Compensation for power capacity of large-scale generator power frequency AC withstand voltage test

The line is as shown.

The equivalent circuit diagram is shown.

As shown in the vector diagram, the phase of the inductive component of the compensating reactor is opposite to the phase of the capacitive current of the test generator, which can offset part of the capacitive current of the test product, reduce the total current in the test circuit, and the capacity of the test equipment. It is also reduced.

The parameters of the compensated reactor are determined as follows.

Rated voltage: should be higher than the test voltage.

Rated current: Should be greater than the current required for compensation.

Rated capacity: Determine the rated capacity based on rated voltage and rated current, and consider leaving a certain margin.

Impedance value: Determine the impedance value based on the rated voltage and rated current.

P and the resistive component of the resistance value should be made as small as possible. The iron core should be made of low-consumption steel sheet, and the wire should be appropriately cross-sectioned to reduce the resistive component.

The test transformer with appropriate parameters compensates for the reactor compensation method, and it is necessary to manufacture a reactor with suitable parameters. The test transformer with appropriate parameters can be used to short-circuit the low-voltage winding, and the short-circuit impedance characteristic of the high-voltage end of the test transformer can be used to compensate the capacitor current of the power-frequency AC withstand voltage test circuit of the generator, and the vector diagram of the reactor compensation can be reduced. The purpose of the device capacity. The test wiring is as shown in the equivalent circuit of the zero compensation test transformer.

The equivalent circuit diagram of the test loop is shown.

It can be seen that the compensation principle is the same as that of the reactor.

The parameters of the test transformer for compensation are determined as follows.

Impedance voltage: Determine the impedance voltage of the test transformer according to the test voltage. The impedance voltage is at the test voltage and has a certain margin.

Rated current: should be greater than the current that needs to be compensated.

Rated voltage: determined according to the impedance voltage and the test voltage, so that the impedance voltage is higher than the test voltage.

Rated capacity: determined by rated voltage and rated current with a certain margin.

2 Inductive component shunt compensation should pay attention to the problem to choose the appropriate parameters can not achieve the purpose of compensation, but also prevent current or voltage resonance.

The voltage resonance is caused by voltage resonance when the capacitive reactance of the test product is equal to the sum of the inductive reactance of the test transformer, the voltage regulator, the compensating inductor component, and the power source to the test voltage side in the test circuit. When voltage resonance occurs, the voltage on the test object and the current on the power supply side increase. In order to avoid voltage resonance, it is necessary to calculate the parameters of each component in the test circuit. The condition for no voltage resonance is: Cx<3.lSX\Q9/wXiCx The maximum allowable capacitance X of the test product! Test the transformer, voltage regulator, compensation inductance component and the sum of the inductive reactance values ​​of the power supply to the test voltage side (n).

The current resonance is caused by the excitation current of the test transformer or the inductance current of the compensation inductance component, and the parallel resonance of the capacitor current of the test generator. To avoid current resonance, select the appropriate test transformer and compensate for the parameters of the inductive component. The conditions for no current resonance are: the rated capacity (kVA) of the Pe test transformer; the rated voltage (kV) of the Ue test transformer; the parameters for calculating the voltage and current resonance do not need to be measured. The electric capacity of the tested generator can be measured by Xilin bridge or current-voltage method. The voltage applied during measurement should not be lower than the rated phase voltage of the generator, not higher than the line voltage of the generator, wiring and AC withstand voltage. Same time. It is preferable to measure the short-circuit reactance XK of the test transformer, the voltage regulator, and the compensation inductance component, which is preferably the same as the current required for the test.

The open circuit reactance X is measured, preferably in accordance with the voltage required for the test.

The wiring should be the same as the AC withstand voltage. Through the actual measurement and accounting, the test equipment and the inductance compensation component with appropriate parameters are selected to avoid voltage and current resonance.

Check the test current waveform AC voltage withstand test power supply, use line voltage, test equipment and inductance compensation components to leave a margin to avoid distortion of the test voltage waveform, in the generator power frequency AC withstand voltage test must Check the voltage waveform, its harmonic component should not exceed 5%, if necessary, can be monitored by an electronic oscilloscope.

Due to the large capacity rise of the generator power frequency AC withstand voltage test, the voltage measurement requires direct measurement of the voltage at the rolling end of the test product. In the course of the test, the indication values ​​of the various meters are closely monitored.

The above theoretical analysis and practical application results show that the use of reactor compensation method and test transformer compensation method, reasonable selection of equipment parameters, can fully achieve the purpose of compensating large-scale generator power frequency AC withstand voltage test equipment and test power supply capacity. It can reduce the capacity of the test equipment and test power supply, reduce the test loop current, and eliminate the need to add a large-capacity test power supply to save money. Avoid the heating of the test leads and joints, which is convenient for field test work and can improve the safety of the test.

Ding Kuichao (1963-), male, bachelor, and grade engineer, mainly engaged in electrical maintenance and testing.

The European Commission promotes energy conservation and the use of renewable energy. The European Commission recently proposed a “European Smart Energy” program, which invested 215 million euros between 2003 and 2006 to support EU countries and regions to save energy, develop renewable energy and raise energy. Action on energy efficiency.

The EU began to adjust its energy policy in 1991, emphasizing energy conservation and the use of renewable energy, and introduced energy plans in 1993 and 1998 respectively. Since the implementation of the sustainable development strategy, the EU has paid more attention to energy policy.

In November 2000, in order to ensure the safety of energy supply and reduce the impact of atmospheric warming, the Green Paper was officially launched. The launch of "European Smart Energy"

The plan is to implement the goals of the Green Paper.

As a major energy consumer, Western European countries are very sensitive to the world oil market. The European Commission believes that "if Europeans do not change the current concept of energy production and consumption, by 2030, the EU will have 7% of energy dependence on imports, of which 95 of oil consumption depends on imports. The dependence on imported energy will constitute an economy, Many threats to politics and the environment. The EU believes that changing energy production and consumption structure is the key to preventing global warming and the greenhouse effect. According to statistics, 94% of carbon dioxide emissions in Europe are caused by the use of energy such as oil, coal and natural gas. The EU is committed to reducing greenhouse gas emissions by 8% from 2008 to 2012. However, if no specific measures are taken, greenhouse gas emissions are expected to increase by 5.2% by 2010. Therefore, the EU Its energy policy and adjustment have a strong sense of urgency.

Developing renewable and non-polluting energy sources and guiding residents and businesses to save energy and “smart” energy consumption is the EU's primary choice for balancing its energy supply and is the goal of the Green Paper. The European Commission has made specific recommendations for this, requiring countries to amend the law to encourage the use of electricity produced by renewable energy. Recommendations such as the use of biofuels and reducing energy consumption in buildings have also recently been proposed.

In order to ensure the implementation of the plan, the European Commission will strengthen the formulation of various technical norms, and use the market competition mechanism to encourage the initiative of countries and regions while ensuring financial support. The Committee requires member countries to increase energy efficiency by 1% per year, increase the consumption of renewable energy from 6% to 12% by 2010, and increase the electricity produced by renewable energy to 22.1% of total electricity generation, thereby effectively reducing Greenhouse gas emissions. Within six months of the formal adoption of the plan, the committee will further determine specific measures.

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