A provincial and local integrated power grid fault handling method

Abstract

The present invention discloses a provincial and local integrated power grid fault handling method. Based on a provincial and local integrated model system, the provincial dispatching department first determines the fault impact and the scope of the power grid that can be adjusted for a predicted fault or a fault to be studied, and sends it to the local dispatching department. The local dispatching department further determines an effective adjustment strategy based on the connection form and switch status of the relevant distribution network and sorts it according to the objective function. The local dispatching department sends the sorted strategies to the provincial dispatching department in turn for risk assessment, and obtains a feasible optimal provincial and local integrated fault handling strategy. The present invention can provide an integrated fault handling auxiliary strategy for provincial and local dispatching, effectively improving the fault handling capability and safe operation level of the power grid.

Description

Technical Field

[0001] The invention relates to a provincial and local integrated power grid fault handling method, belonging to the technical field of power system fault handling. Background Art

[0002] With the continuous increase in power load demand from power grid users and the development of a large number of new energy sources such as distributed power sources, electric vehicles, and DC projects, traditional power grids are facing a series of problems such as tight line capacity, local load imbalance, and insufficient power supply capacity. In addition, the power grid is susceptible to factors such as severe weather, human errors, and equipment aging. Grid failures are inevitable, and effective fault handling methods are needed to ensure power supply and reduce losses.

[0003] The current provincial and municipal power grid dispatching systems are independent, resulting in weak information interactivity and data inconsistencies, which in turn makes it impossible for fault handling solutions to achieve global considerations and overall reliability.

[0004] How to better handle provincial and local power grid faults and achieve the feasibility and rationality of power grid operation is a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0005] Purpose: In order to overcome the deficiencies in the prior art, the present invention provides a provincial and local integrated power grid fault handling method, which realizes data synchronization and business interconnection of provincial and local dispatching systems based on provincial and local integration. For the power grid fault to be handled, the provincial dispatching system first determines the adjustable range and sends it to the local dispatching system, and then the local dispatching system adjusts the operating mode according to the power grid topology and switch status to obtain a fault handling method. The dispatching results of the provincial and local levels are interconnected and verified with each other, thereby improving the reliability of the result strategy and the fault handling capability.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A provincial and local integrated power grid fault handling method comprises the following steps:

[0008] Step 1: The provincial and local integrated power grid model reads the grid equipment model data, power generation and consumption information, switch status, provincial and local power grid boundaries, and power grid operation data of each voltage level of the provincial and local dispatching at the current time section to determine the current provincial and local power grid model.

[0009] Step 2: Based on the risk prediction or expected fault set, determine the fault information that needs to be resolved.

[0010] Step 3: Substitute the fault information to be resolved into the provincial and local power grid model for simulation and perform power flow calculation to obtain the power plants and lines where the power-off equipment and the newly added overloaded and over-limit equipment are located. Combined with the provincial and local power grid boundary information, the scope of the local dispatching power grid affected by the fault is determined. The provincial dispatching system then issues a local dispatching power grid scope adjustment based on the fault operation mode to the local dispatching system.

[0011] Step 4: According to the adjusted local dispatching grid range, the corresponding local dispatching obtains the distribution network switch and load network topology relationship, generates the switch topology constraints corresponding to each wiring method, and generates the load factor matrix L of the power source point substation and switch topology relationship according to the switch topology constraints corresponding to each wiring method. s and the load factor vector B s .

[0012] Step 5: Load factor matrix L based on the topological relationship between power supply point substation and switch s and the load factor vector B s , as well as the 0-1 state of the grid switch before the fault occurs, to determine the various constraints required for the ground regulation to adjust the fault isolation mode.

[0013] Step 6: Set an objective function for the adjustment strategy of the ground-based power distribution network, solve the objective function in combination with the various constraints required for the ground-based power distribution network to adjust the fault isolation mode, obtain the fault handling strategies and sort them, and obtain the sorted fault handling strategies.

