line conditioners. The term "power conditioning" used in this book has much broader meaning than the term harmonic filtering." In other words, the power conditioning is not confined to harmonic filtering, but contains harmonic damping, harmonic isolation, harmonic termination, reactive-power control for power factor correction, power flow control, and voltage regulation, load balancing, voltage-flicker Suction, and/or their combinations. Active power line conditioners are based on leading-edge power electronics technology that includes power conversion circuits, power semiconductor devices, analog/digital signal processing, voltage/current sensors, and control theory. Concepts and evolution of electric powertheory are briefly described below. Then, the need for a consistent set of power definitions is emphasized to deal with electric systems under non-sinusoidal conditions. Problems with harmonic pollution in alternating current systems (ac systems) are classified, including a list of the principal harmonic-producing loads. Basic principles of harmonic compensation are introduced. Finally, this chapter describes the fundaments of power flow control. All these topics are the subjects of scope, and will be discussed deeply in the following chapters of the book. The instantaneouspowertheory, or ―the p-q theory,‖ makes clear the physical meaning of what instantaneous real and imaginary power is in a three-phase circuit. Moreover, it provides insight into how energy flows from a source to a load, or circulates between phases, in a three- phase circuit. This theory can be used in the design and understanding of FACTS (Flexible AC Transmission System) compensators. The book introduces many concepts in the field of active filtering that are unique to this edition. It provides a study tool for final year undergraduate students, graduate students and engineers dealing i-th harmonic pollution problems, reactive power compensation or power quality in general. 2 EXISTING SYSTEM
To obtain efficient SHAPF performance, it is important to choose proper reference generation algorithm and an appropriate current or voltage control strategy. The publication of the instantaneous reactive powertheory caused a great impact in reference generation. Many approaches have been published since then [5–16]. But all of these definitions are computational intensive and do not provide simple expression of instantaneouspower quantity. In year 2004, X. Dai [17-20] introduced generalised instantaneouspowertheory which gives a direct and simple expression for instantaneouspower quantities.
Abstract— In this paper, a three-phase four-wire system connected a nonlinear load, dc/ac four leg voltage source converter to act as a four leg Active Power Filter (APF) using of instantaneouspowertheory is presented. The use of a four-leg voltage- source inverter allows the compensation of current harmonic components, as well as unbalanced current generated by single- phase nonlinear loads. The instantaneouspowertheory is applied to design the APF controller, which shows reliable performances. The MATLAB/SimpowerSystems tool has proved that the proposed control technique compensate the harmonic current drawn by nonlinear loads and controls the reactive power flow.
Abstract- With the rapid use of power electronic converters which are considered as non-linear loads have problems of drawing non-sinusoidal currents and reactive power from source which in turn pollutes the power quality. This paper presents the power quality problems and methods for its correction where two control strategies (p - q instantaneouspowertheory and d - q synchronous reference frame theory) for extracting reference currents for shunt active power filters (SAPF) have been evaluated and their performances have been compared under distorted supply and non-linear load conditions. These theories are used to implement the control algorithm of a shunt active filter which compensates harmonic currents. This paper implements the three phase three wire shunt active power filter to suppress current harmonics. The SAPF performance is validated using MATLAB/Simulink model showing comparisons for the two algorithms.
Now a day renewable energy resources are increasing due to power demand and decreasing of the fossil fuels. Also the requirement of power quality is very essential concern along with power quality. Today the grid-connected photovoltaic (PV) generator has become more popular because of its reliable performance and its ability to come up with power from clean energy resources. The dc output voltage of PV arrays is connected to a dc/dc boost converter using a most power point tracking (MPPT) controller to maximize their produced energy. Then, that converter is coupled to a dc/ac voltage source device (VSC) to let the PV system push electric power to the ac utility. The local load of the PV system can specifically be a nonlinear load, such as computers, compact fluorescent lamps, and plenty of different home appliances, that needs distorted currents. Development of this method is to compensate the distribution system harmonics which is equally urgent. During this case, PV generators should provide the utility with distorted compensation capability that makes currents injected/absorbed by the utility to be sinusoidal. Therefore, the harmonic compensation function is realized through flexible control of dc/ac VSC. Instantaneouspowertheory has successfully completed active power filter (APF) designing with good performance. However, the PV-APF combination has simply been gradually developed for several years.
