Email alert
RSS2019 Vol. 31, No. 7
Display Method:
2019,
31: 1-2.
2019,
31: 070001.
doi: 10.11884/HPLPB201931.190202
Abstract:
With the increase in the system scale and informatization level of the critical national infrastructures, the electromagnetic security in extreme electromagnetic environments such as the high-altitude electromagnetic pulse, the intentional electromagnetic interference and the geomagnetic storm has attracted more attention. Unlike conventional electromagnetic events such as the lightning and the overvoltage in power systems, extreme electromagnetic environments are small-probability but high-risk events whose impact mechanisms and evaluation methods are quite different. And the conventional reliability analysis, which adopts the expected value indexes, is difficult to effectively evaluate and manage the risks related to extreme electromagnetic environments. In this context, this paper presents a triangular pyramid model for the study of electromagnetic security of critical infrastructures. Then taking the power grid as an example, it discusses the implication and significance of electromagnetic resilience to critical infrastructures, and finally makes a proposal for the future study of electromagnetic resilience.
With the increase in the system scale and informatization level of the critical national infrastructures, the electromagnetic security in extreme electromagnetic environments such as the high-altitude electromagnetic pulse, the intentional electromagnetic interference and the geomagnetic storm has attracted more attention. Unlike conventional electromagnetic events such as the lightning and the overvoltage in power systems, extreme electromagnetic environments are small-probability but high-risk events whose impact mechanisms and evaluation methods are quite different. And the conventional reliability analysis, which adopts the expected value indexes, is difficult to effectively evaluate and manage the risks related to extreme electromagnetic environments. In this context, this paper presents a triangular pyramid model for the study of electromagnetic security of critical infrastructures. Then taking the power grid as an example, it discusses the implication and significance of electromagnetic resilience to critical infrastructures, and finally makes a proposal for the future study of electromagnetic resilience.
2019,
31: 070002.
doi: 10.11884/HPLPB201931.190140
Abstract:
The early-time high-altitude electromagnetic pulse is an important component of the electromagnetic effect of high-altitude nuclear burst. The relative simulation research work at home and abroad are studied and compared. One of the classical methods EXEMP is introduced in this paper in detail. The numerical result is compared with the IEC reference value of IEC 61000-2-9. The time domain waveform and spatiotemporal distribution of HEMP are studied using numerical result. The influence of burst parameter including energy and height are studied, the uncertainty is quantified by polynomial chaos method and global sensitivity indices.
The early-time high-altitude electromagnetic pulse is an important component of the electromagnetic effect of high-altitude nuclear burst. The relative simulation research work at home and abroad are studied and compared. One of the classical methods EXEMP is introduced in this paper in detail. The numerical result is compared with the IEC reference value of IEC 61000-2-9. The time domain waveform and spatiotemporal distribution of HEMP are studied using numerical result. The influence of burst parameter including energy and height are studied, the uncertainty is quantified by polynomial chaos method and global sensitivity indices.
2019,
31: 070003.
doi: 10.11884/HPLPB201931.190142
Abstract:
This paper presents an efficient time-domain macromodeling algorithm to calculate current and voltage responses of overhead and buried lines to incident field coupling. Based on transmission line theory, the proposed macromodel adopts the analog behavioral modeling of Spice solvers and generalized Method of Characteristics (MoC) to model the frequency-dependent variables, and to calculate the convolution in time domain. This method has a wide applicability as it can both model field coupling to overhead and buried lines. Compared with the finite different time domain method, there is no need to discretize time and space, and adopt numerical inverse Fourier transform or vector fitting method to obtain transient parameters. The efficiency of the macromodel is not limited by line length, so it is valid for modeling long multiconductor lines. Furthermore, the environment and characteristics of HEMP are studied in time and frequency domain, respectively. Finally, two examples are studied to validate the proposed method for field coupling to overhead and buried lines. Using this method, effects of overhead grounding lines on transient response of three-phase power lines and buried power cables terminated with linear or nonlinear protective loads are investigated, respectively. All results show that the macromodel can efficiently calculate the transient responses of incident field coupling to overhead and buried power lines in time domain, especially for long multiconductors with nonlinear elements.
