Multi-resource frequency coordination control method for direct current transmitting and receiving coexistence type power grid

Abstract

The invention provides a multi-resource frequency coordination control method for a direct-current transmitting and receiving coexistence type power grid, and the method comprises the steps: obtaining an adjustment range of frequency control measure quantity and bearable profit and loss of the target power grid and a connected synchronous power grid through a simulation model of the target power grid; the modeling range of the simulation model comprises a target power grid and a connected synchronous power grid which is in direct current connection with the target power grid through networking; the frequency control measure quantity at least comprises a sending and receiving measure quantity and a resource measure quantity of the target power grid; positive and negative values of the measure transmitting and receiving quantities represent that the connected synchronous power grid transmits power to the target power grid and receives the target power grid power through the networked direct current respectively; determining an objective function and a constraint condition of a frequency control measure amount when a fault occurs by using an adjustment range of the frequency control measure amount and bearable profit and loss amounts of a target power grid and a connected synchronous power grid in response to the fault of the networked direct current; and solving the frequency control measure quantity by using the target function and the constraint condition.

Description

Technical Field

[0001] The present disclosure relates to the field of power systems, and more specifically to a multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid. Background Art

[0002] To optimize the allocation of energy resources over large areas, ultra-high voltage (UHV) direct current (DV) transmission technology, characterized by long transmission distances, a large number of transmission measures, flexible controllability, and excellent economic efficiency, has been widely adopted. While the increasing number of DC transmission projects has significantly improved energy resource allocation capabilities, it has also brought new challenges to grid frequency stability control. On the one hand, the increasing number of DC transmission measures has led to an increasing scale of power disturbances on the grid after DC blocking. On the other hand, the replacement of a large number of synchronous generators within the grid has reduced the system's ability to withstand large frequency fluctuations caused by power surges.

[0003] Current control measures for grid frequency stability include modulated DC, pumped storage pump shedding, load shedding, and generator shedding, or a flexible combination of these resources can be employed according to pre-defined strategies. However, relevant research, both domestically and internationally, has only considered either the DC sending or receiving grid. With the increasing number of conventional DC transmission projects and the emergence of flexible DC transmission projects with bidirectionally adjustable transmission power, a new scenario has emerged: synchronous grids with coexisting DC transmission and reception. Multi-resource frequency coordination in these scenarios presents the following new challenges, which existing frequency control methods struggle to adapt to: First, DC blockages or faults can lead to power surpluses or deficits in the synchronous grid; second, the coordinated control of sending-end DC, receiving-end DC, and flexible DC becomes more complex when DC modulation is employed. Therefore, fully utilizing the various DC and other frequency regulation resources within the grid to achieve multi-resource frequency coordination in DC sending and receiving grids is a key issue in ensuring the safe and stable operation of such grids after large power disturbances. Summary of the Invention

[0004] In view of the above problems, the present disclosure provides a multi-resource frequency coordinated control method for a DC transmission and reception coexisting power grid, including: using a simulation model of a target power grid to obtain an adjustment range of a frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid; the modeling range of the simulation model includes the target power grid and the connected synchronous power grid connected to the target power grid through a networked DC; the frequency control measure amount includes at least a transmission and reception measure amount and a resource measure amount of the target power grid; the transmission and reception measure amount uses positive and negative values to represent the connected synchronous power grid transmitting power to the target power grid and receiving power from the target power grid through the networked DC; in response to a fault in the networked DC, using the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid to determine the objective function and constraint conditions of the frequency control measure amount when the fault occurs; using the objective function and the constraint conditions to solve the frequency control measure amount.

[0005] According to an embodiment of the present disclosure, a simulation model of a target power grid is used to obtain an adjustment range of a frequency control measure amount and an acceptable profit or loss amount of the target power grid and the connected synchronous power grid, including: building a simulation model of the target power grid; using the simulation model, calculating the acceptable profit or loss amount of the target power grid and the connected synchronous power grid by cutting off loads and cutting off units; the acceptable profit or loss amount includes a power shortage upper limit and a power surplus upper limit; according to the actual operation mode of the target power grid, the adjustment range of the resource measure amount is calculated; wherein, the resource measure amount includes one of a pump-cuttable measure amount of a pumped-storage unit, a machine-cuttable measure amount of an operating unit, and a load-cuttable measure amount of a load point; the actual operation mode includes at least one of the operation states of a pumped-storage unit with a cuttable pump, a machine-cuttable operating unit, and a load-cuttable point; according to the actual transmission power and transmission power range of the interconnected DC, the adjustment range of the sending and receiving measure amount is calculated.

[0006] According to an embodiment of the present disclosure, the tolerable profit or loss of the target power grid and the connected synchronous power grids is calculated by shedding loads and units, including: for the target power grid and each connected synchronous power grid, a power deficit is created by shedding units, and a transient stability calculation is performed; in response to the lowest point of the transient frequency curve being equal to the lowest frequency of normal operation of the power grid, an upper limit of the power deficit is determined; for the target power grid and each connected synchronous power grid, a power surplus is created by shedding loads, and a transient stability calculation is performed, and in response to the highest point of the transient frequency curve being equal to the highest frequency of normal operation of the power grid, an upper limit of the power surplus is determined.

[0007] According to an embodiment of the present disclosure, the adjustment range of the resource measure quantity is calculated according to the actual operation mode of the target power grid, including: calculating the upper limit of the cuttable pump measure quantity of the pumped storage unit according to the capacity of the operating cuttable pump pumped storage unit; calculating the upper limit of the cuttable machine measure quantity of the operating unit according to the capacity of the operating cuttable machine operating unit; calculating the upper limit of the cuttable load measure quantity of the load point according to the actual load power of the cuttable load point.

[0008] According to an embodiment of the present disclosure, the adjustment range of the sending and receiving measure quantity is calculated based on the actual transmission power and transmission power range of the networked DC, including: using the upper limit of the transmission power range to subtract the actual transmission power to determine the upper limit of the transmission power of the sending and receiving measure quantity; using the actual transmission power to subtract the lower limit of the transmission power range to determine the upper limit of the receiving power of the sending and receiving measure quantity.

[0009] According to an embodiment of the present disclosure, the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid are used to determine the objective function and constraint conditions of the frequency control measure amount when a fault occurs, including: judging whether the actual transmission power of the faulty interconnected DC exceeds the tolerable profit and loss amount of the target power grid; if the actual transmission power does not exceed the tolerable profit and loss amount of the target power grid, there is no need to solve the frequency control measure amount; if the actual transmission power exceeds the tolerable profit and loss amount of the target power grid, then according to the over-limit value, the objective function and constraint conditions of the frequency control measure amount when the fault occurs are determined.

[0010] According to an embodiment of the present disclosure, the objective function and constraint conditions when a fault occurs are determined based on the over-limit value, including: in response to the actual transmission power exceeding the power shortage upper limit, the objective function of the frequency control measure quantity is determined based on the transmission and reception measure quantity, the pumped storage unit can cut the pump measure quantity, the load point can cut the load measure quantity and the first preset priority; the constraint conditions of the frequency control measure quantity are determined based on the over-limit value, the actual transmission power, the tolerable profit and loss of the connected synchronous power grid and the adjustment range of the frequency control measure quantity; the priorities in the first preset priority are transmission and reception measure quantity, pumped storage unit can cut the pump measure quantity, load point can cut the load measure quantity and the first preset priority. amount and the amount of load shedding measures at the load point; in response to the actual transmission power exceeding the upper limit of the power surplus, the objective function of the frequency control measure amount is determined according to the transmission and reception measure amount, the amount of load shedding measures for the operating units and the second preset priority; the constraint conditions of the frequency control measure amount are determined according to the over-limit value, the actual transmission power, the tolerable profit and loss amount of the connected synchronous power grid and the adjustment range of the frequency control measure amount; the priorities in the second preset priority are the transmission and reception measure amount and the amount of load shedding measures for the operating units from high to low; among them, the first preset priority and the second preset priority are used to determine the order in which the frequency control measure amounts are adopted.

