification of system oscillation in engineering field.

[0157] Figure 3 is a flowchart of the oscillation detection method of the independent power system with pulse load provided by the embodiment of the present application, as shown in Figure 3 The oscillation detection method of the independent power system with pulse load provided by the embodiment of the present application includes:

[0158] S1, obtaining the grid-side voltage and current data of the synchronous motor, pulse load, power electronic converter and other grid-connected devices in the independent power system;

[0159] Specifically, the grid-side voltage and current data are obtained on both sides of the port of each grid-connected device.

[0160] S2, detecting the voltage (current) nonlinear index calculation value of the independent power system under normal background harmonic working condition, so as to take it as a detection threshold value for judging whether the system oscillation is caused by the control amplitude limiting of the power electronic converter.

[0161] S3, monitoring the grid-side port of the synchronous machine to determine if the supplied energy E is increasing gen , identifying whether the pulse load impact causes power oscillation of the synchronous machine;

[0162] Specifically, the synchronous machine can be a synchronous generator. If the supplied energy E gen continuously increases, the synchronous machine has power oscillation caused by pulse load impact, otherwise go to S4.

[0163] S4, searching for power electronic oscillation converters that can participate in the oscillation.

[0164] Specifically, the supplied energy of each power electronic converter network port is extracted and detected, and the oscillation characteristic quantity ΔESP ac of the network port is determined according to the supplied energy. ac Gradually narrow the search range of the oscillation source, find out the to-be-judged power electronic converter that can participate in the oscillation in the search system based on the supplied energy; secondly, according to the VSC control oscillation characteristic quantity H VL and H CL , determine the controller that causes the oscillation, i.e. the voltage and current controller inside the VSC.

[0165] S5, detecting the grid-connected state of each element of the to-be-tested pulse load containing independent power system based on the Hamilton energy of each power electronic converter control system and the detection threshold of the oscillation caused by the amplitude limiting of the converter control, locating the oscillation source, and identifying the power electronic converter in the independent power system that is in the position of the oscillation source.

[0166] Optionally, in step S1, an independent power system circuit is obtained, the independent power system is decomposed according to the role of each element in the system, elements with the same role are classified into the same set, and the port voltage and current instantaneous waveform of each element are measured and collected.

[0167] In step S5, further based on the Hamilton energy of the power electronic converter control system, and in combination with the detection threshold of the oscillation caused by the amplitude limiting of the power electronic converter control in step S2, the power electronic converter in the sample independent power system that is in the position of the oscillation source is identified.

[0168] The oscillation detection method of the independent power system containing the pulse load provided by the embodiment of the present application is characterized in that the energy structure of the power electronic converter such as the voltage source converter (VSC) is used in combination with the nonlinear detection method to propose an identification method of the oscillation of the independent power system in which the power electronic converter is involved, and the method is applied to the oscillation analysis of the independent power system containing the pulse load. The main contents include: on the one hand, the energy structure of the VSC converter is established based on the dissipation theory, and then the energy function of the converter is constructed, and the related characteristic quantity is defined through the energy function of the VSC to realize the oscillation monitoring; on the other hand, the nonlinear detection method is applied to identify the nature of the oscillation of the power electronic device involved in the system in consideration of the amplitude limiting characteristics of the VSC control, and to distinguish the nonlinear oscillation and the linear oscillation. The oscillation detection method of the independent power system containing the pulse load provided by the embodiment of the present application is characterized in that the Hamilton model and the energy structure of the synchronous motor, the pulse load, the power electronic converter and other elements are established, and the corresponding oscillation detection characteristic quantity is defined based on the energy structure of each element to detect the working state of each element of the independent power system containing the pulse load, identify the various oscillation phenomena that may occur in the system, retain the nonlinear characteristics of the oscillation caused by the amplitude limiting of the power electronic converter control, and make the oscillation source positioning result of the independent power system connected with the pulse load more objective and accurate.

[0169] The oscillation detection device of the independent power system containing the pulse load provided by the present application is described below. The oscillation detection device of the independent power system described below can be correspondingly referred to the oscillation detection method of the independent power system containing the pulse load described above.

[0170] Figure 4 The oscillation detection device of the independent power system containing the pulse load provided by the embodiment of the present application is a structural schematic diagram as shown in Figure 4 The oscillation detection device of the independent power system containing the pulse load provided by the embodiment of the present application is a structural schematic diagram as shown in

[0171] The measurement unit 410 is configured to acquire the grid-side voltage data and the grid-side current data of each grid-connected device in the independent power system, wherein the grid-connected device at least includes the synchronous motor, the pulse load and the power electronic converter.