This paper presents an efficient time-domain macromodeling algorithm to calculate current and voltage responses of overhead and buried lines to incident field coupling. Based on transmission line theory, the proposed macromodel adopts the analog behavioral modeling of Spice solvers and generalized Method of Characteristics (MoC) to model the frequency-dependent variables, and to calculate the convolution in time domain. This method has a wide applicability as it can both model field coupling to overhead and buried lines. Compared with the finite different time domain method, there is no need to discretize time and space, and adopt numerical inverse Fourier transform or vector fitting method to obtain transient parameters. The efficiency of the macromodel is not limited by line length, so it is valid for modeling long multiconductor lines. Furthermore, the environment and characteristics of HEMP are studied in time and frequency domain, respectively. Finally, two examples are studied to validate the proposed method for field coupling to overhead and buried lines. Using this method, effects of overhead grounding lines on transient response of three-phase power lines and buried power cables terminated with linear or nonlinear protective loads are investigated, respectively. All results show that the macromodel can efficiently calculate the transient responses of incident field coupling to overhead and buried power lines in time domain, especially for long multiconductors with nonlinear elements.
2019,
31: 070004.
doi: 10.11884/HPLPB201931.180303
Abstract:
The focus of this paper is the electromagnetic characteristics of cylindrical wire grid cage, an equivalent substitute for a hollow conductor cylinder. First of all, the equivalent radius is derived based on the conformal transformation and the equivalent electromagnetic field theory, respectively. Then, the electromagnetic simulation software CST is used to simulate the influence of the density and thickness of the metal wire grid on the risetime, pulse width and peak value of the electric field in the test area. Further, the electric field distributions of the cylindrical wire cage and the hollow conductor cylinder are compared. The results show that the cage structure can completely replace the hollow conductor cylinder and verify the rationality of the equivalent radius theory.
The focus of this paper is the electromagnetic characteristics of cylindrical wire grid cage, an equivalent substitute for a hollow conductor cylinder. First of all, the equivalent radius is derived based on the conformal transformation and the equivalent electromagnetic field theory, respectively. Then, the electromagnetic simulation software CST is used to simulate the influence of the density and thickness of the metal wire grid on the risetime, pulse width and peak value of the electric field in the test area. Further, the electric field distributions of the cylindrical wire cage and the hollow conductor cylinder are compared. The results show that the cage structure can completely replace the hollow conductor cylinder and verify the rationality of the equivalent radius theory.
2019,
31: 070005.
doi: 10.11884/HPLPB201931.180383
Abstract:
During the flashover experiments of parallel-plate electrodes in SF6, a double-peak phenomenon is discovered that a small peak occurs in the front-edge of the applied nanosecond pulse voltage which is originally smooth. In order to explore the cause of this phenomenon, the phenomenon is analyzed theoretically and ascribed to the discharge on the edge of the electrodes. The discharge enlarges the area of the parallel-plate electrodes, thus the equivalent capacitance of the electrodes is increased. The greater the change of the equivalent capacitance is, the more obvious the peak shows. Flashover experiments under different pressures are developed to validate the analysis. The results show that as the pressure increases, the peak is less and less obvious, and the amplitude of the small peak is higher and higher due to the suppression of the discharge in high pressure SF6, which is confirmed by the integrating images of the whole discharge process. Dendritic discharges occur on the edge of the electrodes during the flashover process. In low SF6 pressure, the stems are thick and bright, and generate many branches, but when the pressure is high, the number of stems and branches is reduced and the discharge channel also darkens.
During the flashover experiments of parallel-plate electrodes in SF6, a double-peak phenomenon is discovered that a small peak occurs in the front-edge of the applied nanosecond pulse voltage which is originally smooth. In order to explore the cause of this phenomenon, the phenomenon is analyzed theoretically and ascribed to the discharge on the edge of the electrodes. The discharge enlarges the area of the parallel-plate electrodes, thus the equivalent capacitance of the electrodes is increased. The greater the change of the equivalent capacitance is, the more obvious the peak shows. Flashover experiments under different pressures are developed to validate the analysis. The results show that as the pressure increases, the peak is less and less obvious, and the amplitude of the small peak is higher and higher due to the suppression of the discharge in high pressure SF6, which is confirmed by the integrating images of the whole discharge process. Dendritic discharges occur on the edge of the electrodes during the flashover process. In low SF6 pressure, the stems are thick and bright, and generate many branches, but when the pressure is high, the number of stems and branches is reduced and the discharge channel also darkens.
