# A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids

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^{2}

^{3}

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## Abstract

**:**

## 1. Introduction

- This work aims to formulate a model that can assess the behaviour of distributed energy resources in 14-node IEEE systems that stem from the change in the opening protocol of the disconnector, which establishes a power generating island. The stability analysis it exposes makes it possible to determine the performance of a radial distribution power system given various disturbances. Results have relevance in the operation and planning phases of a distributed generation system.
- As a renewable energy interface, numerous control technologies can be used to operate controlled inverters or rectifiers. In this study, some converters operated in an open-loop control strategy while others operated in a closed-loop control strategy. Furthermore, pulse width modulation techniques at varying carrier frequencies were utilised by these rectifiers or inverters.
- The main contribution of this paper the proposed method not only focused on the transient response but also improve the steady-state response which smooth the voltage, furthermore all inverters are effectively involved to increase capacity of the microgrid for better power management.
- The hybrid microgrid was equipped with nonlinear and linear loads, typical energy storage systems, and balanced and unbalanced loads. Moreover, this paper thoroughly describes the model with all the data needed to tackle the abovementioned studies.
- This paper offers a design process for the digital PR current controller implemented to a GCI. The procedure describes a step-by-step method for calculating the resonant and proportional gains, as well the resonant path’s coefficients. Its main contribution is helping facilitate and providing support to researchers who are tasked with designing GCI that incorporates present control strategies in a digital environment. The paper will also present an analysis of the frequency domain of a digital PR controller. This analysis utilised the fictitious w-domain. The case-study demonstrated the efficacy of GCI that uses a digital PR current controller, which was designed with the help of the proposed procedure. The paper also demonstrates how the proposed procedure has validity for a number of resonant path PR controllers.

## 2. Proposed System Description

## 3. Distributed Hybrid Energy Generation System

#### 3.1. Photovoltaic Modelling

^{−23}J/K q is the charge of the electron (1.602 × 10

^{−19}C), ${I}_{o,cell}$ is the saturation current or reversed leakage of the photovoltaic, ${I}_{ph,cell}$ is the photocurrent (A) of the photovoltaic, ${R}_{s,cell}$, is the series resistance of photovoltaic, ${R}_{p,cell}$ is parallel resistance of photovoltaic.

^{2}), ${I}_{ph;n}$ represents the photocurrent when it is under the nominal condition (typically a 1000 w/m

^{2}irradiance and 25 °C temperature), $G$ is a measured solar irradiance in w/m

^{2}${K}_{i}$ is the temperature coefficient [30]. In this paper, the electrical parameters of the SPR-305E-WHT-D solar is extracted and used to simulate this modular model. These parameters are listed in Table 1.

#### 3.2. Batteries

#### 3.3. Loads

#### 3.4. Diesel Generator

_{1}, T

_{2}and T

_{3}refer to time constants of the regulator (seconds). Below is the actuator transfer function:

#### 3.5. The Lines Data

## 4. Controller of the Inverters

## 5. Controller of Proportional Resonant

## 6. Case-Study

## 7. Proposed System Analysis

## 8. Voltage Analysis

## 9. Power Flow Result

## 10. Active Power Balance per Bus

## 11. Analysis Reactive-Power Balance

## 12. Buss Power Factor

## 13. Power Loss to Lines

## 14. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 14.**(

**a**) The output of the PR controller, (

**b**) error signal of the PR controller during the 180-degree reference change.

Parameters | Values |
---|---|

Series connected modules | $7$ |

Parallel string | $1$ |

Maximum current ${I}_{mp}$ | 5.58 (A) |

Maximum voltage $\left({V}_{mp}\right)$ | 54.7 (V) |

Short-circuit current $\left({I}_{sc}\right)$ | 5.96 (A) |

Voltage of open circuit $\left({V}_{oc}\right)$ | 6.42 (V) |

Temperature coefficient of $\left({I}_{sc}\right)$ | 0.061745 (%/°C) |

Temperature coefficient of $\left({V}_{oc}\right)$ | −0.27269 (%/°C) |

Shunt resistance $\left({R}_{sh}\right)$ | 269.5934 Ω |

Series resistance $\left({R}_{s}\right)$ | 0.37152 Ω |

Diode saturation curent ${I}_{o}$ | $6.3\times {10}^{-1}$(A) |

Number of cells | 96 |

Loads Name | Min-Loads (kVA) | Max-Loads (KVA) | Load Type | Power Factor |
---|---|---|---|---|

