A method for adjusting power flow before maintenance considering the phase shifter closing device of distribution network

Abstract

The present invention belongs to the field of power system operation and optimization, and discloses a method for adjusting the flow before maintenance considering a phase shifter closing device of a distribution network. The phase shifter closing device is installed on a closing line. Since the phase shifter can adjust the voltage amplitude and phase difference at both ends, the line can complete the safe closing before maintenance when the voltage difference between the nodes at both ends is large. The method includes the following steps: determining the line that needs to be closed; establishing a distribution network flow optimization model considering the phase shifter closing device; and outputting the optimization result. The method considers adding a phase shifter closing device to a closing line where the voltage is difficult to control, so as to reduce the voltage difference on both sides of the closing line, optimize the flow, and ensure the safety of the closing.

Description

Technical Field

[0001] The invention belongs to the field of power system operation and optimization, and in particular relates to a pre-maintenance power flow adjustment method considering a phase shifter closing device of a distribution network. Background Art

[0002] As the economic and safe operation of power systems has received increasing attention, how to reduce network losses, improve power supply quality and increase economic benefits has become a practical problem facing the power sector.

[0003] Phase-shifting transformers inject lateral or longitudinal voltage in series in the transmission line to change the voltage amplitude and phase at the device installation point, thereby effectively controlling the line flow. The technology of phase shifters is relatively mature, and the maintenance of phase shifters is simple and economical, so it is considered to be applied to closed-loop control devices.

[0004] Before the distribution network is overhauled, load transfer is required, which will involve the closing operation of some lines. Due to the voltage difference on both sides of the closing loop, a large closing loop impact current will be generated, causing a huge impact on the line, and even causing great harm to the entire system, bringing immeasurable consequences. It is a practical issue that must be considered to control the voltage difference on both sides of the closing loop within a safe range. In addition, some lines still have a large voltage difference that is difficult to adjust, and countermeasures need to be proposed. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for adjusting the flow before maintenance of a distribution network phase shifter closing device, thereby solving the problem in the prior art that there is a voltage difference on both sides of the closing loop, which will generate a large closing loop impact current, causing a huge impact on the line and even causing great harm to the entire system.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for adjusting power flow before maintenance considering a phase shifter closing device of a distribution network comprises the following steps:

[0008] S1 determines the line that needs to be closed;

[0009] S2 establishes a distribution network power flow optimization model considering the phase shifter closing device;

[0010] S3 outputs the power flow optimization results.

[0011] Furthermore, the lines that need to be closed in the distribution network are interconnection lines that are not put into operation when the distribution network is actually in operation, and lines used for load transfer or dispatching.

[0012] Furthermore, the closed-loop circuit equipped with the phase shifter closed-loop device reduces the closed-loop voltage difference through the phase shifter.

[0013] Furthermore, the phase shifter loop closing device changes its own voltage difference by adjusting the configuration value to compensate for the voltage difference on both sides of the loop closing circuit.

[0014] Furthermore, the objective function of the distribution network power flow optimization model considering the phase shifter closing device is:

[0015]

[0016] Among them, U i , U j Represent the node voltages at i and j respectively; G ij , B ij denote the conductance and susceptance of lines i and j respectively; represents the voltage phase difference between nodes i and j; b represents the number of closed-loop lines without phase shifter closed-loop devices installed; T represents the set of closed-loop lines without phase shifter closed-loop devices installed; ΔU i 2 U represents the square of the voltage amplitude difference between the nodes on both sides of the i-th closed-loop line without the phase shifter closed-loop device installed; imax , U imin They respectively represent the maximum and minimum values ​​allowed for the voltage of the i-th closed-loop line without a phase shifter closing device installed; It represents the square of the voltage phase difference between the nodes on both sides of the i-th closed-loop line without the phase shifter closed-loop device installed; Respectively represent the maximum and minimum values ​​of the voltage phase of the i-th closed-loop line without the phase shifter closed-loop device installed; σ 1i is the penalty function coefficient of the voltage amplitude of the i-th closed-loop line without the phase shifter closed-loop device installed, σ 2i is the penalty function coefficient of the voltage phase of the i-th closed-loop line without a phase shifter closed-loop device installed.

[0017] Furthermore, the closed-loop line without the phase shifter closed-loop device installed realizes voltage control by adjusting the control variables of the optimization model.

[0018] Furthermore, the control variables of the optimization model include generator terminal voltage and node reactive power compensation.

[0019] Furthermore, the output power flow optimization results include the minimum network loss value obtained by optimization and the optimal parameter value when the network loss is minimum.

[0020] Furthermore, the optimal parameter values ​​when the network loss is minimized include the generator terminal voltage V G , reactive power compensation Q at node i ci .

[0021] Beneficial effects of the present invention:

[0022] The present invention takes the safety of the closed loop into consideration during the process of optimizing the power flow of the distribution network. Phase shifter closed loop devices are installed on some closed loop lines, which solves the problem that the voltage difference on both sides of the closed loop line is large and difficult to adjust, ensures the safety of the closed loop operation, reduces the impact of the closed loop current on the system, and also reduces the network loss of the system, effectively ensuring the safe and economical operation of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a flow chart of a method for optimizing power flow in a distribution network according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, the present invention provides a technical solution, a method for adjusting the flow before maintenance considering the phase shifter closing device of the distribution network. In the process of optimizing the flow of the distribution network, when considering the line load transfer and dispatch, there are multiple lines that need to be closed. The closing lines where some voltages are difficult to adjust are added with a phase shifter closing device to reduce the voltage difference on both sides of the closing line, thereby ensuring the safety of the closing operation and the safe operation of the entire system. The method includes the following steps:

[0027] S1 determines the line that needs to be closed;

[0028] S2 establishes a distribution network power flow optimization model considering the phase shifter closing device;

[0029] S3 outputs the power flow optimization results.

[0030] Further explanation is given for step S1:

[0031] In step S1, before the distribution network lines are inspected and repaired, they need to be closed. The closed lines are interconnection lines that are not put into operation during the actual operation of the distribution network, as well as lines used for load transfer or dispatching.

[0032] Further explanation is given for step S2:

[0033] In step S2, the closed-loop circuit equipped with a phase shifter closed-loop device reduces the closed-loop voltage difference through the phase shifter.

[0034] In step S2, the phase shifter loop closing device changes its own voltage difference by adjusting the configuration value to compensate for the voltage difference on both sides of the loop closing line.

[0035] In step S2, the objective function of the distribution network power flow optimization model considering the phase shifter loop closing device is:

[0036]

[0037] Among them, the first item represents the active network loss of the distribution network, and the second and third items represent the amplitude difference and phase difference of the voltage on both sides of each closed-loop line. Both are added to the target in the form of penalty functions to ensure that the voltage on both sides of the closed-loop meets the requirements.

[0038] Among them, U i , U j Represent the node voltages at i and j respectively; G ij , B ij denote the conductance and susceptance of lines i and j respectively; represents the voltage phase difference between nodes i and j; b represents the number of closed-loop lines without phase shifter closed-loop devices installed; T represents the set of closed-loop lines without phase shifter closed-loop devices installed; ΔU i 2 U represents the square of the voltage amplitude difference between the nodes on both sides of the i-th closed-loop line without the phase shifter closed-loop device installed; imax , U imin They respectively represent the maximum and minimum values ​​allowed for the voltage of the i-th closed-loop line without a phase shifter closing device installed; It represents the square of the voltage phase difference between the nodes on both sides of the i-th closed-loop line without the phase shifter closed-loop device installed; Respectively represent the maximum and minimum values ​​of the voltage phase of the i-th closed-loop line without the phase shifter closed-loop device installed; σ 1i is the penalty function coefficient of the voltage amplitude of the i-th closed-loop line without the phase shifter closed-loop device installed, σ 2i is the penalty function coefficient of the voltage phase of the i-th closed-loop line without a phase shifter closed-loop device installed.

[0039] In step S2, the phase shifter loop closing device is constrained as follows:

[0040]

[0041]

[0042] -13≤T1≤13, T1∈N

[0043] -13≤T2≤13, T2∈N

[0044] in, is the angle value adjusted by the phase shifter; k is the multiple of the phase shifter voltage regulation; T1 and T2 are the configuration values ​​of the phase shifter, which are used to adjust the voltage phase angle and amplitude respectively; U1 and U2 are the voltage values ​​on both sides of the phase shifter respectively.

[0045] In step S2, the distribution network is subject to the following constraints:

[0046] (1) Power balance constraints:

[0047]

[0048]

[0049] Among them, P i , Q i Respectively represent the active and reactive input at node i; U i , U j Represent the voltage at node i and node j respectively; G ij , B ij They represent the conductance and susceptance of line ij respectively; Represents the voltage phase difference between nodes i and j.

