###### Abstract  
This article examines the mechanisms for cross-border interchange of the regulating reserves (RRs), i.e., the imbalance-netting process (INP) and the cross-border activation of the RRs (CBRR). Both mechanisms are an additional service of frequency restoration reserves in the power system and connect different control areas (CAs) via virtual tie-lines to release RRs and reduce balancing energy. The primary objective of the INP is to net the demand for RRs between the cooperating CAs with different signs of interchange power variation. In contrast, the primary objective of the CBRR is to activate the RRs in the cooperating CAs with matching signs of interchange power variation. In this way, the ancillary services market and the European balancing system should be improved. However, both the INP and CBRR include a frequency term and thus impact the frequency response of the cooperating CAs. Therefore, the impact of the simultaneous operation of the INP and CBRR on the load-frequency control (LFC) and performance is comprehensively evaluated with dynamic simulations of a three-CA testing system, which no previous studies investigated before. In addition, a function for correction power adjustment is proposed to prevent the undesirable simultaneous activation of the INP and CBRR. In this way, area control error (ACE) and scheduled control power are decreased since undesired correction is prevented. The dynamic simulations confirmed that the simultaneous operation of the INP and CBRR reduced the balancing energy and decreased the unintended exchange of energy. Consequently, the LFC and performance were improved in this way. However, the impact of the INP and CBRR on the frequency quality has no unambiguous conclusions. To avert the activation of the RRs with different signs in the cooperating CAs, and thus reduce the RRs, a grid-control cooperation (GCC) platform was implemented in Germany, where four transmission system operators (TSOs), i.e., 50 Hertz, Amprion, TenneT, and TransnetBW have been collaborating since 2008 [5]. In the following years, many continental European countries joined and the GCC platform developed into the international GCC (IGCC) platform, with the aim to further reduce RRs and increase the reliability of the power system's operation [6; 7; 8; 9]. Hence, the INP was developed and put in operation, where the cooperating CAs with different signs of power variations can exchange the balancing energy and thus compensate the power variations [10; 11]. Therefore, CAs with a surplus of power can exchange with CAs having power shortages [12]. A comparable approach, i.e., area control error (ACE) diversity interchange, was implemented in North America in 1993, but does not consist of actual responses from the control units [13; 14; 15]. A further reduction of power-system operating costs and increasingly stringent requirements for the quality of the Load-Frequency Control (LFC) defined by the new network codes require further development of the INP with a functionality that will enable CBRR [16]. Therefore, in the first quarter of 2020, the development of the CBRR started that will be put in operation in continental Europe in 2022 [3]. The aim of the development and operation of the CBRR is to improve the ancillary services market and the European balancing system [17]. Similar to the INP, the same control-demand approach and implementation in the control structure will be used for the CBRR. However, the primary objective of the CBRR will be the activation of the RRs in the cooperating CAs and importing into its own CA, thereby reducing the balancing energy [18]. CBRR will only be achievable if the cooperating CAs have matching signs of power deviations. Consequently, CAs with a surplus of power can activate the RRs only in CAs with a surplus of power. Both mechanisms, i.e., INP and CBRR, reduce the balancing energy, while releasing the RRs and, therefore, reducing the associated economic costs.