**2. System description**

The building solar system structure is given in **Figure 1**. It is composed of a PV panels in parallel with a battery energy storage system which are linked to a DC bus, a DC/AC power converter, and an LCL filter interfacing between DC and AC bus. Single- and three-phase linear and nonlinear loads are connected to the AC bus.

The linear building loads are modeled by a resistive load, and the nonlinear ones are modeled by a rectifier connected to a capacitive filter at the DC side. This model is conformed to many building loads, similar to televisions, personal computers, and fluorescent lamp ballast [12]. In case of three-phase balanced loads, the neutral current is zero, but since several building loads are single phase and include electronic converters, their waves include harmonics which induce a nonzero neutral current. Regarding neutral wire, the more common considered structures are presented in **Figure 2**. The first structure is based on DC-link neutral point where the neutral wire is generated via two identical capacitors (**Figure 2a**). In the second structure, the neutral wire is generated through a Delta/Star grounded transformer as shown in **Figure 2b** [13]. As to the third configuration, it is based on four-leg

power converter (**Figure 2c**) [14–16]. In this chapter the structure with transformer

• Grid connected mode: this mode is activated when the grid is available. In this case, the power surplus is injected into the grid, and if the consumption is superior to local generation, the power flow will be directed from the grid to loads and eventually to charge batteries according to their stat of charge (SOC).

• Standalone mode: this mode is activated when the grid is absent. In this case, building loads are supplied first by the PV system then if necessary by the BESS. In case of power deficit, the shedding of non-priority loads is carried out.

An overview of the control of each converter presented in **Figure 2b** is

Batteries are frequently integrated to PV systems thanks to their special energy characteristics. Indeed, batteries have a high energy density, which ensure long time of stable operation. The charging time and number of cycles depend on the

The battery power flow is bidirectional. In discharge mode, the power is supplied by battery, and in charging mode, the power is absorbed by battery. For both modes, the state of charge limits should be respected to not affect the battery

The PV system presents two operating modes according to the grid state:

is adopted.

**Figure 2.**

**3. Power converter control**

*Different structures that integrate the fourth wire.*

*Control Analysis of Building-Integrated Photovoltaic System*

*DOI: http://dx.doi.org/10.5772/intechopen.91739*

**3.1 BESS DC/DC converter control**

subsequently presented.

adopted technology.

lifetime.

**57**

**Figure 1.** *Photovoltaic system including BESS.*

*Control Analysis of Building-Integrated Photovoltaic System DOI: http://dx.doi.org/10.5772/intechopen.91739*

This chapter investigates the operation of PV system devoted to building application. It gives an overview of the control of all integrated power converters and then explains in details the control of the DC/AC power converter in both operation modes, namely, standalone mode and grid connected mode. For the grid connected mode, the control must ensure that the AC bus voltage remains within the acceptable range, and for standalone mode the DC/AC converter is controlled to

This chapter first outlines overall system description, followed by a review of each power converter control. A detailed mathematical study is dedicated to the DC/AC converter control in grid connected and autonomous modes. Simulation

The building solar system structure is given in **Figure 1**. It is composed of a PV panels in parallel with a battery energy storage system which are linked to a DC

The linear building loads are modeled by a resistive load, and the nonlinear ones are modeled by a rectifier connected to a capacitive filter at the DC side. This model is conformed to many building loads, similar to televisions, personal computers, and fluorescent lamp ballast [12]. In case of three-phase balanced loads, the neutral current is zero, but since several building loads are single phase and include electronic converters, their waves include harmonics which induce a nonzero neutral current. Regarding neutral wire, the more common considered structures are presented in **Figure 2**. The first structure is based on DC-link neutral point where the neutral wire is generated via two identical capacitors (**Figure 2a**). In the second structure, the neutral wire is generated through a Delta/Star grounded transformer as shown in **Figure 2b** [13]. As to the third configuration, it is based on four-leg

DC and AC bus. Single- and three-phase linear and nonlinear loads are connected

results and experimental validation are subsequently presented.

bus, a DC/AC power converter, and an LCL filter interfacing between

inject generated PV power into the AC-link.

*Numerical Modeling and Computer Simulation*

**2. System description**

to the AC bus.

**Figure 1.**

**56**

*Photovoltaic system including BESS.*

**Figure 2.** *Different structures that integrate the fourth wire.*

power converter (**Figure 2c**) [14–16]. In this chapter the structure with transformer is adopted.

The PV system presents two operating modes according to the grid state:

