Characteristic signal generation method and device of power distribution network, equipment and storage medium

Abstract

The invention relates to the technical field of power distribution networks, and provides a characteristic signal generation method, device and equipment of a power distribution network and a storage medium, and the method comprises the steps: determining a corresponding actively-detected low-frequency characteristic signal parameter after the power distribution network breaks down; generating a target low-frequency signal by adopting a corresponding signal modulation technology according to the characteristic signal parameter; when it is confirmed that the power distribution network breaks down, an energy storage power station is controlled to start a three-phase low-frequency signal active injection mode so as to actively inject the corresponding target low-frequency signal; and according to the target low-frequency signal, determining a target fault line with a fault and a fault type. According to the technical scheme, the identifiability of fault features is enhanced in an active mode.

Description

[Technical field]

[0001] The present application relates to the technical field of power distribution networks, and in particular to a method, device, equipment and storage medium for generating characteristic signals of a power distribution network. [Background technology]

[0002] The depletion of fossil energy and the increasingly serious environmental pollution have made it urgent to accelerate the development and utilization of new energy. The realization of the "dual carbon" goal is a long way to go. To this end, the current power grid is guided by the transformation of the energy structure and vigorously develops an active distribution system with renewable clean energy as the main body and distributed power sources as an important form. With the introduction of large-scale distributed power sources into the power grid, the continuous access of more power electronic devices, especially large-capacity converters, has increased the capacitance of the power grid to the ground to a certain extent. In addition, in order to meet the growing power supply demand, the grid structure of the distribution network has accelerated its complexity, and the number of cable lines has continued to increase, which has further significantly increased the capacitive current in the event of a fault. Once a ground fault occurs, the fault arc caused by the increased capacitive current to the ground poses a more serious threat to the safety of power equipment and personnel.

[0003] At present, the distribution network generally adopts the operation mode of neutral point grounding through arc suppression coil. In this type of resonant grounding system, single-phase grounding fault is the most common fault type, accounting for about 70% to 80% of all faults. Although the arc suppression coil can reduce the residual current at the fault point, thereby reducing the impact on the power system equipment in the short term, if the grounding fault is not detected and resolved in time, it may still cause insulation damage, thereby triggering multi-phase or multi-point faults, posing a major threat to the safety and stable operation of the distribution network. Therefore, in order to avoid further development of the accident, it is necessary to select the fault line as soon as possible. [Summary of the invention]

[0004] The embodiments of the present application provide a method, device, equipment and storage medium for generating characteristic signals of a distribution network, aiming to solve technical problems in related technologies such as easy omission and misjudgment of data anomalies in power data anomaly detection, which affects the efficiency of power settlement and business analysis.

[0005] In a first aspect, an embodiment of the present application provides a method for generating a characteristic signal of a distribution network, comprising:

[0006] Determine the low-frequency characteristic signal parameters of the active detection corresponding to the failure of the distribution network;

[0007] According to the characteristic signal parameters, a target low-frequency signal is generated by using a corresponding signal modulation technology;

[0008] When it is confirmed that the distribution network fails, the energy storage power station is controlled to start a three-phase low-frequency signal active injection mode to actively inject the corresponding target low-frequency signal;

[0009] A target fault line and a fault type are determined according to the target low-frequency signal.

[0010] In one embodiment, optionally, the low-frequency characteristic signal parameter includes at least one of the following: a low-frequency frequency value and a low-frequency injection duration.

[0011] In one embodiment, optionally, according to the characteristic signal parameters, a corresponding signal modulation technology is used to generate a target low-frequency signal, including:

[0012] According to the characteristic signal parameters, a sine pulse width modulation technique is used to control the switching state of the switching device by comparing the data of the triangular wave carrier and the sine wave modulation wave to generate an initial low-frequency signal;

[0013] A group of initial low-frequency signals with the same phase are respectively superimposed on the industrial frequency three-phase modulation wave of the energy storage power station to generate the target low-frequency signal.

[0014] In one embodiment, optionally, the target low-frequency signal is generated according to the following expression:

[0015]

[0016] Among them, u' aref 、u' bref 、u' cref represents the three-phase target low-frequency signal, A represents the amplitude of the industrial frequency three-phase modulation wave; ω represents the industrial frequency signal angular frequency; A' represents the amplitude of the initial low-frequency signal, ω' represents the angular frequency of the initial low-frequency signal; r(t) represents the target low-frequency signal injection function, r(t) = u(t-t0)-u(t-t0-T), wherein t0 represents the low-frequency injection time, T represents the low-frequency injection duration, and u(t) represents the step function.