[0014] Step 7: Select the first fault handling strategy in the sorted fault handling strategies, and send it back to the provincial dispatching station for simulated power flow calculation verification. Obtain a comparison of power-off devices and newly added overloaded and over-limit devices, and perform a risk assessment on the provincial dispatching power grid. If there is a risk, feedback is given to the local dispatching station, and the local dispatching station sends the next fault handling strategy in the sorted order. The provincial dispatching station continues to verify it until the provincial dispatching station's risk assessment is within a reasonable range. The fault handling strategy is then output as the final strategy.

[0015] As a preferred solution, the provincial and local integrated power grid model includes all primary equipment, topology and power flow of 10kV-110kV at the prefectural level and 220kV-500kV at the provincial level, and is stored in the provincial and local integrated power grid platform.

[0016] As a preferred solution, the fault information includes: the location of the fault, the fault type, the duration, the impact on node lines of different voltage levels, and the predicted probability of the fault occurring.

[0017] As a preferred solution, the method for determining the scope of the ground-controlled power grid affected by the fault is as follows:

[0018] Step 3.1: Record the provincial power grid measurement information before the fault and adjust the provincial power grid model operation mode according to the expected fault information.

[0019] Step 3.2: Use power flow calculation to simulate and record the power changes of the provincial power grid, and compare it with the state before the fault to determine the specific branches affected by the fault.

[0020] Step 3.3: Based on the provincial branches affected by the fault, the downstream subordinate local dispatch and the fault scope are obtained. The provincial dispatch eliminates some key lines and loads that cannot be adjusted, and determines the scope of operation mode adjustment required for the local dispatch grid, and sends it to the local dispatch.

[0021] As a preferred solution, the power flow calculation must meet the following constraints:

[0022]

[0023]

[0024] Where, P i With Q i represents the injected active and reactive power of node i; for each branch, P ji , Q ji , I ji is the active power, reactive power and current value from node j to node i, P ik , Q ik is the active and reactive power from node j to node k, r ij 、x ij represents the resistance and reactance of branch (i, j); Φ(i) and Ψ(i) represent the power flowing into and out of the set of nodes connected to node i, respectively; N represents all branches in the entire network, N S Indicates all fault branches in the fault information.

[0025] As a preferred solution, the load coefficient matrix L s and the load factor vector B s The following relationship must be satisfied:

[0026]

[0027] Where, P G,adj It represents the power delivered by the 220kV or 500kV main transformer with the number adj corresponding to the fault identified by the provincial power grid. S is the switch column vector, S1~S n is the switch column vector of each topology unit, L s,1 ~L s,n is the linear coefficient row vector of the active power balance equation in each topological unit, B s,1 ~B s,n is the load factor vector, and I is the unit row vector.

[0028] As a preferred solution, the constraints required for the ground adjustment to adjust the fault isolation mode include:

[0029] 1) After the ground dispatcher adjusts the fault isolation mode, each power source point and switch status in the distribution network must meet the active power balance constraints, as follows:

[0030] P G,adj -(L s,adj S+B s,adj +ΔP G,adj )=0 adj=1,2,…N T

[0031] Where, L s,adj is the linear coefficient row vector of the active power balance equation in each topological unit; △P G,adj The load control quantity required for the adj main transformer under the mode adjustment, N T Indicates the number of main transformers at the power point, B s,adj represents the load factor vector of adj main transformer, P G,adj It represents the power delivered by the 220kV or 500kV main transformer numbered adj corresponding to the fault determined by the provincial power grid, and S is the switch column vector.

[0032] 2) To ensure the safe operation of the power grid, the operation mode needs to be adjusted to prevent overload of power supply points and feeders, namely:

[0033]

[0034] Where, P F,line Indicates the feeder line transmission power, P G,adj,max and P F,line,max They represent the maximum power allowed to be sent down by the main transformer adj and the maximum power allowed to be transmitted by the feeder line, N F Indicates the number of feeder lines in the distribution network.

