A power system supply guarantee deduction method, system and storage medium

Abstract

The present invention discloses a power system power supply guarantee deduction method, system and storage medium, relating to the technical field of power supply guarantee. The method includes determining the electrical influence factors for which there is a minimum demand for the reserved capacity of conventional power sources in the target area by combining the characteristics and functions played by conventional power sources in power grid operation and the contradictions faced by the power grid after the reduction of the proportion of conventional power sources. This power system power supply guarantee deduction method, system and storage medium study and analyze the guaranteed capacity of conventional power sources in the target area from two aspects of global influence factors and regional influence factors, and by establishing an objective function and constraining the objective function, realize the analysis and simulation of the power system in the target area, and then use the nodal system for verification to ensure the accuracy of the objective function analysis, making the obtained results more accurate and more convenient for power planning in the target area based on the analysis results, and reducing the risk of large power outages in the target area under various circumstances.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply guarantee, and particularly relates to a power system supply guarantee deduction method, system and storage medium. Background Art

[0002] Under the background of the construction of a new power system, the installed capacity of new energy has increased rapidly. The large-scale output uncertainty, inertia-free, and weakly controllable power sources are continuously connected. The grid balance, system security, and stability control characteristics will change fundamentally.

[0003] In order to prevent operation risks such as power imbalance and system instability caused by large-scale new energy squeezing the space of conventional power sources, it is necessary to clarify the guaranteed capacity of conventional power sources to guide the development and operation of the power grid. The guaranteed capacity of conventional power sources refers to the minimum guaranteed amount of conventional power sources required by the power grid to ensure the safe and stable operation of the power grid and the reliable supply of important loads. It can adapt to different operation modes in the target stage and has the ability to resist the risk of large-scale power outages caused by different factors. Summary of the Invention

[0004] The purpose of the present invention is to provide a power system supply guarantee deduction method, system and storage medium to solve the above deficiencies in the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A power system supply guarantee deduction method includes the following steps:

[0006] Combined with the characteristics and functions of conventional power sources in power grid operation, and the contradictions faced by the power grid after the reduction of the proportion of conventional power sources, determine the electrical influencing factors with the lowest demand for the guaranteed capacity of conventional power sources in the target area;

[0007] Study the demand for the guaranteed capacity of conventional power sources in different new energy scenarios in the target area, and determine the role of conventional power sources in the dynamic response process of power grid power imbalance;

[0008] Study the demand for the guaranteed capacity of conventional power sources in the target area under the constraint of network-wide balance, and determine the main influencing factors of the guaranteed capacity of conventional power sources in the target area;

[0009] Study the demand for the guaranteed capacity of conventional power sources in each region of the target area respectively, and determine the main influencing factors of the guaranteed capacity of conventional power sources in each region of the target area;

[0010] Simulate the time-sequential operation of the power system in the target area and establish an objective function;

[0011] Set constraint conditions for the objective function and update the objective function;

[0012] Verify and analyze the updated objective function based on a standard example system.

[0013] Furthermore, the electrical influencing factors are divided into global influencing factors and regional influencing factors.

[0014] Furthermore, the global influencing factors include frequency stability and overall network power balance.

[0015] Furthermore, the regional influencing factors include zonal power balance, power flow evacuation, voltage stability, and short-circuit ratio.

[0016] Furthermore, the study on the guaranteed capacity requirements of conventional power sources under different new energy scenarios specifically includes:

[0017] Studying the guaranteed capacity requirements of conventional power sources under frequency stability constraints;

[0018] Studying the relationship between the guaranteed demand capacity and new energy output under different unit starting levels;

[0019] Studying the relationship between the guaranteed demand capacity and new energy output under different load levels, and conducting simulation analysis.

[0020] Furthermore, when studying the guaranteed capacity requirements of conventional power sources in the target area under the overall network balance constraint, the summer and winter peaks are selected as the basic methods for sensitivity analysis of the guaranteed supply capacity of conventional units under different new energy output scenarios and the overall network balance constraint.

[0021] Furthermore, the objective function is modeled using a mixed-integer linear programming model, adopting a unit commitment model with a time step of one hour, and including curtailment penalties for wind power and curtailment penalties for photovoltaic power.

[0022] Furthermore, the constraint conditions include power balance constraints, reserve constraints, network constraints, generator output constraints, ramping constraints, upper limits on switching power, and minimum start-stop time constraints.

[0023] A power system guaranteed supply deduction system includes a memory and a processor coupled to the memory. The processor is configured to execute the power system guaranteed supply deduction method based on instructions stored in the memory.

[0024] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements a power system guaranteed supply deduction method.

[0025] Compared with the prior art, a power system supply guarantee deduction method, system and storage medium provided by the present invention study and analyze from two aspects of global influencing factors and regional influencing factors, the guaranteed capacity of conventional power sources in the target area, and by establishing an objective function and constraining the objective function, the analysis and simulation of the power system in the target area are realized. Then, the IEEE-118 node system is used for verification to ensure the accuracy of the objective function analysis, so that the obtained results are more accurate, and it is more convenient to carry out power planning for the target area based on the analysis results, reducing the risk of large power outages in the target area under various circumstances. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings.

[0027] Figure 1 It is a method step diagram provided by an embodiment of the present invention;

[0028] Figure 2 It is a wiring diagram of the IEEE-118 node system provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further introduce the present invention in detail with reference to the drawings.

[0030] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined. In addition, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0033] In the case of no conflict, the various embodiments of the present disclosure and the features in the embodiments may be combined with each other.

[0034] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. As used herein, the singular forms "a" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprises" and / or "consists of" are used in this specification, it specifies the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0036] The embodiments described herein may be described with reference to the plan views and / or cross-sectional views by means of the ideal schematic diagrams of the present disclosure. Therefore, the example illustrations may be modified according to the manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to the embodiments shown in the drawings, but include modifications of the configurations formed based on the manufacturing process. Therefore, the regions illustrated in the drawings have schematic properties, and the shapes of the regions shown in the drawings illustrate the specific shapes of the regions of the elements, but are not intended to be restrictive.

[0037] Unless otherwise defined, all terms (including technical and scientific terms) used herein shall have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in common dictionaries shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0038] Please refer to Figure 1 - Figure 2 , a power system supply guarantee deduction method, comprising:

[0039] 1. Combining the characteristics and functions of conventional power sources in power grid operation, and the contradictions faced by the power grid after the reduction of the proportion of conventional power sources, it is determined that the electrical influencing factors with the lowest demand for the reserved capacity of conventional power sources can be divided into two types: global and regional;

[0040] Among them, the global influencing factors include the following two: (1) Frequency stability: Conventional power sources can provide inertia support and frequency regulation reserve for the power grid. In the scenario of high proportion of new energy and small start-up of conventional power sources, the system's frequency regulation ability is weakened, and there is a risk of triggering the action of the under-frequency load shedding device after the loss of a single power source. (2) Overall network power balance: Due to the uncertainty, randomness and volatility of the output of new energy, its peak shaving ability and credible output are limited. Although the installed capacity of new energy is large, it is still difficult to become the main body of power and electricity supply. The overall network power supply still needs to rely on controllable and stable conventional power sources for a long time, and gradually improve the balance characteristics through the dynamic regulation mode of "new energy + energy storage".

[0041] The regional influencing factors include the following four: (1) Sub-region power balance: The 220kV sub-region power supply mainly depends on the power received by the 500kV main transformers within the sub-region and the power output of power sources. Constraints on sub-region power supply such as main transformer N-1 in summer peak and main transformer N-1-1 in spring and autumn put corresponding requirements on the capacity of conventional power sources within the sub-region. If the guaranteed capacity within the sub-region is insufficient, the power supply will face a severe situation. (2) Power flow evacuation: For example, even if the power resources are sufficient, the insufficient transmission capacity of key channels such as north-south power transmission and west-east power transmission still cannot meet the reliable power supply. There are contradictions such as power congestion in areas such as Jiangbei and Ningzhen and power shortage in the southern part of Suzhou, Wuxi and Changzhou. Therefore, the restriction of the transmission capacity of key channels puts requirements on the capacity of conventional power sources in key regions. (3) Voltage stability: Conventional power sources can provide reactive voltage support for the power grid. There may be problems with weak voltage support in areas with large loads, high power reception and small start-up. In case of faults, there may be a risk of voltage instability, and there is a certain demand for the capacity of conventional power sources in local areas. (4) Short-circuit ratio: When a conventional DC feeds into an active network and certain voltage support is required, the multi-infeed short-circuit ratio / effective short-circuit ratio needs to meet the strong system requirement of 3.0 / 2.5 to prevent operation risks caused by the "strong DC and weak AC" characteristics, and thus put requirements on the capacity of conventional power sources in the DC near area.

[0042] 2. Research on the guaranteed capacity requirements of conventional power sources under different new energy scenarios, specifically including:

[0043] Research on the guaranteed capacity requirements of conventional power sources under frequency stability constraints:

[0044] Through research, it is found that conventional power sources provide inertia support, primary frequency modulation support, and secondary frequency modulation support during the dynamic response process of grid power imbalance. After large-scale new energy sources, external DCs and other non-inertia and weak-support power sources occupy the space of conventional power sources, the grid frequency stability ability gradually weakens.

[0045] Since the load level is relatively low during the frequency flood season, the power received by the hydropower DC is high, the start-up of conventional power sources is small, and the contradiction of frequency stability is the most prominent. Therefore, the low valley during the flood season is selected as the basic method for sensitivity analysis of the guaranteed supply capacity of conventional units under frequency stability constraints for different new energy output scenarios. Specifically:

[0046] Research on the relationship between the guaranteed demand capacity and new energy output at different start-up levels to obtain the demand capacity of conventional power sources in the target area under the current frequency stability constraints;

[0047] Research on the relationship between the guaranteed demand capacity and new energy output at different load levels, and conduct simulation analysis. It is obtained that the proportion of new energy + external power received limit under frequency constraints increases with the increase of the load level, while the absolute value of the minimum start-up demand capacity of conventional power sources at different load levels is relatively fixed.

[0048] 3. Research on the guaranteed capacity requirements of conventional power sources under the constraints of overall network balance:

[0049] Since the power supply guarantee pressure of the summer and winter power grids is large and the requirement for the peak load capacity of conventional power sources is high, the contradiction of overall network balance is the most prominent. The summer and winter peaks are selected as the basic methods for sensitivity analysis of the guaranteed supply capacity of conventional units under the constraints of overall network balance for different new energy output scenarios. Specifically:

[0050] Analyze the new energy output characteristics during the peak load period, calculate the new energy output, and consider whether to include it in the peak power balance analysis according to the proportion of new energy output during the peak period;

[0051] Evaluate the guaranteed capacity requirements of conventional power sources under the power supply guarantee constraints during the summer and winter peaks;

[0052] It is found that the guaranteed capacity of conventional power sources is mainly restricted by the power balance constraint, and the power grid still maintains a high degree of dependence on conventional power sources before the balance adjustment mode is effectively broken through.

[0053] 4. Research on the guaranteed capacity requirements of conventional power sources in each region of the target area respectively to determine the main influencing factors of the guaranteed capacity of conventional power sources in each region of the target area:

[0054] 5. Simulate the time - series operation of the power system in the target area; the core of the time - series production simulation is the unit commitment model, which is usually modeled as a mixed - integer linear programming model. Generally, a unit commitment model with a time step of one hour is adopted. Specifically:

[0055] Establish the objective function. The objective function usually also includes curtailment penalty for wind power and curtailment penalty for photovoltaic power. The formula is:

[0056]

[0057] where \(k\) is the number of subsystems, \(T\) is the total operation time. Since the time step is 1 hour, then \(T = 8760\) (8784 in a leap year), \(C i G (t)\) is the generation cost of thermal power units, is the start - up cost of thermal power units, is the shut - down cost of thermal power units, \(\theta S is the curtailment penalty for photovoltaic power, \(\theta W is the curtailment penalty for wind power, \(P S，k (t)\) is the actual power generation of the photovoltaic power station, \(P W，k (t)\) is the actual power generation of the wind farm.

[0058] The objective function mainly consists of two parts. The first part is the operation cost of thermal power units, including the generation cost, start - up cost and shut - down cost of thermal power units. The second part is the penalty for the curtailment of power generation in new - energy power stations. Although the fixed cost of new - energy power stations is relatively high, the marginal generation cost is extremely low and can be regarded as 0. The same is true for hydropower stations. Therefore, the generation costs of wind farms, photovoltaic power stations and hydropower stations are not considered in the objective function.

[0059] The generation cost curve of thermal power units is usually represented by a quadratic curve:

[0060]

[0061] To linearize the model to accelerate the solution speed, the quadratic coal - consumption curve is often piece - wise linearized. In theory, as long as the number of segments is large enough, the obtained piece - wise linear function can be completely equivalent to the original quadratic function. The error introduced by piece - wise linearization is inversely proportional to the square of the number of segments. For a simplified model, the number of segments can be taken as 1.

[0062] Set the constraint conditions of the objective function

[0063] 1. Power balance constraint, the formula is:

[0064]

[0065] where \(P G，i (t)\) is the actual output of thermal power units, \(T I，k(t), T O，k P(t) is the power flowing in and out of the tie line of the k-th subsystem. L，k P(t) is the power load of the subsystem.

[0066] 2. Reserve constraint, the formula is:

[0067]

[0068] u i u(t) is the start-stop state of the unit. When the unit is in the grid-connected state, it is 1; otherwise, it is 0.

[0069] ε W，k , ε S，k is the maximum prediction error of the wind power and photovoltaic power plants in subsystem k.

[0070] η L，k is the reserve coefficient of the load, generally taken as 5%.

[0071] The reserve constraint means that in order to cope with the uncertainty of load and new energy output, a certain reserve margin needs to be reserved to deal with unexpected situations, and it is divided into up reserve and down reserve. The maximum prediction error is the maximum error between the predicted new energy output situation and the actual output situation.

[0072] 3. Grid constraint

[0073] For interconnected subsystems, the exchange power on the tie line shall not be higher than the line transmission power limit. The formula is:

[0074]

[0075] P ij P(t) is the exchange power on the tie line.

[0076] 4. Generator output constraint

[0077] Due to physical characteristics, thermal power units have a minimum stable combustion limit. When starting and operating stably, their output must be greater than this value. For new energy power sources, their maximum output is affected by natural conditions, and the actual output should be less than their maximum dispatchable output. The formula is:

[0078]

[0079]

[0080]

[0081] p G，i are the rated capacity and minimum technical output of the thermal power unit respectively.

[0082] 5. Ramp Constraints

[0083] In addition to the operating constraints, the ramp constraints also limit the processing range of the units. The ramp constraint refers to the ability of a unit to increase or decrease its output within a scheduling period. In the MILP model, the big-M method is usually used for modeling:

[0084]

[0085]

[0086] R U，i and R D，i are the hourly power up-ramp capacity and power down-ramp capacity of the unit, respectively.

[0087] 6. Constraints on the Upper Limit of Starting and Shutting Down Power

[0088] When the unit just starts up, its output ramps up from 0, and the output at this moment cannot be greater than the upper limit of starting power. Vice versa. The big-M method is also used for linearization modeling:

[0089]

[0090]

[0091] S U，i and S D，i are the per-unit values of the upper limit of starting power and the upper limit of shutting down power at the moment of unit startup, respectively.

[0092] 7. Minimum Starting and Stopping Time Constraints

[0093] Considering the operating economy of the unit and the impact of starting and stopping on the unit's life, thermal power units should not be started and stopped frequently. Each thermal power unit declares its minimum running time and minimum shutdown time according to its own situation. The formula is:

[0094]

[0095]

[0096] where T U，i (t) and T D，i (t) are the minimum running time and minimum shutdown time of the unit, respectively.

[0097] Verification and Analysis Based on the Standard Example System

[0098] Reference Figure 2, the IEEE-118 bus system is used to verify and analyze the accuracy of the time-series production simulation method. Based on the original load and installed capacity, the load level and system installed capacity are increased, and equipment such as wind power, photovoltaic, energy storage, and off-site tie lines are added, and the time-series operation curves of the load, wind power and photovoltaic, off-site tie lines, etc. are given.

[0099] The present invention also provides a power system power supply guarantee deduction system, including a memory and a processor coupled to the memory. The processor is configured to execute a power system power supply guarantee deduction method based on instructions stored in the memory.

[0100] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, a power system power supply guarantee deduction method is implemented.

[0101] Only some exemplary embodiments of the present invention are described by way of illustration above. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. A power system supply guarantee deduction method, characterized in that: It includes the following steps: Combining the characteristics and functions of conventional power sources in power grid operation, and the main contradictions faced by the power grid after the reduction of the proportion of conventional power sources, determine the electrical influencing factors for the minimum demand for the reserved capacity of conventional power sources in the target area; Study the guaranteed capacity demand of conventional power sources under different new energy scenarios in the target area, and determine the role of conventional power sources in the dynamic response process of power grid power imbalance; Study the guaranteed capacity demand of conventional power sources in the target area under the constraint of overall network balance, and determine the main influencing factors of the guaranteed capacity of conventional power sources in the target area; Study the guaranteed capacity demand of conventional power sources in each region of the target area respectively, and determine the main influencing factors of the guaranteed capacity of conventional power sources in each region of the target area; Simulate the time-sequential operation of the power system in the target area and establish an objective function; Set constraint conditions for the objective function and update the objective function; Verify and analyze the updated objective function based on the standard example system; The study on the guaranteed capacity demand of conventional power sources under different new energy scenarios in the target area specifically includes: Study the guaranteed capacity demand of conventional power sources under the constraint of frequency stability; Study the relationship between the guaranteed demand capacity and new energy output under different startup levels; Study the relationship between the guaranteed demand capacity and new energy output under different load levels, and conduct simulation analysis; When studying the guaranteed capacity demand of conventional power sources in the target area under the constraint of overall network balance, select the summer and winter peaks as the basic methods for sensitivity analysis of the guaranteed supply capacity of conventional units under different new energy output scenarios under the constraint of overall network balance.

2. The power system supply guarantee deduction method according to claim 1, characterized in that: The electrical influencing factors are divided into global influencing factors and regional influencing factors.

3. The power system supply guarantee deduction method according to claim 2, characterized in that: The global influencing factors include frequency stability and overall network power balance.

4. A power system supply guarantee deduction method according to claim 3, characterized in that: The regional influencing factors include sectional power balance, power flow evacuation, voltage stability, and short-circuit ratio.

5. A power system supply guarantee deduction method according to claim 1, characterized in that: The objective function is modeled using a mixed-integer linear programming model, adopting a unit commitment model with a time step of one hour, and including wind curtailment penalty and PV curtailment penalty.

6. The method for power system supply guarantee deduction according to claim 1, characterized in that: The constraint conditions include power balance constraint, reserve constraint, grid constraint, generator output constraint, ramping constraint, on-off power upper limit constraint, and minimum start-stop time constraint.

7. A power system guaranteed supply deduction system, including a memory, and a processor coupled to the memory, the processor being configured to execute a power system guaranteed supply deduction method according to any one of claims 1-6 based on instructions stored in the memory.

8. A computer-readable storage medium, on which a computer program is stored, the computer program realizing a power system guaranteed supply deduction method according to any one of claims 1-6 when executed by a processor.

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