A unit maintenance planning method, device, computer equipment and storage medium

Abstract

The present invention relates to the field of power grid maintenance technology, and in particular to a unit maintenance planning method, device, computer equipment and storage medium. The unit maintenance planning method that takes into account the flexibility requirements and inertia support of the local power grid provided by the embodiment of the present invention constructs a standby constraint that takes into account the climbing ability of the unit and an inertia constraint of power loss, and solves the maintenance plan model constructed based on the cost of unit power generation, maintenance and standby based on the standby constraint and the inertia constraint to obtain the unit maintenance plan result. Since the standby constraint takes into account the climbing ability of the unit, the climbing ability can enable the power of the unit to be quickly restored when a fault occurs, thereby realizing the flexibility adjustment of the local power grid; at the same time, an inertia constraint is constructed, that is, the unmaintained unit can provide a certain inertia support during maintenance, so that when the unit is maintained according to the unit maintenance plan result, the safety and flexibility of the power grid operation can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid maintenance, and in particular to a unit maintenance planning method, device, computer equipment and storage medium. Background Art

[0002] The formulation of maintenance plans is one of the core businesses of power system dispatching and operation. The main task of the maintenance plan is to reasonably arrange the maintenance combination mode and shutdown period of power generation, transmission and transformation equipment on the premise of ensuring the safety, reliability and economy of power system operation, so as to improve the refinement level of power system operation.

[0003] At present, the maintenance plan is usually determined by solving the constructed maintenance plan model based on the constructed constraints. However, for the local power grid that may be decoupled, the maintenance of the units in the local power grid will lead to a decrease in system inertia and a decrease in emergency regulation flexibility. Although the existing maintenance plans involve the flow transfer caused by the maintenance in terms of constraints, the constraints brought by inertia support and flexibility requirements are not taken into account, which may cause the determined maintenance plan to fail to meet the power grid operation requirements. Summary of the invention

[0004] In view of this, the present invention provides a unit maintenance plan method, device, computer equipment and storage medium to solve the problem in the prior art that the determination of the maintenance plan cannot meet the power grid operation requirements.

[0005] In a first aspect, the present invention provides a unit maintenance planning method that takes into account the flexibility requirements and inertia support of a local power grid, the method comprising: constructing a standby constraint that takes into account the climbing capability of the unit based on changes in power grid power and frequency during power grid failures; constructing an inertia constraint for power loss based on local power grid decoupling and global power grid N-1 failures; constructing a maintenance planning model based on the costs of unit power generation, maintenance, and standby; solving the maintenance planning model based on the standby constraint and the inertia constraint to obtain a unit maintenance planning result.

[0006] The unit maintenance planning method provided by the present invention, which takes into account the flexibility demand and inertia support of the local power grid, constructs a standby constraint that takes into account the climbing ability of the unit and an inertia constraint of power loss, and solves the maintenance planning model constructed based on the cost of unit power generation, maintenance and standby based on the standby constraint and the inertia constraint, to obtain the unit maintenance planning result. Since the standby constraint takes into account the climbing ability of the unit, the climbing ability can enable the unit power to be quickly restored when a fault occurs, thereby realizing the flexibility adjustment of the local power grid; at the same time, an inertia constraint is constructed, that is, the unmaintained unit can provide a certain inertia support during maintenance, so that when the unit is maintained according to the unit maintenance plan result, the safety and flexibility of the power grid operation can be guaranteed.

[0007] In an optional embodiment, based on the changes in grid power and grid frequency when a grid fault occurs, a backup constraint that takes into account the unit's climbing capability is constructed, including: determining the power recovery time based on the changes in grid power and grid frequency when a grid fault occurs; and constructing a backup constraint that takes into account the unit's climbing capability based on the N-1 constraint of reserved backup of the grid unit, the constraint that the backup is greater than or equal to the missing power, and the constraint that the backup is less than or equal to the climbing capacity within the power recovery time.

[0008] In an optional embodiment, the changes in grid power and grid frequency during a grid failure include three time periods. In the first time period, the power is missing a first power and the frequency drops to a dead zone frequency. In the second time period, the power is restored to power balance at a climbing rate and the frequency drops from the dead zone frequency to a preset minimum frequency. In the third time period, the power increases and the frequency recovers.

[0009] In an optional embodiment, based on the changes in grid power and grid frequency during a grid failure, determining the time for power recovery includes: determining a first relationship between the duration of a first time period and the first power and the dead zone frequency; determining a second relationship between the duration of a second time period and the ramp rate and the first power; determining the time for power recovery based on the relationship between grid frequency and power, the first relationship, and the second relationship, the time for power recovery being the duration of the second time period.

