CN114204603B - Current injection method and system during low-voltage ride through of new energy power system - Google Patents

Current injection method and system during low-voltage ride through of new energy power system Download PDF

Info

Publication number
CN114204603B
CN114204603B CN202111491023.3A CN202111491023A CN114204603B CN 114204603 B CN114204603 B CN 114204603B CN 202111491023 A CN202111491023 A CN 202111491023A CN 114204603 B CN114204603 B CN 114204603B
Authority
CN
China
Prior art keywords
new energy
voltage
current
energy power
grid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202111491023.3A
Other languages
Chinese (zh)
Other versions
CN114204603A (en
Inventor
黎金鑫
叶畅
占萌
曹侃
马锐
张亚耀
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Huazhong University of Science and Technology
Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd
Original Assignee
Huazhong University of Science and Technology
Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huazhong University of Science and Technology, Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd filed Critical Huazhong University of Science and Technology
Priority to CN202111491023.3A priority Critical patent/CN114204603B/en
Publication of CN114204603A publication Critical patent/CN114204603A/en
Application granted granted Critical
Publication of CN114204603B publication Critical patent/CN114204603B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • H02J3/40—Synchronising a generator for connection to a network or to another generator
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • 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
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • 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
    • Y02E40/30—Reactive power compensation

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention discloses a current injection method and a current injection system in a low-voltage ride through period of a new energy power system, and belongs to the field of transient stability control of the new energy power system. In order to improve the synchronous operation capability between the power generation equipment and the power grid during the voltage crossing of the new energy power system, the invention provides a new current injection strategy, namely, when the voltage of the power grid at the grid side is equal to a set value, active current and reactive current reference values are generated according to a reference current generation mode in a normal state; when the grid voltage at the grid side is lower than a set value, determining an active current and reactive current reference value according to the actual value of the grid voltage; the synchronous operation capability between the equipment and an infinite power grid can be improved when the new energy power generation system has serious faults and generates serious voltage drops, so that the new energy power generation equipment is prevented from easily being disconnected from the system when the new energy power generation equipment has faults, and the utilization rate of renewable energy sources is improved.