This paper proposed concept of PV based active power filter for power quality improvement using instantaneouspowertheory controller. This controller can be implemented for two purposes i.e, one for to supply power from PV system and other one is for filtering the harmonics caused by non-linear load. In this paper PI, Fuzzy Controllers are developed for controlling Dc link voltage. The performance of this system can be tested and verified in Matlab/Simulink. From the results we conclude that, Fuzzy Logic Controller shows better performance over conventional controller.
Three phase three wire distribution system are facing severe power quality problems such as poor voltage regulation , high reactive power and harmonics current burden , load unbalancing , etc. For the improvement of power quality FACTS devices are used. FACTS devices are SSSC, UPFC, SVC , D-STATCOM etc. In this paper D-STATCOM is used to solve power quality problems. There are many different control strategies are used to control the D-STATCOM. Different control strategies are Instantaneouspowertheory (IRP) , Synchronous Reference frame theory (SRF) , Symmetrical component theory (SC), modified p-q theory etc. In this SRF control strategy is used to control the D-STATCOM. MATLAB simulation is presented with D-STATCOM using SRF control strategy.
The Phase locked loop estimate voltage and phase angle by feedback loop. The reactive and real power is de- termined by using instantaneouspowertheory. Here fuzzy block is used separately for direct current computa- tion and inverse current. The above functional block diagram Figure 3. As two sources connected through a transmission lines .Instantaneous current values is taken from three phase transmission line, then current is measured by using current transformer. Three phase current values are converted to two phase reference frame as α and β by Clarke transformation.
The PQ theory is widely used to control three phase active power filter which is based on the transformation from three phase quantities (abc) to two phase quantities (αβ) and calculation of instantaneous active and reactive powers . The PQ theory consists of Clarke transformation, phase lock loop (PLL), power losses calculation, digital low pass filter and hysteresis current controller. The inputs required for this control system are line voltages (va, vb and vc), line currents (ia, ib and ic) and dc bus voltage (vdc) as show in Figure-2. The line voltages and currents will be transformed to vα, vβ, iα and iβ. On the other hand, the dc bus voltage (vdc) will be compared with dc bus reference voltage (vdcref) to produce dc power signal (Pdc). Then, the dc power and active power signal will be used to produce reference current signal (ia*, ib* and ic*). The hysteresis current controller will generate PWM signal from PLL signals and the reference currents .
Hence a control strategy for a hybrid power filter constituted by a series active filter and a passive filter connected in parallel with the load is proposed. The control strategy is based on the dual vectorial theory of electric power. The new control approach achieves the following targets. Suitable for variable loads as the reactive power variation is compensated by the active filter. Therefore, with the proposed control strategy, the active filter improves the harmonic compensation features of passive filter and reactive power is compensated. Also the currents harmonics are eliminated. Simulations with the MATLAB-Simulink platform were performed with different loads and with variation in the source impedance. The proposed technique can also be extended by creating LG /LL faults at the source side. The shunt passive and series active filters works effectively to compensate the source currents by injecting compensating currents at the point of common coupling under the application of LG/LL faults at the source side.
While at the beginning of the 1990s inverter air conditioners had some drawbacks, these have been mostly overcome, the conversion losses are lower and filters suppress most of the electromagnetic interference generated in inverters. Since permanent-magnet motors are used, rather than conventional squirrel cage induction motors, motors use less power and no current is required for magnetizing the rotor. Inverter-based air conditioners are therefore more energy efficient. 100% of air conditioners in Japan use DC inverter compressors. For conventional households where each indoor unit is connected to a single dedicated outdoor unit, inverters are the preferred option, as partial loading is the common mode there. The higher initial expense is balanced by lower energy bills. In a typical setting the pay-back time is about two years (depending upon the usage). For more modern installations where an outdoor unit is connected to multiple indoor units there are better options also available.
