Automatic voltage control method considering anticipated N-1 off-network fault of new energy station

Abstract

The invention provides an automatic voltage control method considering an anticipated N-1 off-network fault of a new energy station, and belongs to the technical field of automatic voltage control of a power system. The method comprises the following steps: when a preset calculation period arrives, constructing a coordination control partition model of a new energy gathering area; on the basis of the coordination control partition model, calculating the voltage variation of any new energy station in the partition to other buses in an off-network manner; and on the basis of the voltage variation, according to a calculation model of a voltage safety feasible region, calculating a bus voltage operation limit value of each bus in the partition under the condition of considering all new energy station N-1 off-network faults in the partition, and updating the bus voltage operation limit value to a reactive voltage automatic control system so as to realize automatic voltage control of the new energy station anticipated N-1 off-network faults. According to the invention, the system voltage can meet the requirement of safe operation of the voltage of each new energy station under the normal condition and after any new energy station is offline, and the adjustment target of safe, stable and high-quality voltage is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic voltage control of electric power systems, and in particular relates to an automatic voltage control method taking into account an expected N-1 off-grid fault of a new energy station. Background Art

[0002] As the capacity of new energy grid-connected becomes larger and larger, the problem of voltage stability in the new energy gathering area becomes prominent and has become one of the main obstacles hindering the normal grid-connected operation of new energy.

[0003] Large-scale renewable energy generation is highly intermittent, and the voltage fluctuations in the grid-connected area caused by changes in active output are relatively severe. When a fault or disturbance occurs, the voltage in the grid-connected area may change significantly and cause a chain of wind farms in the area to disconnect from the grid. Since it is difficult to achieve real-time control of the renewable energy regional power grid in an ultra-short time after a fault, preventive control is an effective solution.

[0004] In the process of multiple renewable energy stations disconnecting from the grid in a large-scale renewable energy collection area, the renewable energy collection area actually operates in an "unreasonable", "high risk" and "low margin" state before the fault. Although it meets the constraints of normal operation, once a disturbance occurs (such as a renewable energy station disconnecting from the grid), it loses the ability to continue to maintain normal operation after N-1. However, there is currently no automatic voltage control method that takes into account the expected N-1 disconnection fault of renewable energy stations. Summary of the invention

[0005] The purpose of the present invention is to fill the gap in the existing technology and propose an automatic voltage control method that takes into account the expected N-1 off-grid failure of a new energy station. The present invention can ensure that the system voltage can meet the requirements of safe operation of the voltage of each new energy station under normal circumstances and after any new energy station is off-grid, and achieve the goal of safe, stable and high-quality voltage regulation.

[0006] The embodiment of the present invention provides an automatic voltage control method taking into account the expected N-1 off-grid fault of a new energy station, including:

[0007] When the preset calculation cycle arrives, a coordinated control partition model of the new energy collection area is constructed; wherein the coordinated control partition is composed of a 500kV new energy collection station and a 220kV new energy field station under the new energy collection station;

[0008] Based on the coordinated control partition model, calculating the voltage change of other busbars caused by the disconnection of any new energy station in the partition;

[0009] Based on the voltage variation, according to the calculation model of the voltage safety feasible region, the bus voltage operation limit of each bus in the partition is calculated under the consideration of the N-1 off-grid fault of all new energy stations;

[0010] The bus voltage operating limit is updated to the reactive voltage automatic control system to realize automatic voltage control of the expected N-1 grid-off fault of the new energy station.

[0011] In a specific embodiment of the present invention, the coordinated control partition model is recorded as in, Indicates a 500-220kV coordinated control zone; Represents a partition The 500kV main transformer equipment set included; Represents a partition The included 500kV main transformer is connected to the high-voltage side 500kV busbar equipment set; Represents a partition The included 220kV busbar equipment set on the medium voltage side connected to the 500kV main transformer; Represents a partition The medium-voltage side of the 500kV main transformer included in it is connected to the high-voltage side busbar equipment of the lower-level 220kV substation and power plant.

[0012] In a specific embodiment of the present invention, the calculation of the voltage change of other busbars caused by any new energy station being disconnected from the grid in the subzone includes:

[0013] 1) Obtain the partition based on the Jacobian matrix in the Newton-Raphson power flow algorithm After any new energy station j is injected into the busbar where the unit reactive power is output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Reactive voltage sensitivity of other busbars i

[0014] 2) Based on the Jacobian matrix in the Newton-Raphson power flow algorithm, after the busbar where the new energy station j is located injects unit active output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Active voltage sensitivity of other busbars i

[0015] 3) Based on the results of steps 1) and 2), solve the partition After any new energy station j is disconnected from the grid, the voltage change value of other busbars i in the zone is:

[0016]

[0017] in, is the current real-time active power output of the new energy station j, is the current real-time reactive power output of the new energy station j; ΔV j,i is the voltage change on bus i caused by the disconnection of new energy station j from the grid; ΔV j,i >0 indicates the voltage increase amplitude of bus i caused by the jth new energy station disconnecting from the grid, ΔV j,i <0 indicates the voltage reduction amplitude of bus i caused by the j-th renewable energy station being disconnected from the grid.

