Provincial and Local Cooperative Control Method and System Based on Fault Monitoring and Section Overlimit

Abstract

The present invention relates to the technical field of power dispatching control, and specifically relates to a provincial and local collaborative control method and system based on fault monitoring and section over-limit. The method includes: integrating multi-source data of the tripping of 500 kV transmission line switches sent by substations, and judging N-2 fault events of 500 kV transmission lines and 220 kV transmission section over-limit events; if both N-2 fault events and 220 kV transmission section over-limit events occur simultaneously, then according to the provincial and local new energy automatic adjustment demand calculation model, determine the optimal adjustment target value of the new energy output of the province and the local area; according to the obtained optimal adjustment target value, and in accordance with a certain adjustment step length, automatically send it to the unified adjustment new energy power stations under the jurisdiction of the provincial dispatching and local dispatching of the power grid division where the over-limit section belongs to execute, so as to orderly and accurately control the new energy output and eliminate the situation of section over-limit overload. The present invention realizes orderly, rapid and accurate control of the new energy output in case of faults, eliminates the situation of section over-limit overload, ensures the safe and stable operation of the power grid and realizes the maximum consumption of new energy.

Description

Technical Field

[0001] The present invention relates to the technical field of power dispatching control, and particularly to a provincial and local collaborative control method and system based on fault monitoring and section over-limit. Background Art

[0002] At present, in areas with high new energy penetration rate, it is usually necessary to deploy safety and stability control devices at the new energy power station end. After a N-2 fault occurs in the key transmission channel when the new energy output is large, the new energy safety and stability control device needs to send a generator tripping command to the new energy power station according to a predetermined strategy to achieve the coordinated tripping control of the new energy units, avoid the overload of relevant lines or sections, and ensure the safe and stable operation of the power grid.

[0003] However, the direct generator tripping control method has poor flexibility and efficiency, and cannot achieve the maximum consumption of new energy. There is an urgent need to study a new energy provincial and local collaborative emergency automatic control method covering N-2 fault monitoring and section over-limit monitoring, calculation of provincial and local new energy automatic regulation requirements and coordinated control, to achieve orderly, fast and accurate control of new energy output in case of faults, eliminate section over-limit overload conditions, and finally achieve "regulation instead of tripping", ensure the safe and stable operation of the power grid and achieve the maximum consumption of new energy.

[0004] The first published document "Research on the Safety and Stability Control Strategy of New Energy Power Grid Based on Logical Operation" (Renewable Energy, Vol. 40, No. 5, 2022, pp. 675-682) discloses a safety and stability control strategy of new energy power grid based on logical operation and its standardized description method for control equipment. First, by analyzing the changes in the operating states of power grid generating units when the power grid undergoes operating disturbances or faults due to factors such as new energy output fluctuations, a power grid operating state evolution model is established; then, taking the distance between the spatial position of the power grid operating state parameters and the allowable boundary for its safe and stable operation as the judgment criterion, a safety and stability control startup criterion for the new energy power grid is established, and a safety and stability optimization control model with the goal of optimal control cost is established; using the logical operation method, the safety and stability control strategies under different operating states are described, and a safety and stability control strategy table for control equipment is established.

[0005] The second published document, "Preliminary Exploration of the Mechanism of Large-Scale Distributed Energy Participating in the Secure and Stable Control of the Large Power Grid" (Automation of Electric Power Systems, Vol. 45, No. 18, 2021, pp. 1-8), discloses an interaction mechanism based on a virtual power plant (VPP). First, it analyzes the evolution process of the power system under the dual-carbon goal and dissects the challenges faced in its secure and stable operation. Second, it elaborates on the definition, composition structure, and functional characteristics of the VPP, revealing its connotation of integrating a large amount of heterogeneous distributed energy resources (DER) to interact friendly with the large power grid. Then, it constructs a hierarchical control architecture of the VPP based on multi-agent technology and proposes its internal operation and the mechanism for participating in the secure and stable control of the large power grid. Finally, it points out that the VPP is a new technical form for the new power system to absorb a high proportion of renewable energy, and there are several technical issues in this field that need to be focused on.

[0006] However, the new energy grid secure and stable control method designed in the first document still directly trips the new energy generators, which has poor flexibility and cannot achieve the maximum consumption of new energy. The second document mainly focuses on the research of the mechanism of a large number of low-voltage distributed power sources participating in the secure and stable control of the large power grid, lacking the calculation of emergency automatic regulation requirements and coordinated control methods for centralized and medium-voltage distributed new energy, and cannot meet the actual application requirements. Summary of the Invention

[0007] Object of the Invention: In order to overcome the deficiencies of the prior art, the present invention provides a provincial and local collaborative control method based on fault monitoring and section over-limit, which solves the problems that the control method of directly tripping the generator by deploying a secure and stable control device at the new energy power station end in the prior art has poor flexibility and efficiency and cannot achieve the maximum consumption of new energy. The present invention also provides a provincial and local collaborative control system based on fault monitoring and section over-limit.

[0008] Technical Solution: According to the first aspect of the present invention, there is provided a provincial and local collaborative control method based on fault monitoring and section over-limit, and the method includes the following steps:

[0009] S1: Integrate multi-source data of the 500 kV transmission line switch tripping sent by the substation to judge the N-2 fault event of the 500 kV transmission line and the 220 kV transmission section over-limit event;

[0010] S2: If the N-2 fault event and the 220 kV transmission section over-limit event occur simultaneously, then determine the optimal adjustment target value of the provincial and local new energy output according to the provincial and local new energy automatic adjustment demand calculation model, and the provincial and local new energy automatic adjustment demand calculation model includes an optimization objective function with the minimum new energy curtailment and two parts of constraint conditions, namely system constraints and unit characteristic constraints;

[0011] S3 Automatically send the obtained optimal adjustment target value to the unified regulation new energy power stations under the jurisdiction of the provincial power dispatching and local power dispatching of the power grid sub-region where the over-limit section belongs according to a certain adjustment step size for execution, so as to orderly and accurately control the output of new energy and eliminate the over-limit and overload conditions of the section.

[0012] Further, it includes:

[0013] The specific steps of step S1 include:

[0014] S11 Real-time monitor the remote signal conversion conditions of the switch positions on both sides of the 500kV transmission line, the total accident of the interval, and the protection action signal.

[0015] S12 Judge whether an N-2 fault event occurs: First, judge whether a line tripping fault occurs. The conditions for this event to occur are:

[0016] The switch conversion on the local side of the line YX / SOE + the total accident of the interval YX / SOE / the protection action signal YX / SOE, and the signal time interval does not exceed 30 seconds; and / or

[0017] The switch conversion on the local side of the line YX / SOE + the switch conversion on the opposite side of the line YX / SOE, and the signal time interval does not exceed 30 seconds; The above information is usually displayed on the user interface of the power system monitoring and protection device.

[0018] Secondly, if two 500kV transmission lines trip successively within one minute and the active power after the line fault is less than the zero drift value, it is determined that an N-2 fault event has occurred;

[0019] S13 Judge whether a section over-limit event occurs; The conditions for this event to occur are:

[0020] Real-time monitor the current value of the relevant 220kV transmission section of the power grid. If the current value of any transmission section exceeds its rated current-carrying capacity, it is determined that a section over-limit event has occurred.

[0021] Further, it includes:

[0022] In step S2, the optimization objective function of the provincial and local new energy automatic adjustment demand calculation model is expressed as:

[0023]

[0024] In the formula: is the wind and light abandonment amount of the aggregated new energy i of the unified regulation new energy power station or the 220kV substation in the region; N is the number of aggregated new energy of the unified regulation new energy power station or the 220kV substation in the region.

[0025] Further, it includes:

[0026] The constraint conditions of the land-saving new energy automatic regulation demand calculation model include: system constraints and unit characteristic constraints. The system constraints include power balance constraints and network security constraints;

[0027] Among them, the power balance constraint is expressed as:

[0028]

[0029] In the formula: Since the DC power flow model is adopted, the influence of network loss is ignored; L f is the system load after subtracting the power received by the regional power grid at the current moment; W i is the output value of the aggregated new energy i of the unified regulation new energy power station or the 220 kV substation in the region at the current moment; are the output value and power regulation amount of the conventional unit i at the current moment respectively, M is the number of conventional units, and the amount of wind and light abandonment satisfies:

[0030] The network security constraint is expressed as:

[0031]

[0032] In the formula: p g,k 、p W,k 、p WS,k and p L,k are the adjusted active power output of the conventional unit connected to node k, the active power output of the aggregated new energy of the unified regulation new energy power station or the 220 kV substation in the region, the wind and light abandonment power, and the load respectively. X kl is the reactance value of branch kl, θ k and θ l are the voltage phase angles of node k and node l respectively; is the active power flow limit of branch kl; among them, formula (1) is the system power flow balance equation expressed by the DC power flow model, and formula (2) is the line power capacity limit constraint.

[0033] Furthermore, it includes:

[0034] The unit characteristic constraints include: the upper and lower limits of the active power output of the conventional unit and the output adjustment constraint of the new energy power station. The upper and lower limits of the active power output of the conventional unit are expressed as:

[0035]

[0036] In the formula, and are the maximum and minimum active power outputs of the conventional unit i respectively;

[0037] To ensure the fairness of new - energy power station consumption, in accordance with the principle of consistency of the aggregated new - energy load rates of each unified - regulation new - energy power station or regional 220kV substation, the aggregated new - energy regulation power of each unified - regulation new - energy power station or regional 220kV substation shall meet the following constraints for the new - energy power station output regulation:

[0038]

[0039] In the formula, is the rated output of the aggregated new - energy i of the unified - regulation new - energy power station or regional 220kV substation.

[0040] Furthermore, the method further includes:

[0041] S4 To ensure the fairness of the consumption of non - unified - regulation new - energy power stations under the jurisdiction of the local dispatching, in accordance with the principle of consistency of the non - unified - regulation new - energy load rates in the region, the decomposition strategies of each non - unified - regulation new - energy power station are as follows:

[0042] The curtailment of wind and light of each non - unified - regulation new - energy power station in the aggregated new - energy i of the regional 220kV substation shall satisfy:

[0043]

[0044] In the formula, V i 、 are the active power output and rated output of the non - unified - regulation new - energy power station.

