Method for quickly determining maximum allowable reactive power of synchronous machine

Abstract

The application provides a method for quickly determining the maximum allowed reactive power of a synchronous motor, and is characterized in that the method comprises the following steps: inputting rated working condition parameters required for calculation; calculating the coordinates of a rated operating point; calculating the coordinates of the center of a rotor constant excitation curve; calculating the distance from the center of the rotor constant excitation curve to the rated operating point; and calculating the maximum allowed reactive power of the synchronous motor. The application realizes the quick calculation of the maximum allowed reactive power of the synchronous motor through the input of three basic electromagnetic parameters of the rated working condition of the synchronous motor and through four simple steps, is suitable for synchronous motors such as synchronous generators and synchronous phase modulators, is compatible with thermal power full-speed generators, nuclear power half-speed generators, and various capacity non-salient pole phase modulators, and is compatible with various non-salient pole turbine synchronous motors with water-hydrogen cooling, double-water internal cooling, full-hydrogen cooling, and air cooling.

Description

Technical Field

[0001] This invention relates to a convenient calculation method for quickly determining the maximum reactive power of a synchronous motor operating in a delayed phase. It can be used in the research and product design and development of delayed phase output reactive power of synchronous motors and belongs to the field of electromagnetic technology of synchronous motors. Background Technology

[0002] With the development of power technology, the maximum allowable reactive power output of synchronous motors such as synchronous generators and synchronous condensers needs to be considered in the design and development process. This is to provide the power system with the main technical parameters of the synchronous motors, and also to provide key performance data for changing the rated operating conditions of the units after many years of operation.

[0003] Previously, power users typically obtained the maximum permissible reactive power output of a synchronous motor by consulting the manufacturer or by referring to the PQ output diagram of the synchronous generator. However, when changing the rated operating conditions of a unit after many years of operation, the original PQ output diagram is no longer applicable. To quickly and accurately determine the maximum permissible reactive power, a new and convenient calculation method is needed. Summary of the Invention

[0004] The purpose of this invention is to quickly and accurately determine the maximum permissible reactive power of a synchronous motor based on a few parameters such as rated capacity, rated power factor, rated voltage, and synchronous reactance when changing the rated operating conditions of a generator unit after many years of operation.

[0005] To achieve the above objectives, the technical solution of the present invention provides a method for rapidly determining the maximum permissible reactive power of a synchronous motor, characterized by comprising the following steps:

[0006] Step 1: Input the rated operating parameters required to complete the calculation, including the rated operating capacity. Rated power factor and synchronous reactor ; Step 2: Calculate the coordinates of the rated operating point A. ,have:

[0007]

[0008] In the formula, The horizontal axis represents the active power value at the rated operating point A, i.e., the active power under rated operating conditions. The vertical coordinate represents the reactive power value at the rated operating point A, i.e., the reactive power under rated operating conditions. Step 3: Calculate the coordinates of the center E of the rotor constant excitation curve. ,have:

[0009] In the formula, The ordinate of the reactive power value is the value of the center E of the rotor constant excitation curve. Step 4: Calculate the distance from the center E of the rotor constant excitation curve to the rated operating point A.

[0010] Step 5: Calculate the maximum allowable reactive power of the synchronous motor. , .

[0011] Preferably, in step 4, the distance The calculation formula is: .

[0012] Preferably, the coordinate calculation formulas for the rated operating point A recorded in step 2, the center E of the rotor constant excitation curve recorded in step 3, and the distance calculation formulas in step 4 are used in EXCEL language. The calculation formula and the maximum permissible reactive power of the synchronous motor recorded in step 5. The calculation formula for the maximum permissible reactive power of synchronous motors is compiled. Automatically calculate the rated operating capacity in the Excel file. Rated power factor and synchronous reactor Input synchronous motor maximum permissible reactive power After automatically calculating the Excel file, the maximum allowable reactive power of the synchronous motor is automatically calculated. .

[0013] This invention enables rapid calculation of the maximum permissible reactive power of a synchronous motor by inputting three basic electromagnetic parameters under rated operating conditions, through four simple steps. It is applicable to synchronous generators, synchronous condensers, and other synchronous motors, and is compatible with full-speed generators in thermal power plants, half-speed generators in nuclear power plants, and large-capacity salient-pole synchronous condensers. It is also compatible with various salient-pole turbine synchronous motors with cooling methods including water-hydrogen cooling, dual water internal cooling, all-hydrogen cooling, and air cooling. Since only three parameters need to be input for automatic calculation of the maximum permissible reactive power, this invention is well-suited for providing technical parameters for new machines and for on-site modification of existing machines, achieving the goal of conveniently, quickly, and accurately obtaining the maximum reactive power value. Because there is no need to redraw the synchronous motor's PQ output diagram when the rated operating conditions change, this invention overcomes the shortcomings of existing technologies and achieves technical advantages such as less input data, simple operation, rapid calculation and drawing, and a concise and intuitive process. Attached Figure Description

[0014] Figure 1A schematic diagram of the electromagnetic phasors of the synchronous motor in this embodiment of the invention; Figure 2 Schematic diagram of input data in an embodiment of the present invention; Figure 3 A schematic diagram of the output calculation results in an embodiment of the present invention; Figure 4 The present invention provides a flowchart of a method for quickly determining the maximum permissible reactive power of a synchronous motor. Detailed Implementation

[0015] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0016] like Figure 4 As shown in the figure, the method for quickly determining the maximum permissible reactive power of a synchronous motor disclosed in this embodiment specifically includes the following steps: Step 1: Input the rated operating parameters required to complete the calculation: The three input parameters required for construction include: rated operating capacity. (Unit: MVA), Rated Power Factor (Unit: pu), Synchronous Reactance (unit:%).

