CN112531705A - Asymmetric fault ride-through system and method for three-phase four-wire virtual synchronous generator - Google Patents
Asymmetric fault ride-through system and method for three-phase four-wire virtual synchronous generator Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
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Abstract
The application discloses an asymmetric fault ride-through system and method of a three-phase four-wire system virtual synchronous generator, when an asymmetric fault occurs in a power grid, a public coupling point voltage of the power grid is obtained through an acquisition module, a fault type detection module detects whether a corresponding phase of the power grid has the fault or not and the fault type of a fault phase according to the public coupling point voltage, and meanwhile, an internal potential selection module calculates a virtual impedance value according to the fault type, so that the virtual impedance module adds virtual impedance to the fault phase according to the virtual impedance value to limit the current of the fault phase until the fault phase is recovered to be normal, and then the virtual impedance is removed; if the phase has no fault, an inertia link and a damping link are added through the virtual synchronous control module, so that the phase is kept stable. The three-phase three-wire system VSG control system solves the technical problems that the existing three-phase three-wire system VSG technology has high requirements on a controller in engineering practice and is difficult to realize in a high-power system.
Description
Technical Field
The application relates to the technical field of electric power, in particular to an asymmetric fault ride-through system and method of a three-phase four-wire virtual synchronous generator.
Background
In the current research, most of distributed clean energy is connected to a large power grid in the form of a micro-grid, and the micro-grid is a small power generation and distribution system formed by combining a distributed micro-source, an energy storage system, a current transformer, a load and the like, and can realize internal self-management and control. The micro-grid mainly has two operation modes: the method comprises the following steps of merging a grid-connected mode of a large power grid and an island mode separated from the large power grid, wherein the grid-connected mode needs to be merged into the power grid through a grid-connected inverter; however, the two control modes are easily affected by power grid fluctuation such as load fluctuation or short-circuit fault due to high response speed and small rotational inertia, and related scholars propose a Virtual Synchronous Generator (VSG) based on an electromagnetic equation and a mechanical equation of the Synchronous Generator, and the stability of the microgrid is improved by the fact that the Virtual Synchronous Generator has the characteristics of strong inertia and damping.
However, when the power grid has an asymmetric fault, the voltage on the power grid side drops asymmetrically, and the output voltage of the VSG cannot change suddenly due to inertia, so that a large impulse current is generated on the line. If the VSG is disconnected from the large power grid, the distributed micro-source utilization efficiency is low. Therefore, in engineering application, the inverter is required to have fault ride-through capability, and can still maintain a grid-connected state during a short fault period of a power grid, and meanwhile, power support is provided for the power grid.
At present, when an asymmetric fault occurs in a power grid, virtual synchronous control is mainly switched to current mode control through a three-phase three-wire system VSG to suppress impulse current, but the strategies have high requirements on a controller in engineering practice and are difficult to realize in a high-power system.
Disclosure of Invention
The embodiment of the application provides an asymmetric fault ride-through system and method of a three-phase four-wire system virtual synchronous generator, which are used for solving the technical problems that the existing three-phase three-wire system VSG technology has high requirements on a controller in engineering practice and is difficult to realize in a high-power system.
In view of the above, a first aspect of the present application provides an asymmetric fault ride-through system for a three-phase four-wire virtual synchronous generator, the system comprising:
the device comprises a virtual synchronous control module, a sampling module, a fault type detection module, a virtual impedance module and an internal potential selection module;
the first ends of the sampling modules are connected with three phases of a power grid, and the second ends of the sampling modules are connected with the virtual synchronous control module and the first end of the fault type detection module respectively; the second ends of the virtual synchronous control module and the fault type detection module are connected with the first end of the internal potential selection module; the first end of the internal potential selection module is connected with the first end of the virtual impedance module, and the second end of the virtual impedance module is connected with the second end of the fault type detection module; the power grid is a three-phase four-wire system power grid;
the sampling module is configured to: when the power grid has an asymmetric fault, acquiring the voltage of a public coupling point of the power grid, and sending the voltage of the public coupling point to the fault type detection module;
the fault type detection module is used for: judging whether the corresponding phase has a fault according to the voltage of the common coupling point, if so, detecting the fault type of the fault phase, and sending the fault type to the internal potential selection module, wherein the fault type comprises: the system comprises an internal potential selection module, a single-phase earth fault, a two-phase earth fault and a two-phase short circuit fault, and otherwise, a request instruction is sent to the internal potential selection module;
the internal potential selection module is used for: determining a virtual impedance value according to the fault type, and sending a virtual impedance value instruction to the virtual impedance module; or forwarding the request instruction to the virtual synchronization control module;
the virtual impedance module is configured to: adding virtual impedance to the fault phase according to the instruction of the virtual impedance value to enable the fault phase to be subjected to current limiting, and triggering the fault type detection module until the fault phase is recovered to be normal, and then removing the virtual impedance;
the virtual synchronization control module is configured to: and adding an inertia link and a damping link to the corresponding phase according to the request instruction so as to keep the corresponding phase stable.
