Category Renewable Energy Integration

Case Study and Simulation Results

The proposed method is applied to the abovementioned distribution network. According to a sensitivity analysis, the number of generations and the population size are chosen as, 300 and 20, respectively. The method has been implemented in MATLAB® incorporating some features of MATPOWER suite [19] and MAT – LAB® toolbox for GA [27] on a laptop with core i7, 1.6 GHz processor and 4 GB of RAM.

The minimum energy losses over the year are about 7,532 MWh. The optimal sizes and numbers of WTs at each candidate bus found by the proposed method are given in Table 6.4. It is evident from Table 6.4 that buses 54, 62, and 81 have the

Table 6.4 The optimal numbers, sizes and capacities of WTs obtained by the proposed method

Bus no.

Size

Number

Capacity (MW)

6

9

C

1

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Load-Sharing Control Techniques for LV and MV Networks

The main objective of load-sharing is to distribute the active and reactive loads among the available DGs while maintaining voltage regulation and accommo­dating various types of loads [13]. In LV and MV networks, load-sharing becomes challenging due to the following factors.

• Most DGs have some local loads,

• Most DGs are non-dispatchable RESs, and

• The stability and reliability of the system gain importance, apart from the cost.

R X

Подпись: Fig. 9.1 Power flow via transmission line from nodes a to b [12]image138"Подпись: Q) VbXSb—mrYV-

Sab=Pab+jQab

Three different methods of load sharing are commonly employed: droop-based control, communication-based control, and droop-based control with communi­cation link, as described in the following subsections.

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Impact of G2V on Grid

First-generation mass-market PHEVs, such as the Chevrolet Volt and Nissan Leaf [10, 11], connect to the grid for only battery charging, which is the most basic configuration. G2V includes conventional and fast battery charging systems, and the latter can stress a grid distribution network because its power is high, as a typical PHEV requires more than double an average household’s load [25]. Charging practices in different locations also have an effect on the amount of power taken from an electric grid by a fleet of PHEVs; for example, charging at work in congested urban centres can lead to undesirable peak load [12], which could require significant investments in expensive peak generation...

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Analyzing the Benefits ofEV Participation on the MG Rebuilding

Figure 12.20 compares the MG frequency behavior during the reconnection of loads and non-controllable MS when considering both non-controlled charging and V2G service. At t = 5 s the MGCC enables the reconnection of the first load block causing a frequency deviation of 1.5 Hz, which is then corrected by the secondary control by increasing the controllable generation output. The load reconnection is interleaved with the reconnection of the non-controllable MS at t = 30 s, followed by the reconnection of the second block of loads at t = 50 s. After the restoration

image197

Fig. 12.22 Active power injected by the MG main storage unit

image198

Time (s)

Fig. 12.23 SSMT active power response to the MGCC centralized secondary frequency control

of load there is still sufficient reserve capacity and ...

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DC-DC Converter

The power losses in a power electronic DC-DC converter can be divided into conduction and switching losses, where conduction losses consist of inductor conduction losses and MOSFET conduction losses [28] (Fig.14.7).

• Inductor Conduction Losses Inductor conduction losses is as follows

Pl = I2L x Rl {14.17)

where Rl is the DC-Resistance of the inductor,

The inductor rms current (IL):

D/2

11 = /2 + (14.18)

where /o the output current and D/ the ripple current.

Typically, D/ is about 30 % of the output current. Therefore, the inductor current can be calculated as:

/l = /o x 1.00375 (14.19)

Because the ripple current contributes only 0.375 % of IL, it can be neglected. The power dissipated in the inductor now can be calculated as:

Подпись: (14.20)Pl = /o2 x Rl

• Power Dissipated in the MOSFETs

The power d...

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Illustrative Example and Results

To evaluate the performance of the MAS-based smart grid protection system for the impact of growing penetration of wind energy in the grid, a test system as shown in Fig. 16.2 is used for simulation under different wind power penetration level. In the following sections, we discuss about the function of individual autonomous agents which are responsible for coordinating the protection relays by detecting and isolating a fault with the corresponding CCT information.

Fig. 16.8 Fault current x 104

Подпись: Time (sec)

Подпись: x 104 Fig. 16.9 Breaker fault current

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Genetic Algorithm

A genetic algorithm (GA) is a procedure used to find approximate solutions to search problems through application of the principles of evolutionary biology. The evolutionary process of a GA is a highly simplified and stylized simulation of the biological version. It starts from a population of individuals randomly generated according to some probability distribution, usually uniform and updates this population in steps called generations. Each generation, multiple individuals are randomly selected from the current population based upon some application of

image60

Fig. 5.10 Implementation of a fuzzy logic controller based MPPT

image61

current

Fig. 5.11 Implementation of ANN based MPPT

fitness, bred using crossover, and modified through mutation to form a new population.

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Series-Shunt Compensation

It is clear from the above analysis, that the advantage of both shunt and series compensation of an AC capacitor can be made use of. In shunt compensation, the capacitor is used to compensate the individual induction generators. In series com­pensation, the capacitor is used to compensate the line impedance. The overall result will be an improvement in the voltage and lower losses on the transmission line.

To know the effect of the combined series and shunt compensations, simula­tions are carried out for two different combinations of series-shunt compensation. The same 10 wind turbines are connected at bus 9. Figure 7.21 illustrates the real power generated by WECS versus the voltage at the WECS terminals with various combinations of series-shunt compensations...

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