CN111507572B - Power grid strength evaluation method, device and medium for power system - Google Patents

Power grid strength evaluation method, device and medium for power system Download PDF

Info

Publication number
CN111507572B
CN111507572B CN202010191889.1A CN202010191889A CN111507572B CN 111507572 B CN111507572 B CN 111507572B CN 202010191889 A CN202010191889 A CN 202010191889A CN 111507572 B CN111507572 B CN 111507572B
Authority
CN
China
Prior art keywords
power
circuit ratio
direct current
grid strength
alternating current
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
CN202010191889.1A
Other languages
Chinese (zh)
Other versions
CN111507572A (en
Inventor
田宝烨
姚文峰
黄东启
洪潮
周保荣
郭知非
王彤
杨健
孙鹏伟
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.)
CSG Electric Power Research Institute
China Southern Power Grid Co Ltd
Original Assignee
CSG Electric Power Research Institute
China Southern Power Grid 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 CSG Electric Power Research Institute, China Southern Power Grid Co Ltd filed Critical CSG Electric Power Research Institute
Priority to CN202010191889.1A priority Critical patent/CN111507572B/en
Publication of CN111507572A publication Critical patent/CN111507572A/en
Application granted granted Critical
Publication of CN111507572B publication Critical patent/CN111507572B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q10/00—Administration; Management
    • G06Q10/06—Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
    • G06Q10/063—Operations research, analysis or management
    • G06Q10/0639—Performance analysis of employees; Performance analysis of enterprise or organisation operations
    • G06Q10/06393—Score-carding, benchmarking or key performance indicator [KPI] analysis
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q50/00—Systems or methods specially adapted for specific business sectors, e.g. utilities or tourism
    • G06Q50/06—Electricity, gas or water supply
    • 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
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications

Landscapes

  • Business, Economics & Management (AREA)
  • Human Resources & Organizations (AREA)
  • Engineering & Computer Science (AREA)
  • Economics (AREA)
  • Strategic Management (AREA)
  • General Physics & Mathematics (AREA)
  • Development Economics (AREA)
  • Health & Medical Sciences (AREA)
  • Educational Administration (AREA)
  • Marketing (AREA)
  • Entrepreneurship & Innovation (AREA)
  • Theoretical Computer Science (AREA)
  • Tourism & Hospitality (AREA)
  • Physics & Mathematics (AREA)
  • General Business, Economics & Management (AREA)
  • Operations Research (AREA)
  • Quality & Reliability (AREA)
  • Game Theory and Decision Science (AREA)
  • Public Health (AREA)
  • Water Supply & Treatment (AREA)
  • General Health & Medical Sciences (AREA)
  • Primary Health Care (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a power grid strength evaluation method of a power system, which comprises the following steps: and setting the single direct current system to be in a control mode of fixed direct current and a turn-off angle, wherein the synchronous phase modulator outputs power with preset reactive power. And recording alternating current and direct current operating parameters before and after the current instruction is changed by changing the direct current instruction to calculate the equivalent impedance of the synchronous phase modulator and the equivalent impedance of the power system, and further calculating to obtain the effective short-circuit ratio and the critical effective short-circuit ratio of the power system. And evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio. The invention also discloses a corresponding power grid strength evaluation device and a computer storage medium of the power system.