Optionally, the virtual impedance module further comprises: a low-pass filter;
the low pass filter is used for: and filtering the high-frequency harmonic component of the power grid after adding virtual impedance to the fault phase according to the instruction of the virtual impedance value so as to limit the current of the fault phase.
Optionally, the fault type detection module is specifically configured to:
judging whether the corresponding phase fails according to the voltage of the common coupling point, if so, detecting the fault type of the failed phase according to the fault characteristics;
if the power grid only generates single-phase voltage drop, the power grid has single-phase earth fault; if the power grid simultaneously generates two-phase voltage drops and zero sequence components, the power grid generates two-phase ground faults; if the power grid only generates two-phase voltage drop, two-phase short circuit fault occurs in the power grid; and sending the fault type to the internal potential selection module;
otherwise, the request instruction is sent to the internal potential selection module.
Optionally, the method further comprises: an SPWM module;
the first end of the SPWM module is connected with the second end of the internal potential selection module;
the SPWM module is used for: when the power grid normally operates, the second end of the SPWM module is connected with the power grid in parallel.
Optionally, the virtual synchronization control module is further configured to:
and performing active frequency modulation and reactive voltage regulation control on the power grid.
A second aspect of the present application provides an asymmetric fault ride-through method for a three-phase four-wire virtual synchronous generator, which is applied to the asymmetric fault ride-through system for a three-phase four-wire virtual synchronous generator described in the first aspect, where the system includes:
s1, when the power grid has an asymmetric fault, a sampling module acquires the voltage of a public coupling point of the power grid and sends the voltage of the public coupling point to a fault type detection module, wherein the power grid is a three-phase four-wire system power grid;
s2, the fault type detection module judges whether the corresponding phase has faults according to the voltage of the common coupling point, if so, detects the fault type of the fault phase and sends the fault type to the internal potential selection module, and the fault type comprises: the system comprises an internal potential selection module, a single-phase earth fault, a two-phase earth fault and a two-phase short circuit fault, and otherwise, a request instruction is sent to the internal potential selection module;
s3, the internal potential selection module determines a virtual impedance value according to the fault type and sends a virtual impedance value instruction to the virtual impedance module; or forwarding the request instruction to a virtual synchronous control module;
s4, adding virtual impedance to the fault phase according to the instruction of the virtual impedance value by the virtual impedance module so that the fault phase is subjected to current limiting, and returning to the step S2 until the fault phase is recovered to be normal, and then removing the virtual impedance;
and S5, adding an inertia link and a damping link to the corresponding phase by the virtual synchronous control module according to the request instruction, so that the corresponding phase is kept stable.
Optionally, after adding a virtual impedance to the fault phase according to the instruction of the virtual impedance value to current-limit the fault phase, the method further includes:
and filtering high-frequency harmonic components of the power grid through a low-pass filter.
Optionally, step S2 specifically includes:
the fault type detection module judges whether the corresponding phase has a fault according to the voltage of the public coupling point, if so, the fault type of the fault phase is detected;
if the power grid only generates single-phase voltage drop, the power grid has single-phase earth fault; if the power grid simultaneously generates two-phase voltage drops and zero sequence components, the power grid generates two-phase ground faults; if the power grid only generates two-phase voltage drop, two-phase short circuit fault occurs in the power grid; and sending the fault type to the internal potential selection module;
otherwise, the request instruction is sent to the internal potential selection module.
Optionally, the method further comprises:
when the power grid normally operates, the SPWM module is connected with the power grid in parallel.
Optionally, after step S5, the method further includes:
and the virtual synchronous control module is used for carrying out active power frequency modulation and reactive power voltage regulation control on the power grid.