[0011] According to an embodiment of the present disclosure, the sending and receiving measures include at least the first interconnected DC measure quantity of the connected synchronous power grid where the fault is located and the second interconnected DC measure quantity of other connected synchronous power grids; the frequency control strategy is solved by using the objective function and constraint conditions, including: in response to the actual transmission power exceeding the power shortage upper limit, the first interconnected DC measure quantity, the pumped storage unit cuttable pump measure quantity, the second interconnected DC measure quantity and the load point cuttable load measure quantity are determined in sequence according to the first preset priority; in response to the actual transmission power exceeding the power surplus upper limit, the first interconnected DC measure quantity, the second interconnected DC measure quantity and the operating unit cuttable machine measure quantity are determined in sequence according to the second preset priority.

[0012] According to an embodiment of the present disclosure, the first interconnected DC measure quantity and the second interconnected DC measure quantity are calculated, including: according to the regulation range of the sending and receiving measure quantities of the connected synchronous power grid where the fault is located, the first interconnected DC measure quantity is proportionally distributed to the interconnected DC in the connected synchronous power grid where the fault is located, so as to obtain the first interconnected DC measure quantity; according to the regulation range of the sending and receiving measure quantities of the interconnected DC in other connected synchronous power grids, the second interconnected DC measure quantity is proportionally distributed to the interconnected DC in other connected synchronous power grids, so as to obtain the second interconnected DC measure quantity.

[0013] A second aspect of the present disclosure provides a multi-resource frequency coordination control device for a DC transmission and reception coexisting power grid, which can be used to implement the above method. The device includes: a modeling and calculation module, which is used to use a simulation model of a target power grid to obtain an adjustment range of a frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid; the modeling range of the simulation model includes the target power grid and the connected synchronous power grid connected to the target power grid through a networked DC; the frequency control measure amount includes at least a transmission and reception measure amount and a resource measure amount of the target power grid; the transmission and reception measure amount is represented by positive and negative values of the connected synchronous power grid transmitting power to the target power grid and receiving power from the target power grid through the networked DC; an optimization model module, which is used to determine the objective function and constraints of the frequency control measure amount when a fault occurs in the networked DC by using the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid; and a model solving module, which is used to solve the frequency control measure amount by using the objective function and the constraints.

[0014] A third aspect of the present disclosure provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors execute the multi-resource frequency coordination control method for the above-mentioned DC transmission and reception coexisting power grid.

[0015] A fourth aspect of the present disclosure further provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, causes the processor to execute the multi-resource frequency coordination control method for the DC transmission and reception coexisting power grid.

[0016] The multi-resource frequency coordination control method for a DC power grid with coexisting transmission and reception, provided herein, establishes grid simulation model data to calculate the active power deficit and surplus capacity of each synchronous power grid, the emergency power modulation capacity of conventional DC and flexible DC with bidirectional power transmission at each sending or receiving end in the target synchronous power grid, and the maximum amount of measures such as pump shedding, load shedding, and generator shedding. Aiming for grid frequency control scenarios following DC blocking faults, the method aims to achieve grid frequency stability with minimal control cost. It fully utilizes the modulation capacity of DC in different power directions in the coexisting transmission and reception grid to achieve power mutual assistance, and combines this with conventional control measures such as pump shedding to achieve multi-resource frequency coordination control. Therefore, the method at least partially addresses the technical issue of the difficulty in safe and stable operation of a DC power grid with coexisting transmission and reception after a large power disturbance. It also enables real-time online generation of a multi-resource coordination control strategy for any DC fault outage scenario based on the actual grid operation mode, and performs rolling corrections based on changes in the grid operation mode. The method features simple calculation, strong operability, and low control cost, and has promising engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flowchart schematically illustrates a method for coordinated frequency control of multiple resources in a DC transmission and reception coexisting power grid according to an embodiment of the present disclosure;

[0018] Figure 2 A flowchart applicable to power grid A according to an embodiment of the present disclosure is schematically shown;

[0019] Figure 3 A schematic diagram of DC interconnection between a synchronous power grid A and other synchronous power grids according to an embodiment of the present disclosure is shown;

[0020] Figure 4 The schematic diagram shows a temporary stable frequency curve under the maximum power shortage that the power grid A can withstand according to an embodiment of the present disclosure;

[0021] Figure 5 The diagram schematically shows a temporary stable frequency curve under the condition of maximum power surplus that the power grid A can withstand according to an embodiment of the present disclosure;

[0022] Figure 6 A block diagram schematically illustrates a structure of a multi-resource frequency coordination control device for a DC transmission and reception coexisting power grid according to an embodiment of the present disclosure;

[0023] Figure 7A block diagram of an electronic device suitable for implementing a multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] Figure 1 A flowchart of a multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid according to an embodiment of the present disclosure is schematically shown. Figure 1As shown, an embodiment of the present disclosure provides a multi-resource frequency coordinated control method for a DC transmission and reception coexisting power grid, including: using a simulation model of a target power grid to obtain an adjustment range of a frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid; the modeling range of the simulation model includes the target power grid and the connected synchronous power grid connected to the target power grid through a networked DC; the frequency control measure amount includes at least a transmission and reception measure amount and a resource measure amount of the target power grid; the transmission and reception measure amount uses positive and negative values to represent that the connected synchronous power grid transmits power to the target power grid and receives power from the target power grid through the networked DC; in response to a fault in the networked DC, using the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid to determine the objective function and constraint conditions of the frequency control measure amount when a fault occurs; using the objective function and constraint conditions to solve the frequency control measure amount.

[0029] Through the embodiments of the present disclosure, by considering constraints such as the regulation capabilities of various resources and the grid's ability to withstand active power shortages, a regulation allocation scheme for various regulation resources participating in frequency coordination control is solved, ensuring the rapid handling of power disturbance faults. Because the frequency control measures take into account the grid's own adjustable resources (pump / generator / load shedding), DC transmission and reception between grids, and the grid's own ability to withstand surpluses and shortages, they cover the grid's internal resources and cross-regional interconnection capabilities, achieving multi-resource coordination. At the same time, through the generation of strategies through mathematical optimization models, the real-time and adaptable control measures are ensured.

[0030] On the basis of the above embodiment, the simulation model of the target power grid is used to obtain the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid, including: building a simulation model of the target power grid; using the simulation model, by cutting off loads and cutting off units, calculating the tolerable profit and loss amount of the target power grid and the connected synchronous power grid; the tolerable profit and loss amount includes the power shortage upper limit and the power surplus upper limit; according to the actual operation mode of the target power grid, the adjustment range of the resource measure amount is calculated; wherein, the resource measure amount includes one of the pump-cuttable measure amount of the pumped storage unit, the machine-cuttable measure amount of the operating unit and the load-cuttable measure amount of the load point; the actual operation mode includes at least one of the operating states of the pumped storage unit with a cuttable pump, the machine-cuttable operating unit and the cuttable load point; according to the actual transmission power and transmission power range of the networked DC, the adjustment range of the sending and receiving measure amount is calculated.