[0172] The first detection analysis unit 420 is configured to monitor the supply energy of each synchronous motor through the grid-side voltage data and the grid-side current data of each synchronous motor, and determine whether the synchronous motor power oscillation caused by the pulse load exists and determine the oscillation source based on the supply energy.

[0173] The second detection analysis unit 430 is configured to monitor oscillation characteristic quantities of each power electronic converter by using the grid-side voltage data and the grid-side current data of each power electronic converter in the absence of synchronous motor power oscillation caused by pulse load, and search for a power electronic converter to be distinguished that is likely to participate in oscillation based on the oscillation characteristic quantities.

[0174] The third detection analysis unit 440 is configured to determine an oscillation source power electronic converter according to Hamilton energy of a power electronic converter control system in which the power electronic converter to be distinguished is located.

[0175] The fourth detection analysis unit 450 is configured to calculate a nonlinear characteristic index value of the oscillation source power electronic converter, compare the nonlinear characteristic index value with a detection threshold value, and determine an oscillation type of the oscillation source power electronic converter.

[0176] The detection threshold value is a nonlinear characteristic index value of the power electronic converter calculated under a normal background harmonic working condition, and the nonlinear characteristic index value is determined based on a bicoherence coefficient of a time sequence signal of the power electronic converter, wherein the time sequence signal is obtained based on the grid-side current data.

[0177] Optionally, the device further comprises a modeling unit configured to establish an energy structure model of each element.

[0178] It should be noted that the device provided by the embodiment of the present application can realize all the method steps achieved by the method embodiment and achieve the same technical effects, and thus the same parts and beneficial effects of the method embodiment will not be described in detail.

[0179] Figure 5 An example of a schematic diagram of a physical structure of an electronic device is shown in FIG. 1. Figure 5As shown, the electronic device can include a processor 510, a communications interface 520, a memory 530, and a communications bus 540, wherein the processor 510, the communications interface 520, and the memory 530 complete mutual communication through the communications bus 540. The processor 510 can invoke a logic instruction in the memory 530 to execute an oscillation detection method for an impulse load independent power system, which includes: obtaining grid-side voltage data and grid-side current data of each grid-connected device in the independent power system, the grid-connected device at least including a synchronous motor, an impulse load, and a power electronic converter; monitoring supply energy of each synchronous motor through the grid-side voltage data and the grid-side current data of each synchronous motor, judging whether there is synchronous motor power oscillation caused by the impulse load based on the supply energy, and determining an oscillation source; in the case where there is no synchronous motor power oscillation caused by the impulse load, monitoring oscillation characteristic quantities of each power electronic converter through the grid-side voltage data and the grid-side current data of each power electronic converter, searching for a to-be-judged power electronic converter possibly participating in oscillation based on the oscillation characteristic quantities; determining an oscillation source power electronic converter according to Hamilton energy of a power electronic converter control system where the to-be-judged power electronic converter is located; calculating a nonlinear characteristic index value of the oscillation source power electronic converter, comparing the nonlinear characteristic index value with a detection threshold value, and determining an oscillation type of the oscillation source power electronic converter; wherein the detection threshold value is a nonlinear characteristic index value of the power electronic converter calculated under a normal background harmonic working condition, and the nonlinear characteristic index value is determined based on a bicoherence coefficient of a timing signal of the power electronic converter, the timing signal being obtained based on the grid-side current data.

[0180] In addition, the logic instruction in the memory 530 described above can be implemented in the form of a software function unit and sold or used as an independent product, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0181] In another aspect, the present application also provides a computer program product comprising a computer program, which can be stored on a non-transitory computer readable storage medium, and the computer program, when executed by a processor, enables a computer to perform the oscillation detection method for an independent power system with pulse loads provided by the above-mentioned methods, which comprises: monitoring supply energy of each synchronous motor through grid-side voltage data and grid-side current data of each synchronous motor, judging whether there is synchronous motor power oscillation caused by pulse loads and determining an oscillation source based on the supply energy; in the case that there is no synchronous motor power oscillation caused by pulse loads, monitoring oscillation characteristic quantities of each power electronic converter through grid-side voltage data and grid-side current data of each power electronic converter, searching for a to-be-judged power electronic converter that may participate in oscillation based on the oscillation characteristic quantities; determining an oscillation source power electronic converter according to Hamilton energy of a power electronic converter control system in which the to-be-judged power electronic converter is located; calculating a nonlinear characteristic index value of the oscillation source power electronic converter, comparing the nonlinear characteristic index value with a detection threshold value, and determining an oscillation type of the oscillation source power electronic converter; wherein the detection threshold value is a nonlinear characteristic index value of the power electronic converter calculated under a normal background harmonic working condition, and the nonlinear characteristic index value is determined based on a bicoherence coefficient of a timing signal of the power electronic converter, and the timing signal is obtained based on the grid-side current data.

