CN109088427B - Method and system for determining minimum starting-up scheme of conventional unit in AC/DC hybrid power grid - Google Patents
Method and system for determining minimum starting-up scheme of conventional unit in AC/DC hybrid power grid 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
- H02J3/38—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
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The invention discloses a method and a system for determining a minimum starting scheme of a conventional unit in an alternating current-direct current hybrid power grid, wherein the method comprises the following steps: establishing a BPA power flow simulation model according to the characteristics of each generator set in the alternating current-direct current series-parallel power grid; determining an original starting-up mode of each conventional unit in the AC-DC hybrid power grid, and obtaining the DC engineering output power of the AC-DC hybrid power grid under the original starting-up mode; the starting-up mode comprises the starting-up quantity of each conventional unit; the starting modes of each conventional unit are adjusted one by one, the direct current engineering output power limit value of the alternating current-direct current series-parallel power grid under each starting mode is calculated, and the adjustment influence evaluation index corresponding to each mode is output; and updating the starting mode according to a preset rule according to the adjustment influence evaluation index, evaluating the safety stability of the alternating current-direct current hybrid power grid N-1 under the updated starting mode by using the BPA power flow simulation model, and determining the minimum starting scheme.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a method and a system for determining a minimum starting scheme of a conventional unit in an alternating current-direct current hybrid power grid.
Background
The new energy sources such as wind energy, solar energy and the like in China are concentrated in distribution, far away from the load center, limited in local consumption scale and mainly depend on the remote centralized and external transmission of an extra-high voltage direct current channel, and the large-scale consumption of the new energy sources such as wind power, solar energy and the like in the three north areas at present is completed.
With the increasing of new energy grid-connected scale, the installed proportion occupied by a conventional power supply is greatly reduced, new energy power supplies such as photovoltaic power, wind power and the like replace the dominant position of traditional energy sources, the structure of an AC/DC hybrid power grid power supply is changed significantly, and the disturbance rejection capability of the system is reduced. Along with the construction of the extra-high voltage direct current engineering, the alternating current-direct current hybrid power grid is converted into an alternating current-direct current hybrid power grid, and main factors affecting the stability of the transmitting end alternating current-direct current hybrid power grid are focused on a direct current near region. When an alternating current fault occurs in a direct current near zone, the conventional power supply is limited when the power is started under the condition of large heat of new energy, the dynamic reactive power reserve of the system is greatly reduced, and reactive power loss is greatly increased when the voltage of a new energy unit drops during the alternating current fault, so that the direct current commutation failure is extremely easy to occur after the alternating current fault in the near zone, the problems of power angle, voltage, frequency and the like caused by the large-range transfer of tide are further caused, and the running risk of stable damage exists in an alternating current-direct current hybrid power grid.
Disclosure of Invention
In order to solve the problem of poor running stability of an alternating current-direct current hybrid power grid when alternating current faults occur in a direct current near zone in the alternating current-direct current hybrid power grid with ultrahigh proportion of new energy sources in the background art, the invention provides a method and a system for determining the minimum starting scheme of a conventional unit in the alternating current-direct current hybrid power grid, wherein the method comprises the following steps:
establishing a BPA power flow simulation model according to the characteristics of each generator set in the alternating current-direct current series-parallel power grid; the generator set comprises a new energy set and a conventional set; the conventional unit comprises a hydroelectric unit and a thermal power unit;
determining an original starting-up mode of each conventional unit in the AC-DC hybrid power grid, and obtaining the DC engineering output power of the AC-DC hybrid power grid under the original starting-up mode; the starting-up mode comprises the starting-up quantity of each conventional unit;
the starting modes of all the conventional units are adjusted one by one, the limit value of the direct current engineering output power of the alternating current-direct current series-parallel power grid under each starting mode is calculated, and the adjustment influence evaluation index of the corresponding power plant unit is output;
and updating the starting mode according to a preset rule according to the adjustment influence evaluation index, evaluating the safety stability of the alternating current-direct current hybrid power grid N-1 under the updated starting mode by using the BPA power flow simulation model, and determining the minimum starting scheme.