[0010] In the present invention, when a fault occurs, power recovery needs to be achieved through the emergency response provided by the reserved reserve. Therefore, it is necessary to determine the power recovery time according to the frequency limitation during the power recovery process, and then determine the reserve constraint based on the recovery time, so that the determined reserve constraint can meet the needs of local power grid flexibility regulation.

[0011] In an optional implementation, based on the local power grid decoupling and the global power grid N-1 fault, an inertia constraint for power loss is constructed, including: when the local power grid is decoupling, determining a first inertia constraint based on the power loss of the interconnection line; and constructing a second inertia constraint when all power grid units N-1 are missing.

[0012] In the present invention, when constructing inertia constraints, the inertia requirements of the global and local power grids are taken into consideration, thereby improving the overall safety of power grid operation.

[0013] In an optional embodiment, a maintenance plan model is constructed based on the costs of unit power generation, maintenance and standby, including: determining a first product of unit output and power generation cost, a second product of unit standby and standby cost, and a third product of maintenance status and maintenance cost within a preset area; and constructing the maintenance plan model by minimizing the sum of the first product, the second product and the third product.

[0014] In the present invention, by considering the costs of power generation, maintenance and standby, and constructing a maintenance plan model with cost minimization, the cost of the maintenance plan result obtained can be minimized.

[0015] In an optional embodiment, before solving the maintenance plan model based on the standby constraint and the inertia constraint, the method also includes: constructing system power balance constraints, unit output constraints, interconnection line power constraints, maintenance constraints, and relationship constraints between unit output, standby and maintenance status.

[0016] In the present invention, in addition to the standby constraint and inertia constraint, the system power balance constraint, unit output constraint, interconnection line power constraint, maintenance constraint and the relationship constraint between unit output, standby and maintenance status are also considered, so that the maintenance plan result obtained by solving meets the safe operation requirements of the power grid.

[0017] In a second aspect, the present invention provides a unit maintenance planning device that takes into account the flexibility requirements and inertia support of a local power grid, the device comprising: a first constraint construction module, for constructing a backup constraint that takes into account the unit's climbing capability based on changes in power grid power and frequency during power grid failures; a second constraint construction module, for constructing an inertia constraint for power loss based on local power grid decoupling and global power grid N-1 failures; a model construction module, for constructing a maintenance planning model based on the costs of unit power generation, maintenance, and standby; a solution module, for solving the maintenance planning model based on the backup constraints and inertia constraints to obtain a unit maintenance planning result.

[0018] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to execute the unit maintenance planning method considering the flexibility demand of the local power grid and inertia support of the above-mentioned first aspect or any corresponding embodiment thereof.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the unit maintenance planning method that takes into account the flexibility requirements of the local power grid and inertia support of the above-mentioned first aspect or any corresponding embodiment thereof.

[0020] In a fifth aspect, the present invention provides a computer program product comprising computer instructions for causing a computer to execute the unit maintenance planning method considering the flexibility requirements of the local power grid and inertia support of the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a flow chart of a unit maintenance planning method considering flexibility requirements of a local power grid and inertia support according to an embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of a frequency change process according to an embodiment of the present invention;

[0024] Figure 3 is a schematic diagram of inertia changes of a local power grid system under different schemes according to an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of a local power grid tie line plan under different schemes according to an embodiment of the present invention;

[0026] Figure 5 is a structural block diagram of a unit maintenance planning device considering flexibility requirements and inertia support of a local power grid according to an embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0029] According to an embodiment of the present invention, there is provided an embodiment of a unit maintenance planning method taking into account the flexibility requirements of the local power grid and inertia support. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in an order different from that shown here.

[0030] In this embodiment, a unit maintenance planning method considering the flexibility demand and inertia support of the local power grid is provided, which can be used for electronic devices such as computers, mobile phones, tablet computers, etc. Figure 1 is a flow chart of a unit maintenance planning method considering local power grid flexibility requirements and inertia support according to an embodiment of the present invention, such as Figure 1 As shown, the process includes the following steps:

[0031] Step S101, based on the changes in grid power and grid frequency when the grid fails, construct a standby constraint that takes into account the climbing ability of the unit. Specifically, the grid failure here can be a disconnection failure that occurs in a local grid, that is, the local grid is disconnected from the upper grid or a larger grid system for some reason and no longer operates synchronously. The disconnection failure of the local grid is more likely to occur in a local grid with a high proportion of new energy. The local grid is different from the global grid. The local grid refers to a power distribution and transmission system operating in a relatively limited geographical area. It may include power plants, substations, distribution lines and end users. The local grid focuses more on meeting the electricity needs of users in the local area. The global grid covers a larger geographical range, that is, it spans a large geographical area. The global grid may include multiple local grids, that is, multiple grids are connected through high-voltage transmission lines to form a global grid. In other embodiments, the grid failure may also be other forms of failure.