[0031] In this embodiment, simulation tools for building grid simulation calculation model data include but are not limited to PSASP, PSD-BPA, ADPSS, etc.; the grid simulation calculation model includes generators and their control systems, grid structure parameters, loads, DC and its control and protection systems, and other AC / DC transmission equipment parameters. The scope of grid simulation modeling must include the AC synchronous grid with DC transmission and reception under study, as well as other synchronous grids connected to the grid via DC. The maximum power shortage / surplus capacity of the grid is calculated through transient stability analysis, that is, when the lowest / highest point frequency of the transient frequency curve just reaches the lowest / highest frequency allowed for normal operation of the grid, the power shortage / surplus of the grid at this time is the maximum power shortage / surplus capacity of the grid. Under low load mode, the grid's ability to withstand power shortages or surpluses is relatively small, and the analysis results under this mode can be used for various fault conditions.

[0032] Through the embodiments of this disclosure, a power grid calculation data model is established, clarifying the calculation sources of various parameters. Specifically, a small-load method is used to calculate the ability of the AC synchronous power grid with coexisting DC transmission and reception, as well as other synchronous power grids connected to this grid via DC, to withstand active power shortages and surpluses. Based on the current actual operation mode F of the power grid, an online analysis is conducted on the emergency power modulation capabilities of the DC transmission and reception terminals and the flexible DC with bidirectional power regulation in the AC synchronous power grid under study. Based on the current actual operation mode F of the power grid, an online analysis is conducted on the maximum amount of regulation measures such as pump, load, and generator trips in the pumped storage power grid under study.

[0033] On the basis of the above embodiment, the tolerable profit or loss of the target power grid and the connected synchronous power grids is calculated by shedding loads and removing units, including: for the target power grid and each connected synchronous power grid, creating a power deficit by shedding units and performing transient stability calculations; in response to the lowest point of the transient frequency curve being equal to the lowest frequency of normal operation of the power grid, determining the upper limit of the power deficit; for the target power grid and each connected synchronous power grid, creating a power surplus by shedding loads and performing transient stability calculations, and in response to the highest point of the transient frequency curve being equal to the highest frequency of normal operation of the power grid, determining the upper limit of the power surplus.

[0034] In this embodiment, it is assumed that the studied power grid is A, which is connected to M other synchronous power grids only through DC transmission, which are counted as power grids B1, B2, ... B M .

[0035] (1) For the M+1 synchronous power grids mentioned above, a power shortage is created in the synchronous power grid by removing the generator sets, and transient stability calculations are performed.

[0036] If the cut-off unit capacity reaches P A,vacancy ,P B1,vacancy ,P B2,vacancy ,…PBM,vacancy When the lowest point frequency of the above synchronous power grid transient frequency curve just reaches the lowest frequency f allowed for normal operation of the power grid min , then P A,vacancy ,P B1,vacancy ,P B2,vacancy ,…P BM,vacancy The upper limit of the power deficit that can be tolerated is determined for the ability of the M+1 power grids to tolerate active power deficit.

[0037] (2) For the M+1 synchronous power grids mentioned above, create a power surplus in the synchronous power grid by removing the load, and perform transient stability calculations. If the load removal capacity reaches P A,surplus ,P B1,surplus ,P B2,surplus ,…P BM,surplus When the highest point frequency of the above synchronous power grid transient frequency curve just reaches the highest frequency f allowed by the normal operation of the power grid max , then P A,surp l us ,P B1,surplus ,P B2,surplus ,…P BM,surplus The power surplus upper limit of the tolerable surplus or loss is determined for the ability of the M+1 power grids to bear active power surplus.

[0038] Through the embodiments of the present disclosure, the grid's bearing capacity is determined through transient stability calculations, and the frequency extremes (lowest / highest points) are used as judgment criteria. The actual grid model is used to conduct simulation analysis to obtain the ability of each synchronous grid to withstand the maximum power deficit / surplus. This is more in line with the actual operating characteristics of the grid, and can effectively evaluate the extreme values that may occur during the fluctuation of the grid frequency curve, with higher evaluation accuracy.

[0039] On the basis of the above embodiments, the adjustment range of the resource measure quantity is calculated according to the actual operation mode of the target power grid, including: calculating the upper limit of the cuttable pump measure quantity of the pumped storage unit according to the capacity of the operating cuttable pump pumped storage unit; calculating the upper limit of the cuttable machine measure quantity of the operating unit according to the capacity of the operating cuttable machine unit; calculating the upper limit of the cuttable load measure quantity of the load point according to the actual load power of the cuttable load point.

[0040] In this embodiment, the upper limit of the pump-cutting measures for the pump-storage units is calculated based on the capacity of the pump-cutting pump-storage units in operation, including: assuming that there are K pump-storage units with emergency pump-cutting functions in the power grid A, it is necessary to first read the operating status U of the above units in the current actual operating mode F of the power grid. k,pump (k∈[1,K]) and pumping power P k,pump (k∈[1,K]), if the unit is in the pumping state, then U k,pump=1, otherwise it is 0, then the upper limit of the pump-cuttable measures of the pumped storage unit is the sum of the unit power of the cuttable pumps in the pumping state:

[0041]

[0042] In this embodiment, the upper limit of the amount of the operating unit that can be cut is calculated based on the capacity of the operating unit that can be cut, including: assuming that there are J conventional units in the power grid A and the new energy station has a high-frequency emergency cut function, it is necessary to first read the operating status U of the above units in the current actual operation mode F of the power grid. j,unit (j∈[1,J]) and generated power P j,unit (j∈[1,J]), if the unit is in the on state, then U j,unit =1, otherwise it is 0, then the upper limit of the amount of measures that can be taken to cut the running units is the sum of the unit power of the running units that can be cut in the power-on state:

[0043]

[0044] In this embodiment, the upper limit of the load shedding measure at the load point is calculated based on the actual load power of the load point that can be shelved, including: assuming that there is a load point I in the power grid A equipped with the precise load shedding function after DC blocking, it is necessary to first read the actual load power P of the load point in the current actual operation mode F of the power grid. i,load (i∈[1,I]), the upper limit of the load shedding measure at the load point is the actual load power and the load shedding point:

[0045]

[0046] It should be noted that pumped storage, conventional units, new energy stations, load operating status and operating power acquisition methods include but are not limited to energy management systems EMS / SCADA and other dispatching automation systems.

[0047] Through the embodiments of the present disclosure, the regulation capabilities of various frequency regulation resources in the power grid are solved by obtaining actual power grid operation data, which can improve the rationality and operability of the multi-resource coordinated control strategy.

[0048] On the basis of the above embodiment, the adjustment range of the sending and receiving measure quantity is calculated according to the actual transmission power and transmission power range of the networked DC, including: using the upper limit of the transmission power range to subtract the actual transmission power to determine the upper limit of the transmission power of the sending and receiving measure quantity; using the actual transmission power to subtract the lower limit of the transmission power range to determine the upper limit of the receiving power of the sending and receiving measure quantity.