2019,
31: 070006.
doi: 10.11884/HPLPB201931.180356
Abstract:
The results of investigation of flashovers and damages of power line insulators due to high voltage pulses with power on and power off have shown that joint action of a pulse disturbance and operating voltage of a power line can lead to catastrophic phenomena in power supply systems. High-voltage transformers are much more important and expensive elements of such systems. A set of ways of transformers tests to joint action of pulse disturbance and operating voltage of a high-voltage power line is presented in this article.
The results of investigation of flashovers and damages of power line insulators due to high voltage pulses with power on and power off have shown that joint action of a pulse disturbance and operating voltage of a power line can lead to catastrophic phenomena in power supply systems. High-voltage transformers are much more important and expensive elements of such systems. A set of ways of transformers tests to joint action of pulse disturbance and operating voltage of a high-voltage power line is presented in this article.
2019,
31: 070007.
doi: 10.11884/HPLPB201931.190184
Abstract:
With the improvement of the intellectualization and overall scale of power grid, modern power system is more and more vulnerable to the threat of high-altitude electromagnetic pulse. Once the key link fails, cascading reactions may occur, resulting in large-scale blackouts. For different electric equipments, their effect modes and threat levels are also different, thus it is necessary to carry out classification research. According to the different effect modes of electric equipments under electromagnetic pulse, this paper divides the equipments into Supervisor Control And Data Acquisition (SCADA) system and relay protection equipment, coil type equipment including transformer and so on, lightning arrestor including line type and equipment type, and other types of equipment. Their effect mechanisms are analyzed in detail. Secondly, considering that there are many kinds of effect levels under the threat of high-altitude electromagnetic pulse, different effect classification methods and multi-level effect evaluation model are introduced. Finally, considering comprehensive impact of vulnerability and importance and the cascading effects among equipment, the fail are links of power system under E1 and E3 are summarized and analyzed, respectively.
With the improvement of the intellectualization and overall scale of power grid, modern power system is more and more vulnerable to the threat of high-altitude electromagnetic pulse. Once the key link fails, cascading reactions may occur, resulting in large-scale blackouts. For different electric equipments, their effect modes and threat levels are also different, thus it is necessary to carry out classification research. According to the different effect modes of electric equipments under electromagnetic pulse, this paper divides the equipments into Supervisor Control And Data Acquisition (SCADA) system and relay protection equipment, coil type equipment including transformer and so on, lightning arrestor including line type and equipment type, and other types of equipment. Their effect mechanisms are analyzed in detail. Secondly, considering that there are many kinds of effect levels under the threat of high-altitude electromagnetic pulse, different effect classification methods and multi-level effect evaluation model are introduced. Finally, considering comprehensive impact of vulnerability and importance and the cascading effects among equipment, the fail are links of power system under E1 and E3 are summarized and analyzed, respectively.
2019,
31: 070008.
doi: 10.11884/HPLPB201931.190118
Abstract:
A new differential switched oscillator is designed to generate a differential damped sinusoidal signal with a center frequency of 300 MHz. Besides, a radiation system based on a differential switched oscillator and associated helical antenna is designed and analyzed. Firstly, the differential switched oscillator with the same central frequency is compared with the single-ended switched oscillator, which shows that the withstand voltage and output voltage of the differential switched oscillator are twice that of the single-ended switched oscillator. Secondly, the design of a differential switched oscillator is introduced. The characteristic impedance and the static electric field distribution of the oscillator are analyzed. The transient performance of the oscillator is simulated. Thirdly, a differential helical antenna is designed as the radiation antenna, in order to match the output form of the differential switched oscillator. Finally, the experimental result with different nitrogen pressure at different radiation distances is introduced. The radiation systems based on single-ended switched oscillator and differential switched oscillator are compared. It is shown that the radiation system can generate a high power mesoband EMP with a center frequency of 300 MHz and a percent bandwidth of about 20%. The maximum intensity of electric field is about 18 kV/m and the radiation factor is about 110 kV. The electric field intensity of the differential radiation system is twice that of the single-ended radiation system.
