# A Two-Grid Interline Dynamic Voltage Restorer Based on Two Three-Phase Input Matrix Converters
###### Abstract
With the aim of extending the compensation range of the IDVR in the event of deep and long-term voltage sags and also of improving its performance in loads with a high power factor, this paper presents a new IDVR topology based on two three-phase input matrix converters (TTI-MC), hence referred to as the two input IDVR (TI-IDVR). In [12], we present a two-input DVR based on the TTI-MC to be applied in CPPs with similar characteristics to those mentioned above. In this paper, features are added to the TI-IDVR that allow a more efficient use of the power provided by the feeders. The proposed TI-IDVR integrates the power of the two feeders to compensate for the disturbances that occur in either of the two feeders. An important contribution of the proposed TI-IDVR with respect to other IDVRs consists of the following: if a swell occurs in any of the feeders, the TI-IDVR takes excess power from the feeder that presents the fault to compensate for the disturbance and does not take power from the healthy feeder; that is, in the case of a swell, the proposed TI-IDVR  
Figure 1: Schematic diagram of the interline dynamic voltage restorers (IDVRs) proposed in the literature. Where DC is Direct Current. behaves like a conventional DVR, unlike other IDVRs that take power from the healthy feeder to compensate for the swell in the feeder that has the fault. The use of an IDVR in multi-feeder distribution systems to mitigate PQ problems has been presented in several publications. In [16; 17; 19; 21], an IDVR is used to mitigate sags. In [15], an IDVR is used to compensate for balanced and unbalanced sags. The compensation of sags, swells and voltage imbalance using an IDVR is presented in [18]. In [22; 23], an IDVR is used to mitigate sags and swells. On the other hand, it should be mentioned due to the importance of DVRs within the IDVR shown in Figure 1, design strategies have been presented that take into consideration that the IDVR must be able to compensate for different types of voltage disturbances in each one of the feeders and the minimum DVR voltage ratings are selected in terms of the generation of the compensation voltage and the energy injection to the capacitor in the dc-link [24; 25]. The proposed TI-IDVR is able to compensate for balanced and unbalanced sags and swells, as well as voltage distortion. Additionally, the TI-IDVR can also compensate for deep and long-term voltage sags and voltage interruptions. That is, the TI-DVR has multi-functional capabilities. In this sense, an important contribution of this work is that, when a voltage interruption occurs in one of the feeders, the proposed TI-IDVR behaves as a reconfiguration and compensation device in multi-feeder distribution systems or in a CPP. All of these features differentiate it from other IDVRs that, as mentioned above, are aimed at compensating sags and swells in one of the feeders. The control algorithm is carried out in the reference frame \(dq\) and can be divided into two parts that are synchronized with each other: (a) the control of the current source inverters (CSIs), and (b) the control of the TTI-MC. There are two feeders in the TI-IDVR system, each with its respective load. The system starts with the voltage measured in feeder 1 (or 2), which is compared with the nominal voltage of sensitive load 1 (or 2) to obtain the difference between them, and thus compensate for the disturbances in feeder 1 (or 2). The injected voltage is synthesized by the respective CSI using the space vector modulation (SVM) scheme. For this, the control algorithm requires the phase angle information of the load voltage in the reference frame \(dq\). The TTI-MC integrates the voltages of the two feeders to build the voltage in the virtual dc-link; this is done by implementing the carrier-based pulse width modulation (MCB-PWM) scheme with two references. The control algorithm generates two sets of reference signals (one set for each of the feeders).