CN106226653A - The transfer law assessment system of the voltage dip of multistage power grid and appraisal procedure - Google Patents

Abstract

The invention discloses a transmission law evaluation system and evaluation method of voltage sags in a multi-level power grid. The transmission law evaluation system includes a power quality monitoring terminal and an evaluation device connected to the power quality monitoring terminal in communication; The quality monitoring terminal includes: a signal acquisition module, which is used to collect the basic power parameters of the bus node to which it belongs; a first judgment module, which is used to process and analyze the three-phase voltage in the basic power parameters to judge whether the node is affected by the voltage sag. Cause the actual voltage amplitude of the node to be lower than the preset threshold value of the rated voltage; The voltage is recorded and processed to record the voltage fault waveform; the first communication module is used to upload the voltage fault waveform and basic power parameters to the evaluation device; the evaluation device has a built-in simulation power grid model of the multi-level power grid.

Description

Evaluation system and evaluation method for transfer law of voltage sag in multi-level power grid

technical field

The invention relates to an evaluation system and an evaluation method of the regularity of each characteristic quantity of voltage sag in a multi-level power grid transmitted through network lines and different transformer connection forms.

Background technique

With the construction of smart grid, the system capacity, scale, voltage level and other rapid development, the complexity and diversity of the system, user productivity and equipment sensitivity increase. Fundamental changes have taken place in the load structure and electrical characteristics, especially renewable energy power generation systems, user equipment and industrial processes based on microelectronics, computers, power electronics and other technologies are increasingly connected to the power grid, and these devices have great influence on the voltage Sags are very sensitive, making voltage sags the most serious power quality problem.

The characteristics of voltage sags caused by different types of short-circuit faults are very different under different system neutral point grounding methods, and different transformer winding wiring methods will affect the transmission of voltage sags. At present, relevant experts at home and abroad have proposed a series of theories related to the characteristics of voltage sags and propagation, but they are limited to theoretical research, and there is no verification of the combination of theory and practice for the actual transmission of voltage sags in multi-level power grids. Therefore, it is necessary to invent a monitoring and evaluation system for voltage sags in multi-level power grids to verify and analyze the magnitude of voltage sags caused by different types of short-circuit faults under different neutral point grounding methods and different transformer winding wiring methods. The phase characteristics and transmission mechanism are of great significance to the improvement of voltage sag control measures and the prevention of large-scale power outages caused by voltage sag.

Contents of the invention

Aiming at the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: to provide a multi-level power grid voltage sag transfer rule evaluation system and evaluation method, which can learn from the power quality of each node in the multi-level power grid. The monitoring terminal obtains the voltage sag data of a multi-level power grid and the monitored power parameters, and realizes the sag source location function through the sag source location algorithm; by importing the multi-level power grid topology and its network parameters in PSD-BPA format into the software system, Combined with the previous positioning results, the simulation transmission analysis of voltage sag is realized. Finally, the transmission characteristics of voltage sag in the multi-level power grid are evaluated by combining the voltage sag recording wave data of the actual grid and the voltage sag simulation results of the actual grid simulation model.

In order to solve the above technical problems, a technical solution adopted by the present invention is to provide a multi-level grid voltage sag transfer rule evaluation system, including a power quality monitoring terminal set at each voltage level bus node in the multi-level grid And an evaluation device communicatively connected to the power quality monitoring terminal;

The power quality monitoring terminal includes:

The signal collection module is used to collect the basic power parameters of the bus node to which it belongs, wherein the basic power parameters include: three-phase voltage, three-phase current, and reactive power;

The first judging module is used to process and analyze the three-phase voltage in the basic power parameters to judge whether the node is affected by the voltage sag and the actual voltage amplitude of the node is lower than the preset threshold value of the rated voltage;

The wave recording module is used to record the voltage to record the voltage fault waveform when the first judging module judges that the actual voltage at the node is lower than the preset threshold value of the rated voltage;

a first communication module, configured to upload the voltage fault waveform and basic power parameters to the evaluation device;

The evaluation device has a built-in simulation grid model of the multi-level power grid, and the evaluation device includes:

The second communication module is used to receive basic power parameters and voltage fault waveforms uploaded by each power quality monitoring terminal;