[0049] In this embodiment, the specific calculation process is as follows:

[0050] (1) Obtain the actual transmission power of all DC transmissions between the studied synchronous grid and another synchronous grid in the current actual operation mode F (the studied grid is a sending end, a receiving end, and a power bidirectional adjustable type). Assume that grid A and grid B m (m∈[1,M]) only through N m (N m ≥1,N m is an integer) DC lines are connected, respectively denoted as DC L m,1 ,L m,2 …L m,Nm First, read the actual DC power delivered to the grid A in the current actual operation mode F of the grid, and record it as P m,1 ,P m,2 …P m,Nm (The power is positive when grid A is the receiving end and negative when grid A is the sending end), and acquisition channels include but are not limited to energy management systems EMS / SCADA and other dispatching automation systems.

[0051] (2) Determine the power regulation type and regulation range of the DC according to the upper and lower limits of the DC operating power. Combined with the actual DC transmission power, calculate the modulation capacity of the DC when the power grid has a power shortage or power surplus.

[0052] Assume that DC L m,1 ,L m,2 …L m,Nm The upper limit of power transmission to grid A is P m,1 ,P m,2 …P m,Nm , the lower limit of power transmission to grid A is P m,1 , P m,2 … P m,Nm When the grid A has a power surplus, the power support capabilities of the above DC are P m,1 - P m,1 ,P m,2 - P m,2 …P m,Nm - P m,Nm When the power grid A has a power shortage, the power support capabilities of the above DC are P m,1 -P m,1 ,P m,2 -P m,2 …P m,Nm -P m,NmIt should be noted that when the upper and lower limits of DC power transmission to Grid A are both positive, Grid A is a conventional DC receiving terminal; when the upper and lower limits of DC power transmission to Grid A are both negative, Grid A is a conventional DC sending terminal; when the upper limit of DC power transmission to Grid A is positive and the lower limit is negative, Grid A is a sending and receiving grid.

[0053] (3) Check whether the connection between grid A and all connected grids B has been completed. m Calculate the emergency power modulation capability of various DC power sources between (m∈[1,M]). If it is not completed, repeat the above calculation steps.

[0054] Through the embodiments of the present disclosure, combined with the characteristics of a power grid with coexisting transmission and reception, DC at the sending and receiving ends and flexible DC with bidirectional power adjustment are all included in the DC modulation resource pool, enriching the frequency regulation means.

[0055] On the basis of the above embodiment, the adjustment range of the frequency control measure amount and the tolerable profit and loss of the target power grid and the connected synchronous power grid are used to determine the objective function and constraint conditions of the frequency control measure amount when a fault occurs, including: judging whether the actual transmission power of the faulty interconnected DC exceeds the tolerable profit and loss of the target power grid; if the actual transmission power does not exceed the tolerable profit and loss of the target power grid, there is no need to solve the frequency control measure amount; if the actual transmission power exceeds the tolerable profit and loss of the target power grid, then determining the objective function and constraint conditions of the frequency control measure amount when a fault occurs based on the over-limit value.

[0056] In this embodiment, grid A and grid B are selected m (m∈[1,M]) between the xth (x∈[1,N m ]) DC line, it is expected that the DC line will stop operating after a fault occurs. If the power transmitted by the DC line to the grid A in operation mode F is P m,x , if -P A,surplus ≤P m,x ≤P A,vacancy , if the power shortage / surplus is within the range of the power grid A's tolerable surplus / surplus, no processing is required; otherwise, according to the power shortage P m,x >P A,vacancy or power surplus P m,x <-P A,surp l us , and solve it.

[0057] It should be noted that the frequency control measure's adjustment range is used to determine the objective function and constraints for the frequency control measure when a fault occurs, and to solve the strategy for each connected DC fault. This strategy can be solved and stored in advance. The multi-resource coordinated control strategy is regenerated at fixed intervals or when any DC power changes significantly. Furthermore, the fixed intervals and criteria for determining significant DC power changes can be determined based on the actual operating conditions of the grid under study. Because the fault resolution strategy is stored in advance, the relevant control strategy can be executed after a fault actually occurs, improving fault handling efficiency.

[0058] Through the embodiments of the present disclosure, based on the current actual operation mode F of the power grid, an optimization model is generated in real time online after a bipolar blocking or other fault that causes a DC outage occurs in any of the DC transmission lines connected to the power grid A, and a multi-resource coordinated control strategy is solved.

[0059] On the basis of the above embodiment, according to the over-limit value, the objective function and constraint conditions when a fault occurs are determined, including: in response to the actual transmission power exceeding the power shortage upper limit, the objective function of the frequency control measure quantity is determined according to the transmission and reception measure quantity, the pump-storage unit switchable pump measure quantity, the load point switchable load measure quantity and the first preset priority; according to the over-limit value, the actual transmission power, the tolerable profit and loss of the connected synchronous power grid and the adjustment range of the frequency control measure quantity, the constraint conditions of the frequency control measure quantity are determined; the priorities in the first preset priority are, from high to low, the transmission and reception measure quantity, the pump-storage unit switchable pump measure quantity, the load point switchable load measure quantity and the first preset priority. the amount of measures for applying and the amount of load shedding at the load point; in response to the actual transmission power exceeding the upper limit of the power surplus, the objective function of the frequency control measure is determined according to the transmission and reception measure, the amount of measures for shedding the running unit and the second preset priority; the constraint conditions of the frequency control measure are determined according to the over-limit value, the actual transmission power, the tolerable profit and loss of the connected synchronous power grid and the adjustment range of the frequency control measure; the priorities in the second preset priority are transmission and reception measure and the amount of measures for shedding the running unit from high to low; among them, the first preset priority and the second preset priority are used to determine the order in which the frequency control measures are adopted.

[0060] In this embodiment, when the power shortage after a DC fault exceeds the grid's bearing capacity, a multi-resource frequency coordination control strategy of DC modulation, pumped storage pump cutting, and load shedding is solved through a mathematical optimization model. Among them, the priority of each type of resource call is from high to low: DC power modulation that is the same as the DC power grids on both sides of the fault, pumped storage pump cutting, other DC power modulation, and load shedding. The constraints that need to be considered include the constraints of each DC modulation capacity, the constraints of each synchronous power grid's ability to bear power shortages, and the constraints of pumped storage pump cutting and load shedding measures. When grid A and grid B m The nth mAfter a DC fault occurs and the power deficit of Grid A exceeds the capacity that the grid can withstand, the quantities of various measures can be determined according to the following optimization model.

[0061] Objective function:

[0062]

[0063] In the formula, P' m,n is the power transmission and reception measure quantity of the nth DC (excluding the blocked DCs) between Grid A and Grid B, P' is the measure quantity of the pump-cutting measure that can be taken by the pumped-storage units in Grid A, P' is the power transmission and reception measure quantity of the tth DC between Grid A and Grid B s (excluding Grid B where the blocked DC is located m ), P' load is the measure quantity of the load-cutting measure that can be taken at the load points in Grid A. a, b, c, and d are measure priority coefficients. Adjusting the DC power between Grid A and Grid B m has the highest priority, which can reduce the power deficit of Grid A caused by DC blocking and the power surplus of Grid B m at the same time; followed by pump-cutting of pumped-storage, which can reduce the power deficit of Grid A caused by DC blocking; then adjusting the DC power connected to Grid A other than the above, which can reduce the power deficit of Grid A caused by DC blocking but will increase the power deficit of Grid B s ; finally, the load-cutting measure can reduce the power deficit of Grid A but will cause power loss of the grid. Therefore, the measure priority coefficients should meet the condition: a < 0 < b < c < d, that is, the power supported by Region B m to Grid A should be as much as possible (but not exceeding the power deficit of Region A), and the other measures should be as little as possible.