A new differential switched oscillator is designed to generate a differential damped sinusoidal signal with a center frequency of 300 MHz. Besides, a radiation system based on a differential switched oscillator and associated helical antenna is designed and analyzed. Firstly, the differential switched oscillator with the same central frequency is compared with the single-ended switched oscillator, which shows that the withstand voltage and output voltage of the differential switched oscillator are twice that of the single-ended switched oscillator. Secondly, the design of a differential switched oscillator is introduced. The characteristic impedance and the static electric field distribution of the oscillator are analyzed. The transient performance of the oscillator is simulated. Thirdly, a differential helical antenna is designed as the radiation antenna, in order to match the output form of the differential switched oscillator. Finally, the experimental result with different nitrogen pressure at different radiation distances is introduced. The radiation systems based on single-ended switched oscillator and differential switched oscillator are compared. It is shown that the radiation system can generate a high power mesoband EMP with a center frequency of 300 MHz and a percent bandwidth of about 20%. The maximum intensity of electric field is about 18 kV/m and the radiation factor is about 110 kV. The electric field intensity of the differential radiation system is twice that of the single-ended radiation system.
2019,
31: 070009.
doi: 10.11884/HPLPB201931.190054
Abstract:
The geomagnetic induced current (GIC) caused by geomagnetic storm may result in DC bias of the transformer, which poses threats to the safe and stable operation of the power grid.Remote real-time monitoring of GIC can provide important reference for grid GIC defense.Based on cloud server, a GIC monitoring system is designed.The data acquisition terminal collects the transformer's neutral point GIC in real time.Using GPRS, the data from multiple monitoring points are sent by different ports to the internal network of the cloud server for storage.It is possible for users to access the data remotely through the public network IP of the cloud server and process data via drawing and downloading.The real-time release and sharing of GIC data has been realized via this system.Combined with the forecast data of space weather, the early warning of GIC is preliminarily realized.Tests of the data acquisition terminal of system and the monitoring software platform based on the cloud server in the laboratory and substation field show that the system has achieved the design requirement and meets the functional requirements.
The geomagnetic induced current (GIC) caused by geomagnetic storm may result in DC bias of the transformer, which poses threats to the safe and stable operation of the power grid.Remote real-time monitoring of GIC can provide important reference for grid GIC defense.Based on cloud server, a GIC monitoring system is designed.The data acquisition terminal collects the transformer's neutral point GIC in real time.Using GPRS, the data from multiple monitoring points are sent by different ports to the internal network of the cloud server for storage.It is possible for users to access the data remotely through the public network IP of the cloud server and process data via drawing and downloading.The real-time release and sharing of GIC data has been realized via this system.Combined with the forecast data of space weather, the early warning of GIC is preliminarily realized.Tests of the data acquisition terminal of system and the monitoring software platform based on the cloud server in the laboratory and substation field show that the system has achieved the design requirement and meets the functional requirements.
2019,
31: 070010.
doi: 10.11884/HPLPB201931.190106
Abstract:
Geomagnetically Induced Current (GIC) can cause DC bias of the transformer.The derivative effect of DC bias may threaten the safety of power equipment and power grid.In view of the fact that many input parameters are uncertain variables in GIC calculations, it is necessary to study the uncertainty of GIC and the sensitivity of GIC to input variables.In this paper, based on polynomial chaos expansion (PCE) and hyperbolic scheme for truncating the polynomial chaos expansion, a GIC uncertainty quantization method is proposed.Using the constructed polynomial chaos expansion, the sensitivity index of GIC to input parameters is derived.For the planned Xinjiang power grid, the proposed method is used to measure the uncertainty of GIC, and the statistics of mean and variance of GIC are obtained.The Sobol sensitivity index is calculated according to the chaotic polynomial coefficient, and the sensitivity of GIC to input parameters such as electric field amplitude and grid DC resistance is obtained.Compared with the Monte Carlo method (MC), this method is not only precise, but also greatly improves the computational efficiency.
