"Stochastic Evaluation of Transient Stability of Distribution Systems Incorporating Distributed Generation (DG)"

Anuradha Kariyawasam (Ph.D. student)
Supervisor: Dr. Aniruddha Gole

Aim of Project

In the initial stages of planning the installation of new DG units, the system planner is faced with many issues to be addressed, one of which will be the impact of the DGs on the transient stability of the power system. The main idea of this research is to present a stochastic evaluation of the effects of DG units on the transient stability of power systems.

Description of Project

There are several uncertainties that have to be considered in the stochastic assessment of transient stability. Fault type, location, impedance, clearing time and duration are the stochastic aspects of faults that can affect the transient stability. Also, because of the probabilistic characteristics of system loads and generators, they must be considered and modeled stochastically. For the same reason, stochastic modeling of DGs is also necessary for accurate results.

In this research, all of the variables mentioned above are modeled as probability density functions, and then by using Monte Carlo method, a variety of system conditions are considered for transient stability evaluation. In this way, the probability of stability (or other introduced indices of transient stability) of the overall system (or any specified section of it, such as lines) can be calculated using the conditional probability theorem.

To examine the method, study cases should be evaluated. As DGs are usually considered to connect to the distribution networks, the method proposed in this thesis will evaluate the transient stability of a distribution network. There are some reports of the advantages and disadvantages of DC distribution networks and the feasibility of using DGs in these networks in the literature. For this reason, the method is applied to a DC distribution network and the effect of DGs on the transient stability of this network is studied. Also, a comparison study of the AC and DC distribution networks incorporating DGs with transient stability viewpoint is investigated.

Another problem that is considered in this research is the allocation of DGs in the distribution networks. Although the location of some kind of DGs (like wind farms) depends on the availability of the energy that provides the electricity as a prime mover, the node of connection of DGs may be considered as a choice for study. Optimum location of DGs is considered to optimize the objective function of the transient stability limits. The optimum penetration level of DGs is also considered for evaluation in the optimum transient stability condition of a distribution system.

Accepted/Published Papers

None available at this time.