[0045] Furthermore, step S3 further includes the confirmation of eliminating section over - limit overload; specifically:

[0046] If the section over - limit event message has not been restored within a certain period of time after the adjustment target is issued, after excluding the new - energy power stations that have not responded to the adjustment, re - enter the provincial - level and local - level new - energy automatic adjustment demand calculation model in step S2 to determine the optimal adjustment target of the provincial - level and local - level new - energy output, and issue it automatically again until the section over - limit overload situation is finally eliminated. Among them, the judgment logic for the new - energy power stations that have not responded to the adjustment is that the actual adjustment amount is less than 30% of the target adjustment amount.

[0047] On the other hand, the present invention also provides a provincial - level and local - level collaborative control system based on fault monitoring and section over - limit, and the system includes:

[0048] A judgment module, used to judge the 500kV transmission line N - 2 fault event and the 220kV transmission section over - limit event according to the multi - source data of the 500kV transmission line switch tripping sent by the integrated substation;

[0049] A model construction module for constructing a provincial and regional new energy automatic regulation demand calculation model. Specifically, if an N-2 fault event and a 220 kV transmission section overlimit event occur simultaneously, the optimal regulation target value of the provincial and regional new energy output is determined according to the provincial and regional new energy automatic regulation demand calculation model. The provincial and regional new energy automatic regulation demand calculation model includes an optimization objective function with the minimum new energy curtailment and two parts of constraint conditions, namely system constraints and unit characteristic constraints.

[0050] A control module for automatically sending the obtained optimal regulation target value to the unified regulation new energy power stations under the jurisdiction of the provincial dispatching and regional dispatching of the power grid partition where the overlimit section belongs according to a certain regulation step size, so as to orderly and accurately control the new energy output and eliminate the overlimit and overload situation of the section.

[0051] Furthermore, the system further includes:

[0052] A non-unified regulation new energy power station decomposition strategy module, which is to ensure the fairness of the consumption of non-unified regulation new energy power stations under the jurisdiction of the regional dispatching. According to the principle of consistency of the load rates of non-unified regulation new energy in each region, the decomposition strategies of each non-unified regulation new energy power station are as follows:

[0053] The curtailment of wind and light of each non-unified regulation new energy power station in the aggregated new energy i of the 220 kV substation in the region Satisfies:

[0054]

[0055] In the formula, V i , are the active power output and rated output of the non-unified regulation new energy power station.

[0056] Furthermore, it includes:

[0057] The control module also includes the confirmation of eliminating the overlimit and overload situation of the section. Specifically:

[0058] If the overlimit event message of the section has not been restored within a certain period of time after the regulation target is sent, after excluding the new energy power stations that have not responded to the regulation, it re-enters the provincial and regional new energy automatic regulation demand calculation model in the model construction module to determine the optimal regulation target of the provincial and regional new energy output, and sends it automatically again until the overlimit and overload situation of the section is finally eliminated. Among them, the judgment logic of the new energy power stations that have not responded to the regulation is that the actual regulation amount is less than 30% of the target regulation amount.

[0059] Beneficial effects: Compared with the prior art, the present invention has the following advantages: The present invention proposes a new energy provincial and local collaborative emergency automatic control method covering two aspects of N-2 fault monitoring and section overlimit monitoring, and calculation and coordinated control of automatic adjustment requirements for new energy at the provincial and local levels, which is more in line with actual requirements, so as to realize orderly, rapid, accurate, and efficient control of new energy output in case of faults, eliminate section overlimit overload situations, and finally achieve "replacement of shedding by adjustment", ensure the safe and stable operation of the power grid, and maximize the consumption of new energy. Description of the Drawings

[0060] Figure 1 It is the flowchart of the emergency collaborative automatic control described in Embodiment 2 of the present invention;

[0061] Figure 2 It is the wiring diagram of the northern sub-region of Yancheng City, Jiangsu Power Grid described in Embodiment 3 of the present invention;

[0062] Figure 3 It is the flowchart of the provincial and local collaborative control method based on fault monitoring and section overlimit described in Embodiment 1 of the present invention;

[0063] Figure 4 It is the structural diagram of the provincial and local collaborative control system based on fault monitoring and section overlimit described in Embodiment 3 of the present invention. Detailed Embodiments

[0064] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0065] Embodiment 1

[0066] The present invention provides a provincial and local collaborative control method based on fault monitoring and section overlimit, as Figure 3 shown, the method includes the following steps:

[0067] S1: Fuse multi-source data of the 500 kV transmission line switch trip sent by the substation, and judge the N-2 fault event of the 500 kV transmission line and the 220 kV transmission section overlimit event;

[0068] S2: If the N-2 fault event and the 220 kV transmission section overlimit event occur simultaneously, determine the optimal adjustment target value of the provincial and local new energy output according to the provincial and local new energy automatic adjustment demand calculation model, and the provincial and local new energy automatic adjustment demand calculation model includes an optimization objective function with the minimum new energy curtailment and two parts of constraint conditions, namely system constraints and unit characteristic constraints;

[0069] According to the obtained optimal regulation target value, S3 automatically issues it to the unified regulation new energy power stations under the jurisdiction of the provincial dispatching and local dispatching of the power grid partition where the over-limit section belongs according to a certain regulation step size, so as to orderly and accurately control the output of new energy and eliminate the over-limit and overload conditions of the section.