[0050] (2) Generator voltage constraints:

[0051] U gmin ≤U g ≤U gmax

[0052] Among them, U g is the generator terminal voltage, U gmax , U gmin are the upper and lower limits of the generator voltage respectively.

[0053] (3) Reactive power compensation constraints:

[0054] Q cimin ≤Q ci ≤Q cimax

[0055] Among them, Q ci is the reactive power compensation at node i, Q cimax , Q cimin They are the upper and lower limits of reactive power compensation respectively.

[0056] (4) Loop line constraints:

[0057] |ΔU*|≤0.05

[0058]

[0059] Among them, ΔU*, Indicates the per unit value and phase difference of the voltage difference between the nodes on both sides of the closed-loop line.

[0060] In step S2, the closed-loop line without the phase shifter closed-loop device installed realizes voltage control by adjusting the control variables of the optimization model (the control variables of the optimization model include the generator terminal voltage and node reactive power compensation).

[0061] In step S3, the output power flow optimization result includes the minimum network loss value obtained by optimization and the optimal parameter value when the network loss is the smallest (the optimal parameter value includes the generator terminal voltage V G , reactive power compensation Q at node i ci ).

[0062] The present invention takes the safety of the closed loop into consideration during the process of optimizing the power flow of the distribution network. Phase shifter closed loop devices are installed on some closed loop lines, which solves the problem that the voltage difference on both sides of the closed loop line is large and difficult to adjust, ensures the safety of the closed loop operation, reduces the impact of the closed loop current on the system, and also reduces the network loss of the system, effectively ensuring the safe and economical operation of the distribution network.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0064] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for adjusting power flow before maintenance considering a phase shifter closing device of a distribution network, characterized in that: The following steps are involved: S1 determines the line that needs to be closed; S2 establishes a distribution network power flow optimization model considering the phase shifter closing device; S3 outputs the power flow optimization results; The objective function of the distribution network power flow optimization model of the phase shifter closing device is: in, Ui , Uj Respectively i , j The node voltage at Gij , Bij Respectively indicate lines i , j Conductance and susceptance; φij Representation Node i , j The voltage phase difference; b represents the number of closed-loop lines without the phase shifter closed-loop device installed; T represents the set of closed-loop lines without the phase shifter closed-loop device installed; Indicates i The square of the voltage amplitude difference between the nodes on both sides of the closed-loop line without the phase shifter closed-loop device installed; , Respectively represent i The maximum and minimum values ​​allowed for the voltage of the closed-loop line without a phase shifter closing device installed; Indicates i The square of the voltage phase difference between the nodes on both sides of the closed-loop line without a phase shifter closed-loop device installed; , Respectively represent i The maximum and minimum values ​​of the voltage phase of the closed-loop line without a phase shifter closing device installed; For the i The penalty function coefficient of the voltage amplitude of the closed-loop line without the phase shifter closed-loop device installed, For the i The penalty function coefficient of the voltage phase of the closed-loop line without the phase shifter closed-loop device installed; The control variables of the optimization model include generator terminal voltage and node reactive power compensation; The output power flow optimization results include the minimum network loss value obtained by optimization and the optimal parameter value when the network loss is the minimum; The optimal parameter values ​​for the minimum grid loss include the generator terminal voltage VG , reactive power compensation at node i Q .

2. A method for adjusting power flow before maintenance considering a phase shifter closing device of a distribution network according to claim 1, characterized in that: The lines that need to be closed in the distribution network are the interconnection lines that are not put into operation when the distribution network is actually operating, as well as the lines used for load transfer or dispatching.

3. A method for adjusting power flow before maintenance considering a phase shifter closing device of a distribution network according to claim 1, characterized in that: The closed-loop circuit equipped with a phase shifter closed-loop device reduces the closed-loop voltage difference through the phase shifter.

4. A method for adjusting power flow before maintenance considering a phase shifter closing device of a distribution network according to claim 3, characterized in that: The phase shifter closing device changes its own voltage difference by adjusting the configuration value to compensate for the voltage difference on both sides of the closing line.

5. A method for adjusting power flow before maintenance considering a phase shifter closing device of a distribution network according to claim 4, characterized in that: The voltage of the closed-loop line without the phase shifter closed-loop device is controlled by adjusting the control variables of the optimization model.

Images