Description

Power grid strength evaluation method, device and medium for power system
Technical Field
The invention relates to the technical field of power systems, in particular to a method, a device and a medium for evaluating the power grid strength of a power system.
Background
Energy resources and load requirements of China are distributed in a reverse direction, and large-scale trans-regional transmission of electric energy is inevitable. The high-voltage direct-current transmission has become one of the important modes of 'west-east transmission' in China by virtue of the advantages of the high-voltage direct-current transmission in aspects of large capacity, long distance, regional interconnection and the like. However, the direct current system depends on power grid phase change, and the stable operation of the direct current system needs an alternating current power grid with certain strength as a support, so that the accurate evaluation of the strength of the alternating current power grid has great significance for planning and operating the power system. If the alternating current system is too weak, when the system fluctuates, the alternating current and direct current system is easy to be unstable, and the stable operation of the power system is influenced.
The synchronous phase modulator can provide dynamic reactive support, improves the strength of a power grid so as to improve the stable operation capacity of a system, and is gradually applied to the power grid in recent years. However, how to quantitatively evaluate the receiving-end power grid strength of the single direct current system after the synchronous phase modulator is fed in is still lack of a recognized index at present. From the angle that the dynamic reactive power of the synchronous phase modulator influences the alternating-current bus voltage and further influences the effective short-circuit ratio index, students quantitatively evaluate the strength of a receiving-end power grid fed in by the synchronous phase modulator. However, the method ignores the influence of the dynamic reactive power of the synchronous phase modulator on the critical effective short-circuit ratio of the system, thereby causing inaccurate results and possibly misleading the planning and operation work of the power system.
Disclosure of Invention
The embodiment of the invention aims to provide a power grid strength evaluation method, a device and a medium for a power system, which can accurately evaluate the receiving-end power grid strength of a single direct-current system after being fed by a synchronous phase modulator and provide a reference basis for planning and constructing the power system.
In order to achieve the above object, an embodiment of the present invention provides a method for evaluating a power grid strength of an electric power system, where the electric power system includes a synchronous phase modulator, a single direct-current system, and an alternating-current system; the power grid strength evaluation method of the power system comprises the following steps:
setting the single direct current system to be in a control mode of constant direct current and turn-off angle, and enabling the synchronous phase modulator to output power with preset reactive power;
acquiring the voltage amplitude of an alternating current bus of the power system, the voltage phase of the alternating current bus, active power injected by a direct current system and reactive power consumed by the direct current system; adjusting the direct current instruction according to a preset first instruction adjustment amount, and acquiring the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus after the direct current instruction changes;
calculating the equivalent impedance of the synchronous phase modulator according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes;
calculating the equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating-current bus;
calculating an effective short-circuit ratio and a critical effective short-circuit ratio of the power system according to active power injected by the direct-current system, reactive power consumed by the direct-current system and equivalent impedance of the power system;
and evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio.
As an improvement of the above scheme, the calculating the equivalent impedance of the synchronous phase modulator according to the voltage amplitude of the ac bus and the voltage phase of the ac bus before and after the dc current command change of the power system specifically includes:
according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes, calculating the equivalent impedance of the synchronous phase modulator through the following calculation formula:
Figure BDA0002416227250000021
Figure BDA0002416227250000022
Figure BDA0002416227250000031
wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0002416227250000032
is the equivalent impedance of the synchronous phase modulator; u shape 0 The voltage amplitude of the alternating current bus before the direct current command is changed,
Figure BDA00024162272500000311
the voltage phase of the alternating current bus before the direct current instruction changes; u shape 1 The voltage amplitude of the alternating current bus after the direct current instruction is changed,
Figure BDA0002416227250000033
the voltage phase of the alternating current bus after the direct current instruction is changed; KS is the preset reactive power.
As an improvement of the above scheme, the calculating the equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating-current bus specifically includes:
according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating current bus, calculating the equivalent impedance of the power system through the following calculation formula:
Figure BDA0002416227250000034
wherein the content of the first and second substances,
Figure BDA0002416227250000035
is an equivalent impedance of the power system;
Figure BDA0002416227250000036
is the node self-impedance of the ac busbar.
As an improvement of the above scheme, the calculating an effective short-circuit ratio and a critical effective short-circuit ratio of the power system according to the active power injected by the dc system, the reactive power consumed by the dc system, and the equivalent impedance of the power system specifically includes:
according to the active power injected by the direct current system, the reactive power consumed by the direct current system and the equivalent impedance of the power system, calculating the effective short-circuit ratio and the critical effective short-circuit ratio of the power system by the following calculation formulas:
Figure BDA0002416227250000037
Figure BDA0002416227250000038
wherein the content of the first and second substances,
Figure BDA0002416227250000039
is an equivalent impedance of the power system; ESCR is the effective short circuit ratio; CESCR is the critical effective short circuit ratio;
Figure BDA00024162272500000310
is the node self-impedance of the AC bus; p dc0 Active power, Q, injected for DC system before DC current command change dc0 The reactive power consumed by the direct current system before the direct current instruction changes; gamma is the turn-off angle of the direct current system; mu is a commutation angle of a direct current system; theta.theta. eq Is the equivalent impedance