[0070] Furthermore, it includes:

[0071] The specific steps of step S1 include:

[0072] S11 monitors the remote signal change conditions of the switch positions on both sides of the 500kV transmission line, the total interval accident, and the protection action signal in real time;

[0073] S12 determines whether an N-2 fault event occurs: First, it determines whether a line tripping fault occurs. The conditions for this event to occur are:

[0074] The switch position on the local side of the line changes YX / SOE + the total interval accident YX / SOE / protection action signal YX / SOE, and the signal time interval does not exceed 30 seconds; and / or

[0075] The switch position on the local side of the line changes YX / SOE + the switch position on the opposite side of the line changes YX / SOE, and the signal time interval does not exceed 30 seconds;

[0076] Secondly, if two 500kV transmission lines trip successively within one minute and the active power after the line fault is less than the zero drift value, it is determined that an N-2 fault event occurs;

[0077] S13 determines whether a section over-limit event occurs; the conditions for this event to occur are:

[0078] Monitor the current value of the relevant 220kV transmission section of the power grid in real time. If the current value of any transmission section exceeds its rated current-carrying capacity, it is determined that a section over-limit event occurs.

[0079] Furthermore, it includes:

[0080] In step S2, the optimization objective function of the provincial and local new energy automatic regulation demand calculation model is expressed as:

[0081]

[0082] In the formula: is the curtailment of wind and light of the aggregated new energy i of the unified regulation new energy power station or the 220kV substation in the region; N is the number of aggregated new energy of the unified regulation new energy power station or the 220kV substation in the region.

[0083] Furthermore, it includes:

[0084] The constraint conditions of the described land-saving new energy automatic regulation demand calculation model include: system constraints and unit characteristic constraints. The system constraints include power balance constraints and network security constraints;

[0085] Among them, the power balance constraint is expressed as:

[0086]

[0087] In the formula: Since the DC power flow model is adopted, the influence of network loss is ignored; L f is the system load after subtracting the power received by the regional power grid at the current moment; W i is the output value of the aggregated new energy i of the unified regulated new energy power station or the 220 kV substation in the region at the current moment; are respectively the output value and power regulation amount of the conventional unit i at the current moment, M is the number of conventional units, and the amount of abandoned wind and light satisfies:

[0088] The network security constraint is expressed as:

[0089]

[0090] In the formula: p g,k 、p W,k 、p WS,k and p L,k are respectively the adjusted active power output of the conventional unit connected to node k, the active power output of the aggregated new energy of the unified regulated new energy power station or the 220 kV substation in the region, the abandoned wind and light power, and the load. X kl is the reactance value of branch kl, θ k and θ l are respectively the voltage phase angles of node k and node l; is the active power flow limit of branch kl; among them, Equation (1) is the system power flow balance equation expressed by the DC power flow model, and Equation (2) is the line power capacity limit constraint.

[0091] Furthermore, it includes:

[0092] The unit characteristic constraints include: the upper and lower limits of the active power output of the conventional unit and the output regulation constraint of the new energy power station. The upper and lower limits of the active power output of the conventional unit are expressed as:

[0093]

[0094] In the formula, and are respectively the maximum and minimum active power outputs of the conventional unit i;

[0095] To ensure the fairness of new energy power station consumption, in accordance with the principle of consistency of the aggregated new energy load rates of each unified dispatching new energy power station or 220 kV substation in the region, the aggregated new energy regulation power of each unified dispatching new energy power station or 220 kV substation in the region shall meet the following constraints for the regulation of new energy power station output:

[0096]

[0097] In the formula, is the rated output of the aggregated new energy i of the unified dispatching new energy power station or 220 kV substation in the region.

[0098] Furthermore, the method further includes:

[0099] S4 To ensure the fairness of the consumption of non-unified dispatching new energy power stations under the jurisdiction of the local dispatching, in accordance with the principle of consistency of the non-unified dispatching new energy load rates in the region, the decomposition strategies of each non-unified dispatching new energy power station are as follows:

[0100] The curtailment of wind and light of each non-unified dispatching new energy power station in the aggregated new energy i of the 220 kV substation in the region shall satisfy:

[0101]

[0102] In the formula, V i 、 are the active power output and rated output of the non-unified dispatching new energy power station.

[0103] Furthermore, step S3 further includes the confirmation of eliminating section overlimit overload conditions; specifically:

[0104] If the section overlimit event message has not been restored within a certain period of time after the adjustment target is issued, after excluding the new energy power stations that have not responded to the adjustment, re-enter the provincial and local new energy automatic adjustment demand calculation model in step S2 to determine the optimal adjustment target of the provincial and local new energy output, and issue it automatically again until the section overlimit overload condition is finally eliminated. Among them, the judgment logic of the new energy power stations that have not responded to the adjustment is that the actual adjustment amount is less than 30% of the target adjustment amount.

[0105] Embodiment 2

[0106] On the basis of Embodiment 1, the present invention discloses a provincial and local new energy emergency collaborative automatic control method for replacing the new energy security control device, including the following steps:

[0107] Step 1: 500kV Transmission Line N-2 Fault Monitoring and 220kV Transmission Section Overlimit Monitoring: Integrate multi-source data such as the protection signals and position change signals of the 500kV transmission line switch trips sent by substations, as well as telemetry changes, to comprehensively diagnose the N-2 tripping faults of the transmission line. If it is determined that a 500kV transmission line N-2 fault has occurred, send a message to inform the new energy automatic generation control (AGC) module of the N-2 fault event. At the same time, monitor the current values of the relevant 220kV transmission sections of the power grid in real time. If the current value of any transmission section exceeds its rated current-carrying capacity, send a message to inform the new energy AGC module of the section overlimit event.