The project provides a new control strategy based on the dual formulation of the electric power vectorial theory is proposed. For this, a balanced and resistive load is considered as reference load. The strategy obtains the voltage that the active filter has to generate to attain the objective of achieving ideal behavior for the set hybrid filter-load. When the source voltages are sinusoidal and balanced the power factor is unity, in other words, the load reactive power is compensated and the source current harmonics are eliminated. By this means, it is possible to improve the passive filter compensation characteristics without depending on the system impedance, since the set load-filter would present resistive behavior. It also avoids the danger that the passive filter behaves as a harmonic drain of close loads and likewise the risk of possible series and/or parallel resonances with the rest of the system. In addition, the compensation is also possible with variable loads, not affecting the possible the passive filter detuning.
Therefore, it is highly desirable to carry out extensive research to reduce the cost of DSTATCOM without affecting the efficiency and effectiveness in PQ improvement capability. Renewable energy(RE)penetration in to the electric utility grid is increasing day by day and intermittent nature of these resources affects the quality of supplied power. The weather conditions such as wind speed variations and variable solar insolation affect the power output of REsources. The DSTATCOM may be an effective solution for these problems, hence possibilities of implementation of DSTATCO in RE based power system are required to be explored.
In this case we use wind power generation system. Wind energy source output is variable. We use induction generator. Induction generator is not requiring separated filed circuit. It is variable input and output accepts. Available wind power is
Two control techniques for a three-phase shunt active power filter employing a conventional three-leg converter were developed and a critical comparison between both approaches was carried out. Experimental results using both the control strategy were successfully obtained and reported in this paper. In conclusion the carrier-based control technique provides lower values of THD to source currents during non-linear load when compared to voltage source instantaneous control technique.
evaluation of shunt active power filter(SAPF) for power quality improvement. Power quality complications can be take up using SAPF. A Simulation model of the three-phase shunt active filter had been implemented based on IRP theory The system where we can observe the considerable Improvement in the source current in the norms of total Harmonic distortion (THD) of source current. We can also Observe the correction in the). Properties are restored in the terms of source voltage and Source current are in phase by this implementation. The performance of the SAPF by using the IRP theory for nonlinear load is demonstrated with the MATLAB simulation results.
The term electric power quality (PQ) is generally used to assess and to maintain the good quality of power at the level of generation, transmission, distribution, and utilization of AC electrical power. Since the pollution of electric power supply systems is much severe at the utilization level, it is important to study at the terminals of end users in distribution systems. There are a number of reasons for the pollution of the AC supply systems, including natural ones such as lightening, flashover, equipment failure, and faults (around 60%) and forced ones such as voltage distortions and notches (about 40%). A number of customer’s equipment also pollute the supply system as they draw non sinusoidal current and behave as nonlinear loads. Therefore, power quality is quantified in terms of voltage, current, or frequency deviation of the supply system, which may result in failure or mal-operation of customer’s equipment. However some power quality problems related to the current drawn from the AC mains are poor power factor, reactive power burden, harmonic currents, unbalanced currents, and an excessive neutral current in poly phase systems due to unbalancing and harmonic currents generated by some nonlinear loads .
More importantly, energy storage could not only participate on the sustainable energy, but could also involve deeply in the current energy system. Energy would no longer be wasted if usage could not match the generation. In many extreme weather situation where power outage might occur, energy storage system could meet the need of electricity  .
This work proposes a compensation scheme that provides simultaneous correction of harmonic content and load unbalance for railroad systems using an open delta connection in the power substation. This method is based on the instantaneouspower description of the scheme, using space vector representation of the state variables, and the use of direct power control (DPC) to attain the required correction by minimizing a cost function achieved from the instantaneous active and reactive mismatch .The control strategies presented in this work are experimentally legalized using a DSP based modular power electronic system able to emulate the electric traction system operating conditions, the open delta transformer and the filtering and load balancing converters .
This method presented here control lead acid battery charging faster and efficiently. The control algorithm execute P&O method allow module to operate at maximum power point according to solar irradiation, and match load with the source impedance to provide maximum power. This MPPT model is more suitable because of less cost, easier circuit design. And efficiency of the circuit is increased by 20-25% in case of MPPT solar charge controller compare to a circuit without MPPT. And also saved the extra energy required in mechanical tracking. As Arduino based controlling is used, it