## Architecture For Design Of A Mva Pv Station

Figure 1.3 represented an AC architecture of DG system. For example, a PV system with 2-MW capacity cannot be economical processed at low-voltage DC due to high power losses. The DC system can be used if the DC converters are used to step up the DC voltage of PV system to higher voltages to reduce the power losses. However, today, it is more economical to step up AC voltage to higher voltages for injection to utility system. As shown in Fig. 1.3, the step-up transformer T1 will step up the...

## Newtonraphson Method

The Newton-Raphson Method is an iterative root-finding algorithm that uses the first few terms of the Taylor series of a function f x in the vicinity of a expected solution. The Newton-Raphson Method is widely used in solving power flow problems due to its fast convergence property. This technique has also been used in line-interactive power converter systems. The Newton-Raphson power flow analysis is performed in a power system involving AC-DC-AC switch mode power converters. The...

## The System Topology

Three-phase inverters can be designed to have a three-phase three-wire system where the inverter itself does not provide a neutral point. Typically, a A Yg transformer is used with the secondary center grounded before the inverter powering the load or being connected to utility grid as shown in Fig. 4.1. In this topology, the three-wire system on the A side only has two independent dimensions and 0-axis current cannot flow, which makes the system relatively easy to control. The drawback is the...

## Dg System Operating As Part Of Utility Power System

The architecture of Figs. 1.1 and 1.3 satisfy Renewable Portfolio R P laws that have been mandated by many states. This architecture allows selling and buying energy from local utilities. When a DG grid system is connected to a utility, the DG system bus voltage that is, the infinite bus voltage is maintained by the local utility. Furthermore, the system frequency is controlled by the power system operator. If the DG inverter has a large capacity in the range of MVA rating, then it will be...

## Simulation Using Simulink And Matlab

Simulations of the control algorithm are done using Simulink MATLAB. This section describes the simulation assumptions and the Simulink block diagrams used. The following assumptions are used in building the simulation 1. It is assumed the PWM space vector and the power converter generate ideal voltages according to the commands given by the control. This assumption is valid due to the relatively high switching frequency of the PWM inverter. 2. The three-phase delta-wye transformer is modeled...

## The Island Mode Of Operation

Upon separation from a utility system, if a smart grid DG stays stable, the inverter of the DG system regulates its frequency. If there is only one inverter in the DG system, load frequency control is accomplished through inverter reference frequency using the Pulse Width Modulation PWM technique as part of the DSP controller. The DG system inverter controls its load at the reference AC bus voltage. As load changes, the DSP controller corrects the AC bus voltage. Therefore, as depicted in Figs....

## Voltage And Current Control Of Individual Inverters In Island Mode

In island mode, an inverter unit needs to control load voltage as it is supplying local load with quality power. There are a number of control methods that are used to control the inverter voltage. These methods are PID control, model-based linear control, robust control, sliding mode control, and internal-model-principle-based control. Conventional PI Control Method. This is a classical method of voltage control of an inverter based on proportional-integral PI regulation under stationary...

## Proposed Load Sharing Control Algorithm

3.6.1 Combined Droop Control Method and Average Power Control Method In order to guarantee exact load-sharing of the real power P and the reactive power Q between DGS units, the conventional droop method should be modified by a new control algorithm. To do this, a combination of the droop method, the average power control method, and harmonic sharing control loop is proposed for load-sharing of paralleled inverters. Figure 3.11 shows a Simulink model of an average power generation block used...