[0018] In a specific embodiment of the present invention, the calculation of the bus voltage operating limit of each bus in the partition under the consideration of all new energy stations N-1 off-grid faults includes:

[0019]

[0020] in, Considering the partition for bus i The upper limit of bus voltage operation after the maximum voltage rise caused by the N-1 off-grid fault of all new energy stations in the network, Considering the partition for bus i The lower limit of bus voltage operation after the maximum voltage drop caused by the N-1 off-grid fault of all new energy stations in the network, The pre-set upper limit of voltage safety for bus i. The preset voltage operating safety lower limit for bus i.

[0021] The characteristics and beneficial effects of the present invention are:

[0022] The present invention calculates the voltage sensitivity of each bus in the partition to the active and reactive power currently injected by the new energy station online, finds the change of the voltage of other buses in the partition after any new energy station in the partition is disconnected from the grid, and corrects and controls the bus voltage operation in the partition to ensure that when the new energy station N-1 is disconnected from the grid in the partition, other buses can also operate normally after the accident, so as to avoid the occurrence of large-scale chain disconnection accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is an overall flow chart of an automatic voltage control method taking into account an expected N-1 grid-off failure of a new energy station according to an embodiment of the present invention.

[0024] Figure 2 The figure is a schematic diagram of the network topology of a new energy collection area according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention proposes an automatic voltage control method taking into account an expected N-1 grid-off failure of a new energy station, which is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The embodiment of the present invention provides an automatic voltage control method taking into account the expected N-1 off-grid fault of a new energy station, including:

[0027] When the preset calculation cycle arrives, a coordinated control partition model of the new energy collection area is constructed; wherein the coordinated control partition is composed of a 500kV new energy collection station and a 220kV new energy field station under the new energy collection station;

[0028] Based on the coordinated control partition model, calculating the voltage change of other busbars caused by the disconnection of any new energy station in the partition;

[0029] Based on the voltage variation, according to the calculation model of the voltage safety feasible region, the bus voltage operation limit of each bus in the partition is calculated under the consideration of the N-1 off-grid fault of all new energy stations;

[0030] The bus voltage operating limit is updated to the reactive voltage automatic control system to realize automatic voltage control of the expected N-1 grid-off fault of the new energy station.

[0031] In a specific embodiment of the present invention, the automatic voltage control method considering the expected N-1 fault of the new energy station is as follows: Figure 1 As shown, the following steps are included:

[0032] 1) When the preset calculation cycle arrives, a coordinated control partition model of the new energy collection area is automatically formed according to the characteristics of the power grid operation.

[0033] In this embodiment, the model corresponding to any partition is recorded as in, It represents a 500-220kV coordinated control zone, which consists of a 500kV new energy collection station and a 220kV new energy station under the new energy collection station. Represents a partition The 500kV main transformer equipment set included; Represents a partition The included 500kV main transformer is connected to the high-voltage side 500kV busbar equipment set; Represents a partition The included 220kV busbar equipment set on the medium voltage side connected to the 500kV main transformer; Represents a partition The high-voltage side busbar equipment set of the lower-level 220kV substation and power plant connected to the medium-voltage side of the 500kV main transformer included in the calculation cycle of this embodiment is no more than 15 minutes.

[0034] 2) Based on the model in step 1), online calculation is performed on the voltage change of other buses caused by the disconnection of any new energy station in the zone.

[0035] In this embodiment, the partition The steps for calculating the voltage change of any other bus i except the bus where the station is located when any new energy station j is disconnected from the grid are as follows:

[0036] 2-1) Based on the Jacobian matrix in the Newton-Raphson power flow algorithm, after the busbar where the new energy station j is located injects unit reactive power output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Reactive voltage sensitivity of other busbars i

[0037] 2-2) Based on the Jacobian matrix in the Newton-Raphson power flow algorithm, after the busbar where the new energy station j is located injects unit active power output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Active voltage sensitivity of other busbars i

[0038] 2-3) Based on the results of steps 2-1) and 2-2), solve the partition After any new energy station j is disconnected from the grid, the voltage change value of other busbars i in the zone is:

[0039]

[0040] in, is the current real-time active power output of the new energy station j, is the current real-time reactive power output of the new energy station j; ΔV j,i is the voltage change on bus i caused by the disconnection of new energy station j from the grid; ΔV j,i >0 indicates the voltage increase amplitude of bus i caused by the jth new energy station disconnecting from the grid, ΔV j,i <0 indicates the voltage reduction amplitude of bus i caused by the j-th renewable energy station being disconnected from the grid.