[0064] The constraint conditions should include the following:

[0065] Constraint on the measure quantity of the frequency control measures in Grid A:

[0066]

[0067] Grid B m Constraints on the relevant power transmission and reception measure quantities:

[0068] [[ID=4)]]

[0069]

[0070] In the formula, is the upper limit of the power transmitted from the nth DC between Grid A and Grid B to Grid A, P m m,n is the actual power transmitted from this DC to Grid A under the operation mode F.​​​​​

[0071] The rest are connected to Grid A and Grid B s Relevant delivery and receiving measures quantity constraints:

[0072]

[0073]

[0074] Where, P Bs,vacancy Grid B s The maximum tolerable power shortfall is detailed above. Grid A and Grid B s The upper limit of the power transmitted by the tth DC line to the grid A, P s,t is the actual power delivered by the DC to grid A in operating mode F, see above for details.

[0075] Constraints on the amount of pump-cuttable measures for pumped storage units and the amount of load-cuttable measures at load points:

[0076]

[0077]

[0078] Based on the above objective function and constraints, we can solve the problem of grid A and grid B. m The multi-resource coordinated control strategy to be adopted when the xth DC line between the two lines fails and stops operating, in which the distribution of the sending and receiving measures between the DC lines with the same sending and receiving ends is proportional to the maximum sending and receiving measures of each DC line.

[0079] In this embodiment, when the power surplus after a DC fault exceeds the grid's bearing capacity, a multi-resource frequency coordination control strategy of DC modulation and machine cutting is solved through a mathematical optimization model. Among them, the priority of each type of resource call is from high to low: DC power modulation that is the same as the DC power grids on both sides of the fault, other DC power modulation, and machine cutting. The constraints that need to be considered include the constraints of each DC modulation capacity, the constraints of each synchronous grid's ability to bear power surplus, and the constraints of the amount of machine cutting measures. When grid A and grid B m The nth m When a DC fault causes the power surplus of Grid A to exceed the grid's capacity, the amount of each measure can be determined according to the following optimization model.

[0080] Objective function:

[0081]

[0082] Where, P m ” ,n Grid A and Grid B m The nth DC (excluding blocked DC) sending and receiving measures between the two, P”s,t For the t-th DC power transmission and reception measure quantity P" between power grid A and power grid B s (excluding power grid B where the DC has been blocked m ) unit The measure quantity of the operable generator units that can be tripped by power grid A is P'. e, f, and g are measure priority coefficients. Adjusting the DC power between power grid A and power grid B m has the highest priority, which can simultaneously reduce the power surplus of power grid A and the power deficit of power grid B caused by DC blocking m ; followed by adjusting the DC power of the other DCs connected to power grid A, which can reduce the power surplus of power grid A caused by DC blocking, but will cause an increase in the power surplus of power grid B s ; finally, the tripping measure can reduce the power surplus of power grid A, but will cause an increase in the start-up loss of the power grid and the start-stop cost of coal-fired generator units. Therefore, the measure priority coefficients should satisfy the condition: e < 0 < f < g, that is, the measure quantity of reducing the power transmitted from power grid B to power grid A should be as much as possible (but not exceeding the power surplus of area A), and the other measures should be as little as possible. m The constraint conditions are as follows.

[0083] The constraint conditions include the following.

[0084]

[0085]

[0086] 0 ≤ P m ” ,n ≤ P m,n - P m,n , n ∈ [1, N m and n ≠ x;

[0087]

[0088] 0 ≤ P s ” ,t ≤ P s,t - P s,t , s ∈ [1, M] and s ≠ m, t ∈ [1, N s ;

[0089]

[0090] In the formula, P m,n is the lower limit of the power transmitted from the n-th DC between power grid A and power grid B to power grid A, P m is the lower limit of the power transmitted from the t-th DC between power grid A and power grid B to power grid A, see the above text for details. P s,t is the lower limit of the power transmitted from the n-th DC between power grid A and power grid B to power grid A, P s is the lower limit of the power transmitted from the t-th DC between power grid A and power grid B to power grid A, see the above text for details. P Bs,surplus is power grid B sThe maximum tolerable power surplus is detailed above.

[0091] Based on the above objective function and constraints, we can solve the problem of grid A and grid B. m The multi-resource coordinated control strategy to be adopted when the xth DC line between them fails and stops operating, where the distribution of sending and receiving measures between DC lines with the same sending and receiving ends is proportional to the maximum measure amount of each DC line.

[0092] In this embodiment, it is checked whether all frequency coordination control strategies for all DC lines connected to the power grid A after a fault shutdown have been formulated. If not, a DC line for which no post-fault control strategy has been formulated is selected and continued to be executed.

[0093] Through the embodiments of the present disclosure, by preferentially adopting the same DC power modulation measures as those used in the power grids on both sides of the faulty DC, the problems of power shortage and power surplus in the power grids on both sides caused by the DC fault outage can be alleviated at the same time; the priority coefficient ensures the priority use of low-cost resources (such as DC modulation) and reduces high-cost operations (such as load shedding).

[0094] On the basis of the above embodiment, the sending and receiving measures include at least the first interconnected DC measure quantity of the connected synchronous power grid where the fault is located and the second interconnected DC measure quantity of other connected synchronous power grids; the frequency control strategy is solved by using the objective function and constraint conditions, including: in response to the actual transmission power exceeding the power shortage upper limit, the first interconnected DC measure quantity, the pumped storage unit switchable pump measure quantity, the second interconnected DC measure quantity and the load point switchable load measure quantity are determined in sequence according to the first preset priority; in response to the actual transmission power exceeding the power surplus upper limit, the first interconnected DC measure quantity, the second interconnected DC measure quantity and the operating unit switchable machine measure quantity are determined in sequence according to the second preset priority.

[0095] Through the embodiments of the present disclosure, the priorities of the measures for the faulty synchronous power grid and other synchronous power grids are further refined to ensure that the frequency cost of the strategic coordination is minimized.

[0096] On the basis of the above embodiment, the first interconnected DC measure quantity and the second interconnected DC measure quantity are calculated, including: according to the adjustment range of the sending and receiving measure quantities of the connected synchronous power grid where the fault is located, the first interconnected DC measure quantity is proportionally distributed to the interconnected DC in the connected synchronous power grid where the fault is located, so as to obtain the first interconnected DC measure quantity; according to the adjustment range of the sending and receiving measure quantities of the interconnected DC in other connected synchronous power grids, the second interconnected DC measure quantity is proportionally distributed to the interconnected DC in other connected synchronous power grids, so as to obtain the second interconnected DC measure quantity.

[0097] Through the embodiments of the present disclosure, tasks are allocated according to the maximum adjustable capacity of each DC, thereby avoiding overload of a single DC.

[0098] like Figure 2 As shown, one embodiment of a multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid provided by the present disclosure includes the following steps:

[0099] (1) Establish the power grid simulation calculation model data and use the small load method to calculate the ability of the AC synchronous power grid with DC transmission and reception and other synchronous power grids connected to the power grid through DC to bear the active power shortage and surplus.

[0100] As Figure 3 As an example of the interconnected power grid shown in the figure, power grid A is the synchronous power grid under study, and power grid B1 is connected to the grid through L 1,1 ,L 1,2 ,L 1,3 ,L 1,4 Four DC lines are connected to A (all power grid A are DC sending end), B2 passes L 2,1 ,L 2,2 ,L 2,3 Three DC lines are connected to A (grid A is L 2,1 ,L 2,2 Receiving end, L 2,3 Power can be transmitted in both directions), B3 through L 3,1 ,L 3,2 ,L 3,3 ,L 3,4 Four DC lines are connected to A (grid A is the DC receiving end).