Geomagnetically Induced Current (GIC) can cause DC bias of the transformer.The derivative effect of DC bias may threaten the safety of power equipment and power grid.In view of the fact that many input parameters are uncertain variables in GIC calculations, it is necessary to study the uncertainty of GIC and the sensitivity of GIC to input variables.In this paper, based on polynomial chaos expansion (PCE) and hyperbolic scheme for truncating the polynomial chaos expansion, a GIC uncertainty quantization method is proposed.Using the constructed polynomial chaos expansion, the sensitivity index of GIC to input parameters is derived.For the planned Xinjiang power grid, the proposed method is used to measure the uncertainty of GIC, and the statistics of mean and variance of GIC are obtained.The Sobol sensitivity index is calculated according to the chaotic polynomial coefficient, and the sensitivity of GIC to input parameters such as electric field amplitude and grid DC resistance is obtained.Compared with the Monte Carlo method (MC), this method is not only precise, but also greatly improves the computational efficiency.
2019,
31: 070011.
doi: 10.11884/HPLPB201931.190100
Abstract:
Based on the time-domain field-circuit coupling model of UHV transformer, the partial differential equation model of transient circuit is established by using the principle of energy disturbance in the magnetic field model and the dynamic inductance parameters in the circuit model.For three different load types, resistance, induction and capacitance, the influence of DC bias on winding currents and their harmonics of UHV transformer are calculated.Facing the extremely long transition process caused by large inductance and small resistance of UHV transformer and the inundation of the small DC voltage relative to the 1000 kV AC voltage during the iterative calculation, the time to steady state is greatly shortened by adding series resistance in circuit model, and the calculation error caused by series resistance value is effectively eliminated by voltage iteration compensation.The correctness of the model is verified by comparing the value of DC-bias current and the value of DC component of the series winding current.
Based on the time-domain field-circuit coupling model of UHV transformer, the partial differential equation model of transient circuit is established by using the principle of energy disturbance in the magnetic field model and the dynamic inductance parameters in the circuit model.For three different load types, resistance, induction and capacitance, the influence of DC bias on winding currents and their harmonics of UHV transformer are calculated.Facing the extremely long transition process caused by large inductance and small resistance of UHV transformer and the inundation of the small DC voltage relative to the 1000 kV AC voltage during the iterative calculation, the time to steady state is greatly shortened by adding series resistance in circuit model, and the calculation error caused by series resistance value is effectively eliminated by voltage iteration compensation.The correctness of the model is verified by comparing the value of DC-bias current and the value of DC component of the series winding current.
2019,
31: 070012.
doi: 10.11884/HPLPB201931.190119
Abstract:
Pipeline corrosion is easily aggravated at the boundary of the earth's electrical structure.The pipeline passing through the earth interface is subject to greater risk of geomagnetic storm disaster at the demarcation point.The algorithm in this paper can be used to evaluate the self-evaluation description of geomagnetic storm disaster risk for oil and gas pipelines.This paper holds that the improved algorithm's Parkinson vector is more accurate than the traditional algorithm's Parkinson vector in locating the geodetic interface.On the premise that the earth's interface can be identified, the azimuth of the improved algorithm's Parkinson vector will change from ±180°to 0°or 0°to±180°near the interface, and the closer to the interface, the azimuth can better reflect the inclination of the earth interface, and the length reaches the minimum value at the boundary point.Factors such as conductivity difference between adjacent plots, the frequency of current sources and the angle between the earth's interface and the line direction will affect the distribution characteristics of the improved algorithm's Parkinson vector.The azimuth map and length map can be used to locate the pipeline through the interface position.There is a virtual interface between adjacent earth's interfaces, which needs analysis and exclusion.The simulation results show that these conclusions are correct and have important guiding significance for pipeline protection.
