Parameter design and simulation for animproved direct current side active power filter

Considering the characteristics of the dc side series active power filter (APF) that the output voltage cannot be adjusted and the control circuit is complex , an improved single phase dc series APF topology is proposed. The improvement of the new circuit topology and fundamental working principle are analyzed. Following the circuit power factor pre regulator principle, the designing method for the main circuit parameters is given. The voltage ring and the current ring are designed by using the zero pole method. The main circuit power switch is controlled with the same frequencies, while the control circuit was simplified further. Compared with the paralleled APF, the main circuit of topology structure is simplified and the number of the active switches is reduced, which show low input current harmonics, high power factor, large voltage output adjustment range and low cost. The simulation results prove that the proposed topology is correct and reliable.     

A dual-boost three-phase DC link active power filter based on coupled impedance

A three-phase DC link active power filter (APF)based on coupled impedance and its control strategy are proposed in order to eliminate the input current harmonics of the three-phase diode rectifier. The presented APF is composed of impedance network and two asymmetric dual Boost converters. Average current control is adopted to control the DC link APF. The switch signals of the two asymmetric Boost converters are obtained respectively by leading and trailing edge modulation methods. Compared with the normal DC link active power filter,this topology reduces an active switch and a capacitance. So it can reduce costs,and there is no voltage imbalance in the DC link. Simulation results verify the correctness of the proposed topology and the corresponding control method.     

One-cycle Control Three-phase Four-wire Active Power Filter with Four-arm

This paper presents a three-phase four - wire active power filter based on one-cycle control. This method need not sense the three phase load currents or the three phase voltages, need not use any multipliers. It has simplified circuit , and the controller is composed of four integrators with reset along with several flip-flops, comparators and some analog components. The main circuit switching frequency is constant, which is desirable for industrial applications. Analysis and simulation are carried out with the four-arm inverter, the simulation results verify that the APF with one-cycle control can dynamically and effectually compensate the harmonics, reactive current and zero sequence current.     

Control Method of Single-phase APF

As one-cycle controlled single-phase active power filter(APF) only can compensate harmonics and reactive currents simultaneously,this paper detects circuit based on instantaneous reactive theory and current traces control circuit based on one-cycle control with harmonic current.The control equations and circuit are set up.The results of simulation verify that this scheme is effective and APFs can compensate harmonic and reactive current according to requirement with the distorted source voltages.     

Comparative study of aircraft three-phase power factor corrections

This paper summarizes the requirements of standards for aircraft power supply firstly,and then points out that the input current harmonic and output DC voltage ripple should be considered seriously when designing three-phase power factor correction (PFC)for aircraft under variable line frequency and unbalanced line supply. Based on reviewing the topologies for aircraft three-phase PFC,three typical topologies,i.e. three-phase pulse width modulation (PWM)rectifier,traditional shunt active power filter (APF)and generalized APF,are picked up. A unified single-phase equivalent model is developed for comparing the harmonic suppression performance of the three active PFC schemes. And the switching stress is also calculated for evaluating their efficiency and power density. Three 5 kW PFC are designed by employing each of the three selected schemes. Simulation is carried out to verify the correctness of the theoretical analysis. The theory and simulation results indicate that the generalized APF topology shows the most technical merit for aircraft three-phase PFC. Future research works on generalized APF are also pointed out,which are solving the uncontrollability of its DC output voltage and optimal designing the filter inductors.     

Single-end Flyback High-frequency High-voltage Switching Power Supplies

Based on the research of a practical project of high frequency high voltage switching power supplies,the system design and experimental investigation of a single end flyback high frequency high voltage switching power supply are presented. In order to solve the problem of durable voltage of power MOSFETs that are used in the single end flyback high voltage switching power supply,an effective approach that adopts dual MOSFETs in series connected is proposed.The procedure of the designing and the parameter of each device is given in detail.A prototype of 220 Volt input and 2000V/3mA output is developed, and the validity of the scheme is demonstrated by the experiment.     