According to the technical scheme, the method has the following advantages:
according to the asymmetric fault ride-through system of the three-phase four-wire system virtual synchronous generator, when an asymmetric fault occurs in a power grid, the voltage of a public coupling point of the power grid is obtained through the acquisition module, the fault type detection module detects whether a corresponding phase of the power grid has the fault or not and the fault type of the fault phase according to the voltage of the public coupling point, meanwhile, the internal potential selection module calculates a virtual impedance value according to the fault type, so that the virtual impedance module adds virtual impedance to the fault phase according to the virtual impedance value to enable the fault phase to be limited in current, and the virtual impedance is removed until the fault phase is recovered to be normal; if the phase has no fault, an inertia link and a damping link are added through the virtual synchronous control module, so that the phase is kept stable. The system is a split-phase control system, can effectively ensure that the non-fault of the three-phase four-wire system VSG continuously works in a rated state in sequence when the power grid has an asymmetric fault, and can also effectively limit the impulse current of a fault phase; meanwhile, the three-phase four-wire system topological structure can be used for structurally decoupling three phases, has good unbalanced load capacity and can be well applied to a low-voltage distribution network; the system is simple in structure and easy to realize, and therefore the technical problems that the existing three-phase three-wire system VSG technology has high requirements on a controller in engineering practice and is difficult to realize in a high-power system are solved.
Drawings
Fig. 1 is a system architecture diagram of an asymmetric fault ride-through system of a three-phase four-wire virtual synchronous generator provided in an embodiment of the present application, which is connected in parallel with a power grid;
fig. 2 is a schematic diagram of virtual synchronization control of a virtual synchronization control module provided in an embodiment of the present application;
FIG. 3 is a schematic diagram of a fault-ride-through control provided in an embodiment of the present application;
fig. 4 is a schematic flowchart of an asymmetric fault ride-through method of a three-phase four-wire virtual synchronous generator provided in an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The following is a system description of an asymmetric fault ride-through system of a three-phase four-wire system virtual synchronous generator and a three-phase four-wire system power grid which are connected in parallel.
Referring to fig. 1, in the system, an energy storage system is provided at a dc side, then electric energy conversion is performed through a three-phase bridge circuit, an LC circuit is used to filter output, and then grid connection is performed through a breaker, and meanwhile, a load is provided at an output side. The direct current side forms a neutral point through the split capacitor, and the neutral point of the power grid, the neutral point of the load, the neutral point of the capacitor and the neutral point of the direct current side are connected together through neutral lines.
Wherein U isdcIs the value of the micro-source side DC voltage, Cdc1And Cdc2For splitting the capacitor on the DC side, Rdc1And Rdc2The voltage-sharing resistor is connected in parallel with two ends of the split capacitor; l isfAnd CfRespectively, the inductance and capacitance values, L, of the filter circuitsAnd RsEquivalent inductance and resistance L from the three-phase four-wire VSG output side to the PCCgAnd RgEquivalent inductance and resistance, L, from grid to PCC, respectivelylAnd RlEquivalent inductance and resistance from the load side to the PCC respectively; zloadAnd egabcThree-phase load value and grid voltage value, CB, respectively1And CB2Respectively a load switch and a grid-connected switch uoAnd ioRespectively inverter output voltage and inductive current sampling values.
The following is an introduction to a schematic diagram of virtual synchronization control by a virtual synchronization control module.
Referring to fig. 2, J is a rotational inertia introduced by imitating inertia of a synchronous engine, Dp and Dq are an active loop frequency droop coefficient and a reactive loop voltage droop coefficient, K is a reactive damping coefficient, Tm and Te are a mechanical torque value and a calculated electromagnetic torque value, respectively, Q is an output reactive power value, e is an internal potential output by a control algorithm, θ is a phase of a virtual rotor in the control algorithm, if is a virtual excitation circuit, Mf is a maximum mutual inductance value simulating an excitation winding and a stator winding in the synchronous generator, and io is an inverter output current instantaneous sampling value.
Fig. 3 is a schematic diagram of fault ride-through control provided by the present application, and when the fault type detection module detects a specific fault type, the internal potential selection module performs fault ride-through according to the split-phase control method of the following embodiment of the asymmetric fault ride-through method for the three-phase four-wire virtual synchronous generator, so as to implement impulse current suppression.