Pipeline corrosion is easily aggravated at the boundary of the earth's electrical structure.The pipeline passing through the earth interface is subject to greater risk of geomagnetic storm disaster at the demarcation point.The algorithm in this paper can be used to evaluate the self-evaluation description of geomagnetic storm disaster risk for oil and gas pipelines.This paper holds that the improved algorithm's Parkinson vector is more accurate than the traditional algorithm's Parkinson vector in locating the geodetic interface.On the premise that the earth's interface can be identified, the azimuth of the improved algorithm's Parkinson vector will change from ±180°to 0°or 0°to±180°near the interface, and the closer to the interface, the azimuth can better reflect the inclination of the earth interface, and the length reaches the minimum value at the boundary point.Factors such as conductivity difference between adjacent plots, the frequency of current sources and the angle between the earth's interface and the line direction will affect the distribution characteristics of the improved algorithm's Parkinson vector.The azimuth map and length map can be used to locate the pipeline through the interface position.There is a virtual interface between adjacent earth's interfaces, which needs analysis and exclusion.The simulation results show that these conclusions are correct and have important guiding significance for pipeline protection.
2019,
31: 070013.
doi: 10.11884/HPLPB201931.190120
Abstract:
The specific electrical structure around the homogeneous earth can generate eddy current in this homogeneous geology.In this paper, the equivalent current source is inverted from the data of several geomagnetic stations and the geoelectric model is constructed according to the actual topography.The research explores the influence caused by equivalent current and electrical structure on eddy current characteristics where the eddy current exists, and the mechanism of eddy current generation and eddy current movement in the specific area is revealed.Finally the distribution characteristics of pipe-soil potential (PSP) of oil pipelines laid in the area are calculated.The consistency between the calculated PSP and the observed PSP shows that the eddy can aggravate the influence of geomagnetic disturbance on the pipeline.
The specific electrical structure around the homogeneous earth can generate eddy current in this homogeneous geology.In this paper, the equivalent current source is inverted from the data of several geomagnetic stations and the geoelectric model is constructed according to the actual topography.The research explores the influence caused by equivalent current and electrical structure on eddy current characteristics where the eddy current exists, and the mechanism of eddy current generation and eddy current movement in the specific area is revealed.Finally the distribution characteristics of pipe-soil potential (PSP) of oil pipelines laid in the area are calculated.The consistency between the calculated PSP and the observed PSP shows that the eddy can aggravate the influence of geomagnetic disturbance on the pipeline.
2019,
31: 070014.
doi: 10.11884/HPLPB201931.190173
Abstract:
In the condition of strong magnetic storm, geo-magnetically induced current (GIC) flowing through the neutral point of the transformer, causes the increase of reactive power loss of the transformer.This might lead to overload of the reactive power compensation device, drop of the bus voltage and occurrence of a chain fault, which in turn causes a blackout of the system.Comparing the characteristics of each link in the fault chain and the development law of the power system blackout caused by magnetic storms, the fault chain model is used to simulate the process of power outage under conditions of geomagnetic storm.The article determines the propagation path of cascading failures based on the self-organizing critical theory and the safety margin of non-faulty circuits.Combining the IEEE-RTS 79 system parameters, the geo-location of each bus is estimated.Taking this system as an example and using Power World simulator, the research results verify that the proposed model can reflect the geomagnetic storm parameters against the power system fault chains and the identification of weak links under given grid conditions.The research results can provide a basis for quantifying and preventing disasters in the magnetic storm condition.
In the condition of strong magnetic storm, geo-magnetically induced current (GIC) flowing through the neutral point of the transformer, causes the increase of reactive power loss of the transformer.This might lead to overload of the reactive power compensation device, drop of the bus voltage and occurrence of a chain fault, which in turn causes a blackout of the system.Comparing the characteristics of each link in the fault chain and the development law of the power system blackout caused by magnetic storms, the fault chain model is used to simulate the process of power outage under conditions of geomagnetic storm.The article determines the propagation path of cascading failures based on the self-organizing critical theory and the safety margin of non-faulty circuits.Combining the IEEE-RTS 79 system parameters, the geo-location of each bus is estimated.Taking this system as an example and using Power World simulator, the research results verify that the proposed model can reflect the geomagnetic storm parameters against the power system fault chains and the identification of weak links under given grid conditions.The research results can provide a basis for quantifying and preventing disasters in the magnetic storm condition.
2019,
31: 070015.
doi: 10.11884/HPLPB201931.190171
Abstract:
Geomagnetic disturbances will induce Geomagnetically Induced Current (GIC) in high voltage power grid, which will cause cascading failure in power grid, resulting in power system collapse or blackout.Therefore, research on risk assessment of cascading failure in power grid under geomagnetic storms can provide important reference for preventing accidents caused by geomagnetic storms.This paper analyzes the mechanism of cascading failure under geomagnetic storm conditions and proposes a risk assessment process for cascading failure in power grid under geomagnetic storms.The process can identify the vulnerable links of the power grid under each geomagnetic storm condition, evaluate the risk of the different stages of the vulnerable links by using the load shedding of the power system and use the critical load shedding caused by vulnerable links to evaluate its risk to the power system.Finally, the proposed process is verified by using the IEEE-RTS79 system.The verification results show the feasibility and validity of the proposed process.The results obtained can provide a reference for quantifying and preventing the risk of the power grid under geomagnetic storm conditions.
Geomagnetic disturbances will induce Geomagnetically Induced Current (GIC) in high voltage power grid, which will cause cascading failure in power grid, resulting in power system collapse or blackout.Therefore, research on risk assessment of cascading failure in power grid under geomagnetic storms can provide important reference for preventing accidents caused by geomagnetic storms.This paper analyzes the mechanism of cascading failure under geomagnetic storm conditions and proposes a risk assessment process for cascading failure in power grid under geomagnetic storms.The process can identify the vulnerable links of the power grid under each geomagnetic storm condition, evaluate the risk of the different stages of the vulnerable links by using the load shedding of the power system and use the critical load shedding caused by vulnerable links to evaluate its risk to the power system.Finally, the proposed process is verified by using the IEEE-RTS79 system.The verification results show the feasibility and validity of the proposed process.The results obtained can provide a reference for quantifying and preventing the risk of the power grid under geomagnetic storm conditions.
2019,
31: 070016.
doi: 10.11884/HPLPB201931.190116
Abstract:
Geomagnetic storms are violent disturbances of the geomagnetic field around the world, which produce geomagnetic induced currents (GIC) in power system.Power transformer enters the half-wave saturation state under the influence of GIC.The harmonics and reactive power loss produced by transformer affect the voltage stability of power system and cause the maloperation of relay protection devices in power system.With the increase of voltage level and the expansion of power grid scale, geomagnetic storms will seriously threaten the safe operation of power grid.Based on the analysis of the mechanism of magnetic storm disaster and the description of fault propagation and power system response, this paper deeply understands the influence of geomagnetic storm on power system and its electrical equipment.The prevention and control of secondary hazards of GIC is an important subject in the study of geomagnetic storms.This paper summarizes the research framework and ideas of the impact of magnetic storms on the voltage safety of power grid, combs the research results of the optimal control devices for suppressing DC bias of transformers.An optimized treatment of GIC is proposed which has obvious advantages compared with traditional methods.
Geomagnetic storms are violent disturbances of the geomagnetic field around the world, which produce geomagnetic induced currents (GIC) in power system.Power transformer enters the half-wave saturation state under the influence of GIC.The harmonics and reactive power loss produced by transformer affect the voltage stability of power system and cause the maloperation of relay protection devices in power system.With the increase of voltage level and the expansion of power grid scale, geomagnetic storms will seriously threaten the safe operation of power grid.Based on the analysis of the mechanism of magnetic storm disaster and the description of fault propagation and power system response, this paper deeply understands the influence of geomagnetic storm on power system and its electrical equipment.The prevention and control of secondary hazards of GIC is an important subject in the study of geomagnetic storms.This paper summarizes the research framework and ideas of the impact of magnetic storms on the voltage safety of power grid, combs the research results of the optimal control devices for suppressing DC bias of transformers.An optimized treatment of GIC is proposed which has obvious advantages compared with traditional methods.