Home2 | 13 | 39 | AC | 0.89 |

Home3 | 10 | 29 | AC | 0.9 |

Home4 | 14 | 49 | AC | 0.89 |

Home9 | 100 | 319 | AC | 0.99 |

Home10 | 239 | 799 | AC | 0.9 |

Home11 | 119 | 399 | AC | 0.92 |

Home12 | 239 | 799 | AC | 0.93 |

Home14 | 479 | 1599 | AC | 0.85 |

Home1 | 0.7 | 3 | DC | 0.99 |

Lines | Resistors (ohm) | Inductance | Distances (km) |
---|---|---|---|

1 | 0.029 | 0.016 | 0.15 |

2 | 0.039 | 0.021 | 0.2 |

3 | 0.029 | 0.016 | 0.15 |

4 | 0.079 | 0.043 | 0.4 |

5 | 0.079 | 0.043 | 0.4 |

6 | 0.079 | 0.043 | 0.4 |

7 | 0.019 | 0.01 | 0.1 |

8 | 0.78 | 0.23 | 2 |

9 | 2.36 | 0.70 | 6 |

10 | 2.36 | 0.70 | 6 |

11 | 1.18 | 0.35 | 3 |

12 | 2.36 | 0.7 | 6 |

13 | 1.18 | 0.35 | 3 |

14 | 0.78 | 0.23 | 2 |

**Table 4.**Parameter of the system [34].

Parameters | Units | Symbols |
---|---|---|

Inductance of Inverters | H | ${L}_{inv}$ |

resistance of Inverter | Ω | ${R}_{inv}$ |

DC link Voltage | V | ${V}_{dc}$ |

Switch frequency | Hz | ${f}_{sw}$ |

Current sensor gain | A | ${H}_{i}$ |

Inverter power | W | ${P}_{inv}$ |

Sampling frequency | Hz | ${f}_{a}$ |

Sampling angle frequency | Rad/second | ${\omega}_{a}=2\pi {f}_{a}$ |

Sampling period | s | ${T}_{a}=1/{f}_{a}$ |

Grid peak voltage | V | ${V}_{p}$ |

Frequency of grid | Hz | ${f}_{g}$ |

Angle frequency of grid | Rad/s | ${\omega}_{g}=2\pi {f}_{g}$ |

Parameters | Units | Symbols |
---|---|---|

Inductance of Inverter | $10\mathrm{mH}$ | ${L}_{inv}$ |

Resistance of Inverter | $0.5\mathrm{m}\mathsf{\Omega}$ | ${R}_{inv}$ |

Voltage of DC link | $450\mathrm{V}$ | ${V}_{dc}$ |

Current sensor gain | 0.1 A | ${H}_{i}$ |

Power of inverter | 1500 W | ${P}_{inv}$ |

Sampling angle frequency | $1.88\times {10}^{5}$ Rad/s | ${\omega}_{a}=2\pi {f}_{a}$ |

Sampling period | $34\mu \mathrm{s}$ | ${T}_{a}=1/{f}_{a}$ |

Grid Peak voltage | $180\mathrm{V}$ | ${V}_{p}$ |

Angular frequency of grid | $377\mathrm{Rad}/\mathrm{s}$ | ${\omega}_{g}=2\pi {f}_{g}$ |

Inductance of grid | $100\mu \mathrm{H}$ | ${L}_{g}$ |

Resistor of grid | $0.1\mathrm{m}\mathsf{\Omega}$ | ${R}_{g}$ |

Resonant angle frequency | 377 Rad/s | ${\omega}_{r}=2\pi {f}_{r}$ |

Resonant bandwidth | $1.5\mathrm{Hz}$ | ${B}_{s}$ |

Bandwidth of Resonant angular | $10\mathrm{rad}/\mathrm{s}$ | ${B}_{s}=2\pi {B}_{s}$ |