Referring to fig. 1 and fig. 4, the following is a first embodiment of an asymmetric fault ride-through system of a three-phase four-wire virtual synchronous generator according to an embodiment of the present application, including: the device comprises a virtual synchronous control module, a sampling module, a fault type detection module, a virtual impedance module and an internal potential selection module;
the first ends of the sampling modules are connected with three phases of a power grid, and the second ends of the sampling modules are connected with the first ends of the virtual synchronous control module and the fault type detection module respectively; the second ends of the virtual synchronous control module and the fault type detection module are connected with the first end of the internal potential selection module; the first end of the internal potential selection module is connected with the first end of the virtual impedance module, and the second end of the virtual impedance module is connected with the second end of the fault type detection module; the power grid is a three-phase four-wire system power grid.
The sampling module is used for: when the power grid has an asymmetric fault, the voltage of the public coupling point of the power grid is obtained, and the voltage of the public coupling point is sent to the fault type detection module.
The fault type detection module is used for: judging whether the corresponding phase has a fault according to the voltage of the common coupling point, if so, sending the fault type to an internal potential selection module after detecting the fault type of the fault phase, wherein the fault type comprises: and the single-phase earth fault, the two-phase earth fault and the two-phase short circuit fault are detected, otherwise, a request instruction is sent to the internal potential selection module.
The internal potential selection module is used for: determining a virtual impedance value according to the fault type, and sending an instruction of the virtual impedance value to a virtual impedance module; or forwarding the request instruction to the virtual synchronization control module.
The virtual impedance module is used for: and adding virtual impedance to the fault phase according to the instruction of the virtual impedance value to enable the fault phase to be subjected to current limiting, and triggering the fault type detection module until the fault phase is recovered to be normal, and then removing the virtual impedance.
The virtual synchronization control module is used for: and adding an inertia link and a damping link to the corresponding phase according to the request instruction so as to keep the corresponding phase stable.
It should be noted that the acquisition module is u in fig. 1pccFor the convenience of understanding, the present application is described by using an acquisition module, the acquisition module is connected to A, B, C phases of a three-phase four-wire system power grid, and N is a zero line of the three-phase four-wire system power grid. The virtual synchronous control module is also connected with a filter circuit in the three-phase four-wire system power grid and is used for adding an inertia link and a damping link into a normal phase so as to keep the phase stable. The internal potential selection module is used for selecting virtual synchronous internal potential and virtual impedance internal potential in fig. 1, and the fault type detection module is used for detecting faults in fig. 1.
It can be understood that, when the fault type detection module determines that A, B, C phase has a fault, it sends a command to the internal potential selection module, so that the internal potential selection module controls the virtual synchronization control module or the virtual impedance module to operate accordingly. If the phase a of the A, B, C fails and the phase B, C fails, the fault type detection module detects the specific fault type of the phase a according to the pcc voltage, when the fault type is calculated through the internal potential selection module, the virtual impedance module needs to add the virtual impedance to the phase A in the power grid, the virtual impedance module is enabled to add virtual impedance to the internal potential outlet of the phase A in the power grid, the fault ride-through control module is used for limiting the current of the phase A, continuously judging whether the phase A has eliminated the fault through the fault type detection module, and removing the virtual impedance until the fault is eliminated, wherein the fault ride-through control is only a temporary state when the fault occurs and is not a normal state of system operation, therefore, the virtual synchronous control state needs to be returned in time after the fault is cleared, so that the surge current is restrained.
Meanwhile, as the B, C phase does not have a fault, the fault type detection module sends a signal to the internal potential selection module to control the virtual synchronous control module to work, so that the virtual synchronous control module adds an inertia link and a damping link to the B, C phase in the power grid, and the B, C phase is kept stable.
Therefore, the system can carry out split-phase control when one part of the phases of the power grid normally operates and the other part of the phases of the power grid has asymmetric faults, so that the non-fault phases continuously work in a rated state, and simultaneously, the impact current of the fault phases can be effectively limited.
