# A Study of Order Modification for Reactive Power Support by Wind Farm during Communication Failure
## 1 Introduction  
The continuous integration of large-scale wind farms has recently led to an increase in wind powered energy to the conventional power grid. Due to a dependence on environmental factors, this status could raise several reliability issues within the power system industry, potentially affecting the entire system. Most importantly, as wind turbines exhibit output fluctuation characteristics according to their relative wind energy environments [1], a high degree of wind power penetration can greatly affect the utility power grid. To prevent this problem, an accurate prediction system of wind resources has been developed which can reduce calculation errors between predicted power and real power output [2, 3]. Furthermore, following major developments in power electronic technology, costs have decreased, as mentioned in Reference [4]. As a result, a variety of compensation devices have been used to handle real power balance, which is mainly controlled by transmission and system operators (TSO) [5, 6]. With regard to conversion devices, previous non-reactive power capability devices, without the flexibility of power control, have been substituted with voltage-source converter (VSC) topologies, and the utilization of turbines has provided great performance in ancillary services [7]. Also, TSOhas utilized a range of capabilities within power system operations by the employment of related management solutions [8]. Owing to the variating characteristics of wind conditions, a conventional optimal power flow (OPF) method cannot be directly applied, therefore, several modified solutions have been introduced [9]. The general management solution dispatches a reference quantity to each turbine, according to the predicted power output, not only to maintain the voltage level of the connection point, but also to follow the order from the TSO, as described in References [10; 11]. As a result of research related to the supply of reactive power from VSC interfaced wind systems, several management plans have utilized their own optimized solutions. Reference [12] focuses on the reduction of switching loss for each power electronic device within windfarms, in the occurrence of unexpected events, such as a simple fault or unpredictable thrusts of wind. Using a flow management scheme, case studies suggest that the reactive control algorithm can contribute to the life cycle of each wind turbine. Reference [13] suggests a reactive power control algorithm to minimize the switching loss of power electronic devices, by introducing a loss estimation model within the loop of the control process. These applications are based on an order allocation method, which means a controller has to interact with individual devices. Therefore, communication equipment and related platforms have a significant importance in the previously mentioned solutions. Usage would be reliant on a supervisory control and data acquisition (SCADA) basis, but would also require a human-machine interface, in order to ascertain grid conditions. However, to overcome unpredicted reaction delays and security issues which can be generated within those architectures, self-automation also needs to be integrated, as described in previous studies [14; 15; 16]. Both telecommunication lines and wireless networks within a power system, particularly for a protection scheme, as in References [17; 18], point to online reliabilities. This has led to the installation of additional support options which secure a stable management process. In this regard, automated logics from the previous protection scheme in the SCADA network have been refined in terms of the conventional grid, as in Reference [14], the inverter prevalence network, as in Reference [15], and power flow optimization using connected sensors, as in Reference [16]. As an increase is expected in micro based networks, this trend will be required for the improvement of self-efficiency.