[0017] In one embodiment, optionally, the method further comprises:

[0018] Receive input setting instructions;

[0019] According to the setting instruction, the amplitude of the initial low-frequency signal is set to be equal to the output rated current of the energy storage power station.

[0020] In one embodiment, optionally, the method further comprises:

[0021] When the three-phase low-frequency signal active injection mode is turned on, the timing starts;

[0022] When the timing duration is equal to the low-frequency injection duration, the active injection mode of the three-phase low-frequency signal is turned off.

[0023] In one embodiment, optionally, when the energy storage power station is controlled to start the three-phase low-frequency signal active injection mode, the DC filter capacitor of the energy storage converter of the energy storage power station is converted into a split capacitor through switch control.

[0024] In a second aspect, an embodiment of the present application provides a characteristic signal generating device for a distribution network, comprising:

[0025] A parameter determination module, used to determine the low-frequency characteristic signal parameters of the active detection corresponding to the failure of the distribution network;

[0026] A generating module, used to generate a target low-frequency signal by using a corresponding signal modulation technology according to the characteristic signal parameters;

[0027] A signal injection module, used to control the energy storage power station to start a three-phase low-frequency signal active injection mode when it is confirmed that the distribution network has a fault, so as to actively inject the corresponding target low-frequency signal;

[0028] The fault determination module is used to determine the target fault line and the fault type according to the target low-frequency signal.

[0029] In a third aspect, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for generating characteristic signals of the distribution network when executing the computer program.

[0030] In a fourth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for generating characteristic signals of the distribution network are implemented.

[0031] In the scheme implemented by the characteristic signal generation method, device, system, equipment and storage medium of the above distribution network, the low-frequency characteristic signal parameters of the active detection corresponding to the distribution network fault are determined; according to the characteristic signal parameters, the target low-frequency signal is generated by using the corresponding signal modulation technology; when it is confirmed that the distribution network has a fault, the energy storage power station is controlled to start the three-phase low-frequency signal active injection mode to actively inject the corresponding target low-frequency signal; according to the target low-frequency signal, the target fault line and fault type of the fault are determined. In the present invention, the high controllability of the energy storage converter is utilized, and the three-phase low-frequency voltage signal with the same phase is superimposed on the original modulation wave, thereby realizing the smooth injection of the three-phase low-frequency current signal with the same phase, without the need to add an additional signal generating device, and having good economy; at the same time, the invention realizes the precise injection of the low-frequency same-phase detection current signal by integrating a specific control strategy in the energy storage converter. The implementation of this strategy makes fault detection no longer completely dependent on the natural change of electrical quantity when the fault occurs, but enhances the identifiability of fault characteristics in an active way; the acquisition and detection system of the present invention has a high degree of real-time performance. Through real-time monitoring and rapid response mechanisms, the system can detect low-frequency in-phase detection current signals within a very short time after a fault occurs, and extract and analyze characteristic signals, thereby realizing functions such as fault line selection; the present invention also has good adaptability and flexibility. Since the injection and monitoring strategies of the detection signals can be dynamically adjusted according to the real-time status of the power grid, the present invention can adapt to different power grid operating conditions and fault types, and can improve the universality of fault detection.

Brief Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic flow chart of a method for generating a characteristic signal of a distribution network according to an embodiment of the present application is shown.

[0034] Figure 2 Schematic diagram of the implementation principle of the present invention

[0035] Figure 3 It is a schematic diagram of an implementation scenario of the present invention;

[0036] Figure 4 is a system structure diagram of an energy storage power station in an embodiment of the present invention;

[0037] Figure 5 , Figure 6 and Figure 7 is a control strategy block diagram of a traditional energy storage power station in an embodiment of the present invention;

[0038] Figure 8 This is a control block diagram of an energy storage converter with active injection of a 10 Hz in-phase signal in an embodiment of the present invention;

[0039] Fig. 9 It is an overall control block diagram of an energy storage converter with an additional 10Hz in-phase signal active injection mode in an embodiment of the present invention;

[0040] Fig.10 is a schematic diagram of a 35kV distribution network simulation model in an embodiment of the present invention;

[0041] Fig.11 and Fig.12 It is a diagram showing the effect of generating a 10 Hz in-phase signal during a fault of the energy storage converter in an embodiment of the present invention.