[0035] As a preferred solution, the objective function includes:

[0036] min F=f1+f2

[0037] Where F is the objective function for adjusting the ground fault handling method, f1 is the cost of the number of switch operations, and f2 is the load control cost.

[0038] Cost of switching operations f1:

[0039]

[0040] Where, subscript u represents voltage level, K uis the switch operation cost coefficient corresponding to the voltage level; w is the switch number, Ns is the set of switches in the fault impact range; S' w and S w Respectively represent the switch status before and after the mode change.

[0041] Load control cost f2:

[0042]

[0043] Where N adj Indicates the set of power main transformers that need to control the load after mode adjustment, C adj Indicates the cost coefficient corresponding to each power load control, △P G,adj It indicates the load control amount required for adjusting the adj main transformer.

[0044] Beneficial Effects: The present invention provides a method for handling provincial and local integrated power grid faults. Based on a provincial and local integrated model system, the provincial dispatching authority first determines the fault impact and the scope of the grid that can be adjusted for a predicted or pending fault, and then transmits this information to the local dispatching authority. The local dispatching authority then determines effective adjustment strategies based on the relevant distribution network wiring configuration and switch status, and ranks them according to an objective function. The local dispatching authority then sends these ranked strategies to the provincial dispatching authority for risk assessment, ultimately deriving a feasible and optimal provincial and local integrated fault handling strategy.

[0045] This method can provide an integrated fault handling auxiliary strategy for provincial and local dispatching, effectively improving the fault handling capability and safe operation level of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the overall flow chart of the provincial and local integrated power grid fault handling method of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described below with reference to specific embodiments.

[0048] like Figure 1 As shown, a provincial and local integrated power grid fault handling method includes the following steps:

[0049] Step 1: The provincial and local integrated power grid model reads the grid equipment model data, power generation and consumption information, switch status, provincial and local power grid boundaries, and power grid operation data of each voltage level of the provincial and local dispatching at the current time section to determine the current provincial and local power grid model.

[0050] Step 2: Based on the risk prediction or anticipated fault set, determine the fault information that needs to be resolved. The fault information includes: the location of the fault, the fault type, the duration, the impact on node lines of different voltage levels, and the predicted probability of the fault to ensure the practicality of the generated disposal strategy.

[0051] Step 3: Substitute the fault information to be resolved into the provincial and local power grid model for simulation and perform power flow calculation to obtain the power plants and lines where the power-off equipment and the newly added overloaded and over-limit equipment are located. Combined with the provincial and local power grid boundary information, the scope of the local dispatching power grid affected by the fault is determined. The provincial dispatching system then issues a local dispatching power grid scope adjustment based on the fault operation mode to the local dispatching system.

[0052] Step 4: According to the scope of the local dispatching grid to be adjusted determined in step 3, the corresponding local dispatching obtains the 110kV, 35kV and 10kV distribution network switches and load network topology, generates the switch topology constraints corresponding to each wiring method, and generates the load factor matrix L of the power source point substation and switch topology relationship based on the switch topology constraints corresponding to each wiring method. s and the load factor vector B s .

[0053] Step 5: Based on the load factor matrix L of the power point substation and switch topology relationship in step 4 s and the load factor vector B s , as well as the 0-1 state of the grid switch before the fault occurs, to determine the various constraints required for the ground regulation to adjust the fault isolation mode.

[0054] Step 6: Set an objective function for the local dispatching and distribution network adjustment strategy. Solve the objective function based on the constraints required for the local dispatching and fault isolation adjustment determined in Step 5. Obtain and rank the fault handling strategies to obtain the ranked fault handling strategies. The objective function includes minimizing the number of switch changes and minimizing the load control amount.