[0017] Step 2: Calculate the coordinates of the rated operating point A. ,in:

[0018]

[0019] In the formula, The horizontal axis represents the active power value at the rated operating point A, i.e., the active power under rated operating conditions, in MW. The vertical coordinate represents the reactive power value at the rated operating point A, i.e., the reactive power under rated operating conditions, in Mvar.

[0020] The position of rated operating point A on the phasor diagram of the synchronous motor is as follows: Figure 1 As shown.

[0021] Step 3: Calculate the coordinates of the center E of the rotor constant excitation curve. Since the center E of the rotor constant excitation curve lies on the reactive Q axis, its abscissa is:

[0022] Its vertical axis is related to the rated operating capacity. and synchronous reactor The relationship is:

[0023] In the formula, The ordinate of the rotor constant excitation curve represents the reactive power value in Mvar, expressed as the vertical axis of the curve's center E. The "×100" in the calculation formula is due to the synchronous reactance. The unit is "%", therefore the multiplier of 100 needs to be retained in the formula to account for the synchronous reactance. Convert to per-unit value.

[0024] The position of the center E of the rotor constant excitation curve on the phasor diagram of the synchronous motor is as follows: Figure 1 As shown.

[0025] Step 4: Calculate the distance from the center E of the rotor constant excitation curve to the rated operating point A. (Unit: MVA), according to the formula for the distance between two points:

[0026] Step 5: Calculate the maximum allowable reactive power of the synchronous motor. (Unit: Mvar) .

[0027] The method provided by this invention can be completed manually (the calculation result can be obtained by using a scientific calculator according to the formula disclosed in this invention). To more intuitively illustrate the calculation idea proposed by this invention, this embodiment selects EXCEL from the OFFICE office software as the input and output interface, and the calculation of this invention can be realized by using EXCEL's function functions.

[0028] like Figure 2 As shown in this embodiment, under the Windows operating system, an Excel file named TQMAX (Tubine synchronous machine's Quantity of reactive power with Maximumvalue calculation method) was created using the Excel language to quickly determine the maximum permissible reactive power of a synchronous motor. This program is a regular Excel document, a spreadsheet tool under the Windows operating system.

[0029] The following is an example of a 700MW dual water-cooled generator to calculate its maximum allowable reactive power. The specific operation process is as follows: Step 1: Open Excel, as follows Figure 2As shown, below the cell “1. Input Data”, enter three parameters in sequence, including the rated operating capacity. =777.8MVA, rated power factor =0.9, Synchronous Reactance =262%.

[0030] Step 2: As Figure 3 As shown, because the calculation formula in EXCEL is based on the application of simple EXCEL functions according to the formula content of this invention, the calculation results of "2. Calculate the coordinates of the rated operating point A" to "5. Calculate the maximum allowable reactive power of the synchronous motor" are automatically generated.

Claims

1. A method for rapidly determining the maximum permissible reactive power of a synchronous motor, characterized in that, Includes the following steps: Step 1: Input the rated operating parameters required to complete the calculation, including the rated operating capacity. Rated power factor and synchronous reactor ; Step 2: Calculate the coordinates of the rated operating point A. ,have: In the formula, The horizontal axis represents the active power value at the rated operating point A, i.e., the active power under rated operating conditions. The vertical coordinate represents the reactive power value at the rated operating point A, i.e., the reactive power under rated operating conditions. Step 3: Calculate the coordinates of the center E of the rotor constant excitation curve. ,have: In the formula, The ordinate of the reactive power value is the value of the center E of the rotor constant excitation curve. Step 4: Calculate the distance from the center E of the rotor constant excitation curve to the rated operating point A. ; Step 5: Calculate the maximum allowable reactive power of the synchronous motor. , .

2. The method for rapidly determining the maximum permissible reactive power of a synchronous motor as described in claim 1, characterized in that, In step 4, the distance The calculation formula is: .

3. The method for rapidly determining the maximum permissible reactive power of a synchronous motor as described in claim 1, characterized in that, Using Excel, the coordinates of the rated operating point A recorded in step 2, the coordinates of the center E of the rotor constant excitation curve recorded in step 3, and the distance in step 4 are calculated based on these formulas. The calculation formula and the maximum permissible reactive power of the synchronous motor recorded in step 5. The calculation formula for the maximum permissible reactive power of synchronous motors is compiled. Automatically calculate the rated operating capacity in the Excel file. Rated power factor and synchronous reactor Maximum permissible reactive power of input synchronous motor After automatically calculating the Excel file, the maximum allowable reactive power of the synchronous motor is automatically calculated. .

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