CN109521321B - Compensation voltage prediction method for full compensation of controllable voltage source - Google Patents
Compensation voltage prediction method for full compensation of controllable voltage source Download PDFInfo
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- CN109521321B CN109521321B CN201910089407.9A CN201910089407A CN109521321B CN 109521321 B CN109521321 B CN 109521321B CN 201910089407 A CN201910089407 A CN 201910089407A CN 109521321 B CN109521321 B CN 109521321B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
Abstract
The method for predicting the compensation voltage of the controllable voltage source full compensation can quickly and accurately calculate the compensation output value of the controllable voltage source during single-phase grounding under various topological structures of the controllable voltage source grounding current full compensation, is quick, effective and simple, and can be well suitable for an actual power distribution network system.
Description
Technical Field
The application relates to the technical field of single-phase grounding full compensation of a power grid, in particular to a compensation voltage prediction method for full compensation of a controllable voltage source.
Background
In a power grid system, particularly in a medium-low voltage power distribution network system, single-phase earth faults account for the absolute majority of the total number of faults. The neutral point grounding mode of the medium and low voltage distribution network mainly comprises a neutral point ungrounded mode, a neutral point grounded mode through an arc suppression coil or a neutral point grounded mode through a low-value resistor. Under the mode that the neutral point is not grounded, grounding current is not compensated and operates with faults, and personal electric shock risks exist. Under the mode that the neutral point is grounded through the arc suppression coil, the arc suppression coil compensates grounding capacity flow after single-phase grounding, grounding electric arcs can be extinguished, a system can operate with faults, but certain grounding residual flow still exists in the grounding point, and personal electric shock risks still exist. Under the mode that the neutral point is grounded through a low-value resistor, the grounding circuit is tripped through the zero sequence protection of the circuit of the relay protection device, and the power supply reliability cannot be guaranteed. The grounding current of the power grid system is fully compensated, the grounding point current can be compensated to a minimum value when single-phase grounding is carried out, the system can still operate with faults, and the personal electric shock danger of the grounding point is eliminated.
Disclosure of Invention
The application provides a compensation voltage prediction method for controllable voltage source full compensation, and aims to solve the problems that an existing compensation voltage determination method for current full compensation is complex and is difficult to apply to an actual power distribution network system.
The application provides a compensation voltage prediction method for full compensation of a controllable voltage source, which is applied to determining the full compensation voltage of a power distribution network ground fault by adopting the controllable voltage source, and comprises the following steps:
obtaining a phase angle and an amplitude of an initial voltage of a three-phase voltage, wherein the initial voltage is a voltage of a target phase without a ground fault;
calculating the difference value between the phase angle of the initial voltage of a target phase and the phase angles of the initial voltages of the other two phases to obtain a first phase angle difference value and a second phase angle difference value, wherein the target phase is any phase in a three-phase power supply;
calculating the difference value between the absolute value of the first phase angle difference value and the absolute value of the second phase angle difference value according to the first phase angle difference value and the second phase angle difference value to obtain a third phase angle difference value;
controlling the controllable voltage source to output an initial detection voltage, and acquiring a voltage amplitude value and a phase angle of the initial detection voltage;
adjusting the phase of the initial detection voltage according to a preset adjustment step length, and measuring the corresponding voltage phase angle of three phases;
respectively calculating to obtain the difference value between the measured voltage phase angle of the target phase and the measured voltage phase angles of the other two phases to obtain a fourth phase angle difference value and a fifth phase angle difference value;
calculating the difference value of the absolute value of the fourth phase angle difference value and the absolute value of the fifth phase angle difference value according to the fourth phase angle difference value and the fifth phase angle difference value to obtain a sixth phase angle difference value;
judging whether the absolute value of the sixth phase angle difference value is smaller than the absolute value of the third phase angle difference value, if so, according to the phase angle of the detection voltage of the controllable voltage source obtained by adjustment and the phase angle and the voltage amplitude of the initial voltage of the target phase, the adopted formula is as follows:
calculating to obtain the voltage amplitude and the phase angle of the compensation voltage of the controllable voltage source; if it isIf not, jumping to the step of adjusting the phase of the initial detection voltage;
wherein, UphIs the voltage magnitude of the initial voltage of the target phase,
to adjust the resulting phase angle of the detected voltage of the controllable voltage source,
is the phase angle of the initial voltage of the target phase, Ucom is the voltage amplitude of the compensation voltage of the controllable voltage source, ∠ Ucom is the phase angle of the compensation voltage of the controllable voltage source.
Further, the preset adjusting step is between 0.01 and 0.5 degrees.
Further, the frequency of the initial detection voltage is 50Hz, and the voltage amplitude is 100V-1000V.
Further, the controllable voltage source is connected with an arc suppression coil in parallel.
According to the technical scheme, the compensation voltage prediction method for the controllable voltage source full compensation is provided, the compensation output value of the controllable voltage source during single-phase grounding can be rapidly and accurately calculated under various topological structures of controllable voltage source grounding current full compensation, and the calculation method is rapid, effective, simple and convenient and can be well suitable for an actual power distribution network system.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.
FIG. 1 is a circuit diagram of an embodiment of a compensation circuit for full compensation of a controllable voltage source applied in the present application;
FIG. 2 is a circuit diagram of another embodiment of a compensation circuit for full compensation of a controllable voltage source applied in the present application;
fig. 3 is a flowchart of a compensation voltage prediction method for full compensation of a controllable voltage source according to the present application.
