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The gradual depletion of the fossil fuels along with their adverse implications on the global environment is a matter of increasing concern. To add to this further, the future progress and development of any country is judged by its capacity to harness the renewable sources of energy like wind, solar and geothermal energy. Of the various forms of renewable energies available, wind energy happens to...
This paper proposes a new control method for battery storage in an autonomous microgrid. The battery output is controlled in such a manner that the bus voltages in the microgrid system are maintained during disturbances such as load change, loss of micro sources or power limit in the DGs. An artificial neural network (ANN) based controller is used to determine the reference power for the battery to...
This paper compares the performance of two droop control schemes in a hybrid microgrid. With presence of both converter interfaced and inertial sources, the droop controller share power in a decentralized fashion. Both the droop controllers facilitate reactive power sharing based on voltage droop. However in frequency droop control, the real power sharing depends on the frequency, while in angle droop...
Adaptive phasor power oscillation damping controllers (APPODs) produce superior large signal performance with very little reliance on accurate system models. However, recursive phasor estimation, online frequency correction and adaptive phase-shift are involved which makes modeling such APPODs difficult in stability studies. Possible interaction with other controllers (e.g. lead-lag compensators)...
This paper describes the operation of a microgrid that contains a custom power park (CPP). The park may contain an unbalanced and/or nonlinear load and the microgrid may contain many distributed generators (DGs). One of the DGs in the microgrid is used as a compensator to achieve load compensation. A new method is proposed for current reference generation for load compensation, which takes into account...
In this paper, the stability of an autonomous microgrid with multiple distributed generators (DG) is studied through eigenvalue analysis. It is assumed that all the DGs are connected through Voltage Source Converter (VSC) and all connected loads are passive. The VSCs are controlled by state feedback controller to achieve desired voltage and current outputs that are decided by a droop controller. The...
In this paper, a new power sharing control method for a microgrid with several distributed generation units is proposed. The presence of both inertial and non-inertial sources with different power ratings, maximum power point tracking, and various types of loads pose a great challenge for the power sharing and system stability. The conventional droop control method is modified to achieve the desired...
This paper illustrates the challenges towards achieving a robust phasor POD (power oscillation damping), a concept introduced and developed by ABB. A Phasor POD extracts the oscillatory part of the measured signal in the form of a phasor and applies a suitable phase shift to derive the damping control action. For a thyristor controlled series capacitor (TCSC), a phase shift of 90 degrees with respect...
This paper compares the performance of angle and frequency droops in an autonomous microgrid that only contains voltage source converter (VSC) interfaced distributed generators (DGs). As a VSC can instantaneously change output voltage waveform, power sharing in a microgrid is possible by controlling the output voltage angle of the DGs through droop. The angle droop is able to provide proper load sharing...
This paper proposes operation and control of converter based single phase distributed generators (DG) in a utility connected grid. A common utility practice is to distribute the household single-phase loads evenly between the three phases. The voltage unbalance between the phases remains within a reasonable limit. However the voltage unbalance can be severe if single-phase rooftop mounted PVs are...
This paper describes control methods for proper load sharing between parallel converters connected to microgrid in a distributed generation system. The system stability is investigated during load sharing for safe operation and proper control. The dynamic response of the system is compared under different load conditions. Both inertia-less and inertial loads are considered in grid connected and islanded...
In this paper a robust control method of a doubly fed induction generator driven by wind turbine (WT-DFIG) is proposed. The rotor of the induction generator is connected to the power grid using two back to back power convertors. Two controllers, rotor side controller and grid side controller, are deployed for proper tracking of power captured by the wind turbine. Traditionally PI controller is used...
This paper illustrates robust fixed order power oscillation damper design for mitigating power systems oscillations. From implementation and tuning point of view, such low and fixed structure is common practice for most practical applications, including power systems. However, conventional techniques of optimal and robust control theory cannot handle the constraint of fixed-order as it is, in general,...
This paper highlights the importance of considering the phase angle of the residues (residue angle) in addition to their magnitude while selecting appropriate feedback signals for damping control design. Residue angle is closely related to the phase compensation requirement at each modal frequency and hence should not differ significantly over adjacent frequencies. This is especially true when the...
Summary form only given. Research effort has been given to locate the optimal locations of thyristor-controlled series capacitor (TCSC) and their initial compensation levels using mixed-integer programming (MIP). As a useful technique for combinatorial optimisation over integer and continuous variables, the MIP approach can provide robust performance as well as high computational efficiency while...
This paper describes control methods for proper load sharing between parallel converters connected to microgrid supplied by distributed generators. The model of the microgrid power system is simulated in PSCAD. It is assumed that the microgrid supplies a load both in grid connected and islanded modes. Both passive loads and inertial loads are considered. A control strategy is proposed to improve the...
This paper presents a new approach for designing multi-input-single-output (MISO) damping controller for a TCSC in a multi-machine power system. The damping controller design uses particle swarm optimization (PSO) to determine the coefficients of single or multi-stage lead-lag compensators. The classical technique works well in the design of lead-lag compensators for SISO controllers. But, there is...
This paper demonstrates the design and implementation of a robust damping controller for damping the low frequency (0.1-2 Hz) electromechanical modes in an interconnected power system. The robust control design is formulated as Hinfin norm optimization problem and the solution is sought numerically using LMIs. This allows additional pole-placement constraints to be imposed to ensure that the time...
As a useful tool for combinatorial optimisation over continuous and discrete variables, the mixed-integer linear programming (MILP) approach can address complex control and planning models providing high computational efficiency as well as robust behavior. On power system planning, previous work using MILP employed conventional dc load flow model neglecting reactive power, power loss and transformer...
This work is a step towards real-time implementation of a single-input single-output (SISO) adaptive controller scheme for power oscillations damping (POD) making use of fast power electronic devices such as FACTS (flexible AC transmission systems). The adaptive control is based on a recursive parameter estimation using Kalman filtering techniques and a pole shifting method which takes into consideration...
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