[0032] When a disconnection fault occurs, power loss will occur, and the maintenance of the unit will also cause the inertia of the power grid to decrease. Therefore, it is necessary to have sufficient emergency backup and sufficient flexible climbing ability to quickly restore the missing power. Therefore, when a power grid fault occurs, it is necessary to determine the climbing ability of the unit and the time constraint of power recovery according to the change of the power grid frequency, that is, the power of the power grid is restored within a certain period of time through the climbing ability of the unit, and the power grid frequency will not be lower than the lower limit within this time, so as to obtain the backup constraint considering the climbing ability of the unit.

[0033] Step S102, based on the local grid decoupling and the global grid N-1 fault, construct an inertia constraint for power loss. Specifically, when the unit is overhauled, the inertia of the grid where it is located will decrease, that is, the overhauled unit cannot provide inertia, so the grid needs to have a certain inertia to ensure that the frequency change rate is not too low, such as not lower than the lowest frequency change rate of the grid. Among them, the grid inertia is a physical concept that describes the dynamic stability of the power system. It is not the inertia of objects in the traditional sense. In the power system, the inertia mainly comes from the kinetic energy stored in the rotating elements (such as rotors) of the synchronous generator due to their mass and rotation state. When the load in the power grid changes suddenly, such as the start or stop of a large motor, this kinetic energy can temporarily help the system maintain frequency stability until other control mechanisms (such as frequency regulation units) intervene. In short, the existence of grid inertia helps to resist instantaneous changes in frequency and provides a natural "buffer" effect.

[0034] For a local power grid, when a disconnection failure occurs, if maintenance is carried out at this time, the inertia provided by the unmaintained units needs to ensure that the frequency change rate will not be lower than the lowest frequency change rate of the power grid. For the global power grid, the situation of a single unit failure is considered. This embodiment mainly considers the N-1 failure of the power grid, where the N-1 failure principle of the power grid refers to a safety standard used in the planning, design and operation of the power system. It requires that even if the most important equipment in the system (such as a generator set, transmission line or transformer) fails or stops operating, the power system can still maintain stable operation without voltage collapse or frequency instability, and can continue to supply power to all users normally. Similar to the disconnection of the local power grid, in the N-1 power grid failure of the global power grid, it is also necessary to ensure that the inertia provided by the unmaintained units needs to ensure that the frequency change rate will not be lower than the lowest frequency change rate of the power grid.

[0035] Step S103, constructing a maintenance plan model based on the cost of generating, maintaining and maintaining the unit. Specifically, this embodiment constructs a maintenance plan model with the goal of minimizing the cost of generating, maintaining and maintaining the unit.

[0036] Step S104, solve the maintenance plan model based on the backup constraint and the inertia constraint to obtain the unit maintenance plan result. Specifically, the constructed maintenance plan model is a linear model. When solving, linear programming optimization solving software such as CPLEX can be used to solve and obtain the unit maintenance plan result. Among them, when solving, it is necessary to consider the backup constraint and the inertia constraint, so that the obtained unit maintenance plan result meets the flexibility requirements and inertia support of the local power grid.

[0037] The unit maintenance planning method considering the flexibility demand and inertia support of the local power grid provided by the embodiment of the present invention constructs a standby constraint considering the climbing ability of the unit and an inertia constraint of power loss, and solves the maintenance planning model constructed based on the cost of unit power generation, maintenance and standby based on the standby constraint and inertia constraint to obtain the unit maintenance planning result. Since the standby constraint takes into account the climbing ability of the unit, the climbing ability can enable the power of the unit to be quickly restored in the event of a fault, thereby achieving the flexibility adjustment of the local power grid; at the same time, an inertia constraint is constructed, that is, the unmaintained unit can provide a certain inertia support during maintenance, so that when the unit is maintained according to the unit maintenance plan result, the safety and flexibility of the power grid operation can be guaranteed.

[0038] In this embodiment, a unit maintenance planning method considering the flexibility demand and inertia support of the local power grid is provided, and the process includes the following steps:

[0039] Step S201: construct a backup constraint that takes into account the ramping capability of the unit based on changes in the power grid and the frequency of the grid when a grid fault occurs.

[0040] Specifically, the above step S201 includes:

[0041] Step S2011, based on the changes in grid power and grid frequency during a grid failure, determine the time for power recovery; wherein, the changes in grid power and grid frequency during a grid failure include three time periods, in the first time period, the power is missing a first power, and the frequency drops to a dead zone frequency, in the second time period, the power is restored to power balance at a climbing rate, and the frequency drops from the dead zone frequency to a preset minimum frequency, and in the third time period, the power increases and the frequency recovers.

