Ratna Ika Putri

Digital Control of Parallel-Connected DC-DC Converters

This paper presents a digitally-controlled paralleled DC-DC converter. The main objective of the digital control is to achieve load sharing while operating at close to peak efficiency over an extremely wide load range. Results from computer simulations using Simulink show the digital control could indeed accomplish the objectives, but the improvements over a single converter depend on the original efficiency characteristics of the converters. An application for a high-power electric vehicle charger utilizing this converter setup is considered.

Wind farm site selection base on fuzzy analytic hierarchy process method; Case study area Nganjuk

The selection of site wind farm is an important element in building a wind power generation to get a site that is capable of produce maximum energy, economic and environmental agreeable. It is obtained if proposed alternative sites has continuous wind resources, access to the grid, good topography, land costs are cheap, reduce noise blade and available road access. The site proposed of study is Sukomoro, Rejoso, Lengkong, Nganjuk and Pace. It will be decided using Fuzzy Analytic Hierarchy Process(F-AHP) based on multi criteria eg, technical, economic and environment. The decision making process is decided by compare each element of main criteria with each of altenative so that to get a best site, it is best highest weight to recommend. In this study show that, weight of final is resulted by each alternative are Sukomoro is 0.3205, Rejoso is 0.1632, Lengkong is 0.1218, Nganjuk is 0.3095 and Pace is 0.0602. Based on testing, Sukomoro to get highest weight so that it is recommended for use by governments and companies electricity as a reference in policy formulation and calculate cost of electricity.

Controlled bidirectional converter using PID for charging battery in the stand-alone wind turbine system with Modified P&O to obtain MPPT

The main problem which often occurs in wind turbine systems is getting the maximum power output and maintaining the DC link voltage at a constant value through wind fluctuation. This paper proposed to maintain the DC link voltage during stand-alone condition, it takes a battery as energy storage with a bidirectional buck-boost converter to regulate charging and discharging mode, alternately. Control of bidirectional DC-DC converter using PID controller. Meanwhile, Modified Perturbation and Observation algorithm to set switching of quadratic boost converter for obtaining the Maximum Power Point (MPP) of the wind energy system. The results of this research, the efficiency of wind turbine system can be improved up to 98,176% using the modified P&O.

Modified firefly algorithm for maximum power point tracking of a small stand alone wind power system

To increase efficiency of wind power system, the system have to work at maximum power. This paper proposes a new modification of the algorithms firefly by updating the coefficient p and neglected α and γ to get the maximum power from the wind turbines use a permanent magnet synchronous generator. The method differs from the standard firefly just ignore α and γ to accelerate convergence alone. The simulation with modified FA results compared with modified perturb and observe (P&O) and standard Firefly. Convergence process of the proposed algorithm is faster and more efficient in tracking the point of maximum peak. Ripple in steady state conditions are also lower than standard FA and Modified P & O. The average efficiency and convergence time that achieved by using modified firefly are 99,03% and 1,83s.

Optimum control strategy of grid connected PMSG wind turbine based on energy storage system

Nowadays, wind energy, as a source of electrical energy, are growing rapidly to substitute fossil energy. The power generated wind turbine is fluctuating that is influenced by wind speed so that it takes the appropriate controlling to get the maximum energy and the constant power for grid. This paper presents control for variable speed permanent magnet synchronous generator (PMSG) wind turbine that is connected to the grid. To extract the maximum power, Particle Swarm Optimization (PSO) method is used to get optimal power coefficient (Cp) through setting duty cycle for the boost converter. Control of bidirectional converter is aimed to control the DC-link voltage and smoothes the delivered power to the grid using the battery as energy storage. Bidirectional converter controlling will set the charging and discharging of the battery to meet the power grid required using a PID controller. To achieve unity power factor, voltage source inverter is controlled using PI control. Based on simulation results, the controller has worked very well. PSO can maintain Cp at optimal value of 0.48 against wind speed variation. DC-link voltage could be maintained at constant value of 400V for changes in wind speed through setting the charging and discharging of the battery by bidirectional converters.

Modeling and control of permanent magnet synchronous generator variable speed wind turbine

The use of wind energy as a source of electrical energy is increasing along with the limited fossil energy and increase environmental awareness to the greenhouse effect. This paper presents the modeling and control of permanent magnet synchronous generator (PMSG) for wind turbines. To get optimal power, the generator must be able to rotate at the optimum speed so that it is required speed controller for PMSG. Speed control is done by control of the current by using the PI controller. PI controller is chosen because of its simplicity and easy to implement. Based on the results of the simulation, modeling and control of PMSG produces good performance.

Stochastic Petri Nets for very short-term wind speed modeling

To overcome the limitations of fossil energy and protect the environment from emissions of greenhouse gases, it is essential to develop the use of renewable energy as a substitute. At present, one of the renewable sources of energy is wind energy, which has the advantage of being pollution free and inexhaustible. However, the use of wind energy is strongly influenced by wind speed, which is not constant. Such varying wind speeds lead to the creation of fluctuated wind power. Consequently, there is a need for modeling and the accurate prediction of wind speed to help optimize the design of the turbine and control system in a wind energy conversion system to maintain system stability. This paper presents the modeling of very short-term wind speed using Stochastic Petri Nets (SPN) that is based on the measurement results of wind speed in Nganjuk. In this study, Stochastic Petri Nets was designed by using 7 places and 7 transitions. Transition to the SPN is defined as a function that generates random values using a uniform function. Wind speed data that was generated during a 500 seconds interval, was compared with the observed wind speeds. The comparison of the generated wind speed and observed ones shows that both its statistical characteristic have similar value.