Figure BDA0002416227250000041
The phase angle of (c).
As an improvement of the above scheme, the evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio specifically includes:
calculating the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio as a short-circuit ratio;
acquiring the power grid strength grade of the alternating current system according to a mapping relation of preset power grid strength and short circuit ratio; and recording the corresponding relation between different short-circuit ratio values and power grid strength grades by the mapping relation between the power grid strength and the short-circuit ratio value.
As an improvement of the scheme, the power grid strength grades comprise three grades of stronger alternating current power grid strength, weaker alternating current power grid strength and extremely weak alternating current power grid strength.
As an improvement of the above scheme, the mapping relationship between the preset grid strength and the short-circuit ratio specifically includes:
when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is greater than or equal to 2, the alternating-current system is in a power grid strength grade with stronger power grid strength;
when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is greater than 1 and less than 2, the alternating-current system is in a power grid strength level with weaker power grid strength;
and when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is less than or equal to 1, the alternating current system is in a power grid strength grade with extremely weak power grid strength.
The embodiment of the present invention further provides a device for evaluating grid strength of an electric power system, including: the system comprises a control mode setting module, an operating parameter acquisition module, a first equivalent impedance calculation module, a second equivalent impedance calculation module, a short-circuit ratio calculation module and a power grid strength evaluation module; wherein the content of the first and second substances,
the control mode setting module is used for setting the single direct current system to be a control mode of constant direct current and a turn-off angle, and the synchronous phase modulator outputs power with preset reactive power;
the operation parameter acquisition module is used for acquiring the voltage amplitude of an alternating current bus of the power system, the voltage phase of the alternating current bus, active power injected by the direct current system and reactive power consumed by the direct current system; adjusting the direct current instruction according to a preset first instruction adjustment amount, and acquiring the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus after the direct current instruction changes;
the first equivalent impedance calculation module is used for calculating the equivalent impedance of the synchronous phase modulator according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes;
the second equivalent impedance calculation module is used for calculating the equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating-current bus;
the short circuit ratio calculation module is used for calculating an effective short circuit ratio and a critical effective short circuit ratio of the power system according to active power injected by the direct current system, reactive power consumed by the direct current system and equivalent impedance of the power system;
and the power grid strength evaluation module is used for evaluating the power grid strength of the alternating current system fed in by the synchronous phase modulator according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio.
The embodiment of the present invention further provides a power grid strength evaluation apparatus of an electric power system, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the power grid strength evaluation apparatus implements the power grid strength evaluation method of the electric power system as described above.
The embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, where when the computer program runs, a device in which the computer-readable storage medium is located is controlled to execute the method for evaluating the grid strength of the power system as described above.
Compared with the prior art, the method, the device and the medium for evaluating the power grid strength of the power system are characterized in that the single direct current system is set to be a control mode of constant direct current and a turn-off angle, and the synchronous phase modulator outputs power with preset reactive power; under the rated operation state of the power system, alternating current and direct current operation parameters before and after the current instruction changes are recorded through changing the direct current instruction, and the equivalent impedance of the power system is further calculated through calculating the equivalent impedance of the synchronous phase modulator according to the recorded operation parameters, so that the accuracy of calculating the equivalent impedance of the power system is improved, and the effective short-circuit ratio and the critical effective short-circuit ratio of the power system are finally calculated accurately. And evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio. The method can accurately calculate the effective short-circuit ratio and the critical effective short-circuit ratio of the power system after the synchronous phase modulator is fed in, so that the alternating current power grid strength of the system after the synchronous phase modulator is fed in can be more accurately evaluated, and a reference basis is provided for planning and building the power system.
Drawings
Fig. 1 is a schematic structural diagram of an electrical power system according to a first embodiment of the present invention;
fig. 2 is a schematic flowchart illustrating steps of a method for evaluating grid strength of an electric power system according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart illustrating steps of a preferred grid strength evaluation method for an electrical power system according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a grid strength evaluation device of an electric power system according to a second embodiment of the present invention;
fig. 5 is a schematic structural diagram of another power grid strength evaluation apparatus for an electric power system according to a third embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
Fig. 1 is a schematic structural diagram of an electric power system according to a first embodiment of the present invention. In an embodiment of the invention, the power system comprises an alternating current system, a single direct current system and a synchronous phase modulator. In the process of transmitting power by a single direct current system, an alternating current power grid with certain strength is required as a support. The synchronous phase modulator can provide dynamic reactive support, the strength of an alternating current power grid is improved, and the problem that the stable operation of the whole power system is influenced because the power transmission capacity of a direct current system is limited due to the fact that the alternating current system is too weak is avoided. The power grid strength of the alternating current system after the synchronous phase modulator is fed into the system is accurately evaluated, the working parameter setting of the power system can be guided, and a reference basis is provided for planning and construction of the power system.