[0042] Specifically, Figure 2 As shown, when a grid failure occurs, there will be a power loss P c , and at the same time, during the first period of power loss, the grid frequency changes from f 0 down to the deadband frequency f 0- f db The dead frequency refers to a frequency range that does not trigger control actions in the generator or power electronic equipment control system in order to prevent frequent switching operations caused by small frequency fluctuations. Within this range, even if the system frequency fluctuates, the controller will not respond, thus avoiding excessive wear of the equipment and unnecessary adjustment actions.

[0043] Therefore, when the grid frequency reaches the dead zone frequency, the controller response will be triggered, that is, the emergency standby response will be controlled, thus entering the second time period. In the second time period, the system power begins to recover through the emergency standby response, but the system frequency will further decrease before the power is restored to balance. However, the system frequency cannot be reduced infinitely, that is, the system will set a minimum frequency. Therefore, before the system is reduced to the minimum frequency, an emergency response is required to restore the power balance. Therefore, the second time period ( t db - t nad ) can be the time period during which power is restored from missing power to power balance and frequency is reduced from dead zone frequency to minimum frequency. In the emergency response process, it can be assumed that power is restored at a ramp rate u.

[0044] After the power is restored to balance, it enters the third time period, during which the grid frequency starts to rise and the grid power further increases from the balance node.

[0045] According to the above analysis, during the change of grid frequency and grid power, according to the lower limit requirement of system operating frequency, the system needs to nad The unit reserve is greater than the missing power at all times to ensure that the system will not drop below the preset minimum frequency f nadLower, based on this, the flexibility constraint that meets the system requirements is constructed, that is, the backup constraint that takes into account the unit's climbing capability.

[0046] Therefore, the above step S2011 includes:

[0047] Step a1, determining a first relationship between a first time period duration, a first power, and a dead zone frequency; specifically, as Figure 2 As shown, in the first time period, i.e., the time period when power loss occurs, the grid frequency changes from Down to the deadband frequency , in the power-time curve, the power at time 0 is Pc , The power at the moment is .therefore The area of ​​(which can be approximated as a trapezoid) is approximately equal to In the frequency-time curve, the frequency offset is 0 at time 0. Time frequency offset , moment of inertia H The energy required to bring about this change is Therefore, according to and The two are equal. At the same time, since the dead zone frequency is a known quantity, the system frequency reaches Time for:

[0048]

[0049] In the formula, H is the system inertia; K d is the response factor of the system load ，P d System load ，f 0 is the standard frequency of the power grid, P c is the system power missing value.

[0050] Step a2, determining the second relationship between the duration of the second time period, the ramp rate, and the first power. Specifically, in the second time period, the system power recovers from the first power to a balanced state (power is 0), and thus the second relationship can be obtained according to the ramp rate (the slope of the curve in the second time period in the figure), and is expressed by the following formula:

[0051]

[0052] Step a3, determining the power recovery time according to the relationship between the grid frequency and the power, the first relationship and the second relationship, where the power recovery time is the duration of the second time period. Specifically, the relationship between the grid frequency and the power is as follows:

[0053]

[0054] Where: H is the system inertia; f t For the moment t The system frequency, P c is the system power missing value, P u,t For emergency standby at all times t The standby call output; K d is the response factor of the system load ，P d System load ，f 0 is the standard frequency of the power grid.

[0055] Therefore, according to the relationship between grid frequency and power, t nad Time satisfies the following third relation:

[0056]

[0057] In the formula, f nad The minimum frequency of the system.

[0058] Bring the second relation into the third relation to eliminate t nad , and then bring the first relation into the elimination t db , it can be seen that the system's flexible adjustment ability u for:

[0059]

[0060] Based on this and the second relationship, we know that the system needs to be at t0 (t0=t nad -t db ) to complete power recovery within the time required to ensure that the system frequency is higher than f nad The time t0 is expressed by the following formula:

[0061]

[0062] Step S2012, based on the N-1 constraint of the reserved reserve of the power grid unit, the constraint that the reserve is greater than or equal to the missing power, and the constraint that the reserve is less than or equal to the climbing capacity within the power recovery time, a reserve constraint considering the unit's climbing ability is constructed. Specifically, in the emergency response phase, i.e., the above-mentioned second time period, power recovery needs to be achieved by reserving a reserve, and the reserve needs to meet the following conditions:

[0063] (1) Region k Medium Unit i The reserve that can be provided is not greater than the ramp capacity that can be provided within the time t0:

[0064]

[0065] In the formula, ui For the crew i The climbing rate, I is the total number of units in region k. rt,k,i Indicates sub-area k Medium Unit i In the period t Reserved for backup; for Time period sub-area The interconnection line power. For the crew exist t The maintenance state at the moment is a 0-1 variable. If it is equal to 0, it is in operation state, and if it is equal to 1, it is in maintenance state. Region k represents the area covered by the local power grid.