Further, constructing a BPA tide simulation model according to the composition of each generator set in the AC-DC series-parallel power grid and the characteristic parameters of the AC-DC series-parallel power grid; the characteristic parameters of the alternating current-direct current series-parallel power grid comprise a grid structure, generator parameters, load parameters, line parameters, transformer parameters and direct current engineering parameters of each generator set.
Further, the step of adjusting the startup modes of the conventional units one by one, calculating the output power of the direct current engineering of the alternating current-direct current series-parallel power grid under each startup mode, and outputting the adjustment influence evaluation index under each mode comprises the following steps:
based on an original starting mode, one unit of each conventional power plant is turned off one by one, and a direct-current engineering output power limit value under the condition of turning off the unit is obtained by taking an alternating-current/direct-current series-parallel power grid alternating-current three-phase permanent N-1 fault and a direct-current monopole locking fault as limit limiting conditions;
under the starting mode of shutting down the unit, the calculation formula of the adjustment influence evaluation index corresponding to the single unit of the power plant is as follows:
wherein IDC i Evaluating the index for the adjustment impact in this case; p (P) i A power limit value for the dc engineering output in this case; p (P) DC The power is sent out by the direct current engineering of the alternating current-direct current hybrid power grid in the original starting mode.
Further, according to the adjustment influence evaluation index corresponding to each condition of a single unit output of each conventional power plant; and carrying out positive sequence sequencing on the multiple adjustment influence evaluation indexes to obtain an influence sequencing result of shutting down a single unit of each conventional power plant on the direct-current stable operation of the alternating-current and direct-current hybrid power grid at the alternating-current and direct-current hybrid transmission end.
Further, the updating the startup mode according to the adjustment influence evaluation index and the preset rule includes:
step 1, setting the starting number of a conventional power plant running only one unit in a current starting mode to be 1 in a minimum starting scheme;
step 2, shutting down one unit in the conventional power plants with the maximum influence evaluation indexes among the rest conventional power plants in the alternating-current and direct-current hybrid power grid according to the influence sequencing result to form primary optimization of a power-on mode of the generator unit;
step 3, evaluating the safety stability of the optimized alternating current-direct current hybrid power grid N-1;
if the evaluation result passes, returning to the step 1 for execution under the power-on mode of the optimization;
if the evaluation result does not pass, setting the starting number of the conventional power plant in the minimum starting scheme as the number before the optimization, deleting the conventional power plant in the influence sequencing result, and returning to the step 2 for execution;
and 4, after the starting-up numbers of all the conventional power plants in the minimum starting-up scheme are set, outputting the minimum starting-up scheme.
Further, before adjusting the starting mode of each conventional unit one by one, the method comprises the following steps:
using a BPA power flow simulation model to evaluate the safety stability of the AC/DC hybrid power grid N-1 in an original starting mode;
and updating the starting mode according to the evaluation result.
Further, when the result of evaluating the safety stability of the ac/dc hybrid power grid N-1 in the original starting mode by using the BPA power flow simulation model is that the safety stability does not pass, the method includes:
step 1, setting the starting number of a conventional power plant with all units running in the current starting mode as the corresponding total unit number in a minimum starting scheme;
step 2, starting one unit in the conventional power plants with the maximum influence evaluation indexes among the rest conventional power plants in the alternating-current and direct-current hybrid power grid according to the influence sequencing result to form primary optimization of a power-on mode of the generator unit;
step 3, evaluating the safety stability of the optimized alternating current-direct current hybrid power grid N-1;
if the evaluation result passes, setting the starting number of the conventional power plant in the minimum starting scheme as the number before the optimization, deleting the conventional power plant in the influence sequencing result, and returning to the step 2 for execution;
if the evaluation result does not pass, returning to the step 1 for execution under the power-on mode of the optimization;
and 4, screening out all the conventional power plants with the complete running of all the units after the starting numbers of all the conventional power plants in the minimum starting scheme are set, selecting the power plant with the minimum unit capacity from the rest power plants, increasing the minimum starting number by one, keeping the minimum starting number of the rest power plants unchanged, and outputting the minimum starting scheme of all the conventional power plants.
Further, the evaluating the safety stability of the ac/dc hybrid power grid N-1 includes:
according to the BPA power flow simulation model, simulating and calculating a main grid line and a main transformer three-phase permanent N-1 short circuit fault of the AC/DC hybrid power grid, and simulating and calculating a DC single-stage blocking fault of the AC/DC hybrid power grid;
and judging the transient stability level of the AC/DC hybrid power grid after the fault according to preset unit power angle, system voltage and system frequency stability criteria.
The system for determining the minimum starting-up scheme of a conventional unit in an AC/DC hybrid power grid comprises:
the simulation model building unit is used for building a BPA power flow simulation model according to the characteristics of each generator set in the alternating-current and direct-current hybrid power grid; the generator set comprises a new energy set and a conventional set; the conventional unit comprises a hydroelectric unit and a thermal power unit;
the starting-up mode adjusting unit is used for determining an original starting-up mode of each conventional unit in the AC/DC hybrid power grid and obtaining the DC engineering output power of the AC/DC hybrid power grid under the original starting-up mode; the starting-up mode comprises the starting-up quantity of each conventional unit;
the starting-up mode adjusting unit adjusts the starting-up modes of the conventional units one by one, calculates the limit value of the output power of the direct current engineering of the alternating current-direct current series-parallel power grid under each starting-up mode, and outputs the adjustment influence evaluation index of the corresponding power plant unit;
the starting-up mode optimizing unit updates the starting-up mode according to a preset rule according to the adjustment influence evaluation index and determines the minimum starting-up scheme;
the stability evaluation unit is used for evaluating the safety stability of the alternating current-direct current hybrid power grid N-1 by using the BPA power flow simulation model established by the simulation model establishment unit.
Further, the simulation model building unit builds a BPA tide simulation model according to the composition of each generator set in the AC/DC hybrid power grid and the characteristic parameters of the AC/DC hybrid power grid; the characteristic parameters of the alternating current-direct current series-parallel power grid comprise a grid structure, generator parameters, load parameters, line parameters, transformer parameters and direct current engineering parameters of each generator set.
Furthermore, the starting mode adjusting unit is used for stopping one unit of each conventional power plant one by one on the basis of an original starting mode, and taking an alternating current/direct current hybrid power grid alternating current three-phase permanent N-1 fault and a direct current monopole locking fault as limit limiting conditions to obtain a direct current engineering output power limit value under the condition of stopping the unit;
under the starting mode of shutting down the unit, the starting mode adjusting unit calculates the calculation formula of the adjusting influence evaluation index corresponding to the single unit of the power plant as follows:
wherein IDC i Evaluating the index for the adjustment impact in this case; p (P) i A power limit value for the dc engineering output in this case; p (P) DC The power is sent out by the direct current engineering of the alternating current-direct current hybrid power grid in the original starting mode.
Furthermore, the starting-up mode adjusting unit is used for outputting an adjusting influence evaluation index corresponding to each condition according to a single unit of each conventional power plant which is shut down; and carrying out positive sequence sequencing on the multiple adjustment influence evaluation indexes to obtain an influence sequencing result of shutting down one unit of each conventional power plant on the direct-current stable operation of the alternating-current and direct-current hybrid power grid at the alternating-current and direct-current hybrid transmission end.
Furthermore, the starting-up mode optimizing unit is used for setting the starting-up number of the conventional units in each conventional power plant in the minimum starting-up scheme of the alternating-current/direct-current hybrid power grid; the starting-up mode optimizing unit is communicated with the starting-up mode adjusting unit and the stability evaluating unit to obtain the required influence ordering result and stability evaluating result in real time.
The beneficial effects of the invention are as follows: the technical scheme of the invention provides a method and a system for determining the minimum starting-up scheme of a conventional unit in an alternating-current/direct-current hybrid power grid, the method and the system monitor the safety and stability of the power grid under various starting-up schemes by establishing a simulation model for the alternating-current/direct-current hybrid power grid, and confirm the minimum starting-up scheme on the premise of safety and stability of the power grid according to the obtained unit adjustment influence indexes.
Drawings
Exemplary embodiments of the present invention may be more completely understood in consideration of the following drawings:
FIG. 1 is a flowchart of a method for determining a minimum startup scheme of a conventional unit in an AC/DC hybrid power grid according to an embodiment of the present invention;
fig. 2 is a block diagram of a system for determining a minimum startup scheme of a conventional unit in an ac/dc hybrid power grid according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the examples described herein, which are provided to fully and completely disclose the present invention and fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like elements/components are referred to by like reference numerals.
Unless otherwise indicated, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, it will be understood that terms defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
FIG. 1 is a flowchart of a method for determining a minimum startup scheme of a conventional unit in an AC/DC hybrid power grid according to an embodiment of the present invention; as shown in fig. 1, the method includes:
specifically, the method for determining the minimum startup scheme of the conventional unit is mainly applied to a transmitting end power grid of an alternating current-direct current hybrid power grid; constructing a BPA power flow simulation model according to the composition of each generator set in the AC-DC series-parallel power grid and the characteristic parameters of the AC-DC series-parallel power grid; the characteristic parameters of the alternating current-direct current series-parallel power grid comprise a grid structure, generator parameters, load parameters, line parameters, transformer parameters and direct current engineering parameters of each generator set.
the original starting-up mode of each conventional unit in the alternating current-direct current series-parallel power grid can be an existing starting-up mode before the minimum starting-up scheme is determined, and the starting-up mode specifically comprises the starting-up quantity of one or more conventional units in each of a plurality of conventional power plants (such as a hydropower plant, a thermal power plant and the like);
specifically, on the basis of an original starting mode, one unit of each conventional power plant is turned off one by one, namely the starting mode, and the direct current engineering output power limit value under the condition of turning off the unit is obtained by taking an alternating current/direct current hybrid power grid alternating current three-phase permanent N-1 fault and a direct current monopole locking fault as limit conditions; sequentially reciprocating to obtain the adjusting film studio evaluation index corresponding to each starting mode;
under the starting mode of shutting down the unit, the calculation formula of the adjustment influence evaluation index corresponding to the single unit of the power plant is as follows:
wherein IDC i Evaluating the index for the adjustment impact in this case; p (P) i A power limit value for the dc engineering output in this case; p (P) DC The power is sent out by the direct current engineering of the alternating current-direct current hybrid power grid in the original starting mode.
According to the adjustment influence evaluation index corresponding to each condition output by a single unit of each conventional power plant; and carrying out positive sequence sequencing on the multiple adjustment influence evaluation indexes to obtain an influence sequencing result of shutting down a single unit of each conventional power plant on the direct-current stable operation of the alternating-current and direct-current hybrid power grid at the alternating-current and direct-current hybrid transmission end. And 140, updating the starting mode according to a preset rule according to the adjustment influence evaluation index, evaluating the safety stability of the alternating current/direct current hybrid power grid N-1 under the updated starting mode by using the BPA power flow simulation model, and determining the minimum starting scheme.
The determined minimum starting scheme is the minimum standard for ensuring the stable operation of the alternating current-direct current hybrid power grid;
further, updating the startup mode according to the adjustment influence evaluation index and a preset rule, including:
step 1411, setting the number of startup of a conventional power plant running only one unit in a current startup mode to be 1 in a minimum startup scheme;
in the conventional power plants, if the unit is turned off again, the conventional power plants have no power output, and have additional influence on the power grid, in order to ensure the running stability of the power grid, the minimum starting number of each conventional power plant is 1, so that all the conventional power plants can be put into the power grid, and when the minimum starting number is reached, the starting number of the conventional power plants is fixed, and the subsequent shutdown test is not participated;
step 1412, shutting down one unit in the conventional power plants with the maximum influence evaluation index among the rest conventional power plants in the alternating-current and direct-current hybrid power grid according to the influence sequencing result to form primary optimization of the power-on mode of the generator unit;
according to the influence sequencing result of each conventional power plant on the direct-current stable operation of the alternating-current and direct-current hybrid power grid, selecting the conventional power plant with the largest influence, and shutting down one unit of the conventional power plant to enable the unit to approach to the minimum starting scheme quickly;
step 1413, evaluating the safety stability of the optimized alternating current-direct current hybrid power grid N-1;
the safety stability assessment calculates the main grid line and the main transformer three-phase permanent N-1 short circuit fault of the alternating current-direct current hybrid power grid in a simulation mode according to the BPA power flow simulation model, and calculates the direct current single-stage blocking fault of the alternating current-direct current hybrid power grid in a simulation mode;
and judging the transient stability level of the AC/DC hybrid power grid after the fault according to preset unit power angle, system voltage and system frequency stability criteria.
If the evaluation result passes, returning to the step 1411 for execution under the power-on mode of the optimization;
if the evaluation result passes, it indicates that the system is still in a stable state in the starting mode of shutting down the unit, and the subsequent scheme determination can be continued for the existing starting mode in this starting mode, where after the shutting down of this time is completed, there is a possibility that only one group of units is stored in the conventional power plant corresponding to the unit that is shut down by this time optimization, so that the process needs to be continued in step 1411;
if the evaluation result does not pass, setting the number of the startup of the conventional power plant in the minimum startup scheme as the number before the optimization, deleting the conventional power plant in the influence sequencing result, and returning to the step 1412 for execution;
the evaluation is not passed, which indicates that the influence of the shutdown unit on the whole power grid has caused instability of the power grid; the unit cannot be shut down, and the number of the conventional power plants corresponding to the unit cannot be shut down any more, and the number of the power plants is fixedly set as the number before the optimization;
because the optimization does not involve the shutdown of a certain unit, the execution 1411 is not needed, and the direct execution 1412 is needed;
step 1414, after the number of the startup of all the conventional power plants in the minimum startup scheme is set, outputting the minimum startup scheme;
after the cyclic execution, the final optimized starting scheme is obtained as the minimum starting scheme until all energy plants are traversed.
Further, before adjusting the starting mode of each conventional unit one by one, the method comprises the following steps:
using a BPA power flow simulation model to evaluate the safety stability of the AC/DC hybrid power grid N-1 in an original starting mode;
updating the starting mode according to the evaluation result;
if the evaluation result passes in the original starting mode, it indicates that there is an optimizable space in the existing starting mode, that is, steps 1411 to 1414 are performed;
if the evaluation result does not pass under the original starting mode, the method comprises the following steps:
step 1421, setting the starting number of the conventional power plant with all units running in the current starting mode as the corresponding total unit number in the minimum starting scheme;
step 1422, starting one unit in the conventional power plants with the maximum influence evaluation index in the rest conventional power plants in the AC/DC hybrid power grid according to the influence sequencing result to form primary optimization of the starting mode of the generator unit;
step 1423, evaluating the safety stability of the optimized alternating current-direct current hybrid power grid N-1;
if the evaluation result passes, setting the number of the startup of the conventional power plant in the minimum startup scheme as the number before the optimization, deleting the conventional power plant in the influence sequencing result, and returning to step 1422 for execution;
if the evaluation result does not pass, returning to step 1421 for execution under the power-on mode of the optimization;
step 1424, screening out all the conventional power plants with the minimum unit capacity from the rest power plants after the number of the power plants in the minimum power scheme is set, adding one power plant with the minimum unit capacity to the rest power plants, keeping the minimum power plant number unchanged, and outputting the minimum power scheme of all the conventional power plants.
Fig. 2 is a block diagram of a system for determining a minimum startup scheme of a conventional unit in an ac/dc hybrid power grid according to an embodiment of the present invention. As shown in fig. 2, the system includes:
the simulation model building unit 210 is configured to build a BPA power flow simulation model according to characteristics of each generator set in the ac/dc series-parallel power grid by using the simulation model building unit 210; the generator set comprises a new energy set and a conventional set; the conventional unit comprises a hydroelectric unit and a thermal power unit;
further, the simulation model building unit 210 builds a BPA tide simulation model according to the composition of each generator set in the ac/dc series-parallel power grid and the characteristic parameters of the ac/dc series-parallel power grid; the characteristic parameters of the alternating current-direct current series-parallel power grid comprise a grid structure, generator parameters, load parameters, line parameters, transformer parameters and direct current engineering parameters of each generator set.
The starting-up mode adjusting unit 220, wherein the starting-up mode adjusting unit 220 determines an original starting-up mode of each conventional unit in the alternating-current and direct-current hybrid power grid, and acquires the direct-current engineering output power of the alternating-current and direct-current hybrid power grid under the original starting-up mode; the starting-up mode comprises the starting-up quantity in each conventional unit;
the startup mode adjusting unit 220 adjusts the startup modes of each conventional unit one by one, calculates the output power limit value of the direct current project of the alternating current-direct current series-parallel power grid under each startup mode, and outputs the adjustment influence evaluation index of the corresponding power plant unit;
furthermore, the startup mode adjustment unit 220 is configured to shut down one unit of each conventional power plant one by one based on an original startup mode, and obtain a limit value of the output power of the dc project under the condition of shutting down the unit by using the ac-dc hybrid power grid ac three-phase permanent N-1 fault and the dc monopole locking fault as limit conditions;
in the power-on mode of shutting down the unit, the power-on mode adjusting unit 220 calculates a calculation formula of an adjustment impact evaluation index corresponding to the single unit of the power plant as follows:
wherein IDC i Evaluating the index for the adjustment impact in this case; p (P) i A power limit value for the dc engineering output in this case; p (P) DC The power is sent out by the direct current engineering of the alternating current-direct current hybrid power grid in the original starting mode.
Further, the startup mode adjusting unit 220 is configured to stop the adjustment impact evaluation index corresponding to each condition according to a single unit output of each conventional power plant; and carrying out positive sequence sequencing on the multiple adjustment influence evaluation indexes to obtain an influence sequencing result of shutting down one unit of each conventional power plant on the direct-current stable operation of the alternating-current and direct-current hybrid power grid at the alternating-current and direct-current hybrid transmission end.
The startup mode optimizing unit 230 updates the startup mode according to a preset rule according to the adjustment influence evaluation index, and determines a minimum startup scheme;
further, the startup mode optimizing unit 230 is configured to set the startup number of the conventional units in each conventional power plant in the minimum startup scheme of the ac/dc hybrid power grid; the power-on mode optimizing unit 230 obtains the required influence ordering result and stability evaluation result in real time by communicating with the power-on mode adjusting unit 220 and the stability evaluation unit.
The stability evaluation unit 240, where the stability evaluation unit 240 is configured to evaluate the safety stability of the ac/dc hybrid power grid N-1 by using the BPA power flow simulation model established by the simulation model establishing unit 210.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Those skilled in the art will appreciate that the modules in the apparatus of the embodiments may be adaptively changed and disposed in one or more apparatuses different from the embodiments. The modules or units or components of the embodiments may be combined into one module or unit or component and, furthermore, they may be divided into a plurality of sub-modules or sub-units or sub-components. Any combination of all features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or units of any method or apparatus so disclosed, may be used in combination, except insofar as at least some of such features and/or processes or units are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Reference to step numbers in this specification is used solely to distinguish between steps and is not intended to limit the time or logical relationship between steps, including the various possible conditions unless the context clearly indicates otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features but not others included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments. For example, any of the embodiments claimed in the claims may be used in any combination.
Various component embodiments of the present disclosure may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. The present disclosure may also be implemented as an apparatus or system program (e.g., a computer program and a computer program product) for performing a portion or all of the methods described herein. Such a program embodying the present disclosure may be stored on a computer readable medium, or may have the form of one or more signals. Such signals may be downloaded from an internet website, provided on a carrier signal, or provided in any other form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the disclosure, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The disclosure may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware.
The foregoing is merely a specific embodiment of the disclosure, and it should be noted that it will be apparent to those skilled in the art that several improvements, modifications, and variations can be made without departing from the spirit of the disclosure, and these improvements, modifications, and variations are to be considered within the scope of the present application.
Claims (13)
1. A method for determining a minimum starting scheme of a conventional unit in an alternating current-direct current hybrid power grid comprises the following steps:
establishing a BPA power flow simulation model according to the characteristics of each generator set in the alternating current-direct current series-parallel power grid; the generator set comprises a new energy set and a conventional set; the conventional unit comprises a hydroelectric unit and a thermal power unit;
determining an original starting-up mode of each conventional unit in the AC-DC hybrid power grid, and obtaining the DC engineering output power of the AC-DC hybrid power grid under the original starting-up mode; the starting-up mode comprises the starting-up quantity of each conventional unit;
the starting modes of each conventional unit are adjusted one by one, the direct current engineering output power limit value of the alternating current-direct current series-parallel power grid under each starting mode is calculated, and the adjustment influence evaluation index corresponding to each mode is output;
and updating the starting mode according to a preset rule according to the adjustment influence evaluation index, evaluating the safety stability of the alternating current-direct current hybrid power grid N-1 under the updated starting mode by using the BPA power flow simulation model, and determining the minimum starting scheme.
2. The method according to claim 1, characterized in that: constructing a BPA power flow simulation model according to the composition of each generator set in the AC-DC series-parallel power grid and the characteristic parameters of the AC-DC series-parallel power grid; the characteristic parameters of the alternating current-direct current series-parallel power grid comprise a grid structure, generator parameters, load parameters, line parameters, transformer parameters and direct current engineering parameters of each generator set.
3. The method of claim 1, wherein the step of adjusting the startup modes of each conventional unit one by one, calculating the dc engineering output power of the ac/dc hybrid grid in each startup mode, and outputting the adjustment impact evaluation index in each mode comprises:
based on an original starting mode, one unit of each conventional power plant is turned off one by one, and a direct-current engineering output power limit value under the condition of turning off the unit is obtained by taking an alternating-current/direct-current series-parallel power grid alternating-current three-phase permanent N-1 fault and a direct-current monopole locking fault as limit limiting conditions;
under the starting mode of shutting down the unit, the calculation formula of the adjustment influence evaluation index corresponding to the single unit of the power plant is as follows:
wherein, IDC i Evaluating the index for the adjustment impact in this case; p (P) i A power limit value for the dc engineering output in this case; p (P) DC The power is sent out by the direct current engineering of the alternating current-direct current hybrid power grid in the original starting mode.
4. A method according to claim 3, characterized in that: according to the adjustment influence evaluation index of a single unit of each conventional power plant; and carrying out positive sequence sequencing on the multiple adjustment influence evaluation indexes to obtain an influence sequencing result of each conventional power plant single unit on the direct-current stable operation of the alternating-current and direct-current hybrid power grid.
5. The method of claim 4, wherein updating the power-on mode according to the adjustment impact assessment index and the preset rule comprises:
step 1, setting the starting number of a conventional power plant running only one unit in a current starting mode to be 1 in a minimum starting scheme;
step 2, shutting down one unit in the conventional power plants with the maximum influence evaluation indexes among the rest conventional power plants in the alternating-current and direct-current hybrid power grid according to the influence sequencing result to form primary optimization of a power-on mode of the generator unit;
step 3, evaluating the safety stability of the optimized alternating current-direct current hybrid power grid N-1;
if the evaluation result passes, returning to the step 1 for execution under the power-on mode of the optimization;
if the evaluation result does not pass, setting the starting number of the conventional power plant in the minimum starting scheme as the number before the optimization, deleting the conventional power plant in the influence sequencing result, and returning to the step 2 for execution;
and 4, after the starting-up numbers of all the conventional power plants in the minimum starting-up scheme are set, outputting the minimum starting-up scheme.
6. The method of claim 4, wherein before adjusting the power-on mode of each conventional unit one by one, the method comprises:
using a BPA power flow simulation model to evaluate the safety stability of the AC/DC hybrid power grid N-1 in an original starting mode;
and updating the starting mode according to the evaluation result.
7. The method according to claim 6, wherein when the result of evaluating the safety and stability of the ac/dc hybrid power grid N-1 in the original power-on mode by using the BPA power flow simulation model is that the safety and stability are not passed, the method comprises:
step 1, setting the starting number of a conventional power plant with all units running in the current starting mode as the corresponding total unit number in a minimum starting scheme;
step 2, starting one unit in the conventional power plants with the maximum influence evaluation indexes among the rest conventional power plants in the alternating-current and direct-current hybrid power grid according to the influence sequencing result to form primary optimization of a power-on mode of the generator unit;
step 3, evaluating the safety stability of the optimized alternating current-direct current hybrid power grid N-1;
if the evaluation result passes, setting the starting number of the conventional power plant in the minimum starting scheme as the number before the optimization, deleting the conventional power plant in the influence sequencing result, and returning to the step 2 for execution;
if the evaluation result does not pass, returning to the step 1 for execution under the power-on mode of the optimization;
and 4, screening out all the conventional power plants with all the units running after the minimum starting number of each conventional power plant is set, selecting a power plant with the minimum unit capacity from the rest power plants, increasing the minimum starting number by one, keeping the minimum starting number of the rest power plants unchanged, and outputting the minimum starting scheme of all the conventional power plants.
8. The method according to claim 1, characterized in that: the evaluation of the safety stability of the AC/DC hybrid power grid N-1 comprises the following steps:
according to the BPA power flow simulation model, simulating and calculating a main grid line and a main transformer three-phase permanent N-1 short circuit fault of the AC/DC hybrid power grid, and simulating and calculating a DC single-stage blocking fault of the AC/DC hybrid power grid; and judging the transient stability level of the AC/DC hybrid power grid after the fault according to preset unit power angle, system voltage and system frequency stability criteria.
9. A system for determining a minimum starting-up scheme of a conventional unit in an alternating current-direct current hybrid power grid, the system comprises:
the simulation model building unit is used for building a BPA power flow simulation model according to the characteristics of each generator set in the alternating-current and direct-current hybrid power grid; the generator set comprises a new energy set and a conventional set; the conventional unit comprises a hydroelectric unit and a thermal power unit;
the starting-up mode adjusting unit is used for determining an original starting-up mode of each conventional unit in the AC/DC hybrid power grid and obtaining the DC engineering output power of the AC/DC hybrid power grid under the original starting-up mode; the starting-up mode comprises the starting-up quantity of each conventional unit;
the starting-up mode adjusting unit adjusts the starting-up modes of the conventional units one by one, calculates the limit value of the output power of the direct current engineering of the alternating current-direct current series-parallel power grid under each starting-up mode, and outputs the adjustment influence evaluation index of the corresponding power plant unit;
the starting-up mode optimizing unit updates the starting-up mode according to a preset rule according to the adjustment influence evaluation index and determines the minimum starting-up scheme;
the stability evaluation unit is used for evaluating the safety stability of the alternating current-direct current hybrid power grid N-1 by using the BPA power flow simulation model established by the simulation model establishment unit.
10. The system according to claim 9, wherein: the simulation model building unit builds a BPA power flow simulation model according to the composition of each generator set in the AC/DC hybrid power grid and the characteristic parameters of the AC/DC hybrid power grid; the characteristic parameters of the alternating current-direct current series-parallel power grid comprise a grid structure, generator parameters, load parameters, line parameters, transformer parameters and direct current engineering parameters of each generator set.
11. The system according to claim 9, wherein: the starting-up mode adjusting unit is used for stopping one unit of each conventional power plant one by one on the basis of an original starting-up mode, and taking an alternating current/direct current hybrid power grid alternating current three-phase permanent N-1 fault and a direct current monopole locking fault as limit limiting conditions to obtain a direct current engineering output power limit value under the condition of stopping the unit;
under the starting mode of shutting down the unit, the starting mode adjusting unit calculates the calculation formula of the adjusting influence evaluation index corresponding to the single unit of the power plant as follows:
wherein IDC i Evaluating the index for the adjustment impact in this case; p (P) i A power limit value for the dc engineering output in this case; p (P) DC The power is sent out by the direct current engineering of the alternating current-direct current hybrid power grid in the original starting mode.
12. The system according to claim 11, wherein: the starting-up mode adjusting unit is used for evaluating indexes according to adjustment influence of a single unit of each conventional power plant; and carrying out positive sequence sequencing on the plurality of adjustment influence evaluation indexes to obtain an influence sequencing result of shutting down one unit of each conventional power plant on the direct-current stable operation of the alternating-current and direct-current hybrid power grid.
13. The system according to claim 12, wherein: the starting-up mode optimizing unit is used for setting the starting-up number of the conventional units in each conventional power plant in the minimum starting-up scheme of the alternating-current/direct-current hybrid power grid; the starting-up mode optimizing unit is communicated with the starting-up mode adjusting unit and the stability evaluating unit to obtain the required influence ordering result and stability evaluating result in real time.
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| CN111049130B (en) * | 2019-12-11 | 2022-07-01 | 中国电力科学研究院有限公司 | Method and system for determining maximum power transmission scale of power grid system |
| CN112072714B (en) * | 2020-09-10 | 2022-03-15 | 国网湖南省电力有限公司 | Online-calculation-based power system minimum startup mode optimization method |
| CN113078688B (en) * | 2021-04-06 | 2023-02-14 | 中国南方电网有限责任公司 | Day-ahead thermal power starting optimization method and system for preventing and controlling standby shortage risk |
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