[0108] Step 2: Calculation of Provincial and Local New Energy Automatic Regulation Requirements and Coordinated Control: As Figure 1 shown, if the new energy AGC module receives both N-2 fault and section overlimit event messages simultaneously, it will start the calculation function of provincial and local new energy automatic regulation requirements to quickly determine the optimal regulation target for the new energy output of provinces and localities. The new energy AGC module issues commands to centralized and distributed new energy power stations to execute automatically according to the regulation target values of each provincial and local new energy power station and the corresponding regulation step sizes, and precisely controls the new energy output in an orderly manner to eliminate the situation of section overlimit and overload.

[0109] The specific method of Step 1 is as follows:

[0110] (1) Based on the SCADA function module of the dispatching automation system, monitor the remote signal position changes of the switch positions on both sides of the 500kV transmission line, the total accident of the interval, and the protection action signals in real time. If any of the following occurs:

[0111] 1) The switch position change on the local side of the line (YX / SOE) + the total accident of the interval (YX / SOE) / the protection action signal (YX / SOE), and the signal time interval does not exceed 30 seconds;

[0112] 2) The switch position change on the local side of the line (YX / SOE) + the switch position change on the opposite side of the line (YX / SOE), and the signal time interval does not exceed 30 seconds.

[0113] If any of the above logics is satisfied, a line tripping fault will be pushed.

[0114] (2) If two 500kV transmission lines trip successively within one minute, and the active power after the line fault is less than the zero drift value (the zero drift is set to 3.05MW), send a message to inform the AGC of the N-2 double-line fault.

[0115] (3) Monitor the current values of the relevant 220kV transmission sections of the power grid in real time. If the current value of any transmission section exceeds its rated current-carrying capacity, send a message to inform the new energy AGC module of the section overlimit event.

[0116] The specific method of Step 2 is as follows:

[0117] (1) Provincial and local new energy automatic regulation demand calculation: If the new energy AGC module receives both the N-2 fault and section overlimit event messages simultaneously, the provincial and local new energy automatic regulation demand calculation function is started to quickly determine the optimal regulation target for the output of provincial and local new energy.

[0118] 1) Optimization objective. To minimize the curtailment of wind and solar energy to the greatest extent, an optimization objective function with the minimum curtailment of wind and solar energy of new energy is constructed:

[0119]

[0120] In the formula: is the curtailment of wind and solar energy of the aggregated new energy i of the unified regulated new energy power station or the 220 kV substation in the region; N is the number of aggregated new energy of the unified regulated new energy power station or the 220 kV substation in the region.

[0121] 2) Constraint conditions

[0122] The constraint conditions include two parts: system constraints and unit characteristic constraints. The former includes the power balance constraint and network security constraint of the system; the latter includes the upper and lower limits of the active power output of conventional units and the output regulation constraint of new energy power stations.

[0123] (a) Power balance constraint

[0124]

[0125] In the formula: Since the DC power flow model is adopted, the influence of network losses is ignored; L f is the system load after subtracting the power received by the regional power grid at the current moment; W i is the output value of the aggregated new energy i of the unified regulated new energy power station or the 220 kV substation in the region at the current moment; are respectively the output value and power regulation amount of the conventional unit i at the current moment, and M is the number of conventional units. The curtailment of wind and solar energy satisfies:

[0126] (b) Network security constraint

[0127]

[0128]

[0129] In the formula: p g,k 、p W,k 、p WS,k and p L,kThey are respectively the adjusted active power output of the conventional units connected to node k, the aggregated active power output of the unified regulated new energy power stations or the new energy aggregated at the 220 kV substations in Region 2, the wind and light curtailment power, and the load, X kl is the reactance value of branch kl, θ k and θ l are respectively the voltage phase angles of node k and node l; is the active power flow limit of branch kl.

[0130] Equation (1) is the system power flow balance equation expressed by the DC power flow model, and Equation (2) is the line power capacity limit constraint. Since both contain the variables to be solved for the branch power and the node voltage phase angles, it increases the dimension of the decision variables, and when the system scale is large, it will cause difficulties in solving. The solution is to introduce the transfer distribution factor vector The transfer distribution factor describes the impact of the power change injected at node k on the power change on the line. These factors can be used to convert the power change of the node into the power change on the line to express the relationship between the flows of all branches and the net input power of each node. Specifically, the transfer distribution factor can be defined as:

[0131]

[0132] In the formula: P kl is the power flow of branch kl, P g,i is the power generation of node i. The partial derivative indicates how the power flow of line kl will change when the power generation of node i changes. Then, the line power flow can be expressed as a function of the node power using the transfer distribution factor:

[0133]

[0134] Perform equivalent substitution on Equation (1) and Equation (2), where:

[0135]

[0136] Obtain Equation (3) and Equation (4):

[0137]

[0138] In this way, Equation (1) and Equation (2) are simplified to functions that only contain node powers.

[0139] (c) Constraints on the upper and lower limits of the active power output of conventional units

[0140]

[0141] In the formula, and They are the maximum and minimum active power outputs of the conventional unit i respectively.