Resonant gains | ${\U0001d4c0}_{\U0001d4c7}$ | 1 |

**Table 6.**Designed digital Proportional-Resonant (PR) controller [34].

Parameters | Variables | Values |
---|---|---|

Proportional gain | ${\U0001d4c0}_{\U0001d4c5}$ | 0.827 |

Resonant gain | ${\U0001d4c0}_{\U0001d4be}$ | 234.02 |

B0 coefficient | ${\U0001d4b7}_{0}$ | $3.14\times {10}^{-4}$ |

B1 coefficient | ${\U0001d4b7}_{1}$ | $-3.14\times {10}^{-4}$ |

B2 coefficient | ${\U0001d4b7}_{2}$ | 0 |

A0 coefficient | ${\U0001d4b6}_{0}$ | 1 |

A1 coefficient | ${\U0001d4b6}_{1}$ | −1.99 |

A2 coefficient | ${\U0001d4b6}_{2}$ | 0.99 |

Bus | Angle (Degree) | V | ${\mathcal{Q}}_{\mathit{\U0001d4f0}}$ | ${\mathcal{P}}_{\mathit{\U0001d4f0}}$ | ${\mathcal{Q}}_{1}$ | ${\mathcal{P}}_{1}$ | ${\mathcal{Q}}_{\mathbf{transfer}}$ | ${\mathcal{P}}_{\mathbf{transfer}}$ |
---|---|---|---|---|---|---|---|---|

1 | −29 | 0.91 | 14 | 30 | ||||

2 | −29.9 | 0.94 | 6 | 15 | ||||

3 | −32 | 0.92 | 12 | 19 | 15 | 21 | ||

4 | −30 | 0.93 | 26 | 49.9 | ||||

5 | −34 | 0.95 | 25 | 49 | ||||

6 | −32 | 0.94 | 350 | 480 | ||||

7 | −29 | 0.96 | 90 | 90 | ||||

8 | −65 | 0.96 | 50 | 140 | ||||

9 | −29 | 0.93 | 0.70 | 109 | ||||

10 | −29 | 0.93 | 140 | 190 | ||||

11 | −29 | 0.99 | 70 | 89 | ||||

12 | −29 | 0.89 | 140 | 190 | ||||

13 | −29 | 0.93 | 70 | 89 | ||||

14 | −29 | 0.91 | 280 | 380 | 79 | 19 |

Bus | Angle (Degree) | V | ${\mathcal{Q}}_{\mathit{\U0001d4f0}}$ | ${\mathcal{P}}_{\mathit{\U0001d4f0}}$ | ${\mathcal{Q}}_{1}$ | ${\mathcal{P}}_{1}$ | ${\mathcal{Q}}_{\mathbf{transfer}}$ | ${\mathcal{P}}_{\mathbf{transfer}}$ |
---|---|---|---|---|---|---|---|---|

1 | −30.1 | 0.89 | 29.99 | 45 | ||||

2 | −29.5 | 0.90 | 5 | 39 | ||||

3 | −30.3 | 0.91 | 41 | 65 | 42 | 59 | ||

4 | −32.4 | 0.92 | 90 | 125 | ||||

5 | −30.3 | 0.93 | 60 | 37 | ||||

6 | −32.2 | 0.94 | 1080 | 790 | ||||

7 | −31.1 | 0.90 | 350 | 560 | ||||

8 | −59.99 | 0.91 | 430 | 680 | ||||

9 | −29.9 | 0.93 | 37 | 330 | ||||

10 | −30.1 | 0.91 | 430 | 580 | ||||

11 | −29.99 | 0.92 | 220 | 280 | ||||

12 | −29.8 | 0.91 | 450 | 580 | ||||

13 | −29.7 | 0.89 | 1670 | 1820 | ||||

14 | −29.3 | 0.92 | 90 | 120 | 350 | 230 |

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## Share and Cite

**MDPI and ACS Style**

Alhasnawi, B.N.; Jasim, B.H.; Issa, W.; Esteban, M.D.
A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids. *Appl. Sci.* **2020**, *10*, 6120.
https://doi.org/10.3390/app10176120

**AMA Style**

Alhasnawi BN, Jasim BH, Issa W, Esteban MD.
A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids. *Applied Sciences*. 2020; 10(17):6120.
https://doi.org/10.3390/app10176120

**Chicago/Turabian Style**

Alhasnawi, Bilal Naji, Basil H. Jasim, Walid Issa, and M. Dolores Esteban.
2020. "A Novel Cooperative Controller for Inverters of Smart Hybrid AC/DC Microgrids" *Applied Sciences* 10, no. 17: 6120.
https://doi.org/10.3390/app10176120