Detailed Description
Referring to fig. 1, the present application provides a compensation voltage prediction method for full compensation of a controllable voltage source, which is applied to determining a full compensation voltage of a power distribution network ground fault by using the controllable voltage source. Preferably, the controllable voltage source is connected in parallel with a crowbar coil, the specific circuit being shown in fig. 2, where UA、UBAnd UCA, B and phase C of the three-phase voltage.
Referring to fig. 3, another embodiment of the present application provides a compensation voltage prediction method for full compensation of a controllable voltage source based on the above circuit, including the following steps:
step 31: and acquiring the phase angle and amplitude of the initial voltage of the three-phase voltage, wherein the initial voltage is the voltage of the target phase without the ground fault.
Step 32: and calculating the difference value between the phase angle of the initial voltage of the target phase and the phase angles of the initial voltages of the other two phases to obtain a first phase angle difference value and a second phase angle difference value, wherein the target phase is any phase in the three-phase power supply.
Step 33: and calculating the difference value between the absolute value of the first phase angle difference value and the absolute value of the second phase angle difference value according to the first phase angle difference value and the second phase angle difference value to obtain a third phase angle difference value.
Step 34: and controlling the controllable voltage source to output an initial detection voltage, and acquiring the voltage amplitude and the phase angle of the initial detection voltage. The frequency of the initial detection voltage is 50Hz, and the voltage amplitude is 100V-1000V.
Step 35: and adjusting the phase of the initial detection voltage according to a preset adjustment step length, and measuring the corresponding three-phase voltage phase angle. Specifically, the preset adjustment step size is between 0.01 and 0.5.
Step 36: and respectively calculating to obtain the difference value between the measured voltage phase angle of the target phase and the measured voltage phase angles of the other two phases to obtain a fourth phase angle difference value and a fifth phase angle difference value.
Step 37: and calculating the difference value of the absolute value of the fourth phase angle difference value and the absolute value of the fifth phase angle difference value according to the fourth phase angle difference value and the fifth phase angle difference value to obtain a sixth phase angle difference value.
Step 38: judging whether the absolute value of the sixth phase angle difference is smaller than the absolute value of the third phase angle difference, if so, executing step 39; if not, go to step 35.
Step 39: according to the phase angle of the detected voltage of the controllable voltage source obtained by adjustment and the phase angle and the voltage amplitude of the initial voltage of the target phase, the adopted formula is as follows:
and calculating the voltage amplitude and the phase angle of the compensation voltage of the controllable voltage source.
Wherein, UphIs the voltage magnitude of the initial voltage of the target phase,
to adjust the resulting phase angle of the detected voltage of the controllable voltage source,
is the phase angle of the initial voltage of the target phase, Ucom is the voltage amplitude of the compensation voltage of the controllable voltage source, ∠ Ucom is the phase angle of the compensation voltage of the controllable voltage source.
According to the technical scheme, the compensation voltage prediction method for the controllable voltage source full compensation is provided, the compensation output value of the controllable voltage source during single-phase grounding can be rapidly and accurately calculated under various topological structures of controllable voltage source grounding current full compensation, and the calculation method is rapid, effective, simple and convenient and can be well suitable for an actual power distribution network system.
Claims (4)
1. A compensation voltage prediction method for full compensation of a controllable voltage source is applied to determination of full compensation voltage of a power distribution network ground fault by adopting the controllable voltage source, and is characterized by comprising the following steps:
obtaining a phase angle and an amplitude of an initial voltage of a three-phase voltage, wherein the initial voltage is a voltage of a target phase without a ground fault;
calculating the difference value between the phase angle of the initial voltage of a target phase and the phase angles of the initial voltages of the other two phases to obtain a first phase angle difference value and a second phase angle difference value, wherein the target phase is any phase in a three-phase power supply;
calculating the difference value between the absolute value of the first phase angle difference value and the absolute value of the second phase angle difference value according to the first phase angle difference value and the second phase angle difference value to obtain a third phase angle difference value;
controlling the controllable voltage source to output an initial detection voltage, and acquiring a voltage amplitude value and a phase angle of the initial detection voltage;
adjusting the phase of the initial detection voltage according to a preset adjustment step length, and measuring the corresponding voltage phase angle of three phases;
respectively calculating to obtain the difference value between the measured voltage phase angle of the target phase and the measured voltage phase angles of the other two phases to obtain a fourth phase angle difference value and a fifth phase angle difference value;
calculating the difference value of the absolute value of the fourth phase angle difference value and the absolute value of the fifth phase angle difference value according to the fourth phase angle difference value and the fifth phase angle difference value to obtain a sixth phase angle difference value;
judging whether the absolute value of the sixth phase angle difference value is smaller than the absolute value of the third phase angle difference value, if so, according to the phase angle of the detection voltage of the controllable voltage source obtained by adjustment and the phase angle and the voltage amplitude of the initial voltage of the target phase, the adopted formula is as follows:
calculating to obtain the voltage amplitude and the phase angle of the compensation voltage of the controllable voltage source; if not, jumping to the step of adjusting the phase of the initial detection voltage;
wherein, UphIs the voltage magnitude of the initial voltage of the target phase,
for adjusting the phase angle of the detected voltage of the controllable voltage source，
is the phase angle of the initial voltage of the target phase, Ucom is the voltage amplitude of the compensation voltage of the controllable voltage source, ∠ Ucom is the phase angle of the compensation voltage of the controllable voltage source.
2. The method of claim 1, wherein the preset adjustment step size is between 0.01 ° and 0.5 °.
3. The method of claim 1, wherein the initial detection voltage has a frequency of 50Hz and a voltage amplitude of 100V to 1000V.
4. The method of claim 1, wherein the controllable voltage source is connected in parallel with a crowbar coil.
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