[0066] (2) The backup power that all units in the system can provide is greater than the missing power:

[0067]

[0068] In the formula, for Time period sub-area It should be noted that the power lost due to the local power grid disconnection fault is the interconnection line power.

[0069] (3) The reserved spare capacity of the overall power grid units meets the N-1 constraint:

[0070]

[0071] In the formula, Pi,k,t represents the units in region k i In the period t of effort.

[0072] Step S202: constructing an inertia constraint of power loss based on the local power grid disconnection and the global power grid N-1 fault.

[0073] Specifically, the above step S202 includes:

[0074] Step S2021, when the local power grid is disconnected, a first inertia constraint is determined based on the tie line power loss. Specifically, for the local power grid disconnection, the inertia constraint after the tie line power loss (i.e., the tie line is disconnected) is considered, and the inertia constraint (first inertia constraint) is expressed by the following formula:

[0075]

[0076] In the formula, For Region k Internal unit i The inertia of v min represents the minimum frequency change rate of the power grid. In the formula representing the first inertia constraint, the left side of the formula represents the inertia provided by the unmaintained units, and the right side of the formula represents the speed at which the inertia affects the frequency drop. Therefore, the first inertia constraint represents that the inertia provided by the unmaintained units needs to be greater than or equal to the speed at which the frequency drops due to the inertia.

[0077] Step S2022: construct the second inertia constraint when all power grid units N-1 lose power. Specifically, for the global power grid, consider the inertia constraint after the power loss of unit N-1. The inertia constraint (second inertia constraint) is expressed by the following formula:

[0078]

[0079] Where K means that the global power grid includes K regions.

[0080] Step S203, constructing a maintenance plan model based on the cost of power generation, maintenance and standby of the unit;

[0081] Specifically, the above step S203 includes:

[0082] Step S2031, determining a first product of unit output and power generation cost, a second product of unit standby and standby cost, and a third product of maintenance status and maintenance cost in a preset area.

[0083] Step S2032, constructing a maintenance plan model by minimizing the sum of the first product, the second product and the third product.

[0084] Based on the above steps S2031 and S2032, the maintenance plan model can be expressed by the following formula:

[0085]

[0086] Where: T Indicates the total number of time periods, K is the total number of regions, I For Region k The total number of units in ri,k,t For each uniti In the period t Provided spare, Cp,k,i , Cu,k,i For the crew i The power generation cost and standby cost, Cx,t,k,i For the crew i exist t Maintenance costs at all times. for Time period sub-area Medium Unit contribution; for Time period sub-area Medium Unit of spare.

[0087] Step S204: Solve the maintenance plan model based on the standby constraint and the inertia constraint to obtain the unit maintenance plan result. Figure 1 Step S104 of the illustrated embodiment will not be described in detail here.

[0088] In this embodiment, a unit maintenance planning method considering the flexibility demand and inertia support of a local power grid is provided, and the method comprises the following steps:

[0089] Step S301: Based on the changes in grid power and grid frequency when a grid fault occurs, a backup constraint considering the ramping capability of the unit is constructed; see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0090] Step S302: Based on the local grid disconnection and the global grid N-1 fault, construct the inertia constraint of power loss; see Figure 1 Step S102 of the illustrated embodiment will not be described in detail here.

[0091] Step S303: construct a maintenance plan model based on the cost of generating, maintenance and standby of the unit; see Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0092] Step S304, construct system power balance constraints, unit output constraints, tie line power constraints, maintenance constraints, and unit output, standby and maintenance status relationship constraints. Specifically, in addition to the above-mentioned standby constraints and inertia constraints, before solving the maintenance plan model, it is also necessary to construct the following constraints according to the power grid operation status:

[0093] (1) The system power balance constraint is determined based on the output of the unmaintained units, the tie line power, and the load power. The system power balance constraint is expressed by the following formula:

[0094]

[0095] In the formula, P d,t,k for Time zone of the total load.

[0096] (2) Determine the unit output constraint based on the upper and lower limits of the unit output. The unit output constraint is expressed by the following formula:

[0097]

[0098] Where: , Respectively, the regions Medium Unit The upper and lower limits of output.

[0099] (3) Determine the tie line power constraint based on the upper and lower limits of the tie line transmission power. The tie line power constraint is expressed by the following formula:

[0100]

[0101] In the formula, , Respectively, the regions The upper and lower limits of the transmission power of the interconnection line.

