# Solutions to Increase PV Hosting Capacity and Provision of Services from Flexible Energy Resources
## 3 Simulation Results and New Frequency Adaptive _Pu_-Droop
Total simulation time \(t=110\) s.  
Simulations to Study Different Potential Solutions for Increasing LV Network PV Hosting Capacity and Provision of Flexibility Services from DER  
In the following, simulation results from different very low load cases (Tables 2 and 3) with only P-controllers for _PU_-control in PVs and BESSs (Figure 3) are explained in detail. At first, Table 4 presents PV 2 unit's (Figure 1) active (\(P_{\text{PV\_2}}\)) and reactive (\(Q_{\text{PV\_2}}\)) power as well as PV 2 connection point voltage (\(U_{\text{PV\_2}}\)) during over- and under-frequency events in different cases. After that, Tables 5 and 6 show the active and reactive power of BESS 1 and 3 during over- and under-frequency events in different cases. In order to highlight the PV hosting capacity in PV 2 connection point, Figure 4 presents the active power (\(P_{\text{PV\_2}}\)) values of PV 2 during steady-state, over- and under-frequency events in different cases. From Table 4 and Figure 4 it can be seen that the PV hosting capacity in PV 2 connection point (Figure 1) without BESSs in Cases 1a-3b during steady-state operation (\(t=25.0\) s) can be increased with lower (\(20.0\) kV) OLTC setting (Cases 1b, 2b, 3b). During over-frequency event \(50.07\) Hz (\(t=25.0\) s) in Cases 1a-3b without BESSs one can see that best frequency support (frequency control participation) can be achieved in Cases 2a and 2b with utilization of _PU_-control blocking logic (Figure 3) and _Pf_- droop 1 (Figure 2) on PVs. On the other hand, during under-frequency event \(49.8\) Hz (\(t=95.0\) s) in Cases 1a-3b without BESSs it can be seen from Table 4 and Figure 4c that due to load demand response participation to frequency support by disconnecting part of the load at PV 2 connection point, also the PV 2 active power needs to be curtailed in order to avoid local over-voltages. However, this PV curtailment during under-frequency event is not feasible from system-wide perspective and reduces the effect of load demand response to frequency control. Table 4 results also show that, due to used P-controllers for _PU_-control in PV 2 and BESS 3 without any PI-controllers (Figure 3), small voltage limit violations at the PV 2 connection point voltage (\(U_{\text{PV\_2}}\)) can be possible. The effect of BESS 1 and 3 (Figure 1) on the PV hosting capacity in PV 2 connection point can be seen from Cases 4a-5b (Tables 4-6, Figure 4). When comparing Cases 4a and 4b with BESS 1 during steady-state operation (\(t\) = 25.0 s) one can see that PV 2 hosting capacity can be only be increased in Case 4b in which remote LV voltage measurement from PV 2 connection point to BESS 1 (Figure 1) control is utilized through communication. In Cases 5a and 5b with BESS 3 at the PV 2 connection point however, the PV hosting capacity during steady-state operation (\(t\) = 25.0 s, Figure 4a) can be maximized by simultaneously charging BESS 3 (Table 6) in order to avoid local over-voltages. By comparing the simulation results of Cases 5a and 5b (Tables 4-6) during over-frequency event 50.25 Hz (\(t\) = 55.0 s) the effect of _PU_-control blocking logic of PVs and BESSs can be seen. The _PU_-blocking maximizes the BESS 3 participation in frequency support in Case 5b (Table 6), but simultaneously leads to local under-voltage at PV 2 connection point (Table 4). During under-frequency event 49.8 Hz (\(t\) = 95.0 s) in Cases 5a and 5b with BESS 3 it can be seen from Tables 4 and 6 that in Case 5a without _PU_-blocking total active power change (PV2 + BESS 3) is \(\Delta P_{5\_49.8\_{\rm{Hz}}}=\Delta P_{\rm PV\,2}(-87\ {\rm{kW}})+\Delta P_{\rm BESS\,3}(68\ {\rm{kW}})=-19\ {\rm{kW}}\) and in Case 5b with _PU_-blocking \(\Delta P_{5\_49.8\_{\rm{Hz}}}=\Delta P_{\rm PV\,2}(-205\ {\rm{kW}})+\Delta P_{\rm BESS\,3}(201\ {\rm{kW}})=-4\ {\rm{kW}}\).