[0101] After the grid modeling is completed, the low-load operation mode of the entire grid is adjusted. To prevent the triggering of the low-frequency load reduction device, the frequency of each synchronous grid must be guaranteed to be no less than 49.25Hz; to prevent the high-frequency generator disconnection device from being activated, the frequency of each synchronous grid must be guaranteed to be no more than 51Hz. For the studied grid A, when the cut-off unit capacity reaches 1500MW, the synchronous grid frequency reaches a minimum of 49.25Hz. Figure 4 As shown in the figure, when the load removal capacity reaches 2000MW, the synchronous grid frequency reaches a maximum of 51Hz. Figure 5 Therefore, the maximum power deficit that Grid A can withstand is 1500MW, and the maximum power surplus is 2000MW.

[0102] The above method can also be used to solve the maximum power shortage and surplus capacity of synchronous power grids such as B1, B2, and B3, as summarized in the following table:

[0103] Table 1 Maximum power deficit and surplus capacity of each synchronous power grid Unit: MW

[0104]

[0105]

[0106] (2) Based on the actual current operation mode F of the power grid, the emergency power modulation capability of the DC at the sending and receiving ends and the flexible DC with bidirectional power adjustment in the AC synchronous power grid under study is analyzed online.

[0107] First, the energy management system EMS / SCADA reads the four DC lines L between grid A and grid B1 1,1 ,L 1,2 ,L 1,3 ,L 1,4 The actual power transmitted to grid A is -8000MW, -2000MW, -2500MW, and -2500MW respectively.

[0108] DC L 1,1 ,L 1,2 ,L 1,3 ,L 1,4 The lower limits of power transmission to Grid A are -8000MW, -3000MW, -3000MW, and -3000MW, respectively; the upper limits of power transmission to Grid B are -800MW, -300MW, -300MW, and -300MW, respectively. Based on the above calculation formula, the emergency power modulation capability of the DC power is shown in Table 2 (DC modulation capability between Grid A and Grid B1, unit: MW):

[0109] Table 2

[0110] DC Name Operating power Power lower limit Power Cap Grid A's deficit modulation capability Surplus modulation capability of grid A <![CDATA[L 1，1 ]]> -8000 -8000 -800 7200 0 <![CDATA[L 1，2 ]]> -2000 -3000 -300 1700 1000 <![CDATA[L 1，3 ]]> -2500 -3000 -300 2200 500 <![CDATA[L 1，4 ]]> -2500 -3000 -300 2200 500

[0111] Based on the above method, the DC modulation capability between Grid A and Grids B2 and B3 can be calculated, as summarized in Table 3 (DC modulation capability between Grid A and Grids B2 and B3, unit: MW):

[0112] Table 3

[0113]

[0114] (3) Based on the actual current operation mode F of the power grid, the maximum amount of regulation resources such as pump cutting, load cutting, and generator cutting in the pumped storage power grid under study is analyzed online.

[0115] There are eight pumped-storage units in Grid A with emergency pump-tripping capabilities. The operating status and pumping power of these units are shown in the following table. The available pump-tripping measures for each unit can be calculated. The total available pump-tripping measures for Grid A are 300 MW, as summarized in Table 4 (Emergency Pump-tripping Measures for Pumped-storage Units in Grid A, Unit MW).

[0116] Table 4

[0117]

[0118] There are 12 conventional units in Grid A with tripping capabilities. The operating status and power generation of these units are shown in the following table. The amount of tripping measures that can be taken for each unit can be calculated. The total amount of tripping measures that can be taken for Grid A is 300 MW, as summarized in Table 5 (Tripping measures for conventional units in Grid A, unit MW).

[0119] Table 5

[0120]

[0121]

[0122] There are 174 precise load shedding points in power grid A. In actual operation mode F, the maximum load shedding capacity is 3730MW, which is not listed in the detailed table here.

[0123] (4) Based on the actual current operation mode F of the power grid, a multi-resource coordinated control strategy is generated online in real time for all DC transmission lines connected to the power grid A when a bipolar blocking or other fault that causes DC outage occurs. After the actual fault occurs, the relevant control strategy can be executed.

[0124] Because there are many DC transmission projects connected to Grid A, only three typical DC fault outage scenarios are selected here for illustration: power surplus within the tolerance range of Grid A, power deficit exceeding the tolerance range of Grid A, and power surplus exceeding the tolerance range of Grid A.

[0125] When DC L 3,3 When the DC line is shut down due to a fault, the power shortage of Grid A is 1000MW, which does not exceed the maximum power shortage of 1500MW that Grid A can withstand. Therefore, when the DC line is shut down due to a fault, there is no need to take multi-resource coordinated frequency control measures, and the relevant calculations for the next DC line can be carried out directly.

[0126] When DC L 2,1 When the DC system is shut down due to a fault, the power shortage of Grid A is 6000MW, which exceeds the maximum power shortage that Grid A can bear. Therefore, when the DC system is shut down due to a fault, the amount of various measures must be determined according to the optimization model. The priority coefficients of the measures can be taken as: a = -1, b = 1, c = 2, d = 3.

[0127] Objective function:

[0128]

[0129] Constraints on the quantity of grid A measures:

[0130]

[0131] Grid B2 related transmission and reception measures constraints:

[0132] 0≤P'2,2 +P' 2,3 ≤6000;

[0133] P' 2,2 =0;

[0134] 0≤P' 2,3 ≤500;

[0135] In addition, the transmission and reception capacity constraints of the power grids B1 and B3 connected to power grid A are as follows:

[0136]

[0137]

[0138] 0≤P' 1,1 ≤7200; 0≤P' 1,2 ≤1700; 0≤P' 1,3 ≤2200; 0≤P' 1,4 ≤2200;

[0139] P' 3,1 =0;P' 3,2 =0; 0≤P' 3,3 ≤5000; P' 3,4 =0;

[0140] Constraints on pump-shedding and load-shedding measures for pumped storage:

[0141] 0≤P' pump ≤300;

[0142] 0≤P' load ≤3730;

[0143] Based on the above objective function and constraints, we can solve the problem of DC L 2,1 Multi-resource coordination control strategy that should be adopted during fault outage:

[0144] P' 2,2 =0, P' 2,3 =500 P' pump =300, P' load =300.

[0145] That is, DC L 2,3 The modulation capacity of the four DC lines between Grid A and Grid B1 is 500MW. The total modulation capacity of the four DC lines between Grid A and Grid B1 is 1800MW (distributed in proportion to the adjustable capacity of each DC line, that is, the four DC lines have modulation capacities of 974MW, 230MW, 298MW, and 298MW respectively). The total modulation capacity of the four DC lines between Grid A and Grid B3 is 1600MW (distributed in proportion to the adjustable capacity of each DC line, but since only L 3,3It has regulation capability, so all regulation capacity is borne by the DC), the pumped storage pump shedding capacity is 300MW, and the load shedding capacity is 300MW.

[0146] When DC L 1,1 During a fault outage, the power surplus of Grid A is 8000 MW, which exceeds the maximum power surplus that Grid A can withstand. Therefore, when the DC system is shut down due to a fault, the amount of various measures must be determined according to the optimization model. The priority coefficients of the measures can be taken as: e = -1, f = 1, and g = 2.

[0147] Objective function:

[0148]

[0149] Constraints on the quantity of grid A measures:

[0150]

[0151] Grid B1 related transmission and reception measures constraints:

[0152] 0≤P” 1,2 +P” 1,3 +P” 1,4 ≤8000;

[0153] 0≤P” 1,2 ≤1000; 0≤P” 1,3 ≤500; 0≤P” 1,4 ≤500;

[0154] The constraints on the transmission and reception of other power grids B2 and B3 connected to power grid A are as follows:

[0155]

[0156]

[0157] 0≤P” 2,1 ≤5200; 0≤P” 2,2 ≤5200; 0≤P” 2,3 ≤4500;

[0158] 0≤P” 3,1 ≤5200; 0≤P” 3,2 ≤5200; 0≤P” 3,3 ≤200; 0≤P” 3,4 ≤5200;

[0159] Constraints on cutting measures:

[0160] 0≤P” unit ≤2250;

[0161] Based on the above objective function and constraints, we can solve the problem of DC L 1,1 Multi-resource coordination control strategy that should be adopted during fault outage:

[0162] P” 1,2 =1000, P" 1,3 =500, P" 1,4 =500, P” unit =200.

[0163] That is, DC L 1,2 Modulation 1000MW, DC L 1,3 Modulation 500MW, DC L 1,4 The modulation is 500MW. The total modulation of the three DC lines between Grid A and Grid B2 is 1700MW (allocated in proportion to the adjustable amount of each DC line, that is, the three DC adjustment amounts are 593MW, 593MW, and 514MW respectively). The total modulation of the four DC lines between Grid A and Grid B3 is 2100MW (allocated in proportion to the adjustable amount of each DC line, that is, the four DC adjustment amounts are 691MW, 691MW, 27MW, and 691MW respectively). The generator cut-off amount is 200MW. To ensure the minimum generator cut-off amount, G unit,1 unit.

[0164] (5) Every time a fixed time interval passes or when any DC power changes significantly, repeat steps 2 to 4 to regenerate the multi-resource coordinated control strategy.

[0165] Based on the multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid, the present disclosure also provides a multi-resource frequency coordination control device for a DC transmission and reception coexisting power grid. Figure 6 The device is described in detail.

[0166] Figure 6 The structure block diagram of the multi-resource frequency coordination control device for a DC transmission and reception coexisting power grid according to an embodiment of the present disclosure is schematically shown. The device can be used to implement the above method.

[0167] like Figure 6 As shown, the multi-resource frequency coordination control device 600 for a DC transmission and reception coexisting power grid of this embodiment includes a modeling and calculation module 601 , an optimization model module 602 and a model solving module 603 .

[0168] A modeling and calculation module is used to obtain the adjustment range of the frequency control measure quantity and the tolerable profit and loss of the target grid and the connected synchronous grid by using the simulation model of the target grid; the modeling scope of the simulation model includes the target grid and the connected synchronous grid connected to the target grid through the interconnected direct current; the frequency control measure quantity at least includes the sending and receiving measure quantity and the resource measure quantity of the target grid; the sending and receiving measure quantity is represented by the positive and negative values of the connected synchronous grid to transmit power to the target grid through the interconnected direct current and receive power from the target grid.

[0169] The optimization model module is used to determine the objective function and constraints of the frequency control measures when a fault occurs in the interconnected DC system by using the adjustment range of the frequency control measures and the tolerable profit and loss of the target power grid and the connected synchronous power grid.

[0170] The model solving module is used to solve the frequency control measure quantity using the objective function and constraint conditions.

[0171] According to an embodiment of the present disclosure, any multiple modules in the modeling and calculation module 601, the optimization model module 602, and the model solution module 603 can be combined into one module for implementation, or any one of the modules can be split into multiple modules. Alternatively, at least part of the functions of one or more of these modules can be combined with at least part of the functions of other modules and implemented in one module. According to an embodiment of the present disclosure, at least one of the modeling and calculation module 601, the optimization model module 602, and the model solution module 603 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application-specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware, and firmware, or in an appropriate combination of any of them. Alternatively, at least one of the modeling and calculation module 601, the optimization model module 602, and the model solution module 603 can be at least partially implemented as a computer program module, which can perform the corresponding function when the computer program module is executed.

[0172] Figure 7 A block diagram of an electronic device suitable for implementing a multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid according to an embodiment of the present disclosure is schematically shown.

[0173] like Figure 7As shown, the electronic device 700 according to an embodiment of the present disclosure includes a processor 701, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 702 or a program loaded from a storage part 708 into a random access memory (RAM) 703. The processor 701 may, for example, include a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 701 may also include an onboard memory for caching purposes. The processor 701 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0174] Various programs and data required for the operation of the electronic device 700 are stored in the RAM 703. The processor 701, the ROM 702, and the RAM 703 are connected to each other via a bus 704. The processor 701 performs various operations of the method flow according to the embodiment of the present disclosure by executing the programs in the ROM 702 and / or the RAM 703. It should be noted that the programs may also be stored in one or more memories other than the ROM 702 and the RAM 703. The processor 701 may also perform various operations of the method flow according to the embodiment of the present disclosure by executing the programs stored in the one or more memories.

[0175] According to an embodiment of the present disclosure, the electronic device 700 may further include an input / output (I / O) interface 705, which is also connected to the bus 704. The electronic device 700 may further include one or more of the following components connected to the I / O interface 705: an input portion 706 including a keyboard, a mouse, etc.; an output portion 707 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and a speaker; a storage portion 708 including a hard disk; and a communication portion 709 including a network interface card such as a LAN card or a modem. The communication portion 709 performs communication processing via a network such as the Internet. A drive 710 is also connected to the I / O interface 705 as needed. A removable medium 711, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed in the drive 710 as needed, so that a computer program read therefrom can be installed into the storage portion 708 as needed.

[0176] The present disclosure also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments, or may exist independently and not be incorporated into the device / apparatus / system. The computer-readable storage medium carries one or more programs, and when executed, implements the method according to the embodiments of the present disclosure.

[0177] According to an embodiment of the present disclosure, a computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, it may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, apparatus, or device. For example, according to an embodiment of the present disclosure, a computer-readable storage medium may include the ROM702 and / or RAM703 described above and / or one or more memories other than ROM702 and RAM703.

[0178] The embodiments of the present disclosure also include a computer program product, which includes a computer program containing program code for executing the method shown in the flowchart. When the computer program product is run in a computer system, the program code is used to enable the computer system to implement the method provided by the embodiments of the present disclosure.

[0179] The computer program executes the above functions defined in the system / device of the embodiment of the present disclosure when the processor 701 executes the computer program. According to the embodiment of the present disclosure, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0180] In one embodiment, the computer program may be stored on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may be transmitted and distributed in the form of a signal on a network medium, downloaded and installed via the communication portion 709, and / or installed from a removable medium 711. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to wireless, wired, or any suitable combination thereof.

[0181] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 709, and / or installed from a removable medium 711. When the computer program is executed by the processor 701, the above-described functions defined in the system of the embodiment of the present disclosure are performed. According to the embodiment of the present disclosure, the systems, devices, means, modules, units, etc. described above can be implemented by computer program modules.

[0182] According to an embodiment of the present disclosure, the program code for executing the computer program provided by the embodiment of the present disclosure can be written in any combination of one or more programming languages. Specifically, these computer programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages include, but are not limited to, languages such as Java, C++, python, "C" or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, using an Internet service provider to connect via the Internet).

[0183] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0184] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or couplings are intended to fall within the scope of this disclosure.