[0102] (4) The unit needs to meet the construction period requirements during maintenance. At the same time, the maintenance of the generator unit often lasts for multiple periods. Once the maintenance work of the generator unit begins, the maintenance task must be completed uninterruptedly and cannot be stopped. Based on this, the maintenance constraints can be determined and expressed using the following formula:

[0103]

[0104]

[0105] In the formula, Dk,i For the crew i maintenance period. gt,k,i Indicates the start of unit maintenance, 1 indicates a sub-area k unit i exist t Maintenance starts at time , and 0 at other times. ht,k,i Indicates the unit stop maintenance flag, 1 indicates the sub-area k unit i exist t The value is stopped for maintenance at this moment and 0 at other times.

[0106] (5) Based on the unit output, reserved standby and unmaintained unit output, the relationship constraint between the unit output, standby and maintenance status is determined. The relationship constraint is expressed by the following formula:

[0107]

[0108]

[0109] Step S305, solve the maintenance plan model based on the standby constraint and the inertia constraint to obtain the unit maintenance plan result. Specifically, it should be noted that when solving the maintenance plan model, in addition to considering the standby constraint and the inertia constraint, it is also necessary to consider the system power balance constraint, unit output constraint, tie line power constraint, maintenance constraint, and the relationship constraint between unit output, standby and maintenance status constructed in the above step S304, so that the solved unit maintenance plan result meets the safe operation requirements of the power grid.

[0110] The unit maintenance planning method provided by the embodiment of the present invention takes into account the flexibility requirements and inertia support of the local power grid. In the unit maintenance plan, the impact of the operating unit's climbing ability on frequency safety is taken into account. Based on the phased analysis of the frequency change process after the fault occurs, the flexibility adjustment resource spare capacity is reasonably reserved to ensure that the power grid still has sufficient flexibility after the unit maintenance. Compared with the conventional maintenance planning model, the model constructed in this embodiment jointly optimizes the planned power of the interconnection line, while taking into account the inertia requirements of the global and local power grids, and overall improves the safety of power grid operation.

[0111] As a specific application example of the embodiment of the present invention, in order to verify the effectiveness of the unit maintenance planning method considering the flexibility demand and inertia support of the local power grid, a simulation verification is performed based on actual power grid data. In the example system, there are 86 units to be repaired, 23 wind turbines, 363 branches, including a local power grid that may have a risk of disconnection. The minimum frequency change rate is specified to be 2 Hz / s.

[0112] Comparing the unit maintenance results with and without considering the local grid flexibility demand and inertia support, the specific settings are as follows:

[0113] Plan 1: Conventional unit maintenance plan without considering local grid flexibility requirements and inertia support.

[0114] Solution 2: A unit maintenance planning method considering the flexibility demand and inertia support of a local power grid is provided in an embodiment of the present invention, which considers the flexibility demand and inertia support of a local power grid.

[0115] The local power grid system inertia and tie line plan obtained by optimizing the two schemes are as follows: Figure 3 and Figure 4 As shown. Figure 3 It can be seen that the local grid inertia of Scheme 2 is maintained above 3000MWs in weeks 14-52, and that of Scheme 2 is maintained at 3000MWs in weeks 37-52. Therefore, the local grid inertia of the method proposed in the present invention is more abundant than that of Scheme 1 in most periods, which improves the safety of the local grid frequency. However, there are more unit maintenance in the local grid of Scheme 2 in weeks 1-8, and the system inertia is even lower than that of Scheme 1. Figure 4 It can be seen that the tie-line plan of Scheme 1 is between 139 and 224 MW, with less changes and adjustments, which brings greater frequency safety risks to the local power grid during periods with low inertia levels. Scheme 2 considers the impact of the tie-line plan power, especially in periods 1-8, when the power is in the range of 55-74 MW. Therefore, although the system inertia is small in these periods, the tie-line plan is also small, eliminating the frequency safety risk of the power grid after decoupling. At the same time, the tie-line plan is adjusted and increased with the increase of system inertia, realizing the overall optimization of the maintenance plan, tie-line plan and standby reservation considering the inertia support and flexible climbing capability of the local power grid.

[0116] In this embodiment, a unit maintenance planning device that takes into account the flexibility requirements of the local power grid and inertia support is also provided. The device is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0117] This embodiment provides a unit maintenance planning device that takes into account the flexibility requirements and inertia support of the local power grid, such as Figure 5 As shown, including:

[0118] A first constraint building module 51 is used to build a backup constraint considering the ramping capability of the unit based on the changes in the power grid and the frequency of the grid when a grid fault occurs;

[0119] A second constraint building module 52, for building an inertia constraint of power loss based on the local power grid decoupling and the global power grid N-1 fault;

[0120] A model building module 53, for building a maintenance plan model based on the cost of unit power generation, maintenance and standby;

[0121] The solving module 54 is used to solve the maintenance plan model based on the standby constraint and the inertia constraint to obtain the unit maintenance plan result.