According to the asymmetric fault ride-through system of the three-phase four-wire system virtual synchronous generator, when an asymmetric fault occurs in a power grid, the voltage of a public coupling point of the power grid is obtained through the acquisition module, the fault type detection module detects whether a corresponding phase of the power grid has the fault or not and the fault type of the fault phase according to the voltage of the public coupling point, meanwhile, the internal potential selection module calculates a virtual impedance value according to the fault type, so that the virtual impedance module adds virtual impedance to the fault phase according to the virtual impedance value to enable the fault phase to be limited in current, and the virtual impedance is removed until the fault phase is recovered to be normal; if the phase has no fault, an inertia link and a damping link are added through the virtual synchronous control module, so that the phase is kept stable. The system is a split-phase control system, can effectively ensure that the non-fault of the three-phase four-wire system VSG continuously works in a rated state in sequence when the power grid has an asymmetric fault, and can also effectively limit the impulse current of a fault phase; meanwhile, the three-phase four-wire system topological structure can be used for structurally decoupling three phases, has good unbalanced load capacity and can be well applied to a low-voltage distribution network; the system is simple in structure and easy to realize, and therefore the technical problems that the existing three-phase three-wire system VSG technology has high requirements on a controller in engineering practice and is difficult to realize in a high-power system are solved.
Further, on the basis of the first embodiment, the virtual impedance module further includes: a low-pass filter; the low pass filter is used for: and after adding the virtual impedance to the fault phase according to the instruction of the virtual impedance value to enable the fault phase to be limited, filtering out high-frequency harmonic components of the power grid.
It should be noted that, since the inductance part in the virtual impedance added to the fault phase by the virtual impedance module amplifies the high-frequency harmonic component in the output current of the power grid, a low-pass filter (LPF) is added to the port to which the virtual impedance is added to filter the high-frequency harmonic component, thereby improving the high-frequency harmonic disturbance resistance of the system. Meanwhile, a person skilled in the art can introduce a self-adaptive virtual impedance to optimize the instantaneous state of the fault according to actual needs, which is not described herein.
Further, the fault type detection module is specifically configured to: judging whether the corresponding phase has a fault according to the voltage of the common coupling point, if so, detecting the fault type of the fault phase; if the power grid only generates single-phase voltage drop, the power grid has single-phase earth fault; if the power grid simultaneously generates two-phase voltage drops and zero-sequence components, the power grid generates two-phase grounding faults; if the power grid only generates two-phase voltage drop, the power grid has two-phase short circuit fault; and sending the fault type to an internal potential selection module; otherwise, sending a request instruction to the internal potential selection module.
It should be noted that three asymmetric faults have different characteristics, a single-phase voltage drop exists only when a single-phase earth fault occurs, two-phase voltage drops exist when a two-phase earth fault occurs and a two-phase short-circuit fault occurs, but zero-sequence components are not generated in the two-phase earth fault and the two-phase short-circuit fault, so that the type of the occurring fault can be judged by detecting a voltage value of a Point of Common Coupling (PCC) according to the characteristics of the two-phase earth fault and the. When the power grid has asymmetric faults, different virtual impedances are selected according to the fault types to carry out current limiting.
Further, on the basis of the first embodiment, the method further includes: an SPWM module; the first end of the SPWM module is connected with the second end of the internal potential selection module; the SPWM module is used for: when the power grid normally operates, the second end of the SPWM module is connected with the power grid in parallel.
It should be noted that the SPWM module utilizes a module of the SPWM control method, that is, a sinusoidal pulse width modulation technique, and the SPWM control method can obtain three-phase electric sinusoidal voltages in the power grid.
Further, the virtual synchronization control module is further configured to: and performing active frequency modulation and reactive voltage regulation control on the power grid.
It can be understood that the virtual synchronous control module of the embodiment of the present application can also be used for performing active frequency modulation and reactive voltage regulation control on a power grid.
The above is an embodiment of the asymmetric fault ride-through system of the three-phase four-wire virtual synchronous generator provided in the embodiment of the present application, and the following is an embodiment of the asymmetric fault ride-through method of the three-phase four-wire virtual synchronous generator provided in the embodiment of the present application.
Referring to fig. 1 and 4, an embodiment of the present application provides an asymmetric fault ride-through method for a three-phase four-wire virtual synchronous generator, including:
Step 102, the fault type detection module judges whether the corresponding phase has a fault according to the voltage of the common coupling point, if so, detects the fault type of the fault phase and sends the fault type to the internal potential selection module, wherein the fault type comprises: and the single-phase earth fault, the two-phase earth fault and the two-phase short circuit fault are detected, otherwise, a request instruction is sent to the internal potential selection module.