The fault type acquisition module is used to judge the fault type according to the three-phase voltage and three-phase current in the basic power parameters received by the second communication module; the characteristic quantity calculation module is used to obtain the three-phase voltage sag according to the voltage fault waveform The feature quantity information, wherein, the feature quantity information includes sag amplitude, duration, sag start angle, phase jump;

The location information acquisition module of the sag source is used to obtain the location information of the sag source according to the reactive power change in the basic power parameters uploaded by all power quality monitoring terminals;

The simulation module is used to combine the node location information corresponding to the sag source, the voltage sag feature information corresponding to the node, and the fault type to simulate that the impact of the sag source is lower than the rated voltage on the basis of the simulated power grid model. Node information of all nodes with preset voltage thresholds, wherein the node information includes node name, initial voltage, fault voltage, fault type;

The comparison and evaluation module is used to compare and evaluate the measured node information corresponding to all nodes affected by the sag source that are lower than the preset threshold value of the rated voltage with the node information output by simulation, so as to evaluate The consistency of the measured node information and the simulated node information can compare and evaluate the actual transmission law of voltage sag in the multi-level power grid.

Further, the first communication module is further configured to upload the basic power parameters to the evaluation device when the first judging module judges that no voltage sag occurs;

The second communication module is also used to receive the basic power parameters uploaded by the first communication module;

The evaluation device also includes a second judging module, which is used to judge whether the second communication module receives basic power parameters, or basic power parameters and voltage fault waveforms;

The fault type acquiring module is further configured to, when the second judging module judges that what the second communication module receives are basic power parameters and voltage fault waveforms, according to three of the basic power parameters received by the second communication module Phase voltage and three-phase current to judge the fault type;

The feature calculation module is also used to obtain the characteristics of the three-phase voltage sag according to the voltage fault waveform when the second judging module judges that what the second communication module receives is the basic power parameters and the voltage fault waveform quantity information;

The location information acquisition module of the sag source is further configured to, when the second judging module judges that what the second communication module has received are basic power parameters and voltage fault waveforms, according to the reactive function in the basic power parameters The location information of the source of the sag is obtained.

Further, the characteristic quantity calculation module is also used to calculate and obtain the characteristic quantity information of the three-phase voltage sag through an improved single-phase DQ transformation algorithm.

Further, the acquisition module of the position information of the dip source includes:

The rough position information extraction submodule of the sag source is used to obtain the rough area where the sag source occurs according to the non-functional change in the received voltage sag data;

The accurate node obtaining sub-module is used to obtain the accurate node where the sag occurs according to the principle that the closer the node is to the fault point, the greater the voltage drop is.

Further, the simulated power grid model includes a multi-level power grid topology in PSD-BPA format and its network parameters, wherein the network parameters include line impedance, transformer, busbar, load, operation mode, generator, reactive power compensation equipment parameter.

Further, the basic power parameters also include real-time active power of each node, three-phase voltage unbalance degree and phase.

Further, the simulation module of the evaluation device also includes a fault information setting sub-module, which is used for the user to set the line and bus node fault information on the basis of the simulated power grid model, so as to provide accurate location information of the sag source .

Further, the power quality monitoring terminal is a voltage sag synchronous monitoring device, which has a GPS clock module for providing synchronous clock information.

Further, it is characterized in that: the signal acquisition module is connected to the three voltage transformers and the three current transformers at the corresponding bus nodes to collect the basic power parameters.

In order to solve the above technical problems, another technical solution adopted by the present invention is to provide a method for evaluating the transmission law of voltage sags in a multi-level power grid, which includes the following steps:

Receive the basic power parameters and voltage fault waveforms generated by the influence of voltage sags uploaded by the power quality monitoring terminal at the bus node of each voltage level; wherein, the basic power parameters include three-phase voltage, three-phase current, reactive power ;

According to the reactive function changes in the basic power parameters uploaded by all power quality monitoring terminals, the position information of the sag source is obtained;

According to the voltage fault waveform uploaded by each power quality monitoring terminal, the characteristic quantity information of the three-phase voltage sag is obtained, wherein the characteristic quantity information includes the sag amplitude, duration, sag start angle, and phase jump;

On the basis of the pre-imported simulated power grid model, combine the node information corresponding to the sag source and the feature quantity information corresponding to the node to simulate all nodes affected by the sag source that are lower than the preset threshold value of the rated voltage Information, wherein the node information includes node name, initial voltage, fault voltage, fault type;

Comparing and evaluating the measured node information corresponding to the preset threshold value of the rated voltage affected by the sag source with the simulated node information, so as to evaluate the relationship between the measured node information and the simulated node information Consistency, so that the actual transfer law of voltage sags in multi-level power grids can be compared and evaluated.