Fig. 2 is a schematic flow chart illustrating steps of a method for evaluating grid strength of an electric power system according to an embodiment of the present invention. The method for evaluating the power grid strength of the power system according to the embodiment of the invention is implemented through steps S1 to S6:
s1, setting the single direct current system to be in a control mode of constant direct current and a turn-off angle, wherein the synchronous phase modulator outputs power with preset reactive power;
and acquiring the alternating current system and the direct current system, enabling the single direct current system to work in a control mode of constant direct current and a turn-off angle, adjusting a control mode of a synchronous phase modulator to be constant reactive power, and outputting power with preset reactive power KS. Wherein S is the rated capacity of the synchronous phase modulator, and K is the strong excitation multiple and is the inherent parameter of the synchronous phase modulator. Because the synchronous phase modulator is under the control mode of the constant reactive power, the reactive power of the injection system of the synchronous phase modulator is a constant value. In the subsequent adjustment process of the operating parameters of the alternating current system and the direct current system, the value of the reactive power of the injection system of the synchronous phase modulator cannot be changed, so that the accuracy of calculating the power grid strength of the alternating current system after the synchronous phase modulator is fed in is ensured.
S2, acquiring the voltage amplitude of an alternating current bus of the power system, the voltage phase of the alternating current bus, active power injected by a direct current system and reactive power consumed by the direct current system; and adjusting the direct current instruction according to a preset first instruction adjustment amount, and acquiring the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus after the direct current instruction changes.
Acquiring the operating parameters of the power system in the current state under the rated operating state of the power system,particularly comprising the voltage amplitude U of the AC bus 0 Ac bus voltage phase
Figure BDA0002416227250000071
Active power P injected by single direct current system dc0 Reactive power Q consumed by single direct current system dc0 And obtaining the turn-off angle gamma and the commutation angle mu of the single direct current system in a rated operation state.
And then, taking a preset first instruction adjustment amount as an adjustment step length, increasing or decreasing the direct current instruction, and acquiring operation parameters of the power system after the direct current instruction changes, wherein the operation parameters specifically comprise the voltage amplitude U of the alternating current bus 1 Ac bus voltage phase
Figure BDA0002416227250000072
The first instruction adjustment amount is preset according to the actual operation condition of the power system and experience knowledge of a person skilled in the art, for example, the first instruction adjustment amount may be set to 0.01, or may be other suitable small values, which do not affect the beneficial effects obtained by the present invention.
And S3, calculating the equivalent impedance of the synchronous phase modulator according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes.
According to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes, calculating the equivalent impedance of the synchronous phase modulator through the following calculation formula:
Figure BDA0002416227250000081
Figure BDA0002416227250000082
Figure BDA0002416227250000083
wherein the content of the first and second substances,
Figure BDA0002416227250000084
the equivalent impedance of the synchronous phase modulator; u shape 0 The voltage amplitude of the alternating current bus before the direct current command is changed,
Figure BDA0002416227250000085
the voltage phase of the alternating current bus before the direct current instruction changes; u shape 1 The voltage amplitude of the alternating current bus after the direct current instruction is changed,
Figure BDA0002416227250000086
the voltage phase of the alternating current bus after the direct current instruction is changed; KS is the preset reactive power.
And S4, calculating the equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating current bus.
According to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating current bus, calculating the equivalent impedance of the power system through the following calculation formula:
Figure BDA0002416227250000087
wherein the content of the first and second substances,
Figure BDA0002416227250000088
is an equivalent impedance of the power system;
Figure BDA0002416227250000089
node self-impedance of an alternating current bus, belongs to structural parameters of the power system, and is equivalent impedance Z & lttheta & gt and compensation capacitor B of the alternating current system for a single feed system c Are connected in parallel.
And S5, calculating the effective short-circuit ratio and the critical effective short-circuit ratio of the power system according to the active power injected by the direct-current system, the reactive power consumed by the direct-current system and the equivalent impedance of the power system.
According to the active power injected by the direct current system, the reactive power consumed by the direct current system and the equivalent impedance of the power system, calculating the effective short-circuit ratio and the critical effective short-circuit ratio of the power system by the following calculation formulas:
Figure BDA0002416227250000091
Figure BDA0002416227250000092
wherein the content of the first and second substances,
Figure BDA0002416227250000093
is an equivalent impedance of the power system; ESCR is the effective short circuit ratio; CESCR is the critical effective short circuit ratio;
Figure BDA0002416227250000094
is the node self-impedance of the AC bus; p is dc0 Active power, Q, injected for DC system before DC command change dc0 The reactive power consumed by the direct current system before the direct current instruction changes; gamma is the turn-off angle of the direct current system; mu is a commutation angle of a direct current system; theta.theta. eq Is the equivalent impedance
Figure BDA0002416227250000095
The phase angle of (c).
And S6, evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio.
And after the effective short-circuit ratio and the critical effective short-circuit ratio of the power system are obtained through calculation, evaluating the power grid strength of the alternating current system fed into the synchronous phase modulator according to the ratio of the effective short-circuit ratio and the critical effective short-circuit ratio. The larger the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio, the stronger the grid strength of the alternating current system. According to the power grid strength condition of the alternating current system after the synchronous phase modulator is fed into the system, the working parameter setting of the power system is correspondingly guided, the stable operation of the system is ensured, and therefore a reference basis is provided for planning and construction of the power system.
