At present there is a two-ways energy flow in electric distribution grids due to the growth of distributed energy resources (DER) and new customer devices. So, there is growing interest in full observation tools for grid control, protection, etc. Micro Phasor Measurement Unit (µPMU) measures highly accurate time-synchronized samples of current and voltage calculating their corresponding phasors and online transmits the calculating phasors to a phasor data concentrator (PDC). Two algorithms are proposed in this paper. The first algorithm is a new µPMUs full observation algorithm for an unbalanced radial distribution grid with optimum numbers of µPMUs. This algorithm helps in building an observation system of the unbalance distribution grid from the medium voltage (MV) to the low voltage (LV) level. This algorithm includes the effect of mutual inductance and mutual capacitance of MV cables. The second algorithm is a backward/forward sweep unbalanced power flow (UBPF) algorithm for the radial distribution grid in which outputs are compared with electrical power system analysis (ETAP) software outputs for testing the algorithm accuracy. A simulated testing process is applied to check the accuracy of the µPMUs full observation algorithm. By this process, the output phasors measured by μPMU is simulated from backward/forward sweep UBPF outputs in specified buses where μPMU installed and the μPMU full observation algorithm outputs are compared with backward/forward sweep UBPF outputs. The simulated testing process shows the high accuracy of the µPMUs full observation algorithm.