# Achieving Optimal Reactive Power Compensation in Distribution Grids by Using Industrial Compensation Systems

^{*}

## Abstract

**:**

## 1. Introduction

_{inductive}of 0.9 is required for local static voltage stabilization in distribution grids. Local distributions and temporal time availability of industrial reactive power potential need to be taken into consideration. Initial investigations in [22] indicated the inclusion of ICS in reactive power compensation strategies in order to use their cost-effective potential. Further investigation considering the amount and the availability are carried out in Section 2 of this work. Within a survey and a measurement campaign, the reactive power potential of six industrial companies are analyzed.

## 2. Investigation of the Reactive Power Potential of Industrial Compensation Systems

- base load consumers within their industrial grid, which obtain inductive reactive power and
- continually switched-in compensation steps of the ICS.

## 3. A Central Optimal Reactive Power Control Strategy

- transforming the model to an economic optimization by changing the objective function to a minimization of the costs of ${\mathrm{Q}}_{\mathrm{retrieval}}\left(\mathrm{t}\right)$ and setting the compliance of the reactive power exchange as a restriction;
- setting cost limits by modelling additional restrictions;
- using multi-objective techniques; or
- performing economical optimization afterwards.

## 4. An Application Example

- Analysis of the functionality at steady-state conditions and achieving the reactive power objectives and
- Impact on and compliance of the voltage limitations and load flow capacities.

#### 4.1. Description of the Simulation Parameters

- existence of real measured P- and Q-data with a 10-second resolution for each low-voltage load and generation unit, which are implemented in the grid model.
- The grid topology is a typical medium-voltage ring structure and
- the territory of supply is a rural industry area with high load penetration and a typical environment of the six measured industrial companies

^{2}. The grade of cabling amounts 66.9% at a total power line length of 68.1 km. The nominal apparent power of the substation transformer is 25 MVA. The six measured industrial companies with their presented reactive power potential (Figure 2) are implemented randomly into the grid model. The grid topology and the location of the six industrial Q-sources are illustrated in Figure 7.

#### 4.2. Presentation of the Achievements

#### 4.3. Review of the Constraints

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 1.**Composition and measuring points of an exemplary industrial-internal grid with two stations with two transformers each (four plants).

**Figure 2.**Inductive and capacitive reactive power potential of six measured industrial companies displayed by boxplots (red lines show the medium, blue boxes show the upper and lower quartiles and whiskers show the maximum or minimum of the reactive power potentials). Due to its comparatively high values, B6 is presented separately.

**Figure 3.**Effective power consumption (black line, left axis), full-uncompensated reactive power behavior (blue line, right axis), full-compensated reactive power behavior (orange line, right axis), inductive reactive power potential (blue area, right axis) and capacitive reactive power potential (orange area, right axis) with regard to the original reactive power behavior of B6 (grey line, right axis) for the month of December 2017 in minute-resolution.

**Figure 6.**Schematic illustration of the central reactive power control strategy in an exemplary medium-voltage grid with an industrial company with two ICS as reactive power sources.

**Figure 7.**Schematic illustration of the radial topology of the regarded 66-busbar medium-voltage grid with separation points in open position (red) the six implemented industrial companies (blue, B1 to B6) and their reactive power potential (generation units).

**Figure 8.**Maxima (absolute) active (blue) and reactive power behavior (orange) at load buses of the medium-voltage test system (non-simultaneous).

**Figure 9.**P–Q behavior of the regarded medium-voltage grid (logged at the low-voltage site of the substation transformer) before (blue) and after (orange) the reactive power retrieval by the central reactive power control strategy with red circled data points, which exceed the control deviation (green).

**Figure 10.**Root cause analysis for achieving or missing the objective of full compensation (with tolerable control deviation e).

**Figure 11.**Temporal evolvement of the aggregated reactive power potential of the six industrial companies (brown to orange), the reactive power demand of the grid (blue), the deficient reactive power (red), points in time with the minimal simultaneous inductive and capacitive reactive power potential (cyan triangles) and the presentation of extremes of voltage and load flow progressions before (blue) and after (orange) the application of the control process, with labelling the limitations (red); note: lines in apparent power plots are nearly congruent.

Notation | Description | Unit |
---|---|---|

${\mathrm{Q}}_{\mathrm{supply},\mathrm{i}}\left(\mathrm{t}\right)$ | Time-dependent reactive power behavior of plant i at the substation transformer | var |

${\mathrm{Q}}_{\mathrm{ICS},\mathrm{i}}\left(\mathrm{t}\right)$ | Time-dependent reactive power provision of all installed ICSs at plant | var |

${\mathrm{Q}}_{\mathrm{ICS},\mathrm{inst},\mathrm{i}}$ | Installed reactive power of all ICSs at plant i | var |

ID | Sector/Type | Max. Measured Effective Power Consumption in kW | $\sum}_{\mathbf{i}=1}^{\mathbf{n}}{\mathbf{Q}}_{\mathbf{ICS},\mathbf{inst},\mathbf{i}$ in Kvar | Measurement Period in Days | Measurement Resolution |
---|---|---|---|---|---|

B1 | printing company | 2193 | 1000 | 20 | 1-second |

B2 | university | 5872 | 2205 | 22 | 1-minute |

B3 | automotive supplier | 1359 | 1150 | 21 | 1-second |

B4 | manufacturing | 263 | 325 | 22 | 1-second |

B5 | machine building | 1192 | 1150 | 46 | 1-second |

B6 | manufacturing | 7623 | 7075 | 242 | 1-minute |

Minimal Non-Simultaneous Reactive Power Potential | Minimal Simultaneous Reactive Power Potential | Minimal Compensational Effect in Application | |||
---|---|---|---|---|---|

Total in Kvar | Total in Kvar | Change in % | Total in Kvar | Change in % | |

Inductive | 636 | 1388 | 118.2 | 1500 | 135.8 |

Capacitive | −5993 | −6955 | 16.1 | −5168 | −13.7 |

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**MDPI and ACS Style**

Rauch, J.; Brückl, O.
Achieving Optimal Reactive Power Compensation in Distribution Grids by Using Industrial Compensation Systems. *Electricity* **2023**, *4*, 78-95.
https://doi.org/10.3390/electricity4010006

**AMA Style**

Rauch J, Brückl O.
Achieving Optimal Reactive Power Compensation in Distribution Grids by Using Industrial Compensation Systems. *Electricity*. 2023; 4(1):78-95.
https://doi.org/10.3390/electricity4010006

**Chicago/Turabian Style**

Rauch, Johannes, and Oliver Brückl.
2023. "Achieving Optimal Reactive Power Compensation in Distribution Grids by Using Industrial Compensation Systems" *Electricity* 4, no. 1: 78-95.
https://doi.org/10.3390/electricity4010006