Study On Reactive Power Compensation Device Of Power System

With the development of the industry, higher electrical stability is required and the problem about voltage stability should be solved above all. Various kinds of electrical equipments especially inductive loads in the power grid consume vast amount of reactive power. If the quadergy can't be compensated on the spot timely, a large amount of reactive power would flow through the power system. The distribution complexity of reactive power can't only bring about large energy waste, but also affect the safe and stable operation of power grid. Therefore, reactive power compensation is of great significance.This thesis mainly researches on the reactive power compensation for the low voltage network and uses the magnetic-valve controllable reactor (MCR) as VAR compensator, which has been matured these years. The MCR is based on magnetic bias adjustable principle and its output current is determined by the thyristor trigger angle, the bigger of which, the higher the current and the larger the capacity of the reactor. Thus, the DC excitation current and the saturation degree of the iron core can be changed by changing the trigger angle, and so the reactive value of the reactor and the VAR capacity of the SVC are smoothly regulated.This thesis made a study on the test methods of reactive and harmonic currents in the power system, and the design proposal is based on the reactive and harmonic current test method of the instantaneous reactive power theory. That method has real-time property and can provide accurate result, and when it is used to test reactive current, the result is instantaneous, but on the condition of harmonic current, there will be some time delay due to the difference of the harmonic component and filters. After comparing the principles of the two instantaneous reactive power test methods, this essay chooses "ip-iq" operation mode, so that reactive and harmonic current can be tested even if the three-phase network voltage is not sine wave and is distorted.As to the design of three-phase voltage phase-locked loop, the soft phase-locked loop based on the instantaneous reactive power theory is adopted. Replacing analog phase-locked loop with SPLL can't only increase the integration of the circuit board, but also improve the system intelligence and reliability since there's no complicated hardware circuit design, what's more, the amplifier saturation in the analog PLL and the adverse effects on the loop performance caused by DC drift of active loop filter and phase detector are eliminated.As to the design of VAR compensator controller, the core chip of this design is TMS320F2812 which is a 32 bit fixed-point digital signal processor of TI company. That processor processes powerful controllability and can satisfy the measurements, calculation and control requirements of the power system.As to the program design of the VAR compensator, this essay uses the C language, the control program include:main program loop, initialization program, reactive power control program, protection program, etc. The auto-running of these programs enables the VAR compensator to operate automatically.