[0041] This step can be used to calculate the partition After each new energy station is disconnected from the grid, the voltage change value of other buses in the zone.

[0042] 3) Based on the result of step 2), according to the calculation model of voltage safety feasible domain, calculate the bus voltage operation limit of each bus in the zone under the consideration of N-1 grid-off failure of all new energy stations in the zone.

[0043] In this embodiment, the calculation model expression of the voltage safety feasible region of bus i is as follows:

[0044]

[0045] in, Considering the partition for bus i The upper limit of bus voltage operation after the maximum voltage rise caused by the N-1 off-grid fault of all new energy stations in the network, Considering the partition for bus i The lower limit of bus voltage operation after the maximum voltage drop caused by the N-1 off-grid fault of all new energy stations in the network, The pre-set upper limit of voltage safety for bus i. The preset voltage operating safety lower limit for bus i.

[0046] 4) The bus voltage operating limit obtained in step 3) is updated to the reactive voltage automatic control system to realize automatic voltage control of the expected N-1 fault of the new energy station.

[0047] In this embodiment, the voltage operating limit value of bus i obtained in step 3) is Update to the reactive voltage automatic control system so that the real-time voltage measurement value of bus i runs at within the range.

[0048] Then when the next calculation cycle comes, return to step 1).

[0049] The method described in this embodiment is described in detail below in conjunction with a specific embodiment.

[0050] In a specific embodiment of the present invention, Figure 2 This is a typical network topology diagram of a new energy collection area. New energy stations C, D, and E are connected to the upper collection station, namely, the new energy collection station A, through the grid connection point. Among them, the new energy collection station is generally 500kV, and the new energy station is generally 220kV. The new energy station is connected to the power grid through the medium-voltage side of the main transformer of the collection station. In this embodiment, the new energy collection station A and the new energy stations C, D, and E constitute a coordinated control partition.

[0051] In this embodiment, the automatic voltage control method considering the expected N-1 off-grid fault of the new energy station includes the following steps:

[0052] 1) When the calculation cycle arrives (15 minutes in this embodiment), a coordinated control partition model of the new energy collection area is automatically formed according to the characteristics of the power grid operation.

[0053] In this embodiment, the partition model includes: New energy collection station A high voltage side 500kV bus equipment B Ah , Medium voltage side 220kV busbar equipment B Am ; New energy station C high voltage side 500kV busbar equipment B Ch ; New energy station D high voltage side 500kV busbar equipment B Dh ; New energy station E high voltage side 500kV busbar equipment B Eh .

[0054] 2) Based on the model in step 1), online calculation is performed on the voltage change of other buses caused by the disconnection of any new energy station in the partition. The specific steps are as follows:

[0055] 2-1) Based on the Jacobian matrix in the Newton-Raphson power flow algorithm, after the busbar where the new energy station j is located injects unit reactive power output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Reactive voltage sensitivity of other busbars i

[0056] In a specific embodiment of the present invention, the calculated As shown in Table 1:

[0057] Table 1 Reactive voltage sensitivity table of a specific embodiment of the present invention

[0058]

[0059] 2-2) Based on the Jacobian matrix in the Newton-Raphson power flow algorithm, after the busbar where the new energy station j is located injects unit active power output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Active voltage sensitivity of other busbars i

[0060] In a specific embodiment of the present invention, the calculated As shown in Table 2:

[0061] Table 2 Active voltage sensitivity table of a specific embodiment of the present invention

[0062]

[0063]

[0064] 2-3) Based on the results of steps 2-1) and 2-2), solve the partition After any new energy station j is disconnected from the grid, the voltage change value of other busbars i in the zone is:

[0065]

[0066] In this embodiment, the current active power measurement of the new energy station C is The current reactive power measurement is The current active power measurement of the new energy station D is The current reactive power measurement is The current active power measurement of the new energy station E is The current reactive power measurement is The bus voltage change values ​​calculated in this embodiment are shown in Table 3:

[0067] Table 3 Bus voltage variation value table of a specific embodiment of the present invention

[0068]

[0069]

[0070] 3) Based on the results of step 2), according to the calculation model of the voltage safety feasible domain, the bus voltage operating limit of each bus in the zone is obtained when considering the N-1 grid-off failure of all new energy stations.

