Synthetized compensation device in electric power system and synthetized compensation method

Abstract

The device includes voltage detection unit at net side, current detection unit at net side, device of picking-up fundamental current at load side, digital signal processor DSP and control system based on DSP, generator of pulse-width modulation, inverter and LC filter. Structure and control method of combining unsmoothed nonlinear control with observer of expanding state are utilized in the invention. Output, derivative and unknown internal and external interference are observed through observer of expanding state. Harmonic opposite phase compensation is converted to tracking of ideal sine signal. Wattless dynamic compensation is realized through voltage-controlled reactor so as to reduce capacity of inverter to minimum and play filtering action. The invention integrates active filtering, passive filtering and wattless dynamic compensation.

Description

technical field [0001] The invention belongs to the technical field of electric power engineering, and in particular relates to a comprehensive compensation device and a comprehensive compensation method for a power system composed of active and passive components. Background technique [0002] With the rapid development of power technology, various power electronic devices have been widely used in power systems, metallurgy, steel, chemical and other industrial fields, as well as in fields such as transportation, building automation and home life, which makes the harmonics in the power grid The pollution situation is getting worse. Moreover, the capacitors used to improve the power factor in the grid tend to resonate with the system impedance, resulting in harmonic amplification. This has aggravated the harmonic pollution in the power grid. [0003] Harmonics in the grid not only endanger the grid itself but also endanger its peripheral equipment. On the one hand, harmoni...

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Problems solved by technology

[0006] 1. Poor compensation performance due to errors in the parameters of capacitors and inductors; during operation, changes will occur due to changes in ambient temperature, self-heating and aging of capacitor insulation, which will deteriorate the filtering effect of the filter;

[0007] 2. Poor dynamic performance When the load current changes dynamically, its suppression effect on harmonic current is poor;

[0008] 3. Compensation performance is affected by system impedance, and changes in system impedance will affect its filtering effect;

[0009] 4. Even under ideal conditions, it can only produce a better suppression effect on specific order harmonic currents;

[0010] 5. Huge volume, takes up a lot of space

[0013] 1. Since the fundamental wave voltage of the AC power supply is directly applied to the inverter, and the compensation current is completely provided by the inverter, the capacity of the inverter must be large;

[0014] 2. Due to the high cost of power electronic devices, the price of this system is very expensive;

[0015] 3. Since the detection circuit is easily affected by device parameter dispersion and debugging errors, this will affect its compensation performance and needs further improvement;

[0016] 4. Since the active filter device adopts a brand-new structure, it is not suitable for modifying the original passive filter device

The advantages of this integrated power filter device are low cost, certain economical practicability, good filtering performance, and no series or parallel resonance. The detection of harmonics is difficult and the accuracy is low. In addition, in this design, because it focuses on the filtering effect of the power grid, the power factor of the system is not considered, so the effect of reactive power compensation is poor and cannot be completely solved. Integrated Control of Filtering and Reactive Power

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