103, the internal potential selection module determines a virtual impedance value according to the fault type and sends a virtual impedance value instruction to the virtual impedance module; or forwarding the request instruction to the virtual synchronization control module.
And 104, adding virtual impedance to the fault phase by the virtual impedance module according to the instruction of the virtual impedance value to limit the current of the fault phase, and returning to the step 102 until the virtual impedance is removed after the fault phase is recovered to be normal.
And 105, adding an inertia link and a damping link into the corresponding phase by the virtual synchronous control module according to the request instruction, so that the corresponding phase is kept stable.
According to the asymmetric fault ride-through method of the three-phase four-wire system virtual synchronous generator, when an asymmetric fault occurs in a power grid, the voltage of a public coupling point of the power grid is obtained through an acquisition module, a fault type detection module detects whether a corresponding phase of the power grid has the fault or not and the fault type of the fault phase according to the voltage of the public coupling point, meanwhile, an internal potential selection module calculates a virtual impedance value according to the fault type, so that the virtual impedance module adds virtual impedance to the fault phase according to the virtual impedance value to enable the fault phase to be limited in current, and the virtual impedance is removed until the fault phase is recovered to be normal; if the phase has no fault, an inertia link and a damping link are added through the virtual synchronous control module, so that the phase is kept stable. The system is a split-phase control system, can effectively ensure that the non-fault of the three-phase four-wire system VSG continuously works in a rated state in sequence when the power grid has an asymmetric fault, and can also effectively limit the impulse current of a fault phase; meanwhile, the three-phase four-wire system topological structure can be used for structurally decoupling three phases, has good unbalanced load capacity and can be well applied to a low-voltage distribution network; the method is simple to implement, and therefore the technical problems that the existing three-phase three-wire system VSG technology has high requirements on the controller in engineering practice and is difficult to implement in a high-power system are solved.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific processes of the method described above may refer to the corresponding processes in the foregoing system embodiments, and are not described herein again.
The terms "first," "second," "third," "fourth," and the like in the description of the present application and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. An asymmetric fault ride-through system for a three-phase four-wire virtual synchronous generator, comprising: the device comprises a virtual synchronous control module, a sampling module, a fault type detection module, a virtual impedance module and an internal potential selection module;
the first ends of the sampling modules are connected with three phases of a power grid, and the second ends of the sampling modules are connected with the virtual synchronous control module and the first end of the fault type detection module respectively; the second ends of the virtual synchronous control module and the fault type detection module are connected with the first end of the internal potential selection module; the first end of the internal potential selection module is connected with the first end of the virtual impedance module, and the second end of the virtual impedance module is connected with the second end of the fault type detection module; the power grid is a three-phase four-wire system power grid;
the sampling module is configured to: when the power grid has an asymmetric fault, acquiring the voltage of a public coupling point of the power grid, and sending the voltage of the public coupling point to the fault type detection module;
the fault type detection module is used for: judging whether the corresponding phase has a fault according to the voltage of the common coupling point, if so, sending the fault type to the internal potential selection module after detecting the fault type of the fault phase, wherein the fault type comprises: the system comprises an internal potential selection module, a single-phase earth fault, a two-phase earth fault and a two-phase short circuit fault, and otherwise, a request instruction is sent to the internal potential selection module;
the internal potential selection module is used for: determining a virtual impedance value according to the fault type, and sending a virtual impedance value instruction to the virtual impedance module; or forwarding the request instruction to the virtual synchronization control module;
the virtual impedance module is configured to: adding virtual impedance to the fault phase according to the instruction of the virtual impedance value to enable the fault phase to be subjected to current limiting, and triggering the fault type detection module until the fault phase is recovered to be normal, and then removing the virtual impedance;
the virtual synchronization control module is configured to: and adding an inertia link and a damping link to the corresponding phase according to the request instruction so as to keep the corresponding phase stable.
2. The asymmetric fault ride-through system of a three-phase four-wire virtual synchronous generator of claim 1, wherein the virtual impedance module further comprises: a low-pass filter;
the low pass filter is used for: and filtering the high-frequency harmonic component of the power grid after adding virtual impedance to the fault phase according to the instruction of the virtual impedance value so as to limit the current of the fault phase.