[0142] (d) Regulation constraints of new energy power station output

[0143] To ensure the fairness of new energy power station consumption, in accordance with the principle of consistency of the aggregated new energy load rates of each unified regulated new energy power station or 220 kV substation in the region, the aggregated new energy regulation power of each unified regulated new energy power station or 220 kV substation in the region shall meet the following constraints:

[0144]

[0145] In the formula, is the rated output of the aggregated new energy i of the unified regulated new energy power station or 220 kV substation in the region.

[0146] (2) Provincial and local new energy automatic regulation control: The above linear optimization model can be solved by the optimization software CPLEX. The new energy AGC module automatically issues the regulation target values of the above new energy power stations in each province and region to the unified regulated new energy power stations under the jurisdiction of the provincial dispatching and local dispatching of the power grid partition where the over-limit section belongs, according to the regulation step of 10% of the rated output per minute, and precisely controls the new energy output in an orderly manner to eliminate the over-limit and overload of the section.

[0147] Similarly, to ensure the fairness of the consumption of non-unified regulated new energy power stations under the jurisdiction of the local dispatching, in accordance with the principle of consistency of the non-unified regulated new energy load rates in the region, the decomposition strategies of each non-unified regulated new energy power station are as follows:

[0148] The curtailment of wind and light of each non-unified regulated new energy power station in the aggregated new energy i of the 220 kV substation in the region Satisfies:

[0149]

[0150] In the formula, V i 、 are the active power output and rated output of the non-unified regulated new energy power station.

[0151] (3) Elimination of section over-limit: If the section over-limit event message has not been restored within two minutes after the regulation target is issued, after excluding the new energy power stations that have not responded to the regulation (the judgment logic is that the actual regulation amount is less than 30% of the target regulation amount), restart the above-mentioned calculation function of the provincial and local new energy automatic regulation demand, determine the optimal regulation target of the provincial and local new energy output and issue it automatically again until the over-limit and overload of the section are finally eliminated.

[0152] The present invention proposes a new energy provincial and local collaborative emergency automatic control method covering two aspects: N-2 fault monitoring and section overlimit monitoring, and calculation of automatic adjustment requirements and coordinated control of new energy at the provincial and local levels, so as to achieve orderly, fast, and accurate control of new energy output in case of faults, eliminate section overlimit overload situations, ultimately achieve "replacement of tripping with adjustment", ensure the safe and stable operation of the power grid, and maximize the consumption of new energy.

[0153] Embodiment 3

[0154] As Figure 4 shown, the present invention also provides a provincial and local collaborative control system based on fault monitoring and section overlimit, and the system includes:

[0155] A judgment module, configured to judge N-2 fault events of 500kV transmission lines and 220kV transmission section overlimit events according to multi-source data of 500kV transmission line switch tripping sent by integrated substations;

[0156] A model construction module, configured to construct a calculation model for automatic adjustment requirements of provincial and local new energy. Specifically, if N-2 fault events and 220kV transmission section overlimit events occur simultaneously, the optimal adjustment target value of provincial and local new energy output is determined according to the calculation model for automatic adjustment requirements of provincial and local new energy. The calculation model for automatic adjustment requirements of provincial and local new energy includes an optimization objective function with the minimum new energy curtailment and two parts of constraint conditions: system constraints and unit characteristic constraints;

[0157] A control module, configured to automatically send the obtained optimal adjustment target value to the unified regulation new energy power stations under the jurisdiction of the provincial dispatching and local dispatching of the power grid sub-region where the overlimit section belongs according to a certain adjustment step size, so as to orderly and accurately control the new energy output and eliminate the section overlimit overload situation.

[0158] Furthermore, the system further includes:

[0159] A decomposition strategy module for non-unified regulation new energy power stations, which is to ensure the fairness of the consumption of non-unified regulation new energy power stations under the jurisdiction of the local dispatching. According to the principle of consistency of load rates of non-unified regulation new energy in each region, the decomposition strategies of each non-unified regulation new energy power station are as follows:

[0160] The curtailment of new energy of each non-unified regulation new energy power station aggregated in the new energy i of the 220kV substation in the region Satisfies:

[0161]

[0162] In the formula, V i 、 are the active power output and rated output of the non-unified regulation new energy power station.

[0163] Furthermore, it includes:

[0164] The control module further includes the confirmation of eliminating the overload situation of the section crossing the limit; specifically:

[0165] If the section crossing the limit event message has not been restored within a certain period of time after the adjustment target is sent, after excluding the new energy power stations that do not respond to the adjustment, re-enter the provincial and local new energy automatic adjustment demand calculation model in the model construction module, determine the optimal adjustment target of the provincial and local new energy output, and send it automatically again until the overload situation of the section crossing the limit is finally eliminated. Among them, the judgment logic of the new energy power stations that do not respond to the adjustment is that the actual adjustment amount is less than 30% of the target adjustment amount.

[0166] Other technical features of the provincial and local collaborative control system based on fault monitoring and section crossing the limit of the present invention are the same as those of the corresponding provincial and local collaborative control method based on fault monitoring and section crossing the limit of the present invention, and will not be elaborated here.