The evaluation system and evaluation method of the transmission rule of the voltage sag of the multi-level power grid of the present invention can obtain the location information of the voltage sag source and the three-phase voltage by analyzing the voltage sag data of the power quality monitoring terminal installed in the multi-level power grid. The characteristic quantity information of the sag, realizes the simulation of the voltage sag according to the location information of the sag source and the characteristic quantity information, realizes the simulation transfer analysis of the voltage sag, and finally combines the voltage sag recorded wave data of the actual power grid and the simulation model of the actual power grid The results of the voltage sag simulation can evaluate the consistency of other nodes under the influence of a certain voltage sag with the simulated waveform and node information, and evaluate the transfer law and transfer characteristics of the voltage sag between the multi-level grid line and the transformer. When a voltage sag occurs at a certain node, according to its transfer characteristics, other nodes under the same bus will be affected by the voltage sag and cause a voltage sag, and the evaluation and comparison are confirmed according to the set voltage sag threshold The number of nodes, names, etc., and then compare and evaluate the nodes where the original voltage sag occurred and these nodes with the simulated simulation information (including the above-mentioned node information), so as to obtain the transfer law and characteristics of the voltage sag in the multi-level power grid. It is of great significance to improve the follow-up voltage sag control measures and prevent large-scale power outages caused by voltage sags.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a block diagram of the first embodiment of the system for evaluating the transmission law of voltage sags in a multi-level power grid according to the present invention.

Fig. 2 is a block diagram of the power quality monitoring terminal in Fig. 1 .

Fig. 3 is a block diagram of a second embodiment of the system for evaluating the transmission law of voltage sags in a multi-level power grid according to the present invention.

Fig. 4 is a flow chart of the first embodiment of the method for evaluating the transmission law of voltage sags in the multi-level grid according to the present invention.

Fig. 5 is a flowchart of a method for obtaining voltage sag sources in the system for evaluating the transfer law of voltage sags in a multi-level power grid according to the present invention.

Fig. 6 is a calculation flow chart of the voltage sag simulation module of the multi-level power grid of the present invention.

Fig. 7 is a flow chart of the second embodiment of the method for evaluating the transmission law of voltage sags in the multi-level power grid according to the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Fig. 1 and Fig. 2, the evaluation system for evaluating the transmission law of voltage sags in the multi-level power grid of the present invention includes a power quality monitoring terminal corresponding to a number of voltage level bus nodes one by one and an evaluation device connected to the power quality monitoring terminal for communication , each power quality monitoring terminal is set at each voltage level bus node in one-to-one correspondence. in:

The power quality monitoring terminal may be a voltage sag synchronous monitoring device, which has a GPS clock module for providing synchronous clock information. The advantage is that it can effectively guarantee the extremely high time accuracy of the monitoring of the start and end moments of the voltage sag by the power quality monitoring devices at each voltage level, so that the relative time accuracy of the monitoring devices for the same voltage sag source can be monitored synchronously. achieved within 10 microseconds. It can be understood that the above-mentioned GPS clock module is not used to limit the power quality monitoring terminal of the present invention. In some embodiments, the power quality monitoring terminal can also use any existing one for monitoring and collecting electrical signals and A device or device converted into basic electrical parameters.

The power quality monitoring terminal includes a signal acquisition module, a first judgment module, a wave recording module, and a first communication module.

The signal collection module is used to collect the basic power parameters of the bus node to which it belongs. In this embodiment, the signal collection module is connected to the three voltage transformers and the three current transformers at the corresponding bus nodes to collect the basic power parameters. Specifically, the signal acquisition module includes a voltage and current transmission module, a signal conditioning module, an A/D conversion module, and a phase-locked loop, and the voltage and current transmission module is electrically connected to three voltage transformers and three current transformers. connected to receive signals from three voltage transformers and three current transformers, the comprehensive function of the voltage and current transmission module and the signal conditioning module is to convert the obtained voltage signal and current signal into A/D sampling Voltage signal; the A/D conversion module is used to convert the analog signal into a digital signal, and the function of the phase-locked loop is to realize the automatic control of phase synchronization, so as to ensure that the A/D conversion chip can collect data according to the actual frequency of the power grid. In this embodiment, a signal processing module may also be included, and the signal processing module is used to calculate the collected and A/D converted data to obtain the basic power parameters. It can be understood that the signal processing module It can be regarded as a sub-module in the signal acquisition module, or it can be an independent processing module.