[0071] In this embodiment, the calculation model expression of the voltage safety feasible region of bus i is as follows:

[0072]

[0073] In this embodiment, the new energy collection station bus B Ah Pre-set voltage operating safety upper limit Pre-set voltage operating safety lower limit New energy collection station bus B Am Pre-set voltage operating safety upper limit Pre-set voltage operating safety lower limit New Energy Station C Bus B Ch Pre-set voltage operating safety upper limit Pre-set voltage operating safety lower limit New Energy Station D Busbar B Dh Pre-set voltage operating safety upper limit Pre-set voltage operating safety lower limit New Energy Station E Bus B EhPre-set voltage operating safety upper limit Pre-set voltage operating safety lower limit The bus voltage operating limit values ​​calculated in this embodiment after considering the N-1 off-grid fault are shown in Table 4:

[0074] Table 4 Bus voltage operating limit table considering N-1 fault in a specific embodiment of the present invention

[0075]

[0076]

[0077] 4) The bus voltage operating limit obtained in step 3) is updated to the reactive voltage automatic control system to realize automatic voltage control of the expected N-1 fault of the new energy station.

[0078] In this embodiment, the voltage operating limit value of bus i obtained in step 3) is Update to the reactive voltage automatic control system so that the real-time voltage measurement value of bus i runs at within the range.

[0079] Then when the next calculation cycle comes, return to step 1).

Claims

1. An automatic voltage control method considering the expected N-1 off-grid failure of a new energy station, characterized in that: include: When the preset calculation cycle arrives, a coordinated control partition model of the new energy collection area is constructed; wherein the coordinated control partition is composed of a 500kV new energy collection station and a 220kV new energy field station under the new energy collection station; Based on the coordinated control partition model, calculating the voltage change of other busbars caused by the disconnection of any new energy station in the partition; Based on the voltage variation, according to the calculation model of the voltage safety feasible region, the bus voltage operation limit of each bus in the partition is calculated under the consideration of the N-1 off-grid fault of all new energy stations; The bus voltage operating limit is updated to the reactive voltage automatic control system to realize automatic voltage control of the expected N-1 grid-off fault of the new energy station.

2. The method according to claim 1, characterized in that The coordinated control partition model is denoted as in, Indicates a 500-220kV coordinated control zone; Represents a partition The 500kV main transformer equipment set included; Represents a partition The 500kV busbar equipment set on the high-voltage side connected to the 500kV main transformer included; Represents a partition The included 220kV busbar equipment set on the medium voltage side connected to the 500kV main transformer; Represents a partition The medium-voltage side of the 500kV main transformer included in it is connected to the high-voltage side busbar equipment of the lower-level 220kV substation and power plant.

3. The method according to claim 2, characterized in that The calculation of the voltage change of other busbars caused by any new energy station disconnecting from the grid in the subzone includes: 1) Obtain the partition based on the Jacobian matrix in the Newton-Raphson power flow algorithm After any new energy station j is injected into the busbar where the unit reactive power is output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Reactive voltage sensitivity of other busbars i 2) Based on the Jacobian matrix in the Newton-Raphson power flow algorithm, after the busbar where the new energy station j is located injects unit active output, the partition The line voltage amplitude change of other busbars i is recorded as That is, the bus pair partition where the new energy station j is located Active voltage sensitivity of other busbars i 3) Based on the results of steps 1) and 2), solve the partition After any new energy station j is disconnected from the grid, the voltage change value of other busbars i in the zone is: in, is the current real-time active power output of the new energy station j, is the current real-time reactive power output of the new energy station j; ΔV j,i is the voltage change on bus i caused by the disconnection of new energy station j from the grid; ΔV j,i >0 indicates the voltage increase amplitude of bus i caused by the jth new energy station disconnecting from the grid, ΔV j,i <0 indicates the voltage reduction amplitude of bus i caused by the j-th renewable energy station being disconnected from the grid.

4. The method according to claim 3, characterized in that The calculation of the bus voltage operating limit of each bus in the partition under the consideration of all new energy stations N-1 off-grid faults includes: in, Considering the partition for bus i The upper limit of bus voltage operation after the maximum voltage rise caused by the N-1 off-grid fault of all new energy stations in the network, Considering the partition for bus i The lower limit of bus voltage operation after the maximum voltage drop caused by the N-1 off-grid fault of all new energy stations in the network, The pre-set upper limit of voltage safety for bus i. The preset voltage operating safety lower limit for bus i.

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