As a preferred embodiment, referring to fig. 3, which is a schematic flowchart of steps of a preferred method for evaluating grid strength of an electric power system according to one embodiment of the present invention, step S6 is executed through steps S61 to S62:
s61, after the effective short-circuit ratio ESCR and the critical effective short-circuit ratio CESCR are obtained through calculation, the ratio of the effective short-circuit ratio ESCR to the critical effective short-circuit ratio CESCR is calculated
Figure BDA0002416227250000096
As short circuit ratio;
s62, acquiring the power grid strength grade of the alternating current system according to a preset mapping relation between the power grid strength and the short-circuit ratio; and recording the corresponding relation between different short-circuit ratio values and power grid strength grades by the mapping relation between the power grid strength and the short-circuit ratio value.
And in the mapping relation of the ratio of the power grid strength to the short circuit ratio, three power grid strength levels of stronger alternating current power grid strength, weaker alternating current power grid strength and extremely weaker alternating current power grid strength are included. And each power grid strength grade corresponds to a short-circuit ratio value interval, and the interval where the power grid strength grade is located is determined according to the short-circuit ratio value obtained through calculation so as to obtain the corresponding power grid strength grade, so that the power grid strength of the alternating current system after the synchronous phase modulator is fed in is evaluated.
Specifically, when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio
Figure BDA0002416227250000101
When the power grid intensity is higher than the preset power grid intensity, the alternating current system is in a power grid intensity level with higher power grid intensity; when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio
Figure BDA0002416227250000102
While the AC system is in the gridThe power grid strength grade with weaker strength; when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio
Figure BDA0002416227250000103
And when the alternating current system is in the power grid strength grade with extremely weak power grid strength.
After the power grid strength grade of the alternating current system is determined, the working parameter setting of the power system can be correspondingly adjusted according to the power grid strength grade, and therefore the safe and stable operation of the system is guaranteed. For example, when the ac system is at a level with a strong grid strength, the power system may stably operate according to the current operating parameters and operating conditions, and the stability margin is large; when the alternating current system is in a grade with weak power grid strength, the power system can stably operate, but certain risks exist; when the alternating current system is in a grade with extremely weak power grid strength, the power system cannot operate stably, and measures such as reducing direct current transmission power, increasing reactive power injected by a synchronous phase modifier or reducing equivalent impedance of the alternating current system are required to ensure safe and stable operation of the power system so as to improve the power grid strength of the alternating current system.
The embodiment one of the invention provides a power grid strength evaluation method of an electric power system, wherein a single direct current system is set to be a control mode of fixing direct current and a turn-off angle, and a synchronous phase modulator outputs power with preset reactive power; under the rated operation state of the power system, the alternating current and direct current operation parameters before and after the current instruction changes are recorded by changing the direct current instruction, and the equivalent impedance of the power system is further calculated by calculating the equivalent impedance of the synchronous phase modulator according to the recorded operation parameters, so that the accuracy of calculating the equivalent impedance of the power system is improved, and the effective short-circuit ratio and the critical effective short-circuit ratio of the power system are finally calculated accurately. And evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio. The method can accurately calculate the effective short-circuit ratio and the critical effective short-circuit ratio of the power system after the synchronous phase modulator is fed in, so that the alternating current power grid strength of the system after the synchronous phase modulator is fed in can be more accurately evaluated, and a reference basis is provided for planning and building the power system.
Fig. 4 is a schematic structural diagram of a grid strength evaluation apparatus of an electric power system in the second embodiment of the present invention. In the second embodiment of the present invention, the power system includes a synchronous phase modulator, a single dc system and an ac system, and the power grid strength evaluation device 20 of the power system.
The grid strength evaluation device 20 of the power system includes: the system comprises a control mode setting module 21, an operating parameter acquisition module 22, a first equivalent impedance calculation module 23, a second equivalent impedance calculation module 24, a short-circuit ratio calculation module 25 and a power grid strength evaluation module 26; wherein the content of the first and second substances,
the control mode setting module 21 is configured to set the single direct current system to be a control mode of a constant direct current and a turn-off angle, and the synchronous phase modulator outputs power with a preset reactive power;
the operation parameter obtaining module 22 is configured to obtain a voltage amplitude of an ac bus of the power system, a voltage phase of the ac bus, active power injected by the dc system, and reactive power consumed by the dc system; adjusting the direct current instruction according to a preset first instruction adjustment amount, and acquiring the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus after the direct current instruction changes;
the first equivalent impedance calculation module 23 is configured to calculate an equivalent impedance of the synchronous phase modulator according to a voltage amplitude of the ac bus and a voltage phase of the ac bus before and after a dc current instruction of the power system changes;
the second equivalent impedance calculating module 24 is configured to calculate an equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and a node self-impedance of the ac bus;
the short-circuit ratio calculation module 25 is configured to calculate an effective short-circuit ratio and a critical effective short-circuit ratio of the power system according to active power injected by the dc system, reactive power consumed by the dc system, and equivalent impedance of the power system;
