Development of Reactive Power Allocation Method for Radial Structure Wind Farm Considering Multiple Connections

Abstract

In recent years, the number of wind farms consisting of type 3 and type 4 wind turbines located within the distribution system has been growing rapidly. Wind turbines can be utilized as a continuous reactive power source to support the system voltage by taking advantage of their reactive power control capability. This paper aims to further develop the reactive power assignment strategy in order to minimize losses in wind farms described in the published paper. We introduce the method of reconfiguration and numbering to apply the algorithm to the wind farm structure and develop the previously-defined allocation ratio into two types of allocation ratios. The goal is to apply the loss minimization algorithm to a wind farm configuration with up to two wind turbines connected to one ring main unit (RMU). The proposed strategy reduces power loss and increases the real power flow in the wind farm by allocating reactive power to connected wind turbines taking into account the resistance value. The proposed allocation technique is validated in a Real Time Digital Simulator (RTDS)-based Hardware-in-the-loop Simulation (HILS) environment considering the Dongbok wind farm configuration in Jeju, South Korea. In the simulation, a Raspberry Pi acts as a wind farm controller sending a reactive power dispatch signal to each wind turbine via Modbus TCP/IP protocol. The simulation results mean that, applying the proposed algorithm, we can expect loss reduction effects in the wind farm.

Reactive Power Dispatch Algorithm for a Reduction in Power Losses in Offshore Wind Farms

“…In PSO, each d-dimensional particle xi is a possible solution. The particles collaborate as a population to reach a collective goal, usually to minimize a function f [15][16][17][18][19][20].…”

“…Then every particle is evaluated by calculating its fitness value using function f, thus the personal best position (pbest) and global best position (gbest) will be found. The velocity and position of each particle is updated according to pbest and gbest, as in the formula shows below [15][16][17][18][19][20]:…”

“…After updating the velocity and position, a new generation of particles is generated. Repeat the work until the number of iterations reaches the set value or the change of gbest in N iterations is less than M (the value of N and M is set by users) [15][16][17][18][19][20].…”

“…Table 1 shows the development of PSO [15][16][17][18][19][20]. Using the results, the power flow calculation is performed to determine the reactive power dispatch by the rotating machines.…”