Hybrid Power Supply Based on One Cycle Control

A hybrid power supply is composed by both a linear and a switching source connected in parallel and it can improve the dynamic response. But the hybrid power supply cant not effectively reject the perturbations in the power supply. A hybrid power supply based on one cycle control theory is proposed in order to improve the capability and the control precision. A switching source based on one cycle control is adopted in the hybrid power supply. The analysis results indicate that the hybrid power supply can effectively reject the perturbations in the power supply. And the analysis results also show that not only the control precision is improved, but also the control circuit is simple. The simulation resuits given verify the correctness and effectiveness of the proposed method.     

Analysis of Unified Power Flow Controller in Damping Low Frequency Oscillation of Power System

With the development and complication of power system, the problem of low frequency oscillation in electric network becomes obvious. Unified Power Flow Controller is one of the most powerful facilities in Flexible AC Transmission Systems, which can improve the transient stability and damp the low oscillation in power system with suitable control. Considering the characteristics of inverter's output voltage magnitude, adjustment of phase and process of charge and discharge of dc capacitance, the dynamic model of UPFC is proposed by a series of nonlinear differential coefficient equations. Based on UPFC's dynamic model, the linear optimal controller of UPFC with state feedback is proposed. In this way, the low frequency oscillation is damped effectively. A simulation is processed basing the theory.     

Microcomputer Controlled Resistance Welding Power Source

A new tape resistance welding power source based on 80C196KC single-chip microcomputer was developed.The MOSFET group worked at linear state was used as current adjuster.Arbitrary control of current waveform was achieved first in the moment of resistance welding.So that it is possible to weld with optimal current waveform in resistance welding.The power source was used in the welding of bridge band,that solved the problem occurred at traditional welding means,and met the strict requirement of the welding quality of bridge band.The practice shows that it is an ideal power source in the precise welding of minisize metallic workpiece.     

Shunt Active Power Filiter for Harmonic Compensation in DC Side of HVDC Transmission System

A shunt active power filiter(APF) used for harmonic treatment isintroduced in this paper. Basic circuit-theory and main configuration are analyzed. Control scheme and its realization are discussed. Computer simulation is used to verity theoretical analysis. It shows that APF is an interesting alternative for hasmonic treatment compared with conventional passive filter.     

Control Method of Voltage-reactive Power of Substation Based on the Real Time Adjusting Voltage Calculation

The main means of the voltage-reactive power control of substation are adjusting the taps of load-tap-changing transformer or the reasonable capacity of parallel compensating capacitors according to the operation condition of substation.The "nine-area control strategy" is widely used to adjust voltage in the stated range and reduce the transmission capability of reactive power for power system at present.By analyzing the existent shortages of nine-area control mode for voltage-reactive power,an adjusting voltage calculation method is put forward,input data of which are the real time data of current,voltage and power of the substation.Then operation decision of voltage-reactive power control method of substation is made.By the simulating analysis,predigesting method of upper system is built,based on which an applied real time calculating model and calculating steps is given.     

Study on constant current control of inductive power transfer with parameter identification

Aiminy at magnetic exciting current (resonant current) control, a constant current control method based on dynamic parameter identification is put forward. With energy conversion analysis, the energy storage, supply and dissipation functions of the system resonant network are constructed. The reflecting impedance identification functions are obtained by constructing the energy equilibrium relations in a period and among several periods. Furthermore, a constant current control strategy by regulating the system input voltage with Buck converter is presented. Combining the relations among system input voltage, the envelope of resonant current and the input of Buck converter, the constant current control law is proposed. The control law is verified with experiments. For the proposed method, in parameter identification, only the data of zero crossing point of resonant voltage and current are required, which reduces the complexity and costs of sampling system. Also, the constant current control law does not need complex computation and is easy to implement.     

Power transfer regulation mode for current fed CPT system

For the drawback of the power regulation in the existing current fed CPT system, a novel circuit topology and control method is presented, which can realize either Buck or Boost mode and can extend the power regulation scope. The improved topology is modeled, while the relations between the duty cycle and the output power for the two modes are derived for system analysis and design. Simulink and PLECS are used to simulate the PP type CPT system. The simulation results prove the theory analysis.     

