## 6 State of Art in Control and Automation in Distribution Networks
Volt/VAR control (VVC): This is a DMS functionality that is mainly employed in managing voltage levels and reactive power flows throughout the network. Reactive power flows have a major impact on the network voltage profile. Devices employed for VVC encompass those that directly inject reactive power into the grid (e.g., shunt capacitors and shunt reactors), and those that directly control voltage (e.g., load tap-changing (LTC) transformers and voltage regulators). Traditionally, LTCs, voltage regulators, and capacitor banks have been the primary devices used in implementing VVC. With the continued gradual increase in the amount of distributed energy resource technologies integrated into the distribution network, however, these are also anticipated to take part in VVC. Smart inverters, for example, can inject reactive power into the grid and thus constitute a good alternative VVC resource [99; 100]. The VVC functionality facilitates the mitigation against excessively low or high voltages, which may not only impact the power quality but might additionally pose a threat to the safety of electrical equipment. Besides voltage regulation, VVC also plays an important role in minimizing system losses and relieving key network equipment (such as transformers and feeders) of excessive loading (by reducing the capacity required to satisfy a given load demand). Load shedding management: This is a DMS functionality that enables controlled balancing of supply and demand, where the demand exceeds the available supply. The main aim is to preserve the integrity of the entire distribution network by interrupting the electricity supply to non-critical loads to prevent a supply shortfall from cascading and threatening to cause the failure of the whole system. An automated load-shedding management application can detect predetermined trigger conditions that necessitate the initiation of predefined load-shedding control actions. If non-automated, operators have the responsibility to manually initiate the load-shedding operations, which should be done in a safe and controlled manner to always maintain normal service to as large a part of the network as possible. Trigger conditions for load shedding, whether automated or manually initiated, include under-frequency load shedding, limit violations, and time-of-day-based load shedding [101]. Load balancing: This involves re-routing loads to other parts of the network to relieve certain distribution equipment of overload conditions. This is often achieved through network reconfiguration. A feeder load management unit in the load balancing functionality monitors the loads on the feeders and identifies possible areas of congestion that may be susceptible to overload conditions. Feeder reconfiguration may also be used for other network operation improvement measures, such as voltage profile improvement and loss reduction. Other benefits of load balancing include improved network utilization and reduced stress on key network infrastructure [101]. Distribution system state estimation (DSSE): It uses the state vector of the distribution network for estimation, where the least square approach is used on redundant measurements [98]. The industrial sector requires premium power quality, so either current or power methods are used to achieve high computational performance [102; 103]. Optimal feeder reconfiguration (OFR): The main task of this function is to find ways to reduce generation losses by selecting the best radial system configuration. This is attained by solving an optimization that arranges the structure of the distribution network and has a load balance between feeders. The frequently used method due to the challenges of optimization is the switch exchange heuristic [96; 104; 105]. Distribution system short circuit computation (DSSCC): This function evaluates the capability of circuit breakers to perform adequately under maximum current operation conditions. It further checks on relay sensitivity under minimal current faults [97; 106].