[0122] In an optional embodiment, the first constraint construction module includes: a time determination module, which is used to determine the time for power recovery based on changes in grid power and grid frequency during grid failure; a constraint determination module, which is used to construct a backup constraint that takes into account the unit's climbing ability based on the N-1 constraint of reserved backup of the grid unit, the constraint that the backup is greater than or equal to the missing power, and the constraint that the backup is less than or equal to the climbing capacity within the power recovery time.

[0123] In an optional embodiment, the changes in grid power and grid frequency during a grid failure include three time periods. In the first time period, the power is missing a first power and the frequency drops to a dead zone frequency. In the second time period, the power is restored to power balance at a climbing rate and the frequency drops from the dead zone frequency to a preset minimum frequency. In the third time period, the power increases and the frequency recovers.

[0124] In an optional embodiment, the time determination module is specifically used to: determine a first relationship between the duration of a first time period and the first power and the dead zone frequency; determine a second relationship between the duration of a second time period and the climbing rate and the first power; determine the time for power recovery based on the relationship between the grid frequency and power, the first relationship and the second relationship, the time for power recovery being the duration of the second time period.

[0125] In an optional implementation, the second constraint construction module is specifically used to: determine the first inertia constraint based on the power loss of the tie line when the local power grid is decoupled; and construct the second inertia constraint when all power grid units N-1 are missing.

[0126] In an optional embodiment, the model building module is specifically used to: determine the first product of the unit output and the power generation cost, the second product of the unit standby and the standby cost, and the third product of the maintenance status and the maintenance cost within a preset area; and construct a maintenance plan model by minimizing the sum of the first product, the second product and the third product.

[0127] In an optional embodiment, the device also includes: a third constraint construction module, which is used to construct system power balance constraints, unit output constraints, interconnection line power constraints, maintenance constraints, and relationship constraints between unit output, standby and maintenance status.

[0128] The further functional description of each of the above modules is the same as that of the above corresponding embodiments and will not be repeated here.

[0129] The embodiment of the present invention also provides a computer device having the above Figure 5 The unit maintenance planning device considering local grid flexibility requirements and inertia support is shown.

[0130] See also Figure 6 , Figure 6is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Figure 6 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 A processor 10 is taken as an example.

[0131] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0132] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0133] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created by the use of a computer device based on the presentation of a small program landing page, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0134] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0135] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0136] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0137] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0138] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A unit maintenance planning method considering local power grid flexibility requirements and inertia support, characterized in that: The method comprises: Based on the changes in grid power and grid frequency during grid failure, a reserve constraint considering the ramping capability of the unit is constructed; Based on the local grid decoupling and the global grid N-1 fault, the inertia constraint of power loss is constructed; Construct maintenance planning model based on the cost of unit power generation, maintenance and standby; Solving the maintenance plan model based on the standby constraint and the inertia constraint to obtain a unit maintenance plan result; Based on the changes in grid power and grid frequency during grid failure, a reserve constraint considering the ramping capability of the unit is constructed, including: Determine the time for power restoration based on the changes in power and frequency of the power grid when the power grid fails; Based on the N-1 constraint of reserved reserve of power grid units, the constraint of reserve being greater than or equal to missing power, and the constraint of climbing capacity within the time when reserve is less than or equal to the power recovery, a reserve constraint considering the climbing capacity of the unit is constructed; the N-1 constraint of reserved reserve of power grid units includes that the reserved reserve of the entire power grid units satisfies the N-1 constraint; the constraint of reserve being greater than or equal to missing power includes that the reserve that can be provided by all units in the system is greater than the missing power; the constraint of climbing capacity within the time when reserve is less than or equal to the power recovery includes the regional k Medium Unit i The reserve that can be provided is not greater than the ramp capacity that can be provided within the time of power recovery; The changes of the power and frequency of the power grid during a power grid failure include three time periods. In the first time period, the power is lost and the frequency drops to the dead-band frequency. In the second time period, the power is restored to power balance at a ramp rate and the frequency drops from the dead-band frequency to a preset minimum frequency. In the third time period, the power increases and the frequency recovers. Based on the local grid decoupling and the global grid N-1 fault, the inertia constraint of power loss is constructed, including: When the local power grid is disconnected, the first inertia constraint is determined based on the power loss of the tie line. The first inertia constraint is expressed by the following formula: In the formula, For Region k Internal unit i The inertia of For the crew exist The maintenance status at the moment is a 0-1 variable. If it is equal to 0, it is in the running state, and if it is equal to 1, it is in the maintenance state. is the total number of units in region k, is the standard frequency of the power grid, Time period sub-area The tie line power, Indicates the lowest frequency change rate of the power grid; Construct the second inertia constraint when all power grid units N-1 power is missing. The second inertia constraint is expressed by the following formula: In the formula, K means that the global power grid includes K regions, P i,k,t represents the units in region k i In the period t contribution; The maintenance planning model is constructed based on the cost of unit power generation, maintenance and standby, including: Determine a first product of unit output and power generation cost, a second product of unit standby and standby cost, and a third product of maintenance status and maintenance cost in a preset area; The maintenance planning model is constructed by minimizing the sum of the first product, the second product and the third product.