[0042] Fig.13 A block diagram of a characteristic signal generating device for a power distribution network according to an embodiment of the present application is shown. [Specific implementation method]

[0043] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0044] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0045] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0046] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0047] See also Figure 1 , Figure 1 A schematic flow chart of a method for generating a characteristic signal of a distribution network according to an embodiment of the present application is shown.

[0048] like Figure 1 As shown, according to an embodiment of the present application, a method for generating a characteristic signal of a distribution network includes:

[0049] Step S101, determining the low-frequency characteristic signal parameters of the active detection corresponding to the failure of the distribution network;

[0050] In one embodiment, optionally, the low-frequency characteristic signal parameter includes at least one of the following: a low-frequency frequency value and a low-frequency injection duration.

[0051] Furthermore, the step S101 is specifically as follows:

[0052] First, the online positioning scheme needs to consider the impact of the injected signal on the power quality of the system. The low-frequency signal to be injected can be regarded as an interharmonic, and the introduction of interharmonics will cause fluctuations in the root mean square value and peak value of the voltage waveform, thereby generating flicker phenomena and causing visual interference and other hazards. Specifically, the voltage fluctuation frequency formed by the superposition of a certain interharmonic and the fundamental wave is called the modulation frequency or beat frequency, and its calculation formula is

[0053] f=|f IH -hf1|

[0054] Where: f IH is the interharmonic frequency, hf1 is the same as f IH The nearest harmonic order.

[0055] Considering the interharmonics below 50Hz, when f IH Less than 25Hz, the oscillation frequency is itself; when f IH Greater than 25Hz, the oscillation frequency is 50-f IH . Since the interharmonic frequency band that can have a significant impact on the fluctuation of the effective value of voltage is concentrated near the fundamental frequency, and in order to improve the effectiveness of the active fault location scheme, only interharmonics of 25Hz and below are selected. The frequency of the injected detection signal directly affects the size of the equivalent harmonic reactance of the grid branch. As the frequency decreases, the difference in the low-frequency current components flowing through the fault line and the non-fault line becomes more and more obvious. In order to facilitate fault line selection and reduce interference from other frequency signals, the example of the present invention can select a 10Hz sinusoidal signal as a characteristic signal.

[0056] In addition, to prevent the continuous injection of 10Hz detection current signals from having a negative impact on the operation of the power grid, after the energy storage power station starts the 10Hz electrical quantity active detection mode, the harmonic injection will be automatically stopped after a preset time interval. Since the response speed of power electronic devices is in the millisecond level and has high controllability, this paper takes ensuring that the detection signal can achieve fault line selection as the basic principle, and controls the energy storage power station to start the 10Hz in-phase signal injection mode after the fault and last for 1 second, which is conducive to the rapidity of relay protection related work such as fault line selection.

[0057] Finally, in order to construct a clear fault line selection criterion, the amplitude of the detection signal current should be as large as possible in theory. However, the higher the strength of the injected low-frequency signal, the more significant the potential impact on the equipment itself and the power quality of the power grid. In the example of the present invention, since the harmonic signal current is only injected for a short time after the fault, it is sufficient to control its amplitude within the flow capacity of the converter valve. Therefore, the present invention sets the injection signal amplitude to about the rated current value of the energy storage power station output.

[0058] Step S102, generating a target low-frequency signal by using a corresponding signal modulation technique according to the characteristic signal parameters;

[0059] In one embodiment, optionally, step S102 includes:

[0060] According to the characteristic signal parameters, a sine pulse width modulation technique is used to control the switching state of the switching device by comparing the data of the triangular wave carrier and the sine wave modulation wave to generate an initial low-frequency signal;

[0061] A group of initial low-frequency signals with the same phase are respectively superimposed on the industrial frequency three-phase modulation wave of the energy storage power station to generate the target low-frequency signal.

[0062] In one embodiment, optionally, the target low-frequency signal is generated according to the following expression:

[0063]

[0064] Among them, u' aref 、u' bref 、u' cref represents the three-phase target low-frequency signal, A represents the amplitude of the industrial frequency three-phase modulation wave; ω represents the industrial frequency signal angular frequency; A' represents the amplitude of the initial low-frequency signal, ω' represents the angular frequency of the initial low-frequency signal; r(t) represents the target low-frequency signal injection function, r(t) = u(t-t0)-u(t-t0-T), wherein t0 represents the low-frequency injection time, T represents the low-frequency injection duration, and u(t) represents the step function.