[0055] Step 7: The first fault handling strategy among the fault handling strategies ranked in step 6 is sent back by the local dispatch to the provincial dispatch for simulation flow calculation verification. The comparison of power-off devices and newly added overloaded and over-limit devices is obtained to conduct a risk assessment on the provincial dispatch power grid. If there is a risk, it is fed back to the local dispatch and the local dispatch sends the next strategy ranked in step 6. The provincial dispatch continues to verify it until the provincial dispatch risk assessment is within a reasonable range. The strategy is then output as the final strategy.

[0056] The provincial and local integrated power grid model described in step 1 includes all primary equipment at the prefectural level (10kV-110kV) and provincial level (220kV-500kV), such as busbars, main transformers, switches, etc., as well as topology and power flow, and is stored on the provincial and local integrated power grid platform.

[0057] In the hierarchical scheduling of power grids at the provincial and local levels, equipment outages at the provincial level can cause widespread power outages at the prefectural level. These outages also affect the power flow and power balance of the provincial grid. Therefore, the information read into the integrated provincial and local power grid model must be compared with both the provincial and local dispatching grid models to ensure consistency in the underlying data and thus guarantee reliable calculation results.

[0058] The method for determining the scope of the ground-controlled power grid affected by the fault in step 3 is as follows:

[0059] 1) Record the provincial power grid measurement information before the fault and adjust the provincial power grid model operation mode according to the expected fault information.

[0060] 2) Through power flow calculation, simulate and record the power changes of the provincial power grid, and compare it with the state before the fault to determine the branches affected by the fault. The branches include main transformers and lines. The specific power flow calculation must meet the following requirements:

[0061]

[0062]

[0063] Where, P i With Q i represents the injected active and reactive power of node i; for each branch, P ji , Q ji , I ji is the active power, reactive power and current value from node j to node i, P ik , Q ik is the active and reactive power from node j to node k, r ij 、x ij represents the resistance and reactance of branch (i, j); Φ(i) and Ψ(i) represent the power flowing into and out of the set of nodes connected to node i, respectively; N represents all branches in the entire network, N S Indicates all fault branches in the fault information.

[0064] 3) Based on the provincial branches affected by the fault, the downstream subordinate local dispatch and the fault scope are obtained. The provincial dispatch eliminates some key lines and loads that cannot be adjusted, and the scope of the operation mode adjustment required for the local dispatch grid is obtained and issued to the local dispatch.

[0065] The load factor matrix L described in step 4 s and the load factor vector B s The following relationship must be satisfied:

[0066]

[0067] Where, P G,adjIt represents the power delivered by the 220kV or 500kV main transformer with the number adj corresponding to the fault identified by the provincial power grid. S is the switch column vector, S1~S n is the switch column vector of each topology unit, L s,1 ~L s,n is the linear coefficient row vector of the active power balance equation in each topological unit, B s,1 ~B s,n is the load factor vector, and I is the unit row vector.

[0068] Since there are different connection modes of substations in the distribution network, such as direct supply, series supply, T-type series supply and mixed series supply, different vectors and matrices need to correspond to the above formula, and they are determined according to the specific circumstances of the fault range.

[0069] The constraints required for the fault isolation mode adjustment in step 5 include:

[0070] 1) After the ground dispatcher adjusts the fault isolation mode, each power source point and switch status in the distribution network must meet the active power balance constraints, as follows:

[0071] P G,adj -(L s,adj S+B s,adj +ΔP G,adj )=0 adj=1,2,…N T (4)

[0072] Where, L s,adj is the linear coefficient row vector of the active power balance equation in each topological unit; △P G,adj The load control quantity required for the adj main transformer under the mode adjustment, N T Indicates the number of main transformers at the power point, B s,adj represents the load factor vector of adj main transformer, P G,adj It represents the power delivered by the 220kV or 500kV main transformer numbered adj corresponding to the fault determined by the provincial power grid, and S is the switch column vector.