Description

Current injection method and system during low-voltage ride through of new energy power system
Technical Field
The invention belongs to the field of transient stability control of a new energy power system, and particularly relates to a current injection method and a current injection system during low-voltage ride through of the new energy power system.
Background
Because the duty ratio of new energy power generation is continuously improved, the inherent characteristics of low inertia, fast action and the like make the original traditional protection device not suitable, and the research on the transient stability mechanism of a new energy power system and the improvement on the transient stability are urgent.
In the traditional power system mainly based on synchronous machines, rotor motion is mainly based on, and the power system based on new energy has been converted into more complex power electronic electromagnetic dynamic problems. The system nonlinearity and high order features brought by cooperative control among multiple time scales become the main difficulty of stable analysis, have attracted attention of students worldwide, and many transient stability control strategies have also been proposed according to analysis, which are mainly divided into two parts: part of the phase-locked loop structure is changed, and the transient stability of the system is improved by adding/reducing control links or changing control parameters of the phase-locked loop; another part improves transient stability by changing the system parameters to change the active/reactive current injection duty cycle during the fault duration phase. Experiments show that the strategies can improve the transient stability of the new energy system to a certain extent, but when the system has serious voltage drop fault or long fault duration, the synchronous stability of the system is difficult to ensure. Therefore, a control strategy is needed to ensure the synchronous and stable operation of the system even when the new energy power system fails seriously, resulting in serious voltage drop of the power grid.
Disclosure of Invention
In order to meet the above defects or improvement demands of the prior art, the invention provides a current injection method and a current injection system during low voltage ride through of a new energy power system, and aims to improve synchronization stability during the low voltage ride through of the new energy power system.
According to one aspect of the present invention, there is provided a current injection method during low voltage ride through of a new energy power system, comprising:
s1, detecting the grid voltage of a new energy power system at the grid side in real time;
s2, judging whether the grid voltage at the grid side is equal to a set value; if yes, generating active current and reactive current reference values according to a reference current generation mode in a normal state; if not, determining the active current and reactive current reference values according to the actual value of the power grid voltage.
Further, the expression for determining the active current and reactive current reference values according to the actual value of the grid voltage is as follows:
U g representing the grid voltage at the grid side of a new energy power system, L g Representing the inductance of the inductor and,represents the phase of the phase-locked loop, ω represents the phase-locked loop frequency.
Further, by sending a switching signal to the controller, the active current and reactive current reference value generation mode is switched.
Further, when the detected power grid voltage is equal to a set value, outputting a switching signal to be 0; when the voltage of the power grid is lower than a set value, outputting a switching signal to be 1; the switching signal being 0 indicates that an active current and reactive current reference value is generated according to a reference current generation mode in a normal state; the switching signal 1 represents that the active current and reactive current reference values are determined according to the actual value of the power grid voltage.
Further, the generation mode of the reference current value in the normal state is divided into three parts according to the actual value of the network side voltage, and the specific formula is as follows:
according to another aspect of the present invention, there is provided a current injection system during low voltage ride through of a new energy power system, comprising:
a fault detection step of detecting the network side voltage of the new energy power system in real time;
a switching control step, outputting a switching signal to be 0 when the detected power grid voltage is equal to a set value; when the voltage of the power grid is lower than a set value, outputting a switching signal to be 1;
a current reference value calculation mode switching step, when receiving a switching signal of 0, generating an active current reference value and a reactive current reference value according to a reference current generation mode in a normal state; and when the received switching signal is 1, determining an active current and reactive current reference value according to the actual value of the power grid voltage.
In general, the above technical solution conceived by the present invention can achieve the following advantageous effects compared to the prior art.
In order to improve synchronous operation capability between power generation equipment and a power grid in a voltage crossing period of a new energy power system, the invention provides a new current injection strategy, namely, when the voltage of the power grid at the grid side is equal to a set value, active current and reactive current reference values are generated according to a reference current generation mode in a normal state; when the grid voltage at the grid side is lower than a set value, determining an active current and reactive current reference value according to the actual value of the grid voltage; the synchronous operation capability between the equipment and an infinite power grid can be improved when the new energy power generation system has serious faults and generates serious voltage drops, so that the new energy power generation equipment is prevented from easily being disconnected from the system when the new energy power generation equipment has faults, and the utilization rate of renewable energy sources is improved.
Drawings
FIG. 1 is a block diagram of a current injection strategy provided by the present invention;
FIG. 2 is a flow chart of implementation of the current injection strategy provided by the present invention;
FIG. 3 illustrates a conventional current injection strategy during a fault duration phase;
FIG. 4 is a graph showing the output frequency versus which a conventional current injection strategy and a current injection strategy according to the present invention are applied to a new energy power generation device when a general voltage drop occurs;
fig. 5 is a graph showing output frequency versus time when a severe voltage drop occurs in a new energy power generation device by applying a conventional current injection strategy and a current injection strategy according to the present invention, respectively.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In order to improve synchronous operation capability between power generation equipment and a power grid during voltage crossing of a new energy power system, the invention provides a new current injection strategy, which can improve synchronous operation capability between equipment and an infinite power grid when the new energy power generation system has serious faults and generates serious voltage drops, thereby avoiding the new energy power generation equipment from easily being off the power grid with the system when the new energy power generation equipment has faults and improving the utilization rate of renewable energy. Referring to fig. 1, the present invention retains the original structure of multi-time scale control, but switches the mode of taking the reference values of active and reactive currents to the mode described in the present invention during the fault duration phase.
The specific implementation flow is shown in fig. 2. Starting from the grid-connected operation of the new energy power generation equipment, detecting the voltage of the grid side in real time by the detection ring node, and if the voltage of the grid is equal to an ideal value of 1.0p.u., switching the generation modes of the active current reference value and the reactive current reference value is not needed. When the network voltage detection link finds that the network side voltage is lower than the ideal value, a switching signal (flag_I) is sent out d =1 and flag_i q =1) to the controller and sends the actual value after the grid voltage drops to the calculation center of the current injection strategy. The reference values for the active and reactive currents during a fault are calculated according to the following formula:
when the power grid voltage value of the new energy power generation system returns to the normal level 1p.u. after the fault is recovered, the fault detection link again switches the signal (flag_I) d =0 and flag_i q =0) is transmitted to the controller, and the generation mode of the current reference value is switched to the reference current generation mode in the normal state.
For a full-power fan widely applied, the terminal voltage dq component of the full-power fan can be expressed as the following formula after ignoring electromagnetic transient states on a transmission line:
when the network side voltage U g Will lead to u when falling tq Is not equal to zero. While vsc control system phase lock loop input is u tq This will directly result in the output frequency of the phase locked loop gradually moving away from the grid frequency, which is detrimental to the synchronous operation of the power plant and the grid. If the current injection strategy provided by the invention is adopted, u can be caused after the voltage at the network side drops tq The phase locked loop output frequency is quickly returned to the 0p.u. state, thereby ensuring that the phase locked loop output frequency remains synchronized with the grid frequency during the fault.
In contrast to the conventional current injection strategy of fig. 3, for the conventional scheme, considering that the power generation device outputs reactive power preferentially to support the grid voltage during the fault, the current injection strategy is divided into three stages, and although the support of the voltage is ensured, there is a shortage of consideration on the synchronous operation capability of the system. When the voltage drop of the power grid is severe (U g <0.4 p.u.), it is possible that the power plant will run out of sync. The current injection strategy provided by the invention is applicable to various degrees of network side voltage drop, and is generated by an algorithm, so that the generation logic of the reference value is more concise while the synchronous operation capability of the system is ensured in the whole.
The embodiment of the invention adopts an infinite bus voltage drop fault to detect the effectiveness of the current injection strategy provided by the invention. After the bus voltage drops from normal value 1p.u. to 0.35p.u. and 0.05p.u. respectively, the frequency oscillation state of the phase-locked loop output is compared to verify the validity of the proposed strategy. The time domain simulation structure is shown in fig. 4 and 5. If the conventional current injection strategy is adopted, a larger frequency oscillation occurs, which is unfavorable for the synchronous operation of new energy power generation equipment. Although stable over time, if the voltage drop increases, the frequency oscillation of the power generation device increases and cannot be maintained for a prescribed period of time in the power grid, as shown in fig. 5. If the current injection strategy provided by the invention is adopted, the new energy power generation equipment can be kept in a good synchronous running state.
In summary, the current injection strategy for improving the synchronization stability of the fault duration stage in the low-voltage ride through period of the new energy power system provided by the invention can improve the synchronization operation capability of the new energy power generation equipment and the power grid when the power grid voltage drops (no matter whether the power grid voltage is light or heavy), and is easy to realize on the existing equipment.
It will be readily understood by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalent substitutions and improvements made within the spirit and principles of the invention are intended to be included in the scope of the invention.

