Category New developments in renewable energy
The diesel ge4narator is composed of the diesel engine and Wound Rotor Synchronous Generator (wrsg).
a. Diesel Engine
The model of the diesel engine is shown in Fig. 7 (R. Dettmer, 1990; R. Pena et al., 2002; S. Roy et al., 1993). The dynamic of the actuator is modeled by a first order model with time constant Tjand gain К (R. Pena et al., 2008; S. Roy et al., 1993). The combustion bloc is represented with gain К2 and delay t2(R. Dettmer, 1990).
The actuator is modelled as;
1 + sr1
The model of the combustion bloc is given by;
The delay can be expressed as (R. Pena et al., 2002; R. Pena et al., 2008):j
t2 — +
2 2Nnc 4N
h represents the strokes number, nc the number of cylinders and N the speed of diesel generator (rpm), Ф is the fuel ...Read More
a. Doubly-Fed induction Generator
Today, the wind turbines on the market mix and match a variety of innovative concepts with proven technologies both for generators and for power electronics. Wind turbines can operate either with a fixed speed or a variable speed. Most commonly used types of wind turbines generators are asynchronous (induction) and synchronous generators. Among these technologies, asynchronous Doubly Fed Induction Generator (DFIG) has received much attention as one of preferred technology for wind power generation (Fig.4). The DFIG consists of a Wound Rotor Induction Generator (WRIG) with the stator windings directly connected to the constant-frequency three-phase grid and with the rotor windings mounted to a bidirectional back-to-back IGBT voltage source converter...Read More
Wind turbines come in different sizes and types, depending on power generating capacity and the rotor design deployed. Small wind turbines with output capacities below 10 kW are used primarily for residences, telecommunications dishes, and irrigation water pumping applications. Utility-scale wind turbines have high power ratings ranging from 100 kW to 5 MW. Current wind farms with large capacity wind turbine installations are
The structures of Hybrid Power System (HPS) can be classified into two categories: AC coupled and DC-coupled (T. Zhou, 2009).
In an AC-coupled HPS, all sources are connected to a main АС-bus before being connected to the grid. In АС-coupled structure, different sources can be located anywhere in the microgrid with a long distance from each other. However, the voltage and the frequency of the main АС bus should be well controlled in order to ensure the stability of the system and the compatibility with the utility network.
In a DC-coupled HPS, all sources are connected to a main DC-bus before being connected to the grid through a main inverter. In a DC-coupled structure, the voltage and the frequency of the grid are independent from those of each source.
However, not all HPSs can ...Read More
Mamadou Lamine Doumbia, Karim Belmokhtar and Kodjo Agbossou
Additional information is available at the end of the chapter http://dx. doi. org/10.5772/52341
By 2050 the demand for energy could double or even triple as the global population grows and developing countries expand their economies. Energy prices, supply uncertainties, and environmental concerns are driving many countries to rethink their energy mix. The International Energy Agency’s Energy Technology Perspectives2008publication projects that energy sector emissions of greenhouse gases (GHGs) will increase by 130% over 2005 levels, by 2050, in the absence of new policies (IEA, 2008).
Renewable energy is part of the solution for the energy problem, and wind energy is one of the cost-effective options for the ge...Read More
The dynamics of the system can be evaluated by the analysis of the PI control signal. So, once considered both situations of load variation it appears that the stabilization time of the PI controller is approximately 7ms. In addition it presents a small oscillation which proves that the parameters of the PI control are well adapted to the system Figure 29 a) corresponds to the situation of a step-up load condition while Figure 29 b) corresponds to a step-down of load condition. The error of voltage is given by INA101 such as; e =Vmeasured-Vreference and accordingly, the objective of the PI controller is to minimize this error for any load variation, as is shown in the two figures below.
(a) Step-up load condition.
(b) Step-down load condition.
The mai...Read More
The experimental setup is represented in Figure 27. It is used to test the all system composed by the PEM Mark 1020, the SRC and the load. The load is composed by a set of several resistors connected in series, whose variation is performed by a manual switch. The fuel pressure that provides a PEM stack is monitored by a standard dial pressure gauge, which maintains it constant in the range of 0.3 to 0.5bar. The ventilator is used to inject the oxidant flow necessary into the stack in order to produce the electrochemical reaction. The voltage of 26.06V represented by the multimetter corresponds to the open-circuit voltage of the PEM.
The experimental results corresponding to the output voltage and current, the PI controller and the resonant current, are presented in this section to valida...Read More
The control consists of two loops; the loop of the voltage or the fast loop and the loop of he PEM or the slow loop. The voltage controller is responsible of controlling the output voltage of the converter, keeping this in a constant value defined by the user even for load variations. The PEM controller is responsible of controlling the operation of the PEM, keeping it in its optimal point that is, producing the electrical power requested by the load with a minimum current and consequently with a minimum of hydrogen consumption. The control structure of the converter as described is represented in Figure 26.