[0073] 2) To ensure the safe operation of the power grid, the operation mode needs to be adjusted to prevent overload of power supply points and feeders, namely:

[0074]

[0075] Where, P F,line Indicates the feeder line transmission power, P G,adj,max and P F,line,max They represent the maximum power allowed to be sent down by the main transformer adj and the maximum power allowed to be transmitted by the feeder line, N F Indicates the number of feeder lines in the distribution network.

[0076] The specific form of the objective function in step 6 is as follows:

[0077] 1) Switching operation cost f1:

[0078]

[0079] Where, subscript u represents voltage level, K u is the switch operation cost coefficient corresponding to the voltage level; w is the switch number, Ns is the set of switches in the fault impact range; S' w and S w Respectively represent the switch status before and after the mode change.

[0080] 2) Load control cost f2:

[0081]

[0082] Where N adj Indicates the set of power main transformers that need to control the load after mode adjustment, C adj Indicates the cost coefficient corresponding to each power load control, △P G,adj It indicates the load control amount required for adjusting the adj main transformer.

[0083] 3) Overall objective function:

[0084] min F=f1+f2 (8)

[0085] Where F is the objective function for adjusting the ground fault handling method, which needs to include the switch operation cost f1 and the load control cost f2.

[0086] After solving the constraints and objective function for fault handling at the prefecture-level power grid, more than one adjustment strategy can generally be derived. These adjustments also affect the provincial main grid. Therefore, after the resulting strategies are ranked according to their objectives, the provincial coordination team verifies the risk of each strategy to the main grid and ultimately determines the adopted fault handling strategy to ensure the reliability and comprehensiveness of the results.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A provincial and regional integrated power grid fault handling method, characterized by: The following steps are involved: Step 1: The provincial and local integrated power grid model reads the grid equipment model data, power generation and consumption information, switch status, provincial and local grid boundaries, and grid operation data of each voltage level of the provincial and local dispatching at the current time section to determine the current provincial and local grid model; Step 2: Determine the fault information that needs to be resolved based on risk prediction or expected fault sets; Step 3: Substitute the fault information to be resolved into the provincial and local power grid model for simulation and power flow calculation to determine the power plants and lines where the power-off equipment and newly added overloaded equipment are located. Combined with the provincial and local power grid boundary information, the scope of the local dispatching grid affected by the fault is determined. The provincial dispatching system then issues a local dispatching grid scope adjustment to the local dispatching system based on the fault operation mode. Step 4: According to the adjusted local dispatching grid range, the corresponding local dispatching obtains the distribution network switch and load network topology relationship, generates the switch topology constraints corresponding to each wiring method, and generates the load factor matrix L of the power source point substation and switch topology relationship according to the switch topology constraints corresponding to each wiring method. s and the load factor vector B s ; Step 5: Load factor matrix L based on the topological relationship between power supply point substation and switch s and the load factor vector B s , as well as the 0-1 state of the grid switch before the fault occurs, to determine the various constraints required for the ground dispatcher to adjust the fault isolation mode; Step 6: Set an objective function for the adjustment strategy of the local power distribution network mode, solve the objective function in combination with the various constraints required for the local power distribution network to adjust the fault isolation mode, obtain the fault handling strategies and sort them, and obtain the sorted fault handling strategies; Step 7: The first fault handling strategy in the ranking is selected and sent back by the local dispatch to the provincial dispatch for simulated power flow calculation verification. The power outage equipment and newly added overloaded equipment are compared and a risk assessment is performed on the provincial dispatch grid. If there is a risk, the feedback is sent to the local dispatch and the local dispatch sends the next fault handling strategy in the ranking. The provincial dispatch continues to verify until the provincial dispatch risk assessment is within a reasonable range. The fault handling strategy is then output as the final strategy. The load factor matrix L s and the load factor vector B s The following relationship must be satisfied: Where, P G,adj It represents the power delivered by the 220kV or 500kV main transformer with the number adj corresponding to the fault identified by the provincial power grid. S is the switch column vector, S1~S n is the switch column vector of each topology unit, L s,1 ~L s,n is the linear coefficient row vector of the active power balance equation in each topological unit, B s,1 ~B s,n is the load factor vector, I is the unit row vector; The objective function includes: minF=f1+f2 Where F is the objective function for adjusting the ground fault handling method, f1 is the cost of switch operation times, and f2 is the load control cost; Cost of switching operations f1: Where, subscript u represents voltage level, K u is the switch operation cost coefficient corresponding to the voltage level; w is the switch number, Ns is the set of switches in the fault impact range; S' w and S w Respectively indicate the switch status before and after the mode change; Load control cost f2: Where N adj Indicates the set of power main transformers that need to control the load after mode adjustment, C adj Indicates the cost coefficient corresponding to each power load control, △P G,adj It indicates the load control amount required for adjusting the adj main transformer.

