This paper presents on power quality improvement in distributed radial network by using custom power device (CPD). In power system, the power quality issue become more complex at all level. Here, for this concern, we introduce a concept of custom power, basically it is a power electronics controller, to provide a quality of power to the supplier as much as for consumers. Custom power device (CPD) including active power line conditioner (APLC) and static synchronous compensators (STATCOMs), simulating on modified distributed IEEE-15 bus distorted bus system with the help of MATLAB Simulink software to explore performance and the efficiency of each device under various quality (power)disturbances includes voltage swell and sag, interruption in power and total harmonics distortion as well as the performances of allocated CPD in control the voltage quality and reactive power. Here, we used the particle swarm optimization to determine optimal location and sizes of CPD. Here, simulation results reveal all the effect of each device to compensate several types of power quality disturbance depends on the devices configurations and in this paper we much emphasized on STATCOMs and its arrangement.