and the power grid strength evaluation module 26 is configured to evaluate the power grid strength of the alternating current system fed by the synchronous phase modulator according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio.
Preferably, the grid strength evaluation module 26 is specifically configured to:
calculating the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio as a short-circuit ratio;
acquiring the power grid intensity grade of the alternating current system according to a mapping relation of a preset power grid intensity and short circuit ratio; and the mapping relation of the power grid strength and the short-circuit ratio records the corresponding relation between different short-circuit ratio values and power grid strength grades.
The power grid strength grades comprise three grades of stronger alternating current power grid strength, weaker alternating current power grid strength and extremely weak alternating current power grid strength.
Further, the preset mapping relationship between the grid strength and the short-circuit ratio specifically includes:
when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is greater than or equal to 2, the alternating-current system is in a power grid strength grade with stronger power grid strength;
when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is greater than 1 and less than 2, the alternating-current system is in a power grid strength level with weaker power grid strength;
and when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is less than or equal to 1, the alternating current system is in a power grid strength grade with extremely weak power grid strength.
It should be noted that, the power grid strength evaluation apparatus for an electric power system according to the embodiment of the present invention is used for executing all the process steps of the power grid strength evaluation method for an electric power system according to the first embodiment, and working principles and beneficial effects of the two are in one-to-one correspondence, so that details are not repeated.
The embodiment of the invention provides a power grid strength evaluation device of an electric power system, wherein a single direct current system is set to be a control mode of fixing direct current and an off angle, and the synchronous phase modulator outputs power with preset reactive power; under the rated operation state of the power system, alternating current and direct current operation parameters before and after the current instruction changes are recorded through changing the direct current instruction, and the equivalent impedance of the power system is further calculated through calculating the equivalent impedance of the synchronous phase modulator according to the recorded operation parameters, so that the accuracy of calculating the equivalent impedance of the power system is improved, and the effective short-circuit ratio and the critical effective short-circuit ratio of the power system are finally calculated accurately. And evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio. The method can accurately calculate the effective short-circuit ratio and the critical effective short-circuit ratio of the power system after the synchronous phase modulator is fed in, so that the alternating current power grid strength of the system after the synchronous phase modulator is fed in can be more accurately evaluated, and a reference basis is provided for planning and building the power system.
Fig. 5 is a schematic structural diagram of a power grid strength evaluation apparatus of an electric power system in the third embodiment of the present invention. The power grid strength evaluation apparatus 30 of another power system provided by the embodiment of the present invention includes a processor 31, a memory 32, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the power grid strength evaluation method of the power system according to the first embodiment is implemented.
The embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, and when the computer program runs, a device in which the computer-readable storage medium is located is controlled to execute the method for evaluating a grid strength of an electric power system according to the first embodiment.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above may be implemented by a computer program, which may be stored in a computer readable storage medium and executed by a computer to implement the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-only memory (ROM), a Random Access Memory (RAM), or the like.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. The power grid strength evaluation method of the power system is characterized in that the power system comprises a synchronous phase modulator, a single direct current system and an alternating current system; the power grid strength evaluation method of the power system comprises the following steps:
setting the single direct current system to be in a control mode of constant direct current and turn-off angle, and enabling the synchronous phase modulator to output power with preset reactive power;
acquiring the voltage amplitude of an alternating current bus of the power system, the voltage phase of the alternating current bus, active power injected by a direct current system and reactive power consumed by the direct current system; adjusting the direct current instruction according to a preset first instruction adjustment amount, and acquiring the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus after the direct current instruction changes;
calculating the equivalent impedance of the synchronous phase modifier according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes;
calculating the equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating-current bus;
calculating an effective short-circuit ratio and a critical effective short-circuit ratio of the power system according to active power injected by the direct-current system, reactive power consumed by the direct-current system and equivalent impedance of the power system;
and evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio.
2. The method for evaluating the grid strength of the electric power system according to claim 1, wherein the calculating of the equivalent impedance of the synchronous phase modifier according to the voltage amplitude of the ac bus and the voltage phase of the ac bus before and after the dc current command change of the electric power system specifically comprises:
according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes, calculating the equivalent impedance of the synchronous phase modulator through the following calculation formula:
Figure FDA0002416227240000011
Figure FDA0002416227240000021
Figure FDA0002416227240000022
wherein, the first and the second end of the pipe are connected with each other,
Figure FDA0002416227240000029
is the equivalent impedance of the synchronous phase modulator; u shape 0 The voltage amplitude of the alternating current bus before the direct current instruction is changed,
Figure FDA0002416227240000023
the voltage phase of the alternating current bus before the direct current instruction changes; u shape 1 The voltage amplitude of the alternating current bus after the direct current instruction is changed,