In this embodiment, the basic power parameters include at least three-phase voltage, three-phase current, and reactive power. In some embodiments, the basic power parameters may also include active power, three-phase voltage unbalance, phase and so on.

The first judging module is used to process and analyze the three-phase voltage in the basic power parameters to judge whether the actual voltage amplitude of the node is lower than the preset threshold value of the rated voltage due to the influence of the voltage sag.

The wave recording module is used for when the first judging module judges that the actual voltage at the node is lower than the preset threshold value of the rated voltage (for example, lower than 10% or more of the rated voltage, that is, 90% of the rated voltage % or below), then record the voltage to record the voltage fault waveform;

The first communication module is used to upload the voltage fault waveform and the basic power parameters to the evaluation device; the voltage fault waveform and basic power parameters can be packaged and uploaded to the evaluation device through the first communication module The evaluation device is described so that the evaluation device performs evaluation according to the received voltage fault model and corresponding basic power parameters.

The evaluation device is built with a simulated power grid model of the multi-level power grid, and the evaluation device is a software module or system placed in a computer. Specifically, in this embodiment, the evaluation device has a database, and the database module acts as a data center (data storage/reading center) to perform data interaction with other modules of the evaluation device described below. The first communication module is used to transmit the monitored data (basic power parameters and voltage fault waveform) to the database module through the data interface, so as to store the received data in the database module and associate it with the simulated power grid model, and the database module can receive The obtained basic power parameters and voltage fault waveforms are comprehensively sorted and stored, and the imported simulated power grid model is analyzed for data, providing data query functions, etc. In other embodiments, other storage methods can be used as the data center, for example, the imported simulated grid model, data uploaded by the power monitoring terminal, etc. can be stored through the storage module, so that various data can be associated with the simulated grid model.

The simulated power grid model is mainly composed of a PSD-BPA format multi-level power grid topology and its network parameters, wherein the network parameters include parameters of line impedance, transformer, busbar, load, operation mode, generator, and reactive power compensation equipment. In practical application, the multilevel power grid topology and its network parameters in PSD-BPA format can be imported into the database.

In this embodiment, the evaluation device includes a second communication module, a fault type acquisition module, a characteristic quantity calculation module, a sag source location information acquisition module, a simulation module, and a comparison and evaluation module. in:

The second communication module is used to receive basic power parameters and voltage fault waveforms uploaded by each power quality monitoring terminal;

The fault type acquisition module is used to judge the fault type according to the three-phase voltage and three-phase current in the basic power parameters received by the second communication module; specifically, the fault type acquisition module can be judged by the method of symmetrical components Fault type. The fault types include: single-phase fault, two-phase short-circuit fault, two-phase ground short-circuit fault, and three-phase short-circuit fault.

The characteristic quantity calculation module is used to obtain the characteristic quantity information of the three-phase voltage sag according to the voltage fault waveform, wherein the characteristic quantity information includes sag amplitude, duration, sag start angle, phase jump . In this example, the feature quantity information of the three-phase voltage sag is mainly calculated through an improved single-phase DQ transformation algorithm. In other embodiments, the feature quantity information of the three-phase voltage sag can also be obtained by short-time Fourier transform and wavelet transform.

The location information acquisition module of the sag source is used to obtain the location information of the sag source according to the reactive function changes in the basic power parameters uploaded by all power quality monitoring terminals. The module for obtaining location information of sag sources includes the following submodules: a submodule for extracting rough location information of sag sources, which is used to obtain a rough area where sag sources occur according to the non-functional changes in the received voltage sag data ; Accurate node acquisition sub-module, used to acquire the exact node where the sag occurs according to the principle that the closer the node is to the fault point, the greater the voltage drop.