[0065] The following is a detailed description using an injection signal of a 10 Hz detection current signal as an example.

[0066] For energy storage converters, the generation of the required 10Hz detection current signal usually relies on pulse width modulation (PWM) technology. PWM technology is based on the impulse equivalence principle, that is, narrow pulses of different shapes but the same impulse have similar effects on inertial systems. Based on this, sine pulse width modulation (SPWM) technology is used to compare the triangular wave carrier u T And the sine wave modulation wave u refBy controlling the switching state of the switching device at its intersection, a series of narrow pulses with consistent amplitude and adjustable width can be generated to simulate a sine wave. This method does not require additional signal injection equipment and has a low cost.

[0067] There are already precedents in engineering for superimposing modulation waves of other frequency components on the basis of industrial frequency modulation waves. For example, in order to improve the utilization rate of DC voltage and the output capacity of voltage source converters, an effective method is to superimpose a third harmonic of appropriate size on the sinusoidal modulation signal of phase voltage to make it saddle-shaped. It can be seen from the double-sided Fourier theory that under this modulation strategy, the output phase voltage of the converter will contain the superimposed third harmonic content.

[0068] Therefore, the power frequency three-phase modulation wave u generated by the original dual-loop control of the energy storage converter aref 、u bref 、u cref On the basis of the short-term (1s) superposition of a group of in-phase 10Hz sinusoidal signals u a10Hz 、u b10Hz 、u c10Hz , while keeping the modulation ratio less than 1, and then obtain the three-phase composite signal u' aref 、u' bref 、u' cref By performing SPWM modulation, the 10Hz signal injection required for active fault location can be achieved.

[0069] It should be noted that in order to highlight the fault characteristics of the detection signal in the ground fault loop, the 10Hz sinusoidal signal short-term superimposed on the industrial frequency three-phase modulation wave is three-phase in phase. Therefore, during the injection period, the DC filter capacitor of the energy storage converter needs to be transformed into a split capacitor through switch control to provide a flow path for the detection signal.

[0070] Step S103, when it is confirmed that the distribution network fails, the energy storage power station is controlled to start the three-phase low-frequency signal active injection mode to actively inject the corresponding target low-frequency signal;

[0071] After confirming that a ground fault has occurred in the distribution network, on the basis of the existing energy storage power station control strategy, the active injection mode of the same-phase low-frequency signal of the additional energy storage power station is used to realize functions related to relay protection such as fault line selection, fully utilize the high controllability of power electronic equipment, and improve the reliability and sensitivity of related protection.

[0072] Step S104: determining a target faulty line and a fault type according to the target low-frequency signal.

[0073] Furthermore, the step S104 is specifically as follows:

[0074] In the example of the present invention, it is necessary to obtain the zero-sequence current of each segment. However, it is not easy to install zero-sequence current transformers at other locations along the line except at the outlet of the substation. Therefore, it is necessary to design a proper zero-sequence current acquisition scheme along the line. It is noted that fault indicators that measure by phase are generally installed along the line. The zero-sequence current can be synthesized in an appropriate manner based on the three-phase current collected by the fault indicator as the data basis for subsequent judgment. However, since the current three-phase fault indicator current is collected independently and there is no normalized time scale, it is impossible to directly synthesize the zero-sequence component.

[0075] To this end, the present invention proposes two feasible solutions: 1) The three-phase fault indicator is modified on-site, the acquisition control modules of the three are connected through communication or control cables, and the CPU of a phase fault indicator is used to dominate the sampling control to ensure the synchronization of the three-phase signal acquisition. After obtaining the current of the current phase and the other two phases, the dominant fault indicator can directly synthesize the available zero-sequence current, which is called an improved fault indicator in the present invention; 2) The fault indicator maintains the current three-phase independent acquisition mode and continuously transmits the collected current signal back to the main station. After the main station obtains the three-phase current sampling sequence for the section, it uses wavelet analysis and other detection technologies that are very sensitive to signal changes to identify the fault occurrence times tA, tB, and tC corresponding to the three-phase currents, and then roughly aligns the three-phase currents according to these three time scales; then, trace back 1 to 2 cycles from the time of the fault occurrence and directly synthesize the three-phase currents.

[0076] The above solution of the present invention is described in detail below in conjunction with specific embodiments.

[0077] Figure 2 The active fault detection is not only applicable to fault line selection, distance measurement and reclosing operation, but also helps to quickly restore normal operation after protection action. The time sequence of fault processing is as follows: Figure 2 shown.

[0078] Figure 3 The figure shows a distribution network system with 5 outgoing lines. The distribution network operates in a way that the neutral point is grounded through an arc suppression coil. Point G is the grounding fault point, RG is the grounding transition resistance, and the neutral point of the distribution network is drawn from the grounding transformer. When a grounding fault occurs, the energy storage power station starts to inject a low-frequency current signal I into the power grid. in .

[0079] When the transition resistance is small, the equivalent capacitive reactance to ground of the distribution network at a frequency of 10Hz is large, so the shunt through the ground capacitance loop is small. In particular, when a single-phase metal grounding fault occurs, the fault line is approximately short-circuited to the ground, and the non-fault line will basically not shunt the low-frequency current signal injected by the energy storage converter.

[0080] Figure 4 The electrochemical energy storage system is composed of a battery pack, a Buck-Boost circuit, a bidirectional converter, a filter circuit and a control system.

[0081] Figure 5-Figure 7 is a control strategy block diagram of a traditional energy storage power station in an embodiment of the present invention. P / Q control uses the active and reactive power of the energy storage system as reference instructions. Its control block diagram is as follows Figure 5 As shown. ref , Q ref are given power reference values, P and Q are measured and calculated values ​​respectively; i dref 、i qref are the reference values ​​of the dq axis components on the AC side respectively; i d 、i q are the measured and calculated values ​​of the dq axis components on the AC side respectively; u d 、u q are the measured and calculated values ​​of the dq axis components of the inverter output voltage respectively; L is the AC side inductance; θ is the phase angle of the system voltage at the grid connection point.

[0082] The DC / DC converter uses constant voltage control, such as Figure 6 As shown, the DC bus reference value U ref With the actual value U dc The difference between the two values ​​is used by the PI regulator to provide a current reference value I for the energy storage side. ref . When U ref >U dc When U ref dc When the energy storage system is charged.

[0083] When a system fault causes a voltage drop, the current reference value of the energy storage system during low voltage ride-through should meet the following requirements without exceeding the overload capacity of the device:

[0084]

[0085]

[0086] Where: I N is the rated output current of the energy storage system; 1.6 is the ratio of reactive current to voltage change, which is determined according to the standard requirements. In addition, the maximum reactive current under asymmetric fault conditions is set to no more than 1.04I N I max is the maximum output current of the energy storage system. The LVRT control strategy block diagram is as follows Figure 7 shown.

[0087] Figure 8 ​This is a control block diagram of the energy storage converter with active injection of 10Hz in-phase signal in the embodiment of the present invention. aref 、u bref 、u cref On the basis of the short-term (1s) superposition of a group of in-phase 10Hz sinusoidal signals u a10Hz 、u b10Hz 、u c10Hz , while keeping the modulation ratio less than 1, and then obtain the three-phase composite signal u' aref 、u' bref 、u' cref By performing SPWM modulation, the 10Hz signal injection required for active fault location can be achieved.

[0088] It should be noted that in order to highlight the fault characteristics of the detection signal in the ground fault loop, the 10Hz sinusoidal signal short-term superimposed on the industrial frequency three-phase modulation wave is three-phase in phase. Therefore, during the injection period, the PCS DC filter capacitor needs to be transformed into a split capacitor through switch control to provide a flow path for the detection signal.

[0089] Fig. 9 1 is an overall control block diagram of an energy storage converter with an additional 10Hz in-phase signal active injection mode in an embodiment of the present invention. dc It is a DC filter capacitor. Through switch control, it is converted into a split capacitor during signal injection to provide a flow path for the injected signal. PCS adopts SPWM modulation. The inverter AC power is filtered by inductor L and connected to the grid at the common connection point through a step-up transformer. PCC,abc and i PCC,abc are the voltage and current at the common connection point, respectively. After low-pass filter (LPF) and dq transformation, the corresponding d-axis component and q-axis component are obtained: PCC,dq and i PCC,dq ; δ is the rotation vector phase angle extracted by the phase-locked loop; P out and Q out are respectively the active power and reactive power output by the energy storage power station; P ref and Q ref I are the reference values ​​of active power and reactive power provided by the maximum power point tracking (MPPT) controller; d,ref and I q,ref They are the d-axis and q-axis components of the inner loop current reference value respectively; is the voltage per unit value at the common connection point; i in,abc is the current at the common connection point at the injection signal frequency; u in,abcis the voltage superimposed at the injection signal frequency; δ0 is the phase angle when the three phases are in phase.

[0090] Fig.10 It is a schematic diagram of the simulation model of the 35kV distribution network in the embodiment of the present invention. The small current grounding system model shown in the figure below is built by PSCAD / EMTDC simulation software to verify the effect of PCS in achieving 10Hz electrical quantity injection. Assuming that a system fault occurs at 1s, the 10Hz signal component in the PCS three-phase voltage modulation wave and the zero-sequence current at the outlet of the energy storage power station are measured respectively.

[0091] Fig.11 and Fig.12 This is a diagram showing the effect of generating a 10Hz in-phase signal during a fault in an energy storage converter according to an embodiment of the present invention. For an energy storage converter, it is only necessary to superimpose a 10Hz voltage signal with the same phase of the three phases on the basis of the three-phase voltage modulation wave to realize a 10Hz detection current i with the same phase of the three phases. in,abc Specifically, after a fault occurs in the export line of the energy storage power station, under the control of the converter (the transient process is about 20ms), a three-phase phase detection current I with an amplitude of 8.7A (approximately equal to its rated current value) and a frequency of 10Hz can be stably injected into the external power grid. in And it continues to output for 1s. The output signal responds quickly and has good stability. It is also used for relay protection related functions such as fault line selection.

[0092] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0093] Fig.13 A block diagram of a characteristic signal generating device for a power distribution network according to an embodiment of the present application is shown.

[0094] like Fig.13 As shown, in a second aspect, an embodiment of the present application provides a characteristic signal generating device 30 for a distribution network, comprising:

[0095] A parameter determination module 31 is used to determine the low-frequency characteristic signal parameters of the active detection corresponding to the failure of the distribution network;

[0096] A generating module 32, configured to generate a target low-frequency signal by using a corresponding signal modulation technique according to the characteristic signal parameters;

[0097] The signal injection module 33 is used to control the energy storage power station to start the three-phase low-frequency signal active injection mode to actively inject the corresponding target low-frequency signal when it is confirmed that the distribution network fails;

[0098] The fault determination module 34 is used to determine a target faulty line and a fault type according to the target low-frequency signal.

[0099] In one embodiment, optionally, the low-frequency characteristic signal parameter includes at least one of the following: a low-frequency frequency value and a low-frequency injection duration.

[0100] In one embodiment, optionally, the generating module includes:

[0101] A signal generating unit, configured to control the switching state of the switching device by comparing the data of the triangular wave carrier and the sine wave modulation wave according to the characteristic signal parameters and adopting the sine pulse width modulation technology to generate an initial low-frequency signal;

[0102] The superposition unit is used to superimpose a group of initial low-frequency signals of the same phase on the industrial frequency three-phase modulation wave of the energy storage power station to generate the target low-frequency signal.

[0103] In one embodiment, optionally, the target low-frequency signal is generated according to the following expression:

[0104]

[0105] Among them, u' aref 、u' bref 、u' cref represents the three-phase target low-frequency signal, A represents the amplitude of the industrial frequency three-phase modulation wave; ω represents the industrial frequency signal angular frequency; A' represents the amplitude of the initial low-frequency signal, ω' represents the angular frequency of the initial low-frequency signal; r(t) represents the target low-frequency signal injection function, r(t) = u(t-t0)-u(t-t0-T), wherein t0 represents the low-frequency injection time, T represents the low-frequency injection duration, and u(t) represents the step function.

[0106] In one embodiment, optionally, the device further comprises:

[0107] A receiving module, used for receiving input setting instructions;

[0108] A setting module is used to set the amplitude of the initial low-frequency signal to be equal to the output rated current of the energy storage power station according to the setting instruction.

[0109] In one embodiment, optionally, the device further comprises:

[0110] A timing module, used to start timing when the active injection mode of the low-frequency signal with three phases is turned on;

[0111] The closing module is used to close the active injection mode of the low-frequency signal with three phases when the timing duration is equal to the low-frequency injection duration.

[0112] In one embodiment, optionally, when the energy storage power station is controlled to start the three-phase low-frequency signal active injection mode, the DC filter capacitor of the energy storage converter of the energy storage power station is converted into a split capacitor through switch control.

[0113] For the specific definition of the characteristic signal generating device of the distribution network, please refer to the definition of the characteristic signal generating method of the distribution network mentioned above, which will not be repeated here. Each module in the above-mentioned characteristic signal generating device of the distribution network can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0114] It should be understood that the processor may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0115] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the method described in the first aspect of the embodiment is implemented when the processor executes the computer program.

[0116] It should be noted that the above functions or steps that can be implemented by the computer-readable storage medium or electronic device can refer to the relevant description in the aforementioned method embodiment. To avoid repetition, they will not be described one by one here.

[0117] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0118] It should be understood that, although the terms first, second, etc. may be used to describe the setting unit in the embodiments of the present application, these setting units should not be limited to these terms. These terms are only used to distinguish the setting units from each other. For example, without departing from the scope of the embodiments of the present application, the first setting unit may also be referred to as the second setting unit, and similarly, the second setting unit may also be referred to as the first setting unit.

[0119] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0120] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0121] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0122] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0123] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for generating characteristic signals of a distribution network, characterized in that: include: Determine the low-frequency characteristic signal parameters of the active detection corresponding to the failure of the distribution network; According to the characteristic signal parameters, a target low-frequency signal is generated by using a corresponding signal modulation technology; When it is confirmed that the distribution network fails, the energy storage power station is controlled to start a three-phase low-frequency signal active injection mode to actively inject the corresponding target low-frequency signal; A target fault line and a fault type are determined according to the target low-frequency signal.

2. The method according to claim 1, characterized in that The low-frequency characteristic signal parameter includes at least one of the following: a low-frequency frequency value and a low-frequency injection duration.

3. The method according to claim 2, characterized in that According to the characteristic signal parameters, a target low-frequency signal is generated by using a corresponding signal modulation technology, including: According to the characteristic signal parameters, a sine pulse width modulation technique is used to control the switching state of the switching device by comparing the data of the triangular wave carrier and the sine wave modulation wave to generate an initial low-frequency signal; A group of initial low-frequency signals with the same phase are respectively superimposed on the industrial frequency three-phase modulation wave of the energy storage power station to generate the target low-frequency signal.

4. The method according to claim 3, characterized in that The target low-frequency signal is generated according to the following expression: Among them, u' aref 、u' bref 、u' cref represents the three-phase target low-frequency signal, A represents the amplitude of the industrial frequency three-phase modulation wave; ω represents the industrial frequency signal angular frequency; A' represents the amplitude of the initial low-frequency signal, ω represents the angular frequency of the initial low-frequency signal; r(t) represents the target low-frequency signal injection function, r(t) = u(t-t0)-u(t-t0-T), wherein t0 represents the low-frequency injection time, T represents the low-frequency injection duration, and u(t) represents the step function.

5. The method according to claim 4, characterized in that The method further comprises: Receive input setting instructions; According to the setting instruction, the amplitude of the initial low-frequency signal is set to be equal to the output rated current of the energy storage power station.

6. The method according to claim 2, characterized in that The method further comprises: When the three-phase low-frequency signal active injection mode is turned on, the timing starts; When the timing duration is equal to the low-frequency injection duration, the active injection mode of the three-phase low-frequency signal is turned off.

7. The method according to claim 1, characterized in that When the energy storage power station is controlled to start the three-phase low-frequency signal active injection mode, the DC filter capacitor of the energy storage converter of the energy storage power station is converted into a split capacitor through switch control.

8. A characteristic signal generating device for a distribution network, characterized in that: The device comprises: A parameter determination module, used to determine the low-frequency characteristic signal parameters of the active detection corresponding to the failure of the distribution network; A generating module, used to generate a target low-frequency signal by using a corresponding signal modulation technology according to the characteristic signal parameters; A signal injection module, used to control the energy storage power station to start a three-phase low-frequency signal active injection mode when it is confirmed that the distribution network has a fault, so as to actively inject the corresponding target low-frequency signal; The fault determination module is used to determine the target fault line and the fault type according to the target low-frequency signal.

9. A computer device, characterized in that: include: at least one processor; and, a memory communicatively coupled to the at least one processor; The memory stores instructions executable by the at least one processor, wherein the instructions are configured to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: Computer executable instructions are stored, and the computer executable instructions are used to execute the method according to any one of claims 1 to 7.

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