Figure FDA0002416227240000024
the voltage phase of the alternating current bus after the direct current instruction is changed; KS is the preset reactive power.
3. The method for evaluating the grid strength of an electric power system according to claim 2, wherein the calculating the equivalent impedance of the electric power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the ac bus comprises:
according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating current bus, calculating the equivalent impedance of the power system through the following calculation formula:
Figure FDA0002416227240000025
wherein the content of the first and second substances,
Figure FDA0002416227240000026
is an equivalent impedance of the power system;
Figure FDA0002416227240000027
is the node self-impedance of the ac busbar.
4. The method for evaluating grid strength of an electric power system according to claim 3, wherein the calculating an effective short-circuit ratio and a critical effective short-circuit ratio of the electric power system according to the active power injected by the direct-current system, the reactive power consumed by the direct-current system and the equivalent impedance of the electric power system specifically comprises:
according to the active power injected by the direct current system, the reactive power consumed by the direct current system and the equivalent impedance of the power system, calculating the effective short-circuit ratio and the critical effective short-circuit ratio of the power system by the following calculation formulas:
Figure FDA0002416227240000028
Figure FDA0002416227240000031
wherein, the first and the second end of the pipe are connected with each other,
Figure FDA0002416227240000032
is an equivalent impedance of the power system; ESCR is the effective short circuit ratio; CESCR is the critical effective short circuit ratio;
Figure FDA0002416227240000033
is the node self-impedance of the AC bus; p dc0 Active power, Q, injected for DC system before DC command change dc0 The reactive power consumed by the direct current system before the direct current instruction changes; gamma is the turn-off angle of the direct current system; mu is a commutation angle of a direct current system; theta.theta. eq Is the equivalent impedance
Figure FDA0002416227240000034
The phase angle of (c).
5. The method according to claim 1, wherein the evaluating the grid strength of the ac system fed by the synchronous phase modulator according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio comprises:
calculating the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio as a short-circuit ratio;
acquiring the power grid strength grade of the alternating current system according to a mapping relation of preset power grid strength and short circuit ratio; and the mapping relation of the power grid strength and the short-circuit ratio records the corresponding relation between different short-circuit ratio values and power grid strength grades.
6. The method according to claim 5, wherein the grid strength level includes three levels of stronger AC grid strength, weaker AC grid strength, and weaker AC grid strength.
7. The method for evaluating grid strength of an electric power system according to claim 6, wherein the mapping relationship between the preset grid strength and the short-circuit ratio specifically includes:
when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is greater than or equal to 2, the alternating-current system is in a power grid strength grade with stronger power grid strength;
when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is larger than 1 and smaller than 2, the alternating current system is in a power grid strength level with weaker power grid strength;
and when the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio is less than or equal to 1, the alternating-current system is in a power grid intensity level with extremely weak power grid intensity.
8. An apparatus for evaluating grid strength of an electric power system, comprising: the system comprises a control mode setting module, an operation parameter acquisition module, a first equivalent impedance calculation module, a second equivalent impedance calculation module, a short-circuit ratio calculation module and a power grid strength evaluation module; wherein the content of the first and second substances,
the control mode setting module is used for setting a single direct current system as a control mode of constant direct current and a turn-off angle, and the synchronous phase modulator outputs power with preset reactive power;
the operation parameter acquisition module is used for acquiring the voltage amplitude of an alternating current bus of the power system, the voltage phase of the alternating current bus, active power injected by the direct current system and reactive power consumed by the direct current system; adjusting the direct current instruction according to a preset first instruction adjustment amount, and acquiring the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus after the direct current instruction changes;
the first equivalent impedance calculation module is used for calculating the equivalent impedance of the synchronous phase modulator according to the voltage amplitude of the alternating current bus and the voltage phase of the alternating current bus before and after the direct current instruction of the power system changes;
the second equivalent impedance calculation module is used for calculating the equivalent impedance of the power system according to the equivalent impedance of the synchronous phase modulator and the node self-impedance of the alternating-current bus;
the short circuit ratio calculation module is used for calculating an effective short circuit ratio and a critical effective short circuit ratio of the power system according to active power injected by the direct current system, reactive power consumed by the direct current system and equivalent impedance of the power system;
and the power grid strength evaluation module is used for evaluating the power grid strength of the alternating current system after the synchronous phase modulator is fed in according to the ratio of the effective short-circuit ratio to the critical effective short-circuit ratio.
9. An apparatus for evaluating grid strength of an electric power system, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor implementing the method for evaluating grid strength of an electric power system according to any one of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, comprising a stored computer program, wherein when the computer program runs, the computer-readable storage medium controls a device to execute the grid strength evaluation method of the power system according to any one of claims 1 to 7.
CN202010191889.1A 2020-03-18 2020-03-18 Power grid strength evaluation method, device and medium for power system Active CN111507572B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010191889.1A CN111507572B (en) 2020-03-18 2020-03-18 Power grid strength evaluation method, device and medium for power system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010191889.1A CN111507572B (en) 2020-03-18 2020-03-18 Power grid strength evaluation method, device and medium for power system