3. The asymmetric fault ride-through system of a three-phase four-wire virtual synchronous generator according to claim 1, wherein the fault type detection module is specifically configured to:
judging whether the corresponding phase has a fault according to the voltage of the common coupling point, if so, detecting the fault type of the fault phase;
if the power grid only generates single-phase voltage drop, the power grid has single-phase earth fault; if the power grid simultaneously generates two-phase voltage drops and zero sequence components, the power grid generates two-phase ground faults; if the power grid only generates two-phase voltage drop, two-phase short circuit fault occurs in the power grid; and sending the fault type to the internal potential selection module;
otherwise, the request instruction is sent to the internal potential selection module.
4. The asymmetric fault ride-through system of a three-phase four-wire virtual synchronous generator of claim 1, further comprising: an SPWM module;
the first end of the SPWM module is connected with the second end of the internal potential selection module;
the SPWM module is used for: when the power grid normally operates, the second end of the SPWM module is connected with the power grid in parallel.
5. The asymmetric fault ride-through system of a three-phase four-wire virtual synchronous generator of claim 1, wherein the virtual synchronous control module is further configured to:
and performing active frequency modulation and reactive voltage regulation control on the power grid.
6. An asymmetric fault ride-through method of a three-phase four-wire virtual synchronous generator, which is applied to the asymmetric fault ride-through system of the three-phase four-wire virtual synchronous generator of any one of the claims 1 to 5, and comprises the following steps:
s1, when the power grid has an asymmetric fault, a sampling module acquires the voltage of a public coupling point of the power grid and sends the voltage of the public coupling point to a fault type detection module, wherein the power grid is a three-phase four-wire system power grid;
s2, the fault type detection module judges whether the corresponding phase has faults according to the voltage of the common coupling point, if so, detects the fault type of the fault phase and sends the fault type to the internal potential selection module, and the fault type comprises: the system comprises an internal potential selection module, a single-phase earth fault, a two-phase earth fault and a two-phase short circuit fault, and otherwise, a request instruction is sent to the internal potential selection module;
s3, the internal potential selection module determines a virtual impedance value according to the fault type and sends a virtual impedance value instruction to the virtual impedance module; or forwarding the request instruction to a virtual synchronous control module;
s4, adding virtual impedance to the fault phase according to the instruction of the virtual impedance value by the virtual impedance module so that the fault phase is subjected to current limiting, and returning to the step S2 until the fault phase is recovered to be normal, and then removing the virtual impedance;
and S5, adding an inertia link and a damping link to the corresponding phase by the virtual synchronous control module according to the request instruction, so that the corresponding phase is kept stable.
7. The asymmetric fault ride-through method of a three-phase four-wire virtual synchronous generator according to claim 6, wherein after the adding a virtual impedance to the fault phase according to the instruction of the virtual impedance value causes the fault phase to be current limited, further comprising:
and filtering high-frequency harmonic components of the power grid through a low-pass filter.
8. The asymmetric fault ride-through method of the three-phase four-wire virtual synchronous generator according to claim 6, wherein the step S2 specifically includes:
the fault type detection module judges whether the corresponding phase has a fault according to the voltage of the public coupling point, if so, the fault type of the fault phase is detected;
if the power grid only generates single-phase voltage drop, the power grid has single-phase earth fault; if the power grid simultaneously generates two-phase voltage drops and zero sequence components, the power grid generates two-phase ground faults; if the power grid only generates two-phase voltage drop, two-phase short circuit fault occurs in the power grid; and sending the fault type to the internal potential selection module;
otherwise, the request instruction is sent to the internal potential selection module.
9. The asymmetric fault ride-through method of a three-phase four-wire virtual synchronous generator according to claim 6, further comprising:
when the power grid normally operates, the SPWM module is connected with the power grid in parallel.