[0182] In another aspect, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program, when executed by a processor, implements the oscillation detection method for an independent power system with pulse loads provided by the above-mentioned methods, which comprises: monitoring supply energy of each synchronous motor through grid-side voltage data and grid-side current data of each synchronous motor, judging whether there is synchronous motor power oscillation caused by pulse loads and determining an oscillation source based on the supply energy; in the case that there is no synchronous motor power oscillation caused by pulse loads, monitoring oscillation characteristic quantities of each power electronic converter through grid-side voltage data and grid-side current data of each power electronic converter, searching for a to-be-judged power electronic converter that may participate in oscillation based on the oscillation characteristic quantities; determining an oscillation source power electronic converter according to Hamilton energy of a power electronic converter control system in which the to-be-judged power electronic converter is located; calculating a nonlinear characteristic index value of the oscillation source power electronic converter, comparing the nonlinear characteristic index value with a detection threshold value, and determining an oscillation type of the oscillation source power electronic converter; wherein the detection threshold value is a nonlinear characteristic index value of the power electronic converter calculated under a normal background harmonic working condition, and the nonlinear characteristic index value is determined based on a bicoherence coefficient of a timing signal of the power electronic converter, and the timing signal is obtained based on the grid-side current data.

[0183] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment scheme according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0184] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0185] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An oscillation detection method for an independent power system with pulsed load, characterized in that, include: Acquire grid-side voltage and grid-side current data of each grid-connected device in an independent power system, wherein the grid-connected device includes at least a synchronous motor, a pulse load, and a power electronic converter; By monitoring the grid-side voltage and current data of each synchronous motor, the energy supplied to each synchronous motor is monitored, and the presence of synchronous motor power oscillation caused by pulse load is determined based on the energy supplied, and the oscillation source is identified; wherein, the grid-side voltage data of the synchronous motor includes the instantaneous grid-side voltage data of the synchronous motor, and the grid-side current data of the synchronous motor includes the instantaneous grid-side current data of the synchronous motor. In the absence of synchronous motor power oscillation caused by pulse load, the oscillation characteristics of each power electronic converter are monitored using grid-side voltage and grid-side current data. Based on these oscillation characteristics, potential power electronic converters to be identified are searched for. The grid-side voltage data of the power electronic converter includes the three-phase instantaneous voltage data, and the grid-side current data includes the three-phase instantaneous current data. The oscillation source power electronic converter is determined based on the Hamiltonian energy of the power electronic converter control system in which the power electronic converter to be identified is located. Calculate the nonlinear characteristic index value of the oscillation source power electronic converter, compare the nonlinear characteristic index value with the detection threshold, and determine the oscillation type of the oscillation source power electronic converter; The detection threshold is a nonlinear characteristic index value of the power electronic converter calculated under normal background harmonic conditions. The nonlinear characteristic index value is determined based on the biphase coherence coefficient of the timing signal of the power electronic converter, and the timing signal is obtained based on the grid-side current data.

2. The oscillation detection method for an independent power system with pulsed load according to claim 1, characterized in that, The monitoring of the energy supply of each synchronous motor through the grid-side voltage and current data of each synchronous motor includes: The operating frequency of each synchronous motor is obtained by performing a Fourier transform on the instantaneous grid-side voltage data of each synchronous motor. Based on the instantaneous grid-side voltage and instantaneous grid-side current data of each synchronous motor, calculate the average single-phase power of each synchronous motor. The energy supplied to each synchronous motor is calculated based on the energy supply model; The energy supply model is as follows: Among them, E geni This represents the energy supplied to the i-th synchronous motor, i Gi U represents the instantaneous grid-side current data of the i-th synchronous motor. Gi This represents the instantaneous grid-side voltage data of the i-th synchronous motor. ω represents the average single-phase power of the i-th synchronous motor. Gi This represents the operating frequency of the i-th synchronous motor.

3. The oscillation detection method for an independent power system with pulsed load according to claim 1 or 2, characterized in that, The determination of whether synchronous motor power oscillations caused by pulsed loads exist based on the supplied energy, and the identification of the oscillation source, includes: If the energy supplied by the i-th synchronous motor continues to increase, there will be synchronous motor power oscillation caused by pulse load, and the i-th synchronous motor will be the oscillation source. Otherwise, there is no synchronous motor power oscillation caused by pulse load.

4. The oscillation detection method for an independent power system with pulsed load according to claim 1, characterized in that, The monitoring of oscillation characteristics of each power electronic converter using grid-side voltage and current data includes: The oscillation characteristic of the power electronic converter is calculated based on the following formula: p ac =in a and a +in b and b +in c and c ; Where, p ac u represents the instantaneous three-phase AC power of the power electronic converter. a u b u c This represents the three-phase instantaneous voltage data of the power electronic converter, i a i b i c TEF represents the three-phase instantaneous current data of a power electronic converter. ac ΔESP represents the transient energy flow at the AC network port of a power electronic converter. ac This represents the oscillation characteristic of a power electronic converter. τ represents the average value of the three-phase AC instantaneous power of the power electronic converter; τ represents the period.

5. The oscillation detection method for an independent power system with pulsed load according to claim 1, characterized in that, The step of determining the oscillation source power electronic converter based on the Hamiltonian energy of the power electronic converter control system where the power electronic converter to be determined is located includes: Substitute the predetermined control parameters and the corresponding three-phase instantaneous current data, DC voltage and three-phase instantaneous voltage data of the power electronic converter control system into the Hamiltonian energy model to obtain the Hamiltonian energy. If the Hamiltonian energy is abnormal, then the power electronic converter to be identified is an oscillating source power electronic converter.

6. The oscillation detection method for an independent power system with pulsed load according to claim 1, characterized in that, The nonlinear characteristic index value is calculated based on the following formula: in, This represents the maximum estimate of the square of the bicoherence coefficient. This represents the average of the squares of the biphase coherence coefficients. This represents the variance of the square of the biphasic coefficient.

7. The oscillation detection method for an independent power system with pulsed load according to claim 1 or 6, characterized in that, The step of comparing the nonlinear characteristic index value with a detection threshold to determine the oscillation type of the oscillation source power electronic converter includes: If the value of the nonlinear characteristic index is greater than the detection threshold, then the oscillation type is nonlinear oscillation; Otherwise, the oscillation type is linear oscillation.

8. An oscillation detection device for an independent power system with a pulse load, characterized in that, include: The measurement unit is used to acquire grid-side voltage data and grid-side current data of each grid-connected device in an independent power system, wherein the grid-connected device includes at least a synchronous motor, a pulse load, and a power electronic converter; The first detection and analysis unit is used to monitor the supplied energy of each synchronous motor through the grid-side voltage data and grid-side current data of each synchronous motor, and to determine whether there is synchronous motor power oscillation caused by pulse load and to identify the oscillation source based on the supplied energy; wherein, the grid-side voltage data of the synchronous motor includes the instantaneous grid-side voltage data of the synchronous motor, and the grid-side current data of the synchronous motor includes the instantaneous grid-side current data of the synchronous motor. The second detection and analysis unit is used to monitor the oscillation characteristics of each power electronic converter by using grid-side voltage data and grid-side current data of each power electronic converter in the absence of synchronous motor power oscillation caused by pulse load. It is used to search for power electronic converters that may participate in the oscillation based on the oscillation characteristics. The grid-side voltage data of the power electronic converter includes the three-phase instantaneous voltage data of the power electronic converter, and the grid-side current data of the power electronic converter includes the three-phase instantaneous current data of the power electronic converter. The third detection and analysis unit determines the oscillation source power electronic converter based on the Hamiltonian energy of the power electronic converter control system where the power electronic converter to be identified is located. The fourth detection and analysis unit calculates the nonlinear characteristic index value of the oscillation source power electronic converter, compares the nonlinear characteristic index value with the detection threshold, and determines the oscillation type of the oscillation source power electronic converter. The detection threshold is a nonlinear characteristic index value of the power electronic converter calculated under normal background harmonic conditions. The nonlinear characteristic index value is determined based on the biphase coherence coefficient of the timing signal of the power electronic converter, and the timing signal is obtained based on the grid-side current data.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the oscillation detection method for an independent power system with pulsed load as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the oscillation detection method for an independent power system with pulse load as described in any one of claims 1 to 7.

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