2. The provincial and local integrated power grid fault handling method according to claim 1, characterized in that: The provincial and local integrated power grid model includes all primary equipment, topology and power flow of 10kV-110kV at the prefectural level and 220kV-500kV at the provincial level, and is stored in the provincial and local integrated power grid platform.

3. The provincial and local integrated power grid fault handling method according to claim 1, characterized in that: The fault information includes: the location of the fault, the fault type, the duration, the impact on node lines of different voltage levels, and the predicted probability of the fault occurring.

4. The method for handling faults in a provincial and regional integrated power grid according to claim 1, characterized in that: The method for determining the scope of the ground-controlled power grid affected by the fault is as follows: Step 3.1: Record the provincial power grid measurement information before the fault and adjust the provincial power grid model operation mode according to the expected fault information; Step 3.2: Use power flow calculations to simulate and record power changes in the provincial power grid, compare them with the pre-fault state, and determine the specific branches affected by the fault. Step 3.3: Based on the provincial branches affected by the fault, the downstream subordinate local dispatch and the fault scope are obtained. The provincial dispatch eliminates some key lines and loads that cannot be adjusted, and determines the scope of operation mode adjustment required for the local dispatch grid, and sends it to the local dispatch.

5. A provincial and regional integrated power grid fault handling method according to claim 1 or 4, characterized in that: The power flow calculation must meet the following constraints: Where, P i With Q i represents the injected active and reactive power of node i; for each branch, P ji , Q ji , I ji is the active power, reactive power and current value from node j to node i, P ik , Q ik is the active and reactive power from node j to node k, r ij 、x ij represents the resistance and reactance of branch (i, j); Φ(i) and Ψ(i) represent the power flowing into and out of the node set connected to node i, respectively; N represents all branches in the entire network, N S Indicates all fault branches in the fault information.

6. The provincial and local integrated power grid fault handling method according to claim 1, characterized in that: The constraints required for the ground adjustment to adjust the fault isolation mode include: After the ground dispatcher adjusts the fault isolation mode, each power source point and switch status in the distribution network must meet the active power balance constraints, as follows: P G,adj -(L s,adj S+B s,adj +ΔP G,adj )=0adj=1,2,…N T Where, L s,adj is the row vector of linear coefficients of the active power balance equation in each topological unit; △P G,adj The load control quantity required for the adj main transformer under the mode adjustment, N T Indicates the number of main transformers at the power point, B s,adj represents the load factor vector of adj main transformer, P G,adj represents the power delivered by the 220kV or 500kV main transformer with the number adj corresponding to the fault identified by the provincial power grid, and S is the switch column vector; To ensure safe operation of the power grid, the ground regulator needs to adjust the operation mode to prevent overload of power points and feeders, namely: Where, P F,line Indicates the feeder line transmission power, P G,adj,max and P F,line,max They represent the maximum power allowed to be sent down by the main transformer adj and the maximum power allowed to be transmitted by the feeder line, N F Indicates the number of feeder lines in the distribution network.

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