## 6 Conclusions  
This article discusses the simultaneous operation of the INP and CBRR, which no previous studies have investigated. Extensive dynamic simulations of a three-CA test system with the simultaneous operation of the INP and CBRR were performed to evaluate their impact on the frequency quality, the LFC, and performance.  
The results confirmed the conclusions in [20, 21, 22, 23], where the INP and CBRR were analyzed separately. The results of the step change of load and the random load variation confirmed that the impact of the INP and CBRR on frequency deviations has no unambiguous conclusions. In addition, the impact of inertia and synchronizing coefficient is not clear, whereas the increase of droop characteristic results in an increase of frequency deviations. However, both mechanisms reduce the ACE deviations--the INP slightly more than CBRR. The reduction is most pronounced when both mechanisms operate simultaneously. Moreover, the function for correction power adjustment additionally decreased ACE and scheduled control power, which prevents undesirable switching between the INP and CBRR. Both mechanisms also reduce the RoCoF, and the reduction is most pronounced when both mechanisms operate simultaneously. However, there are no unambiguous conclusions as to which mechanism reduces the RoCoF more, and, in most cases, it is the INP. Increase of inertia and droop characteristic results in a decrease of RoCoF, whereas increase of synchronizing coefficients results in an increase of RoCoF. When both mechanisms operate simultaneously, the scheduled control power is greatly reduced and the impact of the INP is greater than the impact of the CBRR. Similarly, the balancing energy as well as the unintended exchange of energy are greatly reduced when both mechanisms operate simultaneously. However, there is no impact of inertia, synchronizing coefficient, and droop characteristic on scheduled control power. Due to the function for correction  
Figure 16: Average values of \(\mu_{\text{RoCoF}_{i  
power adjustment, which prevents undesirable activation of the INP and CBRR, energy exchange was slightly reduced, as expected. Because of the reduced unintended exchange of energy, beneficial economic consequences can be anticipated when the INP and CBRR operate simultaneously.  
One of the tough challenges for all researchers in this domain is the dynamic dimensioning of RRs, considering the INP and CBRR. This article clearly shows that the simultaneous operation of the INP and CBRR reduces the activation of the RRs, which is currently not considered in the reserve dimensioning process.  
Supervision, B.P.; Writing--original draft, M.T.; Writing--review and editing, B.P. All authors have read and agreed to the published version of the manuscript.  
This work was supported by ARRS under Projects P2-0115 and L2-7556.  
Not applicable.  
This study did not report any data.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} RR & Regulating Reserve \\ INP & Imbalance Netting Process \\ CBRR & Cross-Border Activation of the Regulating Reserve \\ CA & Control Area \\ LFC & Load-Frequency Control \\ ACE & Area Control Error \\ ENTSO-E & European Network of Transmission System Operators for Electricity \\ GCC & Grid Control Cooperation \\ TSO & Transmission System Operator \\ IGCC & International Grid Control Cooperation \\ RoCoF & Rate of Change of Frequency \\ LPF & Low Pass Filter \\ SH & Sample and Hold \\ PI & Proportional-Integral \\ \end{tabular}