10. The asymmetric fault ride-through method of the three-phase four-wire virtual synchronous generator according to claim 6, wherein after the step S5, the method further comprises:
and the virtual synchronous control module is used for carrying out active power frequency modulation and reactive power voltage regulation control on the power grid.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865099A (en) * | 2021-04-12 | 2021-05-28 | 李畅 | Amplitude-phase motion analysis system and method for judging frequency motion state of grid-connected inverter under VSG control |
| CN113346507A (en) * | 2021-04-29 | 2021-09-03 | 西安交通大学 | Virtual synchronous machine low voltage ride through method and system based on virtual voltage drop |
| CN114336679A (en) * | 2021-12-23 | 2022-04-12 | 武汉大学 | VSG fault ride-through method considering virtual resistor and fault current limiter |
| CN114709796A (en) * | 2022-04-28 | 2022-07-05 | 西安交通大学 | Generator zero-loss fault current switching-on and switching-off device and method based on phase selection control |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105978042A (en) * | 2016-06-14 | 2016-09-28 | 东南大学 | Fault protection and ride-through control system and method for virtual synchronous machine |
| CN107437821A (en) * | 2017-09-13 | 2017-12-05 | 湖南大学 | Isolated island micro-capacitance sensor virtual machine differentiation fault traversing system and its implementation |
| CN109378799A (en) * | 2018-11-30 | 2019-02-22 | 南方电网科学研究院有限责任公司 | Overcurrent protection method, device and equipment for three-phase four-wire inverter |
| CN109921388A (en) * | 2019-01-17 | 2019-06-21 | 华北电力大学 | The direct current cut-off device and method of hybrid MMC and AC circuit breaker cooperation |
| CN110190618A (en) * | 2019-07-04 | 2019-08-30 | 国家电网公司华中分部 | A kind of AC fault passes through the flexible direct current converter station model equivalent method under operating condition |
| CN110880764A (en) * | 2019-10-30 | 2020-03-13 | 华南理工大学 | Fault processing method for unbalanced distribution network containing inverter type distributed power supply |
| CN111416393A (en) * | 2020-04-15 | 2020-07-14 | 上海电力大学 | Virtual synchronous generator fault current suppression method based on self-adaptive virtual impedance |
-
2020
- 2020-12-18 CN CN202011505630.6A patent/CN112531705A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105978042A (en) * | 2016-06-14 | 2016-09-28 | 东南大学 | Fault protection and ride-through control system and method for virtual synchronous machine |
| CN107437821A (en) * | 2017-09-13 | 2017-12-05 | 湖南大学 | Isolated island micro-capacitance sensor virtual machine differentiation fault traversing system and its implementation |
| CN109378799A (en) * | 2018-11-30 | 2019-02-22 | 南方电网科学研究院有限责任公司 | Overcurrent protection method, device and equipment for three-phase four-wire inverter |
| CN109921388A (en) * | 2019-01-17 | 2019-06-21 | 华北电力大学 | The direct current cut-off device and method of hybrid MMC and AC circuit breaker cooperation |
| CN110190618A (en) * | 2019-07-04 | 2019-08-30 | 国家电网公司华中分部 | A kind of AC fault passes through the flexible direct current converter station model equivalent method under operating condition |
| CN110880764A (en) * | 2019-10-30 | 2020-03-13 | 华南理工大学 | Fault processing method for unbalanced distribution network containing inverter type distributed power supply |
| CN111416393A (en) * | 2020-04-15 | 2020-07-14 | 上海电力大学 | Virtual synchronous generator fault current suppression method based on self-adaptive virtual impedance |
Non-Patent Citations (3)
| Title |
|---|
| 段青等: "孤岛微电网中虚拟机差异化故障穿越方法", 《电网技术》 * |
| 赵慧敏: "下垂控制逆变器并联系统故障特性分析与控制", 《中国优秀硕士论文电子期刊网》 * |
| 马梦思: "微电网不对称故障条件下微源逆变器控制策略研究", 《中国优秀硕士论文电子期刊网》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865099A (en) * | 2021-04-12 | 2021-05-28 | 李畅 | Amplitude-phase motion analysis system and method for judging frequency motion state of grid-connected inverter under VSG control |
| CN112865099B (en) * | 2021-04-12 | 2024-05-03 | 李畅 | Amplitude-phase motion analysis system and analysis method for judging frequency motion state of grid-connected inverter under VSG control |
| CN113346507A (en) * | 2021-04-29 | 2021-09-03 | 西安交通大学 | Virtual synchronous machine low voltage ride through method and system based on virtual voltage drop |
| CN114336679A (en) * | 2021-12-23 | 2022-04-12 | 武汉大学 | VSG fault ride-through method considering virtual resistor and fault current limiter |
| CN114336679B (en) * | 2021-12-23 | 2024-03-08 | 武汉大学 | VSG fault ride-through method considering virtual resistor and fault current limiter |
| CN114709796A (en) * | 2022-04-28 | 2022-07-05 | 西安交通大学 | Generator zero-loss fault current switching-on and switching-off device and method based on phase selection control |
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