Publications (2)

Publication Number Publication Date
CN111507572A CN111507572A (en) 2020-08-07
CN111507572B true CN111507572B (en) 2022-12-06

Family

ID=71871614

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010191889.1A Active CN111507572B (en) 2020-03-18 2020-03-18 Power grid strength evaluation method, device and medium for power system

Country Status (1)

Country Link
CN (1) CN111507572B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112068027B (en) * 2020-08-26 2023-01-17 华北电力大学 Method for identifying short-circuit ratio of flexible direct-current transmission alternating-current system
CN113904375B (en) * 2021-12-10 2022-02-25 中国电力科学研究院有限公司 New energy grid-connected system voltage support strength evaluation method and system
CN115276128A (en) * 2022-07-12 2022-11-01 国网冀北电力有限公司电力科学研究院 Synchronization stability verification method and device for new energy and phase modulator combined system

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109103916B (en) * 2018-09-20 2019-12-10 清华大学 method for evaluating voltage supporting capability of receiving-end power grid of multi-direct-current feed-in system
CN109193633B (en) * 2018-09-28 2019-11-12 清华大学 The optimal configuration method of direct current rated power in a kind of multi-infeed DC system
CN109245148B (en) * 2018-11-19 2021-10-26 清华大学 Voltage stability judging method for flexible direct current access power grid

Also Published As

Publication number Publication date
CN111507572A (en) 2020-08-07

Similar Documents

Publication Publication Date Title
CN111507572B (en) Power grid strength evaluation method, device and medium for power system
CN106950512B (en) Energy storage converter grid-connected and grid-disconnected characteristic integrated detection system and method
CN105977996B (en) Control System for SVG based on DSP and control method
CN112310973B (en) Voltage stabilization control method and system, charging pile and charging station
CN111082450B (en) Method and device for evaluating strength of flexible direct current receiving end power grid and storage medium
CN107147317A (en) A kind of inverter parallel control method based on RC virtual impedances
CN106655195B (en) Active power distribution network high-frequency harmonic power flow calculation method
CN105024390A (en) Micro-grid cell energy storage system frequency modulation control method based on BP nerve network
CN113595093B (en) Reactive voltage automatic control method and device for new energy power station and storage medium
CN111965445B (en) Method and device for evaluating power grid strength of multi-direct-current feed-in system containing synchronous phase modulator
CN110752762A (en) Control method for parallel virtual capacitor of grid-connected converter
CN111416342B (en) Power grid strength evaluation method, device and medium of power system containing STATCOM
CN106972518B (en) Access mode selection method for direct-current (DC) delivery system of small local power grid and energy base
CN110829505B (en) Frequency modulation control method considering active and reactive coupling characteristics and frequency modulation controller
CN104467024A (en) Islanding detection system and method for inverter power source
CN203340031U (en) Power frequency inductance regulation resonance device
CN112039119B (en) Photovoltaic access-containing power distribution network voltage control method and system
CN111416343B (en) Method, device and medium for evaluating DC power boost of power system
CN103986191A (en) Operation feasible zone evaluation method for high-capacity photovoltaic inverter system connected to power grid
CN112421976B (en) Three-level inverter power supply reduced-order modeling method based on hybrid system theory
CN115270504A (en) Power closed-loop type dynamic simulation system for active power distribution network and application method thereof
CN109149660B (en) Reactive power control method and system for photovoltaic power generation system
CN111416341B (en) DC power boost evaluation method, device and medium for power system containing STATCOM
CN105510747A (en) Voltage fluctuation simulating method
Zhao et al. Voltage Stability Analysis for AC/DC System With VSC-HVDC

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