The simulation module is used to combine the node location information corresponding to the sag source, the voltage sag feature information corresponding to the node, and the fault type to simulate that the impact of the sag source is lower than the rated voltage on the basis of the simulated power grid model. The node information of all nodes with preset voltage thresholds, wherein the node information includes node name, initial voltage (namely rated voltage), fault voltage, and fault type; the specific simulation steps of the simulation module are shown in Figure 6, It will not be described in detail here.

The comparison and evaluation module is used to compare and evaluate the measured node information corresponding to all nodes affected by the sag source that are lower than the preset threshold value of the rated voltage with the node information output by simulation, so as to evaluate The consistency of the measured node information and the simulated node information can compare and evaluate the actual transmission law of voltage sag in the multi-level power grid.

In this embodiment, the simulation module of the evaluation device can also optionally include a fault information setting sub-module, which is used for users to set the location and fault type of the fault on the basis of the simulated power grid model, so as to provide the fault information for the simulation module. Provide accurate sag source location information. Adding this fault information setting module has the advantages and functions: when the position source information and/or fault type of the sag source are not as accurate as the position information known to the user, the user can manually modify the position information and/or fault of the sag source type to provide more accurate data for subsequent simulation and evaluation, making subsequent simulation more accurate and evaluation more accurate.

In the embodiment of the present invention, the location information of the voltage sag source and the characteristic quantity information of the three-phase voltage sag can be obtained through the analysis of the voltage sag data of the power quality monitoring terminal installed in the multi-level power grid. The characteristic quantity information realizes the simulation of voltage sag, realizes the simulation transmission analysis of voltage sag, and finally combines the voltage sag recording data of the actual power grid and the voltage sag simulation result of the actual power grid simulation model to evaluate the voltage sag in a certain voltage sag The consistency of other nodes under the influence of the simulation waveform and node information can be used to evaluate the transfer law and transfer characteristics of voltage sag between multi-level power grid lines and transformers. When a voltage sag occurs at a certain node, according to its transfer characteristics, other nodes under the same bus will be affected by the voltage sag and cause a voltage sag. According to the set voltage sag threshold (such as falling to the initial 90% or less of the voltage) to confirm the number, name, etc. of nodes for evaluation and comparison, and then compare and evaluate the nodes where the original voltage sag occurred and these nodes with the simulation information (including the above node information) to obtain the voltage Transfer law and characteristics of sag in multilevel power grid. It is of great significance to improve the follow-up voltage sag control measures and prevent large-scale power outages caused by voltage sags.

Please refer to FIG. 3 . FIG. 3 is a block diagram of a second embodiment of the system for evaluating the transfer law of voltage sags in a multi-level power grid according to the present invention. The evaluation system for evaluating the transfer law of voltage sags in the multi-level power grid of this embodiment includes a power quality monitoring terminal and an evaluation device, and the configuration of the power quality monitoring terminal is the same as or similar to that of the first embodiment. The power quality monitoring terminal of this embodiment includes a signal acquisition module, a first judging module, and a wave recording module that have the same or similar structure or function as those of the first embodiment.

The difference between the power quality monitoring terminal of this embodiment and the first embodiment is:

The first communication module is also used to send the collected basic power parameters to the evaluation device for storage in a normal state (that is, no voltage sag occurs), so as to be inquired by relevant personnel. .

The evaluation device in this embodiment also includes a second communication module, a fault type acquisition module, a characteristic quantity calculation module, a sag source information acquisition module, a simulation module, a comparison and evaluation module, and the like. The difference between the evaluation device of this embodiment and the first embodiment is:

The second communication module in this embodiment is also used to receive the basic power parameters uploaded by the first communication module in a normal state (when no voltage sag occurs);

The evaluation device also includes:

The second judging module is used to judge whether the second communication module receives the basic power parameters, or the basic power parameters and voltage fault waveforms.

The fault type acquisition module of this embodiment is also used to, when the second judging module judges that what the second communication module has received are basic power parameters and voltage fault waveforms, according to the basic power parameters received by the second communication module The three-phase voltage and three-phase current judge the type of fault; the characteristic quantity calculation module of the present embodiment is also used for when the second judgment module judges that what the second communication module receives is the basic power parameter and voltage fault waveform, According to the voltage fault waveform, the feature quantity information of the three-phase voltage sag is obtained, wherein the feature quantity information includes the sag amplitude, duration, sag start angle, and phase jump; the sag source position information acquisition module, It is also used to obtain the position information of the sag source according to the reactive function change in the basic power parameters when the second judging module judges that the received by the second communication module are basic power parameters and voltage fault waveforms.

The evaluation device is used to store the received basic power parameters in a normal state into a corresponding database or a storage module to be associated with the power grid simulation model, so that users can inquire and monitor at any time, and it is more convenient for users to conduct multi-level on-site monitoring. Grid monitoring and management.

Please refer to FIG. 4 . FIG. 4 is a flow chart of a first embodiment of a method for evaluating transfer laws of voltage sags in a multi-level power grid according to the present invention. The method for evaluating the transmission law of voltage sags in the multi-level power grid in this embodiment is based on the above-mentioned transmission law evaluation system, and includes the following steps:

S101. Receive the basic power parameters and voltage fault waveforms generated by the influence of voltage sags uploaded by the power quality monitoring terminal at the bus node of each voltage level; wherein, the basic power parameters include three-phase voltage, three-phase current, Work power;

S102. Obtain the location information of the sag source according to the reactive function change in the basic power parameters uploaded by each power quality monitoring terminal;

Please refer to Figure 5, this step includes the following sub-steps:

S1021. Obtain the voltage sag data received in step S101;

S1022. According to the reactive power variation of the monitoring point, extract the approximate area where the sag source occurs;

S1033, judging the exact node where the sag occurs according to the principle that the closer the node is to the fault point, the greater the voltage drop;

S1044. Output the location information of the dip source according to the exact node.

S103. According to the voltage fault waveform, the feature quantity information of the three-phase voltage sag is obtained, wherein the feature quantity information includes the sag amplitude, duration, sag start angle, and phase jump; the S103 and S102 The steps are not in strict order, and their order can be interchanged.

S104. On the basis of the pre-imported simulated power grid model, combine the node information corresponding to the sag source and the feature quantity information corresponding to the node to simulate all nodes affected by the sag source that are lower than the preset threshold value of the rated voltage The node information, wherein, the node information includes node name, initial voltage, fault voltage, fault type;

Please refer to Figure 6, this step includes the following sub-steps:

S1041. Solve the power flow according to the imported simulated power grid model, and calculate the voltage before the fault; solve the power flow and calculate the voltage of each node before the fault according to the imported power grid model parameters (multi-level power grid topology structure in PSD-BPA format and its network parameters);

S1042, form the admittance matrix of each sequence node; form the admittance matrix of each node of the grid model according to the multi-level power grid topology structure in PSD-BPA format and its network parameters

S1043, scanning the output result of the sag source position output in step S103;

S1044. Calculate the mutual impedance between each node and the fault location (sag source location) and the self-impedance of the fault location according to the admittance matrix;

S1045. Calculate the voltage of each node according to the fault type;

S1046. Determine whether the positioning calculation result has been scanned;

S1047. If yes, output the simulation results (that is, the characteristic quantity of the node corresponding to the sag source, the node information of all nodes lower than the predetermined threshold value of the rated voltage caused by the sag source, etc.), otherwise, go to step S1043. The output results include the four feature information of the node corresponding to the sag source, the node information of the node, and all the threshold values that cause the voltage amplitude to be lower than the rated voltage amplitude due to the influence of the voltage sag of the sag source. node information of the node;

S105. Compare and evaluate the measured node information corresponding to the preset threshold of the rated voltage affected by the sag source with the simulated node information, so as to evaluate the measured node information and the simulated node information The consistency of information, so that the actual transfer law of voltage sags in multi-level power grids can be compared and evaluated.

In the embodiment of the present invention, when a voltage sag occurs at a certain node, according to its transfer characteristics, other nodes under the same bus will be affected by the voltage sag and cause a voltage sag phenomenon. According to the set voltage sag threshold (such as drop to 90% of the initial voltage) to confirm the number, name, etc. of nodes for evaluation and comparison, and then compare and evaluate the nodes where the original voltage sag occurred and these nodes with the simulation information (including the above-mentioned node information) to obtain Transmission law and characteristics of voltage sag in multi-level power grid. It is of great significance to improve the follow-up voltage sag control measures and prevent large-scale power outages caused by voltage sags.

Please refer to FIG. 7 . FIG. 7 is a flow chart of a second embodiment of the method for evaluating the transmission law of voltage sags in a multi-level power grid according to the present invention. This method is carried out based on the evaluation system of the above-mentioned second embodiment, and this method includes the following steps:

S201. Receive the basic power parameters and voltage fault waveforms generated by the influence of voltage sags uploaded by the power quality monitoring terminal at each voltage level bus node, or receive the basic power quality monitoring terminal uploaded by the power quality monitoring terminal at each voltage level bus node. Power parameters; wherein, the basic power parameters include three-phase voltage, three-phase current, and reactive power; if the basic power parameters and voltage fault waveforms are received, enter step S202, and if only the basic power parameters are received , then turn to step S206;

S202. If the basic power parameters and voltage fault waveforms are received, obtain the location information of the sag source according to the reactive function change in the basic power parameters;

S203. According to the voltage fault waveform, the feature information of the three-phase voltage sag is obtained, wherein the feature information includes the sag amplitude, duration, sag start angle, and phase jump; the steps of S103 and S102 There is no strict order, and their order can be interchanged.

S204. On the basis of the pre-imported (or embedded) simulated power grid model, combine the node information corresponding to the sag source and the feature quantity information corresponding to the node to simulate a preset that is affected by the sag source and is lower than the rated voltage Node information of all nodes of the threshold, wherein the node information includes node name, initial voltage, fault voltage, fault type;

S205. Compare and evaluate the measured node information corresponding to the preset threshold of the rated voltage affected by the sag source with the simulated node information, so as to evaluate the measured node information and the simulated node information The consistency of the information, so that the transmission law of the voltage sag can be compared and evaluated.

S206. If the received basic power parameters are received, store the received basic power parameters, so that the basic power parameters are associated with the simulated power grid model, so that they can be queried and monitored by users.

The above is only the embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technical fields, All are included in the scope of patent protection of the present invention in the same way.

Claims (10)

1. a transfer law assessment system for the voltage dip of multistage power grid, including being located at each electric pressure in multistage power grid Electric energy quality monitoring terminal at bus nodes and the apparatus for evaluating being connected with described electric energy quality monitoring terminal communication；

Described electric energy quality monitoring terminal includes:

Signal acquisition module, for gathering the firm power parameter of affiliated bus nodes, wherein, described firm power parameter bag Include: three-phase voltage, three-phase current, reactive power；

First judge module, for carrying out Treatment Analysis to judge whether this node is subject to the three-phase voltage in firm power parameter Voltage dip affects and causes the virtual voltage amplitude pre-set threshold value less than rated voltage of this node；

When the first judge module, record mode block, for judging that the virtual voltage obtained at this node is less than the default valve of rated voltage During value, then voltage being carried out records ripple and processes to enroll voltage failure waveform；

First communication module, for being uploaded to described apparatus for evaluating by this voltage failure waveform and firm power parameter；

Described apparatus for evaluating is built-in with the simulated grid model of described multistage power grid, and described apparatus for evaluating includes:

Second communication module, for receiving firm power parameter and the voltage failure ripple that each electric energy quality monitoring terminal is uploaded Shape；

Fault type acquisition module, the three-phase voltage and three in the firm power parameter received according to the second communication module Phase current failure judgement type；Characteristic quantity computing module, for obtaining three-phase voltage sag according to described voltage failure waveform Characteristic quantity information, wherein, described characteristic quantity information includes temporary range of decrease value, persistent period, drops initial angle, phase hit temporarily；

Fall source location information acquisition module temporarily, in the firm power parameter uploaded according to all electric energy quality monitoring terminals The positional information in source is dropped in reactive power change temporarily；

Emulation module, for combining node location information, this node that fall source is corresponding temporarily on the basis of described simulated grid model Corresponding voltage dip characteristic quantity information, fault type simulate to be affected by this temporary fall source and are less than presetting of described rated voltage The nodal information of all nodes of threshold values, wherein, described nodal information includes nodename, initial voltage, false voltage, fault Type；

Evaluation module, for by the described all nodes being affected the pre-set threshold value less than described rated voltage by fall source temporarily The nodal information of corresponding actual measurement nodal information and simulation data is compared assessment, with evaluate actual measurement nodal information and The concordance of the nodal information of emulation such that it is able to Evaluation goes out voltage dip actual transfer rule in multistage power grid.

2. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that: described the One communication module is additionally operable to, when the first judge module judges not produced voltage dip, described firm power parameter be uploaded To described apparatus for evaluating；

Described second communication module, is additionally operable to receive the firm power parameter that described first communication module is uploaded；

Described apparatus for evaluating also includes the second judge module, is that firm power is joined for judge that the second communication module receives Number, or firm power parameter and voltage failure waveform；

Described fault type acquisition module, is additionally operable to when the second judge module judges to obtain what described second communication module received When being firm power parameter and voltage failure waveform, according to the three-phase electricity in the firm power parameter that the second communication module receives Pressure and three-phase current failure judgement type；

Described characteristic quantity computing module, is additionally operable to judge to obtain that described second communication module receives is when the second judge module When firm power parameter and voltage failure waveform, obtain the characteristic quantity letter of three-phase voltage sag according to described voltage failure waveform Breath；

Described temporary fall source location information acquisition module, is additionally operable to when the second judge module judges that obtaining described second communication module connects Receive be firm power parameter and voltage failure waveform time, obtain according to the idle changes of function in described firm power parameter The positional information in source drops temporarily.

3. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that:

Described characteristic quantity computing module, is additionally operable to be calculated described three-phase voltage sag by the single-phase DQ mapping algorithm improved Characteristic quantity information.

4. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that: described temporarily Fall source location information acquisition module includes:

Fall source coarse position information extracts submodule temporarily, for becoming according to the nonfunctional in the described voltage dip data received Change situation obtains the rough region that fall source occurs temporarily；

Accurately node obtains submodule, obtains generation for falling the biggest principle according to the node voltage that distance fault point is the nearest The accurate node of fall temporarily.

5. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that: described imitative True electric network model includes multistage power grid topological structure and the network parameter thereof of PSD-BPA form, and wherein, described network parameter includes Line impedance, transformator, bus, load, the method for operation, electromotor, reactive-load compensation equipment parameter.

6. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that: described base This parameters of electric power also includes real-time active power, non-equilibrium among three phase voltages and the phase place of each node.

7. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that: institute's commentary The emulation module estimating device also includes that fault message arranges submodule, for supplying user on the basis of described simulated grid model Circuit and bus nodes fault message are set voluntarily, to provide the positional information dropping source the most temporarily.

8. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 1, it is characterised in that: described electricity Can quality monitoring terminal be voltage dip synchronous monitoring device, there is in it gps clock mould for providing synchronised clock information Block.

9. the transfer law assessment system of the voltage dip of multistage power grid as claimed in claim 8, it is characterised in that: its feature Be: described signal acquisition module and three voltage transformers at corresponding bus nodes and three current transformers be all connected with Gather described firm power parameter.

10. a transfer law appraisal procedure for the voltage dip of multistage power grid, comprises the following steps:

Receive that the electric energy quality monitoring terminal at each electric pressure bus nodes uploads is affected by voltage dip and is produced Firm power parameter and voltage failure waveform；Wherein, described firm power parameter includes three-phase voltage, three-phase current, idle merit Rate；

The position in source is dropped temporarily according to the idle changes of function in the firm power parameter that all electric energy quality monitoring terminals are uploaded Confidence ceases；

The voltage failure waveform uploaded according to each electric energy quality monitoring terminal obtains the characteristic quantity information of three-phase voltage sag, its In, described characteristic quantity information includes temporary range of decrease value, persistent period, drops initial angle, phase hit temporarily；

Nodal information corresponding to temporary fall source and this node characteristic of correspondence is combined on the basis of the simulated grid model imported in advance Amount information emulator goes out to be dropped the nodal information that source is affected all nodes of the pre-set threshold value less than described rated voltage temporarily by this, its In, described nodal information includes nodename, initial voltage, false voltage, fault type；

By described by the actual measurement nodal information corresponding to all nodes of the pre-set threshold value that fall source is affected described rated voltage temporarily Compare assessment with the nodal information of emulation, with the concordance of the nodal information of the nodal information Yu emulation that evaluate actual measurement, It is thus possible to Evaluation goes out voltage dip actual transfer rule in multistage power grid.