Claims (4)

1. The current injection method during the low voltage ride through of the new energy power system is characterized by comprising the following steps:
s1, detecting the grid voltage of a new energy power system at the grid side in real time;
s2, judging whether the grid voltage at the grid side is equal to a set value; if yes, generating active current and reactive current reference values according to a reference current generation mode in a normal state; if not, determining an active current reference value and a reactive current reference value according to the actual value of the power grid voltage;
the active current and reactive current reference value is determined according to the actual value of the power grid voltage, and the expression is as follows:
U g representing the grid voltage at the grid side of a new energy power system, L g Representing inductance, theta pll Represents the phase of the phase-locked loop and ω represents the phase-locked loop frequency.
2. The method for current injection during low voltage ride through in a new energy power system of claim 1, wherein the active current and reactive current reference value generation modes are switched by sending a switching signal to the controller.
3. The method for injecting current during low voltage ride through in a new energy power system according to claim 2, wherein the output switching signal is 0 when the detected grid voltage is equal to the set value; when the voltage of the power grid is lower than a set value, outputting a switching signal to be 1; the switching signal being 0 indicates that an active current and reactive current reference value is generated according to a reference current generation mode in a normal state; the switching signal of 1 represents that the active current and reactive current reference values are determined according to the actual value of the power grid voltage.
4. A current injection system during low voltage ride through of a new energy power system, comprising:
a fault detection step of detecting the network side voltage of the new energy power system in real time;
a switching control step, outputting a switching signal to be 0 when the detected power grid voltage is equal to a set value; when the voltage of the power grid is lower than a set value, outputting a switching signal to be 1;
a current reference value calculation mode switching step, when receiving a switching signal of 0, generating an active current reference value and a reactive current reference value according to a reference current generation mode in a normal state; when the receiving switching signal is 1, determining an active current reference value and a reactive current reference value according to the actual value of the power grid voltage;
the active current and reactive current reference value is determined according to the actual value of the power grid voltage, and the expression is as follows:
U g representing the grid voltage at the grid side of a new energy power system, L g Representing inductance, theta pll Represents the phase of the phase-locked loop and ω represents the phase-locked loop frequency.
CN202111491023.3A 2021-12-08 2021-12-08 Current injection method and system during low-voltage ride through of new energy power system Active CN114204603B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111491023.3A CN114204603B (en) 2021-12-08 2021-12-08 Current injection method and system during low-voltage ride through of new energy power system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111491023.3A CN114204603B (en) 2021-12-08 2021-12-08 Current injection method and system during low-voltage ride through of new energy power system