Experimental Analysis on Power Consumption of Chilled Water Pump by Constant Pressure Difference Method with Bypass Valve

The power consumption of frequency conversion chilled water pump of an office building regulated by constant pressure difference method with bypass valve is studied experimentally. A model of power consumption of chilled water pump is proposed. The effects of pressure difference set point of bypass valve on instantaneous and annual power consumption of chilled water pump are analyzed. The simulation results are validated experimentally, which shows that there is a maximum water flow rate which increases with the increase of the pressure difference set point of bypass valve at equilibrium state. There are three pressure operation regions of the bypass valve: under pressure region, constant pressure region and over pressure region. The power consumption of frequency conversion chilled water pump is affected by the pressure difference set point of bypass valve significantly, and it would be minimized as the pressure difference set point of bypass valve is equal to the pressure difference between supply water and return water of the farthest user.     

Integrate Reset Controlled Three Phase Power Factor Correction

A three phase power factor corrector in continuous current mode is introduced. The control equations are deduced and realized by Integrate reset controller. The integrate reset controller is composed of a integration with reset,a RS flip-flop and a comparator,which is very simple. The integrate reset controlled three phase power factor corrector has these characteristics as follows: Constant frequency operation, which is of advantage of the design of filter;the control circuit is simple and no need for multiplier;The result of simulation proves the correction of theory analysis.     

An Adaptive Control (AC) Strategy for Internal Grinding with Power Sensor

An adaptive control (AC) strategy for internal grinding with power sensor is proposed.The strategy consists of control strategy of grinding without empty travel,fuzzy control strategy of grinding with constant power,and state monitoring control strategy of grinding wheel.The fuzzy control strategy with constant power is discussed emphatically.     

Application of Multi-agent Technology in Power System

Modern power system is a complex, open and distributed system. Multi-agent is a new technology of distributed artificial intelligence. It is easy to make the distributed systems run well. The basic principles and the applicable scopes of Multi-agent are described in this paper. Especially the various applications of Multi-agent in power system are introduced, such as security-defense system, secondary voltage control, electricity markets, EMS and power plant. The further studying works of Multi-agent are schemed. The the studying ways in control system, adaptive ability and foreground on wide control fields of power system. applications of the other fields in power system are described, intelligence, communications are pointed out and especially the foreground on wide control fields of power system.     

Predictive Control Approach for Active Power Filter Based on Neural Networks

In this paper, a predictive control approach using neural networks for active power filter is proposed. The control system of active power filter using this method make using of the internal model control technology based on neural networks, meanwhile, to solve its questions such as lag because of calculating using neural networks, a predictive model based on neural networks is introduced. Simulation analysis shows that this control approach can compensate the lag of system and take advantage of self-adaptive characteristic of neural networks. Good result can be obtained.     

Distributed Power Flow Method Based on Ward Equivalent

With interconnecting and developing of power system, the problem of power flow computation on dispersed data resource need to be solved. A new distributed computation method of power flow based on Ward equivalent is presented. According to master-slaver splitting principle, multi-area interconnected power system is divided into master-slaver areas. Boundary buses in different areas are defined as different bus-types. Neighborhood areas are equivalent by Ward equivalent principle, and the equivalent injection power and equivalent impedance are worked out. Power flows from master area to slaver areas are solved by Newton method, and the equivalent injection power and equivalent impedance on the boundary are modified by their solutions. The process above repeats until to convergence. The proposed distributed power flow method takes full advantage of the information of power, voltage, network configuration in neighborhood areas, so it is better on convergence and quality of solution. The proposed algorithm is testified by IEEE 14-bus system and a practical 181-bus system.     

A Integrate-Reset-Controlled Single Phase Power Factor Correction with High Efficiency

A novel single phase boost type power factor correction circuit is introduced .The converter's efficiency is greatly improved by improving on the traditional boost type power factor correction circuit. Integrate Reset Control circuit is adopted to realize unity power factor. The Integrate Reset Control high efficiency single phase boost type power factor corrector has these characteristics as follows: It's constant frequency operation, which is of advantage of the design of filter. The control circuit is very simple and no need for multiplier. The result is quiet perfect, the input current follows the input voltage very well. The efficiency is very high. The result of simulation and experiment proves the correction of theory analysis.