[0167] Relying on this method, the present invention provides a specific case: precisely adjusting the new energy output in the northern region of Yancheng, Jiangsu, to ensure that the power flow sending section does not cross the limit, replacing the stable power cut-off device, and improving the new energy consumption capacity in the northern region of Yancheng by about 300 MW under the N-2 fault condition of the 500 kV Pandang~Binxiang line.

[0168] At present, the installed capacity of wind power in Jiangsu is 22.51 million kilowatts, and the installed capacity of photovoltaic power generation is 38.77 million kilowatts, of which the installed capacity of offshore wind power is 11.82 million kilowatts, ranking first in the country. In areas with a high new energy penetration rate in Jiangsu, new energy stable control devices need to be deployed. After a fault occurs in the new energy transmission channel, a power cut-off instruction is sent to the new energy power plant according to a predetermined strategy to ensure the safe and stable operation of the power grid.

[0169] Taking the northern region of Yancheng City in the Jiangsu Power Grid as an example, as Figure 2 shown, when the output of offshore wind power is large, if a N-2 fault occurs in the 500 kV Pandang~Binxiang line, overload situations will exist in nine circuits such as the 220 kV Binxiang~Tongyun line. It is necessary to deploy stable control devices at nodes such as the 500 kV Binxiang substation, the 220 kV Tongyun substation, and Zhongdian Smart Wind Power to form a stable control system for offshore wind power output and perform joint cut-off control on units such as Zhongdian Smart Wind Power. In order to flexibly, efficiently and leanly control the new energy output under the N-2 fault condition and improve the offshore wind power consumption level, relying on the new energy provincial and local collaborative control system, the N-2 emergency automatic control of the offshore wind power transmission channel is realized.

[0170] The integrated intelligent alarm module of the dispatching technology support system is used to monitor whether an N-2 fault occurs on the 500 kV Pandang-Binxiang double line, and the intelligent limit module is used to automatically monitor whether there is an overload on the nine 220 kV lines. If an N-2 fault occurs and there is a line overload, and the new energy AGC simultaneously receives the N-2 fault and the 220 kV line overlimit event, the automatic control process will be started.

[0171] First, calculate the automatic adjustment requirements of new energy at the provincial and local levels, then send the calculated control targets to control the output of relevant unified-adjusted new energy, and at the same time send the control targets of non-unified-adjusted new energy in Yancheng City to the local dispatching of the city, which is decomposed and executed by the new energy AGC of the local dispatching. Through the orderly and precise adjustment and control of new energy at all voltage levels in the region, the new energy consumption capacity of the northern district of Yancheng City under N-2 fault conditions can be increased by about 300 MW. On June 8, 2023, with the successful closed-loop test, the N-2 emergency collaborative automatic control function of the offshore wind power transmission channel in the city began to be put into trial operation.

[0172] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0173] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A provincial and local collaborative control method based on fault monitoring and section overlimit, characterized in that The method includes the following steps: S1 Fuse multi-source data of the 500kV transmission line switch trip sent by the substation, and judge the N-2 fault event of the 500kV transmission line and the 220kV transmission section over-limit event; S2 If the N-2 fault event and the 220kV transmission section over-limit event occur simultaneously, determine the optimal adjustment target value of the provincial and local new energy output according to the provincial and local new energy automatic adjustment demand calculation model. The provincial and local new energy automatic adjustment demand calculation model includes an optimization objective function with the minimum new energy curtailment and two parts of constraint conditions: system constraints and unit characteristic constraints; S3 According to the obtained optimal adjustment target value, automatically send it to the unified regulation new energy power stations under the jurisdiction of the provincial dispatching and local dispatching of the power grid partition where the over-limit section belongs at a certain adjustment step length, so as to orderly and accurately control the new energy output and eliminate the over-limit and overload conditions of the section.

2. The provincial and local collaborative control method based on fault monitoring and section overlimit according to claim 1, wherein The specific content of step S1 includes: S11 Real-time monitor the remote signal change conditions of the switch positions on both sides of the 500kV transmission line, the total interval accident, and the protection action signal; S12 Judge whether the N-2 fault event occurs: First, judge whether a line trip fault occurs. Second, if two 500kV transmission lines trip successively within one minute and the active power after the line fault is less than the zero drift value, it is determined that the N-2 fault event occurs; S13 Judge whether the section over-limit event occurs; the conditions for this event to occur are: Real-time monitor the current value of the relevant 220kV transmission section of the power grid. If the current value of any transmission section exceeds its rated current-carrying capacity, it is determined that the section over-limit event occurs.

3. The provincial and local collaborative control method based on fault monitoring and section overlimit according to claim 2, characterized in that, In step S2, the optimization objective function of the provincial and local new energy automatic adjustment demand calculation model is expressed as: In the formula: is the curtailment of wind and solar power of aggregated new energy i in the unified dispatching new energy power station or the 220 kV substation in the area; N is the number of aggregated new energy in the unified dispatching new energy power station or the 220 kV substation in the area.

4. The provincial and local collaborative control method based on fault monitoring and section over-limit according to claim 3, wherein The constraint conditions of the provincial and local new energy automatic adjustment demand calculation model include: system constraints and unit characteristic constraints. The system constraints include power balance constraints and network security constraints; Among them, the power balance constraint is expressed as: Wherein: Since the DC power flow model is adopted, the influence of network losses is ignored; L f is the system load after subtracting the power received by the regional power grid from the current moment; W i is the output value of the aggregated new energy i of the new energy power station under unified dispatching or the regional 220 kV substation at the current moment; are the output value and power regulation amount of the conventional unit i at the current moment respectively, M is the number of conventional units, satisfy: The network security constraint is expressed as: Where: p g,k , p W,k , p WS,k and p L,k are respectively the adjusted active power output of the conventional unit connected to node k, the aggregated active power output of the unified regulated new energy power station or the new energy aggregated at the 220 kV substation in area 2, the wind and light curtailment power, and the load. X kl is the reactance value of branch kl, and θ k and θ l are respectively the voltage phase angles of node k and node l; is the active power flow limit of branch kl. Among them, Equation (1) is the system power flow balance equation represented by the DC power flow model, and Equation (2) is the line power capacity limit constraint.

5. The provincial and local collaborative control method based on fault monitoring and section overlimit according to claim 4, wherein The unit characteristic constraints include: the upper and lower limits of the active power output of conventional units and the output adjustment constraints of new energy power stations. The upper and lower limits of the active power output of conventional units are expressed as: In the formula, and are the maximum and minimum active power outputs of the conventional unit i, respectively; In order to ensure the fairness of new energy power station consumption, according to the principle of consistency of the aggregated new energy load rate of each unified regulation new energy power station or 220kV substation in the region, the aggregated new energy adjustment power of each unified regulation new energy power station or 220kV substation in the region meets the output adjustment constraints of the new energy power station as follows: In the formula, is the rated output of the aggregated new energy i of the unified-regulated new energy power station or the 220 kV substation in the area.

6. The provincial and local collaborative control method based on fault monitoring and section over-limit according to claim 5, characterized in that, The method also includes: S4 In order to ensure the fairness of the consumption of non-unified regulation new energy power stations under the jurisdiction of the local dispatching, according to the principle of consistency of the non-unified regulation new energy load rate in the region, the decomposition strategy of each non-unified regulation new energy power station is as follows: The curtailment of wind and solar power of each non-unified regulated new energy power station in the aggregated new energy i of the 220 kV substation in the region Meet the following:[[]] Wherein, V i and are the active power output and the rated power output of the non-uniformly adjusted new energy power station, respectively.

7. The provincial and local collaborative control method based on fault monitoring and section overlimit according to any one of claims 1-5, characterized in that, Step S3 also includes the confirmation of eliminating the over-limit and overload conditions of the section; specifically: If the section over-limit event message has not been restored within a certain period of time after the adjustment target is sent, after excluding the new energy power stations that have not responded to the adjustment, re-enter the provincial and local new energy automatic adjustment demand calculation model in step S2 to determine the optimal adjustment target for the provincial and local new energy output, and send it automatically again until the section over-limit overload situation is finally eliminated. Among them, the judgment logic for the new energy power stations that have not responded to the adjustment is that the actual adjustment amount is less than 30% of the target adjustment amount.

8. A provincial and local collaborative control system based on fault monitoring and section over-limit, characterized in that, The system includes: A judgment module, configured to judge the 500kV transmission line N-2 fault event and the 220kV transmission section over-limit event according to the multi-source data of the 500kV transmission line switch trip sent by the integrated substation; A model construction module, configured to construct a provincial and local new energy automatic adjustment demand calculation model. Specifically, if the N-2 fault event and the 220kV transmission section over-limit event occur simultaneously, according to the provincial and local new energy automatic adjustment demand calculation model, determine the optimal adjustment target value of the provincial and local new energy output. The provincial and local new energy automatic adjustment demand calculation model includes an optimization objective function with the minimum new energy curtailment and two constraint conditions: system constraints and unit characteristic constraints; A control module, configured to automatically send the obtained optimal adjustment target value to the unified power stations of the provincial and local dispatching departments under the jurisdiction of the power grid division where the over-limit section is located according to a certain adjustment step size for execution, so as to orderly and accurately control the new energy output and eliminate the section over-limit overload situation.

9. The provincial and local collaborative control system based on fault monitoring and section over-limit according to claim 8, wherein The system further includes: A non-unified new energy power station decomposition strategy module, which is to ensure the fairness of the consumption of non-unified new energy power stations under the jurisdiction of the local dispatching department. According to the principle of consistency of the load rates of non-unified new energy power stations in each region, the decomposition strategies of each non-unified new energy power station are as follows: The curtailment of wind and solar power of each non-unified regulated new energy power station in the aggregation of new energy i in the 220 kV substation in the region Meet the following conditions: Wherein, V i , are the active power output and rated output of the non-uniformly adjusted new energy power station, is the wind and light abandonment amount of the aggregated new energy i of the uniformly adjusted new energy power station or the regional 220 kV substation.

10. The provincial and local collaborative control system based on fault monitoring and section over-limit according to claim 8, characterized in that, The control module further includes the confirmation of eliminating the section over-limit overload situation. Specifically: If the section over-limit event message has not been restored within a certain period of time after the adjustment target is sent, after excluding the new energy power stations that have not responded to the adjustment, re-enter the provincial and local new energy automatic adjustment demand calculation model in the model construction module to determine the optimal adjustment target for the provincial and local new energy output, and send it automatically again until the section over-limit overload situation is finally eliminated. Among them, the judgment logic for the new energy power stations that have not responded to the adjustment is that the actual adjustment amount is less than 30% of the target adjustment amount.

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