3RD INTERNATIONAL CONGRESS ON TECHNOLOGY - ENGINEERING & SCIENCE - Kuala Lumpur - Malaysia (2017-02-09)

Impact Of A Pv Controller On Stability Of Renewable Energy Based Large Distribution Systems
The impact of a PV controller on small signal stability of renewable energy based distribution systems is presented in this paper. The location of PV generators, loading condition and fault condition are considered in the study. Constant P and constant V control model [1-2] is utilized to represent the PV generator. The output d-axis and q-axis currents (i.e. i_d and i_q) of the DC/AC converter are obtained by first order functions with unity steady-state gain and currents set-points. Two radial distribution systems, IEEE 69-bus system and IEEE 118-bus system, fed by synchronous, induction and PV generators are used as test systems. The distribution systems are represented by a set of nonlinear differential and algebraic equations. Numerical analysis and time domain simulation are conducted to investigate the effect of the controller in improving the small signal behavior of the system. In IEEE 69-bus distribution test system, two synchronous generators are located at buses 20 and 62 with capacities 300 and 400 kW respectively. Two induction generators are located at buses 33 and 46 with capacities 100 and 200 kW respectively. However, in IEEE 118 bus distribution test system four synchronous generators are located at buses 18, 45, 76 and 111 with capacities 1000, 1000, 1600 and 2000 kW respectively. Two induction generators are located at buses 99 and 34 with capacities 500 and 600 kW respectively. Both systems are tested when the PV generators are not connected. Then the PV generators are connected to the systems. The following cases are considered: Case 1: location of the PV generators The weakest buses in the system and the location of the problematic machines as two factors have been considered to specify the best location of the PV generators. In IEEE 69-bus system, two PV generators are selected to be connected to bus 12 and bus 61 with capacities 300 and 200 kW respectively. In IEEE 118 bus system, two PV generators with 2000 kW capacity are connected to buses 80 and 118 respectively. Small signal stability is studied using eigenvalue analysis and participation factor analysis. The results showed that the system stability and damping of oscillations are improved. Case 2: Loading the system Both systems are loaded at different buses. The results with and without PV PI-controller are obtained. The results showed that the system with two PV controllers provides better performance in terms of damping of oscillations and stability when compared to the system with only one PV controller. Case 3: Faults and disturbances Both systems are tested under fault condition. The systems are subjected to a 3-phase fault for 100 msec. Time domain simulation is carried out to show the system response with and without PV controllers. The results showed that the PV controllers surely enhance the stability of distribution system under fault conditions. From the results obtained in this paper using eigenvalue analysis and time-domain simulation, it is concluded that the PV controller improves the small signal stability and damping of oscillations of the distribution systems under different operating conditions.
Lokman Hassan