Publications (2)

Publication Number Publication Date
CN114204603A CN114204603A (en) 2022-03-18
CN114204603B true CN114204603B (en) 2023-08-25

Family

ID=80651235

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111491023.3A Active CN114204603B (en) 2021-12-08 2021-12-08 Current injection method and system during low-voltage ride through of new energy power system

Country Status (1)

Country Link
CN (1) CN114204603B (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103972904A (en) * 2014-04-28 2014-08-06 上海电力学院 Symmetrical drop-off low voltage ride through reactive power control method of photovoltaic power generation system
CN108718094A (en) * 2018-05-24 2018-10-30 新疆大学 A method of it improving large-sized photovoltaic system low-voltage and passes through performance
CN113346562A (en) * 2021-06-18 2021-09-03 江苏大学 Control method for low voltage ride through of permanent magnet direct drive type wind turbine generator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103972904A (en) * 2014-04-28 2014-08-06 上海电力学院 Symmetrical drop-off low voltage ride through reactive power control method of photovoltaic power generation system
CN108718094A (en) * 2018-05-24 2018-10-30 新疆大学 A method of it improving large-sized photovoltaic system low-voltage and passes through performance
CN113346562A (en) * 2021-06-18 2021-09-03 江苏大学 Control method for low voltage ride through of permanent magnet direct drive type wind turbine generator

Also Published As

Publication number Publication date
CN114204603A (en) 2022-03-18

Similar Documents

Publication Publication Date Title
Korompili et al. Review of VSC HVDC connection for offshore wind power integration
CN103997033B (en) A kind of HVDC transmission system possessing DC Line Fault ride-through capability
Papangelis et al. Stability of a voltage source converter subject to decrease of short-circuit capacity: A case study
CN110994662A (en) Start-stop control method for offshore wind power flexible direct current delivery system
CN103414182A (en) Smooth switching method for converting parallel operation of flexible direct current transmission system into island operation
CN103078344A (en) Method for improving double-fed converter low voltage ride through performance
CN115579944A (en) Network-building type energy storage control system and method with self-current-limiting protection capability
Luo et al. A review of low voltage ride through in DFIG under unbalanced grid faults
CN111756266A (en) Multi-inverter parallel common mode circulating current suppression method based on distributed control
CN118263838A (en) Adaptive impedance current limiting control method and system suitable for network-structured energy storage converter
CN111106630A (en) Control method for improving high voltage ride through capability of doubly-fed wind turbine by participation of phase modulator
CN114204603B (en) Current injection method and system during low-voltage ride through of new energy power system
Hu et al. A coordinated and steadily fault ride through strategy under short-circuit fault of the wind power grid connected system based on the grid-forming control
CN109494800B (en) Control method and system for mutual switching between grid connection and grid disconnection of micro-grid
Chen et al. Impact of Frequency Anti-windup Limiter on Synchronization Stability of Grid Feeding Converter
CN116054205A (en) Photovoltaic grid-connected inverter smooth switching control method and system and inverter
CN113178879B (en) Frequency recovery control method suitable for multiple virtual synchronous machines
CN105098768A (en) Capacitive current-based seamless switching control strategy for micro-grid converter
CN112003316B (en) New energy grid connection method
CN115663908A (en) Transient stability analysis method and system for power synchronous control network type converter
CN113437761A (en) Island microgrid transient stability improving method considering mode switching
de la Rubia Herrera et al. Analysis of the behavior of MVDC system in a distribution grid compared to a UPFC system
CN113224795B (en) Wind power grid-connected system transient stability control method based on automatic voltage regulation
Liu et al. Research on LVRT Control Combination Strategy of PV Station
Chen et al. Research on Unit Removal Method Under Islanding Operation of Small Hydropower Microgrid

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant