A decision method of power system partition and unit start-up sequence considering transmission and distribution coordination

Abstract

The application provides a decision-making method for power system partitioning and unit starting sequence considering power transmission and distribution coordination. The method comprises the following steps: setting multiple power transmission and distribution coordination methods; the power distribution network calculates the upward power transmission power characteristic curve and the upward power transmission preparation time, and transmits them to the power transmission network; the power transmission network establishes the selection logic of the upward power transmission power characteristic curve of the power distribution network, models the unified optimization problem of the power system partitioning and unit starting sequence considering power transmission and distribution coordination based on the multiple power transmission and distribution coordination methods; the power transmission network solves the model of the unified optimization problem of the power system partitioning and unit starting sequence considering power transmission and distribution coordination, obtains the power transmission and distribution coordination recovery partitioning and unit starting plan, and the power distribution network adjusts its own operation plan according to the power transmission and distribution coordination recovery partitioning and unit starting plan, so as to realize the information interaction and coordination between the power transmission and distribution networks. The application realizes the rapid recovery of the power system after the fault by overall planning the power transmission and distribution network resources, obtaining the optimal partitioning and the optimal unit starting strategy.

Description

Technical Field

[0001] This invention relates to the field of power distribution network technology, and in particular to a decision-making method for power system zoning and unit start-up sequence that considers transmission and distribution coordination. Background Technology

[0002] Large-scale power outages caused by natural disasters such as typhoons occur frequently, causing serious economic losses and political impacts on society. In the case of unavoidable natural disasters, how to minimize power outage losses through the coordinated preventive measures of the transmission and distribution networks has become an urgent problem to be solved in today's power system.

[0003] In the restoration process of traditional transmission networks, distribution networks are often equated to load points on substations. Due to their "passive" nature, traditional distribution networks can only gradually resume operation according to the restoration plan after the main power grid has been fully charged, provided that safety constraints are met. In recent years, the large-scale integration of distributed power sources within distribution networks has enabled them to assist transmission network restoration during the recovery phase. Currently, research on power system transmission and distribution coordination has gradually permeated power flow calculation, risk assessment, accident screening, unit combination, and economic dispatch. However, research on transmission and distribution coordination restoration after large-scale blackouts is still limited. In recent years, some scholars and experts have begun to consider the coordinated restoration of transmission and distribution networks, including coordination during the black start and load restoration phases. During the unit start-up phase, black start resources are scarce, and the system's power generation capacity is poor. At this time, utilizing the power generation resources of the distribution network can accelerate the restoration process by increasing zoning, starting large-capacity units in advance, and increasing available power generation capacity.

[0004] Currently, existing technologies primarily consider the distribution network's participation in restoration by increasing available generation capacity. They focus on addressing the uncertainty of output when distribution networks (or microgrids) with renewable energy sources participate in restoration, and the distributed decision-making issues between the distribution and transmission networks, which are different stakeholders. Research on transmission-distribution coordination during the load restoration phase generally aims to maximize both the load restoration amount and the restoration speed. It treats the transmission and distribution networks as different decision-making entities, and iteratively interacts to obtain a restoration strategy that satisfies their respective operational constraints and achieves the optimal objective. Summary of the Invention

[0005] This invention provides a decision-making method for power system partitioning and generator start-up sequence that considers transmission and distribution coordination, so as to achieve rapid power system restoration after a fault and reduce power outage losses.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A decision-making method for power system zoning and unit start-up sequence considering transmission and distribution coordination includes:

[0008] Multiple transmission and distribution coordination methods are set up;

[0009] The distribution network calculates the upward power transmission characteristic curve and the upward power transmission preparation time, and transmits the upward power transmission characteristic curve and the upward power transmission preparation time to the transmission network.

[0010] The selection logic for establishing the upward power transmission characteristic curve of the distribution network in the transmission network is used to model the unified optimization problem of power system partitioning and unit start-up sequence considering transmission and distribution coordination based on the various transmission and distribution coordination methods.

[0011] The transmission network solves the model of the unified optimization problem of power system partitioning and unit startup sequence considering transmission and distribution coordination, obtains the transmission and distribution coordination recovery partition and unit startup plan, and sends the transmission and distribution coordination recovery partition and unit startup plan to the distribution network.

[0012] The distribution network adjusts its own operation plan according to the transmission and distribution coordinated recovery zone and the unit start-up plan to realize information exchange and coordination between the transmission and distribution networks.

[0013] Preferably, the method for setting up multiple transmission and distribution coordination methods includes:

[0014] Three methods for coordinated transmission and distribution are set up, including:

[0015] (1) Methods to increase the number of partitions:

[0016] The self-starting resources of the distribution network are activated, gradually restoring the generating units and loads within the network. Under the aggregation effect of local power generation resources, the distribution network starts transformers and transmission lines and sends power upwards, independently supporting the start-up of generating units.

[0017] (2) Methods for starting the unit in advance:

[0018] The distribution network is restored internally and sends power upwards. The distribution network first starts the non-black start unit NBSG, and after the energy is exhausted, the black start unit BSG supports the remaining restoration process.

[0019] (3) Methods to increase available power generation capacity:

[0020] Black-start generators in the transmission network prioritize starting transformer nodes to assist in establishing power transmission paths, while the distribution network prioritizes power supply to critical loads. Once the upstream power transmission path is restored, the distribution network transmits power upstream to enhance the regional power generation capacity, and non-black-start generators are started.

[0021] Preferably, the distribution network calculates the upward power transmission characteristic curve and the upward power transmission preparation time, and transmits the upward power transmission characteristic curve and the upward power transmission preparation time to the transmission network, including:

[0022] The distribution network calculates the upward power transmission characteristic curve and the upward power transmission preparation time. The upward power transmission characteristic curve includes two curves: the stable power transmission capacity curve and the short-term support capacity curve. The upward power transmission characteristic curve and the upward power transmission preparation time are transmitted to the transmission network.

[0023] Integer variables are introduced into the dual-power characteristic curve of the power supply to the distribution network, and the dual-power characteristic curve of the power supply to the distribution network is linearized piecewise.

[0024] (1) Linearization of the stable power delivery capacity curve

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] Where: Ω DS Represents a collection of distribution networks; Indicates the actual power supply time of the distribution network;

[0036] This represents the maximum and initial values ​​of the stable power transmission capacity; Indicates the slope of the curve; These are integer variables (0-1) representing the stage of the power distribution network. and These respectively indicate that the stable power transmission capacity curve of the distribution network is in the ramp-up stage and the maximum power stage; As a continuous variable, its definition is given by equations (7)-(8); It is an integer variable (0-1) indicating whether to select stable power transmission capability. If selected,

[0037] but Otherwise, it is 0; The actual output power indicating stable power delivery capability; This indicates the preparation time for the distribution network to send power upwards, and the earliest time that the distribution network can provide support upwards. This value is given by the distribution network dispatcher.

[0038] Equations (1)-(2) indicate that the stable power delivery capacity curve of the distribution network cannot be in the ramp-up stage and the maximum power stage at the same time; Equations (3)-(6) respectively constrain the time range of each stage; Equation (9) is the actual power delivery time constraint of the distribution network; Equation (10) defines the actual output power of the stable power delivery capacity curve.

[0039] (2) Linearization of the short-term support capacity curve

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050] In the formula: Indicates the power supply preparation time for the distribution network; and This indicates the maximum, initial, and initial values ​​of short-term support capacity, as well as the initial value during the climbing phase. Indicates the slope of the curve; These are integer variables (0-1) representing the stage of the power distribution network. and These respectively indicate that the short-time support capacity curve of the distribution network is in the ramp-up stage and the maximum power stage; As a continuous variable, its definition is given by equations (17)-(18);

[0051] It is an integer variable (0-1) indicating whether short-term support capability is selected. If selected, then... Otherwise, it is 0; The actual output power indicating short-term support capability; This indicates the preparation time for the distribution network to send power upwards, and the earliest time that the distribution network can provide support upwards. This value is given by the distribution network dispatcher.

[0052] Equations (11)-(12) indicate that the short-time support capacity curve of the distribution network cannot be in the ramp-up stage and the maximum power stage at the same time; Equations (13)-(16) respectively constrain the time range of each stage; Equation (19) is the actual power delivery time constraint of the distribution network; Equation (20) defines the actual output power of the short-time support capacity curve.

[0053] Preferably, the selection logic for establishing the upward power transmission characteristic curve of the distribution network in the transmission network includes:

[0054] Introducing integer variables (0-1) to represent the selection of the upward power output characteristic curve:

[0055]

[0056]

[0057]

[0058]

[0059] In the formula: These are the options for selecting two power curves for the distribution network. This indicates the selection of stable power delivery capability. This indicates the selection of short-term support capabilities; These are integer variables of 0-1, representing the stage of the two power output characteristic curves, respectively. Let n be the actual output power of distribution network n at time t. and These represent the actual output power of the stable power delivery capability and the short-term support capability at time t, respectively.

[0060] Equation (21) indicates that the transmission network selects only one power characteristic of the distribution network; Equations (22) and (23) indicate that the actual output corresponding to the power characteristic curve not selected by the transmission network is 0; Equation (24) is the actual power output of the distribution network.

[0061] Preferably, the modeling of the unified optimization problem of power system partitioning and unit startup sequence considering transmission and distribution coordination based on the multiple transmission and distribution coordination methods includes:

[0062] A model is established to address the unified optimization problem of power system zoning and unit startup sequence considering transmission and distribution coordination. This model includes:

[0063] (1) Objective function

[0064]

[0065] In the formula, Represents a set of power transmission network units; and These are the starting power and rated power of the power transmission unit g, respectively.

[0066] (2) Network flow constraints

[0067]

[0068]

[0069]

[0070] In the formula: and Let f represent the set of all black-start generators, non-black-start generators, and all generators in the transmission network; δ(k) represents the line connected to node k; α represents the α-th partition; f lα Let z be a continuous variable, representing the network flow along line l within partition α; iα Let z be an integer variable between 0 and 1, representing whether node i belongs to partition α. ​​If it does, then z... iα =1, otherwise 0;

[0071] Equation (26) indicates that the sum of network flows emitted by node k connected to the black starter unit is equal to the sum of non-black starter units and the distribution network within partition α; Equation (27) indicates that the network flow consumed by node i connected to the non-black starter unit depends on the partition affiliation of node i. If node i belongs to the partition, the consumed network flow is 1, otherwise it is 0; Equation (28) indicates that nodes not connected to the unit do not consume network flows.

[0072] Under the "increase the number of partitions" method, the flow balance constraints of the distribution network node network are as follows:

[0073]

[0074] Where: Ω DS This refers to the equivalent distribution network node in the transmission network.

[0075] Equation (29) indicates that when there are no black-start units in partition α, the network flow is generated by the distribution network node, and the total number of generated network flows is equal to the sum of the non-black-start units in partition α. ​​Introducing an integer 0-1 variable b α , indicating whether BSG exists within partition α, equation (30) is b α Definition:

[0076] |I α | / M≤b α ≤|I α|×M (30)

[0077]

[0078] In the formula: |I α | represents the number of BSGs in partition α, where M is a very large positive integer.

[0079] Using the Big M method, equation (29) can be rewritten in the following form:

[0080]

[0081]

[0082] Equations (32)-(33) indicate that when b α When b = 0, that is, there are no black-start units in partition α, and the distribution network node sends out network flow; when b α When =1, this constraint is not effective. (32)-(33) enable distribution network nodes to form new zones;

[0083] Under the "early start-up of generating units" method, the network flow balance constraints of the distribution network nodes are as follows:

[0084]

[0085] Equation (34) indicates that when both a black-start generator and a distribution network node exist simultaneously within partition α, the black-start generator generates network flow, and the distribution network node absorbs the network flow. Using the Big M method, equation (34) can be rewritten as follows:

[0086]

[0087]

[0088] Equations (35)-(36) indicate that when b α When b = 1, meaning there is a black-start unit within partition α, the distribution network node j absorbs network flow, and the amount of network flow absorbed depends on whether it belongs to partition α; when b α When = 0, the constraint is not effective;

[0089] (3) Partitioning logical constraints

[0090]

[0091]

[0092]

[0093] In the formula: Let N be the set of transmission lines, nodes, and zones; |δ(i)| be the total number of lines connected to node i; y lα It is an integer variable between 0 and 1, indicating whether line j belongs to sub-region α; |J| represents the total number of non-black start units in the system;

[0094] Equation (37) indicates that if a line does not belong to sub-region α, then no network flow from that sub-region will flow on the line; Equation (38) indicates that if node ν does not belong to sub-region α, then none of the connected lines belong to sub-region α; Equation (39) indicates that all nodes belong to a certain sub-region.

[0095] (4) Unit start-up characteristics constraints

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108] In the formula, These are integer variables ranging from 0 to 1, representing whether unit g is in the ramp-up, maximum output, and power absorption stages, respectively. For the introduced auxiliary variables, equations (48)-(49) are their definitions; R g and These represent the ramp rate of unit g and the time of the power absorption process, respectively.

[0109] Equation (40) indicates that unit g cannot be in the ramp-up and maximum output phases simultaneously at time t; Equation (41) -

[0110] (47) defines the time range of the state of unit g; Equation (50) indicates that unit g needs to be started within the total recovery period; Equation (51) defines the active power output of unit g at time t;

[0111] (5) Transmission network recovery state constraints

[0112]

[0113]

[0114]

[0115] In the formula: and This represents the recovery state of node i and line j in sub-region α at time t; t TS Indicates the required restoration time for the power transmission line;

[0116] Equations (52)-(54) represent the restoration conditions for power transmission lines, nodes, and generating units.

[0117] (6) Transmission network restoration logic constraints

[0118]

[0119]

[0120]

[0121]

[0122] Equations (55)-(56) indicate that if node i and line j do not belong to sub-region α, then the restoration of node i and line j is not considered in the restoration process of that sub-region. Equations (57)-(58) indicate that the restored nodes and lines will no longer be de-energized.

[0123] (7) System power generation capacity constraints

[0124]

[0125] Equation (59) indicates that the power generation capacity of the transmission and distribution network must meet the startup requirements of the NBSG.

[0126] As can be seen from the technical solutions provided by the embodiments of the present invention above, the present invention proposes a unified optimization decision-making method for power system partitioning and unit startup sequence under transmission and distribution coordination, which coordinates the resources of the transmission and distribution network to obtain the optimal partitioning and optimal unit startup strategy, thereby achieving the goal of quickly restoring the power system after a fault and reducing power outage losses.

[0127] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0128] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0129] Figure 1 A flowchart of a decision-making method for power system partitioning and unit startup sequence that considers transmission and distribution coordination, proposed in an embodiment of the present invention;

[0130] Figure 2 This is a schematic diagram of three coordinated transportation and distribution methods provided in the embodiments of the present invention;

[0131] Figure 3 A schematic diagram of the upward power transmission characteristic curve of a distribution network is provided in an embodiment of the present invention;

[0132] Figure 4 A topology diagram of a testing system provided in an embodiment of the present invention;

[0133] Figure 5 This invention provides a partitioning result under a different strategy in an embodiment of the invention.

[0134] Figure 6 This invention provides a comparison of the unit startup process under different strategies;

[0135] Figure 7 This invention provides a comparison of system power generation capacity under different strategies. Detailed Implementation

[0136] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0137] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0138] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0139] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments. These embodiments do not constitute a limitation on the embodiments of the present invention.

[0140] Example 1

[0141] The processing steps of the decision-making method for power system partitioning and unit startup sequence considering transmission and distribution coordination provided in this embodiment of the invention mainly include: firstly, proposing the concept of transmission and distribution coordination recovery, and then clarifying the transmission and distribution coordination recovery method; then, linearizing the power characteristic curve of the distribution network's upward transmission, and introducing integer 0-1 variables to realize the choice between two power characteristics of the distribution network; then, for the problems of power system partitioning and unit startup, constructing a unified optimization decision model for power system partitioning and unit startup, and obtaining a power system partitioning and unit startup strategy considering transmission and distribution coordination.

[0142] The processing flow of a decision-making method for power system zoning and unit startup sequence considering transmission and distribution coordination provided by an embodiment of the present invention is as follows: Figure 1 As shown, it includes the following steps:

[0143] Step 1: Set up three transmission and distribution coordination methods.

[0144] The aforementioned transmission and distribution coordination refers to the coordination between the 220kV transmission network and the high-voltage distribution network. The power generation resources of the transmission network mainly consist of synchronous generators such as gas turbines and CHP (Combined Heat and Power) units, while the power generation resources of the distribution network mainly consist of synchronous generators, wind power, and energy storage. It should be noted that distribution networks participating in transmission and distribution coordination must at least possess self-starting capabilities, enabling them to restore lines, units, and critical loads within a short period. Some distribution networks also possess the ability to construct power transmission paths, proactively sending power upwards to support the transmission network.

[0145] Schematic diagrams of the three transmission and distribution coordination methods provided in the embodiments of the present invention are shown below. Figure 2 As shown. This invention, considering the above capabilities, proposes three coordinated transmission and distribution methods:

[0146] (1) Increase the number of partitions

[0147] The distribution network actively sends power upwards to independently support the startup of non-black start units, forming a new recovery zone and improving parallel recovery efficiency. The specific process is as follows: the self-starting resources of the distribution network start up, gradually restoring the units and important loads within the network; subsequently, under the aggregation effect of local power generation resources, the distribution network starts transformers and transmission lines and sends power upwards to independently support the startup of units.

[0148] (2) Start up large-capacity units in advance

[0149] The distribution network with energy constraints actively sends power upwards, activating non-black start generators ahead of time to accelerate the system recovery process. After energy storage is connected to the distribution network, energy constraints may prevent it from supporting the complete recovery process of the generators. Therefore, it needs to coordinate with black start generators in time to jointly support the startup of non-black start generators. Specifically, the distribution network recovers internally and sends power upwards; the distribution network first activates the NBSG (Non-Black Start Generator), and after energy is depleted, the BSG (Black Start Generator) supports the remaining recovery process.

[0150] (3) Increase available power generation capacity

[0151] In this mode, the distribution network lacks the ability to construct a power transmission path and requires the transmission network to assist in restoring transformers and lines before it can transmit power upwards. The specific process is as follows: the black-start units of the transmission network prioritize starting transformer nodes to assist in constructing a power transmission path, and the distribution network prioritizes ensuring power supply to important loads; once the upward power transmission path is restored, the distribution network transmits power upwards to enhance the regional power generation capacity and accelerate the start-up of non-black-start units.

[0152] Step 2: The distribution network transmits the upward power transmission characteristic curve and the upward power transmission preparation time to the transmission network.

[0153] The distribution network dispatching system calculates the power characteristic curve of the distribution network's upward power transmission and the preparation time for upward power transmission, and then transmits the power characteristic curve of the upward power transmission and the preparation time for upward power transmission to the transmission network dispatching system.

[0154] Figure 3 This invention provides a schematic diagram of the upward power transmission characteristic curve of a distribution network, including two curves: a stable power transmission capacity curve and a short-term support capacity curve. Figure 3 In the diagram, the solid line represents the stable power transmission capacity curve, and the dashed line represents the short-term support capacity curve. Preparation time for the distribution network to send power upwards; P a,0n and P b,0n These are the initial values ​​for the two curves; To provide P b,0n Time; P b,rampn P represents the initial value for the climbing process. a,maxn and P b,maxn These are the maximum values ​​of the two curves, respectively.

[0155] Figure 3 The dual-power characteristic curve of the distribution network's upward power transmission is difficult to directly describe with an analytical expression. Therefore, integer variables are introduced into the dual-power characteristic curve of the distribution network's upward power transmission to linearize the curve piecewise, thereby constructing a mathematical model of the distribution network. Then, a solver is used to solve the dual-power characteristic curve of the distribution network's upward power transmission.

[0156] (1) Linearization of stable power delivery capacity curve

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167] Where: Ω DSRepresents a collection of distribution networks; Indicates the actual power supply time of the distribution network;

[0168] This represents the maximum and initial values ​​of the stable power transmission capacity; Indicates the slope of the curve; These are integer variables (0-1) representing the stage of the power distribution network. and These respectively indicate that the stable power transmission capacity curve of the distribution network is in the ramp-up stage and the maximum power stage; As a continuous variable, its definition is given by equations (7)-(8); It is an integer variable (0-1) indicating whether to select stable power transmission capability. If selected,

[0169] but Otherwise, it is 0; The actual output power indicating stable power delivery capability; This indicates the preparation time for the distribution network to send power upwards, and the earliest time that the distribution network can provide support upwards. This value is given by the distribution network dispatcher.

[0170] Equations (1)-(2) indicate that the stable power delivery capacity curve of the distribution network cannot be in the ramp-up stage and the maximum power stage at the same time; Equations (3)-(6) respectively constrain the time range of each stage; Equation (9) is the actual power delivery time constraint of the distribution network; Equation (10) defines the actual output power of the stable power delivery capacity curve.

[0171] (2) Linearization of short-term support capacity curve

[0172]

[0173]

[0174]

[0175]

[0176]

[0177]

[0178]

[0179]

[0180]

[0181]

[0182] In the formula: Indicates the power supply preparation time for the distribution network; and This indicates the maximum, initial, and initial values ​​of short-term support capacity, as well as the initial value during the climbing phase. Indicates the slope of the curve; These are integer variables (0-1) representing the stage of the power distribution network. and These respectively indicate that the short-time support capacity curve of the distribution network is in the ramp-up stage and the maximum power stage; As a continuous variable, its definition is given by equations (17)-(18); It is an integer variable (0-1) indicating whether short-term support capability is selected. If selected, then... Otherwise, it is 0; The actual output power indicating short-term support capability; This indicates the preparation time for the distribution network to send power upwards, and the earliest time that the distribution network can provide support upwards. This value is given by the distribution network dispatcher.

[0183] Equations (11)-(12) indicate that the short-time support capacity curve of the distribution network cannot be in the ramp-up stage and the maximum power stage at the same time; Equations (13)-(16) respectively constrain the time range of each stage; Equation (19) is the actual power delivery time constraint of the distribution network; Equation (20) defines the actual output power of the short-time support capacity curve.

[0184] Step 3: Select the logic for establishing the upward power characteristic curve of the distribution network in the transmission network.

[0185] To establish the selection logic constraint for the dual characteristic curves of the power output from the transmission network to the distribution network, integer 0-1 variables are introduced to represent the selection of the power output characteristic curves from the transmission network to the distribution network:

[0186]

[0187]

[0188]

[0189]

[0190] In the formula: These are the options for selecting two power curves for the distribution network. This indicates the selection of stable power delivery capability. This indicates the selection of short-term support capabilities; These are integer variables of 0-1, representing the stage of the two power output characteristic curves, respectively. Let n be the actual output power of distribution network n at time t. and These represent the actual output power of the stable power delivery capability and the short-term support capability at time t, respectively.

[0191] Equation (21) indicates that the transmission network selects only one power characteristic of the distribution network; Equations (22) and (23) indicate that the actual output corresponding to the power characteristic curve not selected by the transmission network is 0; Equation (24) is the actual power output of the distribution network.

[0192] The dual power characteristic curves for upward power transmission from the distribution network constructed in this invention aim to provide a decision-making basis for the restoration of the transmission network. In actual operation, the distribution network provides two power characteristic curves to the transmission network. The transmission network selects a suitable distribution network power curve with the goal of restoring all units as quickly as possible. Therefore, the selection constraint of the upward power characteristic curve constructed in this invention ensures that the transmission network can only select one curve.

[0193] Step 4: Based on the selection logic of the power transmission network for the upward power transmission characteristic curve, model the unified optimization problem of power system partitioning and unit start-up sequence considering transmission and distribution coordination.

[0194] The models mentioned above for the unified optimization problem of power system zoning and unit startup sequence considering transmission and distribution coordination include:

[0195] (1) Objective function

[0196]

[0197] In the formula, Represents a set of power transmission network units; and These are the starting power and rated power of the power transmission unit g, respectively.

[0198] (2) Network flow constraints

[0199]

[0200]

[0201]

[0202] In the formula: and Let f represent the set of all black-start generators, non-black-start generators, and all generators in the transmission network; δ(k) represents the line connected to node k; α represents the α-th partition; f lα Let z be a continuous variable, representing the network flow along line l within partition α; iα Let z be an integer variable between 0 and 1, representing whether node i belongs to partition α. ​​If it does, then z... iα=1, otherwise 0. Among them, black start units refer to units that can be restarted without external support after shutdown; non-black start units refer to units that require external power support to restart after shutdown.

[0203] Equation (26) indicates that the sum of network flows emitted by node k connected to the black starter unit is equal to the sum of non-black starter units and the distribution network within partition α; Equation (27) indicates that the network flow consumed by node i connected to the non-black starter unit depends on the partition affiliation of node i. If node i belongs to the partition, the network flow consumed is 1, otherwise it is 0; Equation (28) indicates that nodes not connected to the unit do not consume network flows.

[0204] After considering the role of the distribution network, the recovery partition contains distribution network nodes, and it is necessary to define its network flow balance constraints.

[0205] Under the "increase the number of partitions" approach, the flow balance constraints of the distribution network node network are as follows:

[0206]

[0207] Where: Ω DS It is the equivalent distribution network node in the transmission network.

[0208] Equation (29) indicates that when there are no black-start generators in partition α, the network flow emitted by the distribution network node is equal to the sum of the non-black-start generators in partition α. ​​An integer 0-1 variable b is introduced. α , indicating whether BSG exists within partition α, equation (30) is b α Definition.

[0209] |I α | / M≤b α ≤|I α |×M (30)

[0210]

[0211] In the formula: |I α | represents the number of BSGs in partition α, where M is a very large positive integer.

[0212] Using the Big M method, equation (29) can be rewritten in the following form:

[0213]

[0214]

[0215] Equations (32)-(33) indicate that when b α When b = 0, that is, there are no black-start units in partition α, and the distribution network node sends out network flow; when b αWhen =1, the constraint is not effective. (32)-(33) enable the distribution network nodes to form new zones.

[0216] Under the "early start-up of generating units" method, the network flow balance constraints of the distribution network nodes are as follows:

[0217]

[0218] Equation (34) indicates that when both a black-start generator and a distribution network node exist simultaneously within partition α, the black-start generator generates the network flow, and the distribution network node absorbs the network flow. Using the same method as above, and employing the Big M method, equation (34) is rewritten in the following form:

[0219]

[0220]

[0221] Equations (35)-(36) indicate that when b α When b = 1, meaning there is a black-start unit within partition α, the distribution network node j absorbs network flow, and the amount of network flow absorbed depends on whether it belongs to partition α; when b α When the value is 0, the constraint is not effective.

[0222] (3) Partitioning logical constraints

[0223]

[0224]

[0225]

[0226] In the formula: Let N be the set of transmission lines, nodes, and zones; |δ(i)| be the total number of lines connected to node i; y lα It is an integer variable between 0 and 1, indicating whether line j belongs to sub-region α; |J| represents the total number of non-black starter units in the system.

[0227] Equation (37) indicates that if a line does not belong to sub-region α, then no network flow from that sub-region will flow on the line; Equation (38) indicates that if node ν does not belong to sub-region α, then none of the connected lines belong to sub-region α; Equation (39) indicates that all nodes belong to a certain sub-region.

[0228] (4) Unit start-up characteristics constraints

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235]

[0236]

[0237]

[0238]

[0239]

[0240]

[0241] In the formula, These are integer variables ranging from 0 to 1, representing whether unit g is in the ramp-up, maximum output, and power absorption stages, respectively. For the introduced auxiliary variables, equations (48)-(49) are their definitions; R g and These represent the ramp rate of unit g and the time of the power absorption process, respectively.

[0242] Equation (40) indicates that unit g cannot be in the ramp-up and maximum output phases simultaneously at time t; Equation (41) -

[0243] (47) defines the time range of the state of unit g; Equation (50) indicates that unit g needs to be started within the total recovery period; Equation (51) defines the active power output of unit g at time t.

[0244] (5) Transmission network recovery state constraints

[0245]

[0246]

[0247]

[0248] In the formula: r ti,α and u tj,α This represents the recovery state of node i and line j in sub-region α at time t; t TS This indicates the time required to restore the power transmission line.

[0249] Equations (52)-(54) represent the restoration conditions for power transmission lines, nodes, and generating units.

[0250] (6) Transmission network restoration logic constraints

[0251]

[0252]

[0253]

[0254]

[0255] Equations (55)-(56) indicate that if node i and line j do not belong to sub-region α, then the restoration of node i and line j is not considered in the restoration process of that sub-region. Equations (57)-(58) indicate that the restored nodes and lines will no longer be de-energized.

[0256] (7) System power generation capacity constraints

[0257]

[0258] Equation (59) indicates that the power generation capacity of the transmission and distribution network must meet the startup requirements of the NBSG.

[0259] Step 4: The transmission network solves the model of the unified optimization problem of power system partitioning and unit startup sequence considering transmission and distribution coordination to obtain the transmission and distribution coordination recovery partitioning and unit startup plan.

[0260] The model constructed in this invention for the unified optimization problem of power system partitioning and unit start-up sequence considering transmission and distribution coordination is a mixed-integer linear programming model, which can be solved using mature commercial solvers. The solution results include unit start-up time, start-up path, and system power generation capacity.

[0261] The transmission network sends the power usage plan of the distribution network to the distribution network according to the transmission and distribution coordinated recovery zone and the unit start-up plan; finally, the distribution network adjusts its own operation plan according to the usage plan of the transmission network, so as to realize information exchange and coordination between the transmission and distribution networks.

[0262] Example 2

[0263] Figure 4 The test system shown is a real 220kV transmission network in China with 46 nodes. It includes 3 black-start generators and 5 non-black-start generators, which are connected to the high-voltage distribution network at nodes 7, 26 and 35. Among them, DS1 and DS2 have self-starting capability and the ability to construct power transmission paths, while DS3 only has self-starting capability.

[0264] Step 1: According to Figure 4As shown in the figure, the unit parameters are set, and the model of the unified optimization problem of power system partitioning and unit start-up sequence considering transmission and distribution coordination is solved to obtain the unit start-up strategy of the transmission network, as shown in Table 1.

[0265] Table 1 Start-up Strategies for Transmission Network Units

[0266]

[0267] Step 2: Most existing transmission and distribution coordination studies adopt the coordination approach of "increasing available power generation capacity". Combined with the existing parallel recovery strategy, as a comparison strategy, the results of the comparison strategy are obtained.

[0268] Step 3: Compare with the strategy of this invention to obtain the following results. Figure 5 and Figure 6 The partitioning strategies and unit startup processes under different strategies are shown. Finally, the system power generation capacity is solved to obtain the following results: Figure 7 The comparison of system power generation capacity under different strategies is shown.

[0269] In summary, the method of this invention linearizes the upward power transmission characteristics of the distribution network, introduces integer variables to establish selection logic constraints for the power characteristics of the distribution network, constructs partition constraints based on network flow theory, and incorporates the distribution network into the partitioning problem, thereby achieving unified optimization decisions for partitioning and unit startup order, thus accelerating the startup process of transmission network units. The method proposed in this invention can generate a transmission and distribution coordinated recovery strategy after a power outage, serving as an important reference for grid dispatchers' decision-making.

[0270] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing the present invention.

[0271] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the present invention.

[0272] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for apparatus or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The apparatus and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0273] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A decision-making method for power system zoning and unit start-up sequence considering transmission and distribution coordination, characterized in that, include: Multiple transmission and distribution coordination methods are set up; The distribution network calculates the upward power transmission characteristic curve and the upward power transmission preparation time, and transmits the upward power transmission characteristic curve and the upward power transmission preparation time to the transmission network. The selection logic for establishing the upward power transmission characteristic curve of the distribution network in the transmission network is used to model the unified optimization problem of power system partitioning and unit start-up sequence considering transmission and distribution coordination based on the various transmission and distribution coordination methods. The transmission network solves the model of the unified optimization problem of power system partitioning and unit startup sequence considering transmission and distribution coordination, obtains the transmission and distribution coordination recovery partition and unit startup plan, and sends the transmission and distribution coordination recovery partition and unit startup plan to the distribution network. The distribution network adjusts its own operation plan according to the transmission and distribution coordinated recovery zone and the unit start-up plan to realize information exchange and coordination between the transmission and distribution networks; The selection logic for establishing the upward power transmission characteristic curve of the distribution network in the transmission network includes: Introducing integer variables (0-1) to represent the selection of the upward power output characteristic curve: （21） （22） （23） （24） In the formula: , These are the options for selecting two power curves for the distribution network. =1 indicates that a stable power delivery capability is selected. =1 indicates that short-term support capability is selected; , These are integer variables of 0-1, representing the stage of the two power output characteristic curves, respectively. Let n be the actual output power of distribution network n at time t. and These represent the actual output power of the stable power delivery capability and the short-term support capability at time t, respectively. Equation (21) indicates that the transmission network selects only one power characteristic of the distribution network; Equations (22) and (23) indicate that the actual output corresponding to the power characteristic curve not selected by the transmission network is 0; Equation (24) is the actual power output of the distribution network.

2. The method according to claim 1, characterized in that, The aforementioned methods for setting up multiple transmission and distribution coordination include: Three methods for coordinated transmission and distribution are set up, including: (1) Methods to increase the number of partitions: The self-starting resources of the distribution network are activated, gradually restoring the generating units and loads within the network. Under the aggregation effect of local power generation resources, the distribution network starts transformers and transmission lines and sends power upwards, independently supporting the start-up of generating units. (2) Methods for starting the unit in advance: The distribution network is restored internally and sends power upwards. The distribution network first starts the non-black start unit NBSG, and after the energy is exhausted, the black start unit BSG supports the remaining restoration process. (3) Methods to increase available power generation capacity: Black-start generators in the transmission network prioritize starting transformer nodes to assist in establishing power transmission paths, while the distribution network prioritizes power supply to critical loads. Once the upstream power transmission path is restored, the distribution network transmits power upstream to enhance the regional power generation capacity, and non-black-start generators are started.

3. The method according to claim 2, characterized in that, The distribution network calculates the upward power transmission characteristic curve and the upward power transmission preparation time, and transmits the upward power transmission characteristic curve and the upward power transmission preparation time to the transmission network, including: The distribution network calculates the upward power transmission characteristic curve and the upward power transmission preparation time. The upward power transmission characteristic curve includes two curves: the stable power transmission capacity curve and the short-term support capacity curve. The upward power transmission characteristic curve and the upward power transmission preparation time are transmitted to the transmission network. Integer variables are introduced into the dual-power characteristic curve of the power supply to the distribution network, and the dual-power characteristic curve of the power supply to the distribution network is linearized piecewise. (1) Linearization of the stable power transmission capacity curve （1） （2） （3） （4） （5） （6） （7） （8） （9） （10） In the formula: Represents a collection of distribution networks; Indicates the actual power supply time of the distribution network; , This represents the maximum and initial values ​​of the stable power transmission capacity; Indicates the slope of the curve; These are integer variables (0-1) representing the stage of the power distribution network. and These respectively indicate that the stable power transmission capacity curve of the distribution network is in the ramp-up stage and the maximum power stage; As a continuous variable, its definition is given by equations (7)-(8); It is an integer variable (0-1) indicating whether to select stable power transmission capability. If selected, then... =1, otherwise 0; The actual output power indicating stable power delivery capability; This indicates the preparation time for the distribution network to send power upwards, and the earliest time that the distribution network can provide support upwards. This value is given by the distribution network dispatcher. Equations (1)-(2) indicate that the stable power delivery capacity curve of the distribution network cannot be in the ramp-up stage and the maximum power stage at the same time; Equations (3)-(6) respectively constrain the time range of each stage; Equation (9) is the actual power delivery time constraint of the distribution network; Equation (10) defines the actual output power of the stable power delivery capacity curve. (2) Linearization of the short-term support capacity curve （11） （12） （13） （14） （15） （16） （17） （18） （19） （20） In the formula: Indicates the power supply preparation time for the distribution network; , and This indicates the maximum, initial, and initial values ​​of short-term support capacity, as well as the initial value during the climbing phase. Indicates the slope of the curve; These are integer variables (0-1) representing the stage of the power distribution network. and These respectively indicate that the short-time support capacity curve of the distribution network is in the ramp-up stage and the maximum power stage; As a continuous variable, its definition is given by equations (17)-(18); It is an integer variable (0-1) indicating whether short-term support capability is selected. If selected, then... =1, otherwise 0; The actual output power indicating short-term support capability; This indicates the preparation time for the distribution network to send power upwards, and the earliest time that the distribution network can provide support upwards. This value is given by the distribution network dispatcher. Equations (11)-(12) indicate that the short-time support capacity curve of the distribution network cannot be in the ramp-up stage and the maximum power stage at the same time; Equations (13)-(16) respectively constrain the time range of each stage; Equation (19) is the actual power delivery time constraint of the distribution network; Equation (20) defines the actual output power of the short-time support capacity curve.

4. The method according to claim 1, characterized in that, The aforementioned modeling of the unified optimization problem of power system partitioning and unit startup sequence considering transmission and distribution coordination based on the various transmission and distribution coordination methods includes: A model is established to address the unified optimization problem of power system zoning and unit startup sequence considering transmission and distribution coordination. This model includes: (1) Objective function （25） In the formula, Represents a set of power transmission network units; and These are the starting power and rated power of the power transmission unit g, respectively. (2) Network flow constraints （26） （27） （28） In the formula: , and These represent the sets of all black-start generators, non-black-start generators, and all generators in the transmission network, respectively; δ(k) represents the line connected to node k; α represents the α-th partition; For continuous variables, it represents the network flow passing through line l within partition α; Let be an integer variable (0-1) representing whether node i belongs to partition α. ​​If yes, then... =1, otherwise 0; Equation (26) indicates that the sum of network flows emitted by node k connected to the black starter unit is equal to the sum of non-black starter units and the distribution network within partition α. ​​Equation (27) indicates that the network flow consumed by node i connected to the non-black starter unit depends on the partition affiliation of node i. If node i belongs to the partition, the network flow consumed is 1, otherwise it is 0. Equation (28) indicates that nodes not connected to the unit do not consume network flows. Under the "increase the number of partitions" method, the flow balance constraints of the distribution network node network are as follows: （29） In the formula: This refers to the equivalent distribution network node in the transmission network. Equation (29) indicates that when there are no black-start units in partition α, the network flow is generated by the distribution network node, and the total number of generated network flows is equal to the sum of the non-black-start units in partition α. ​​Integer 0-1 variables are introduced. , indicating whether BSG exists within partition α, is given by equation (30). Definition: （30） （31） In the formula: |I α | represents the number of BSGs in partition α, where M is a very large positive integer; Using the Big M method, equation (29) can be rewritten in the following form: （32） （33） Equations (32)-(33) indicate that when When =0, meaning there are no black-start units within partition α, the distribution network node sends a network flow; when When =1, the constraint is ineffective. Equations (32)-(33) enable the distribution network nodes to form new zones. Under the "early start-up of generating units" method, the network flow balance constraints of the distribution network nodes are as follows: （34） Equation (34) indicates that when both a black-start generator and a distribution network node exist simultaneously within partition α, the black-start generator generates network flow, and the distribution network node absorbs the network flow. Using the Big M method, equation (34) can be rewritten as follows: （35） （36） Equations (35)-(36) indicate that when When =1, meaning there is a black-start unit within partition α, the distribution network node j absorbs network flow, and the amount of network flow absorbed depends on whether it belongs to partition α; when When =0, the constraint is not effective. (3) Partitioning logical constraints （37） （38） （39） In the formula: , Let N be the set of transmission lines, nodes, and zones; |δ(i)| is the total number of lines connected to node i; It is an integer variable between 0 and 1, indicating whether line j belongs to sub-region α; |J| represents the total number of non-black start units in the system; Equation (37) indicates that if a line does not belong to sub-region α, then no network flow from that sub-region will flow on the line; Equation (38) indicates that if a node If a node does not belong to sub-region α, then the connected lines do not belong to sub-region α; Equation (39) indicates that all nodes belong to a certain sub-region. (4) Unit start-up characteristic constraints （40） （41） （42） （43） （44） （45） （46） （47） （48） （49） （50） （51） In the formula, (h=1,2,3) are integer variables of 0-1, representing whether unit g is in the ramp-up, maximum output and power absorption stages, respectively; (h=1,2,3) are the introduced auxiliary variables, and equations (48)-(49) are their definitions; R g and These represent the ramp rate of unit g and the time of the power absorption process, respectively. Equation (40) indicates that unit g cannot be in the ramp-up and maximum output stages at the same time t; Equations (41)-(47) define the time range of the state of unit g; Equation (50) indicates that unit g needs to be started within the total recovery period; Equation (51) defines the active power output of unit g at time t. (5) Restored state constraints of power transmission network (52) (53) (54) In the formula: and This represents the recovery state of node i and line j in sub-region α at time t; Indicates the required restoration time for the power transmission line; Equations (52)-(54) represent the restoration conditions for transmission network lines, nodes, and generating units; (6) Logic constraints for power grid restoration (55) (56) (57) (58) Equations (55)-(56) indicate that if node i and line j do not belong to sub-region α, then the restoration of node i and line j is not considered in the restoration process of that sub-region. Equations (57)-(58) indicate that the restored nodes and lines will no longer be de-energized. (7) System power generation capacity constraints (59) Equation (59) indicates that the power generation capacity of the transmission and distribution network must meet the startup requirements of the NBSG.

Images