2. The unit maintenance planning method considering the flexibility demand and inertia support of the local power grid according to claim 1 is characterized in that: Based on the changes in grid power and grid frequency during a grid fault, determine the time for power restoration, including: Determining a first relationship between a first time period duration and a first power and a dead-band frequency; determining a second relationship between the duration of the second time period and the ramp rate and the first power; The power recovery time is determined according to the relationship between the grid frequency and the power, the first relationship, and the second relationship, and the power recovery time is the duration of the second time period.

3. The unit maintenance planning method considering local power grid flexibility requirements and inertia support according to claim 1 is characterized in that: Before solving the maintenance plan model based on the backup constraint and the inertia constraint, the method further includes: Construct system power balance constraints, unit output constraints, interconnection line power constraints, maintenance constraints, and relationship constraints between unit output, standby and maintenance status.

4. A unit maintenance planning device considering the flexibility requirements and inertia support of a local power grid, characterized in that: The device comprises: The first constraint building module is used to build a backup constraint considering the ramping capability of the unit based on the changes of the power grid and the frequency of the power grid when the power grid fails; The second constraint building module is used to build an inertia constraint of power loss based on the local power grid decoupling and the global power grid N-1 fault; Model building module, used to build maintenance planning model based on the cost of unit power generation, maintenance and standby; A solving module, used for solving the maintenance plan model based on the standby constraint and the inertia constraint to obtain a unit maintenance plan result; Based on the changes in grid power and grid frequency during grid failure, a reserve constraint considering the ramping capability of the unit is constructed, including: Determine the time for power restoration based on the changes in power and frequency of the power grid when the power grid fails; Based on the N-1 constraint of reserved reserve of power grid units, the constraint of reserve being greater than or equal to missing power, and the constraint of climbing capacity within the time when reserve is less than or equal to the power recovery, a reserve constraint considering the climbing capacity of the unit is constructed; the N-1 constraint of reserved reserve of power grid units includes that the reserved reserve of the entire power grid units satisfies the N-1 constraint; the constraint of reserve being greater than or equal to missing power includes that the reserve that can be provided by all units in the system is greater than the missing power; the constraint of climbing capacity within the time when reserve is less than or equal to the power recovery includes the regional k Medium Unit i The reserve that can be provided is not greater than the ramp capacity that can be provided within the time of power recovery; The changes of the power and frequency of the power grid during a power grid failure include three time periods. In the first time period, the power is lost and the frequency drops to the dead-band frequency. In the second time period, the power is restored to power balance at a ramp rate and the frequency drops from the dead-band frequency to a preset minimum frequency. In the third time period, the power increases and the frequency recovers. Based on the local grid decoupling and the global grid N-1 fault, the inertia constraint of power loss is constructed, including: When the local power grid is disconnected, the first inertia constraint is determined based on the power loss of the tie line. The first inertia constraint is expressed by the following formula: In the formula, For Region k Internal unit i The inertia of For the crew exist The maintenance status at the moment is a 0-1 variable. If it is equal to 0, it is in the running state, and if it is equal to 1, it is in the maintenance state. is the total number of units in region k, is the standard frequency of the power grid, Time period sub-area The tie line power, Indicates the lowest frequency change rate of the power grid; Construct the second inertia constraint when all power grid units N-1 power is missing. The second inertia constraint is expressed by the following formula: In the formula, K means that the global power grid includes K regions, P i,k,t represents the unit in region k i In the period t contribution; The maintenance planning model is constructed based on the cost of unit power generation, maintenance and standby, including: Determine a first product of unit output and power generation cost, a second product of unit standby and standby cost, and a third product of maintenance status and maintenance cost in a preset area; The maintenance planning model is constructed by minimizing the sum of the first product, the second product and the third product.

5. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the unit maintenance planning method considering the flexibility demand of the local power grid and inertia support as described in any one of claims 1 to 3 by executing the computer instructions.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions for causing a computer to execute the unit maintenance planning method considering local power grid flexibility requirements and inertia support as described in any one of claims 1 to 3.

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