[0185] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be used in combination to advantage. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A multi-resource frequency coordination control method for a DC transmission and reception coexisting power grid, characterized in that: include: Using the simulation model of the target power grid, the adjustment range of the frequency control measures and the tolerable profit and loss of the target power grid and the connected synchronous power grid are obtained; The modeling scope of the simulation model includes the target power grid and the connected synchronous power grid connected to the target power grid via interconnected direct current; the frequency control measure quantity includes at least a sending and receiving measure quantity and a resource measure quantity of the target power grid; the sending and receiving measure quantity represents the connected synchronous power grid transmitting power to the target power grid via interconnected direct current and receiving power from the target power grid by the positive and negative values, respectively; In response to a fault in the interconnected DC system, the objective function and constraints of the frequency control measure amount when the fault occurs are determined using the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid; and the frequency control measure amount is solved using the objective function and constraints.

2. The method according to claim 1, wherein The method of using the simulation model of the target power grid to obtain the adjustment range of the frequency control measure and the tolerable profit and loss of the target power grid and the connected synchronous power grid includes: Build a simulation model of the target power grid; Utilizing the simulation model, the tolerable profit and loss of the target power grid and the connected synchronous power grid is calculated by shedding loads and removing units; the tolerable profit and loss includes a power deficit upper limit and a power surplus upper limit; Calculating an adjustment range of the resource measure amount according to an actual operating mode of the target power grid; wherein the resource measure amount includes at least one of a pump-trippable measure amount for a pumped-storage unit, a machine-trippable measure amount for an operating unit, and a load-trippable measure amount for a load point; and the actual operating mode includes at least one of an operating state of a pumped-storage unit with a switchable pump, an operating unit with a switchable machine, and a load-trippable point; The adjustment range of the transmission and receiving measures is calculated according to the actual transmission power and transmission power range of the networked DC.

3. The method according to claim 2, wherein: The calculation of the tolerable profit and loss of the target power grid and the connected synchronous power grid by shedding loads and units includes: For the target grid and each connected synchronous grid, a power deficit is created by removing units and transient stability calculations are performed. The upper limit of the power deficit is determined in response to the lowest point of the transient frequency curve being equal to the minimum frequency of normal grid operation. For the target grid and each connected synchronous grid, a power surplus is created by shedding loads, and transient stability calculations are performed. In response to the highest point of the transient frequency curve being equal to the maximum frequency of normal grid operation, the upper limit of the power surplus is determined.

4. The method according to claim 2, wherein: Calculating the adjustment range of the resource measure amount according to the actual operation mode of the target power grid includes: Calculate the upper limit of the pump-cutting measures for the pump-storage unit based on the capacity of the pump-cutting pump unit in operation; Calculate the upper limit of the amount of operating units that can be cut off based on the capacity of the operating units that can be cut off; According to the actual load power of the load point that can be cut, calculate the upper limit of the load cutting measures that can be taken at the load point.

5. The method according to claim 2, wherein: The calculating the adjustment range of the transmission and reception quantity according to the actual transmission power and transmission power range of the interconnected DC power includes: Determining the upper limit of the transmission power of the transmission and reception quantity by subtracting the actual transmission power from the upper limit of the transmission power range; The upper limit of the receiving power of the transmission and reception measure is determined by subtracting the lower limit of the transmission power range from the actual transmission power.

6. The method according to claim 2, wherein: The method of determining the objective function and constraint conditions of the frequency control measure amount when a fault occurs by utilizing the adjustment range of the frequency control measure amount and the tolerable profit and loss amount of the target power grid and the connected synchronous power grid includes: Determine whether the actual transmission power of the faulty interconnected DC exceeds the target grid's tolerable profit or loss; If the actual transmission power does not exceed the target grid's tolerable profit or loss, there is no need to solve the frequency control measures; If the actual transmitted power exceeds the tolerable profit or loss of the target power grid, the objective function and constraint conditions of the frequency control measures when a fault occurs are determined based on the over-limit value.

7. The method according to claim 6, wherein: Determining the objective function and constraint conditions when a fault occurs based on the over-limit value includes: In response to the actual transmission power exceeding the power shortage upper limit, determining the objective function of the frequency control measure based on the transmission and reception measure, the pump-storage unit pump-tripping measure, the load-shedding measure at the load point, and a first preset priority; determining the constraint conditions of the frequency control measure based on the over-limit value, the actual transmission power, the tolerable profit and loss of the connected synchronous power grid, and the adjustment range of the frequency control measure; the first preset priority is ranked from high to low as the transmission and reception measure, the pump-storage unit pump-tripping measure, and the load-shedding measure at the load point; In response to the actual transmission power exceeding the upper limit of the power surplus, determining the objective function of the frequency control measure amount based on the transmission and reception measure amount, the operating unit tripping measure amount, and a second preset priority; determining the constraint conditions of the frequency control measure amount based on the over-limit value, the actual transmission power, the tolerable profit and loss of the connected synchronous power grid, and the adjustment range of the frequency control measure amount; the second preset priority level is ranked from high to low by the transmission and reception measure amount and the operating unit tripping measure amount; The first preset priority and the second preset priority are used to determine the order in which frequency control measures are adopted.

8. The method according to claim 7, wherein: The sent and received measure quantities include at least the first interconnected DC measure quantity of the connected synchronous power grid where the fault occurs and the second interconnected DC measure quantity of the other connected synchronous power grids; Using the objective function and constraints, a frequency control strategy is solved, including: In response to the actual transmission power exceeding the power shortage upper limit, determining, in order according to the first preset priority, a first interconnected DC measure amount, a pump-storage unit switchable pump measure amount, a second interconnected DC measure amount, and a load point switchable load measure amount; In response to the actual transmission power exceeding the power surplus upper limit, the first interconnected DC measure amount, the second interconnected DC measure amount and the running unit tripping measure amount are determined in sequence according to the second preset priority.

9. The method according to claim 8, wherein Calculating the first interconnected DC measure quantity and the second interconnected DC measure quantity includes: allocating the first interconnected DC measure quantity to the interconnected DC in the connected synchronous power grid where the fault is located in proportion to the regulation range of the sending and receiving measure quantities of the connected synchronous power grid where the fault is located, so as to obtain the first interconnected DC measure quantity; According to the regulation range of the sending and receiving measure quantities of the interconnected DC in other connected synchronous power grids, the second interconnected DC measure quantity is proportionally distributed to the interconnected DC in the other connected synchronous power grids to obtain the second interconnected DC measure quantity.

10. A multi-resource frequency coordination control device for a DC transmission and reception coexisting power grid, characterized in that: The device can be used to implement the method according to any one of claims 1 to 9, and the device includes: A modeling and calculation module is configured to utilize a simulation model of a target power grid to determine an adjustment range of a frequency control measure and a tolerable profit or loss for the target power grid and a connected synchronous power grid; the simulation model's modeling range includes the target power grid and the connected synchronous power grid connected to the target power grid via interconnected direct current; the frequency control measure comprises at least a sending and receiving measure and a resource measure of the target power grid; the sending and receiving measure, with positive and negative values representing power transmitted to and received from the target power grid by the connected synchronous power grid via interconnected direct current; an optimization model module for determining, in response to a fault in the interconnected DC network, an objective function and constraints for the frequency control measures when a fault occurs, using an adjustment range of the frequency control measures and a tolerable profit or loss of the target grid and the connected synchronous grid; The model solving module is used to solve the frequency control measure quantity by using the objective function and the constraint conditions.

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