Transient Stability Improvement based on Optimal Power Flow using Particle Swarm Optimization

Abstract

Optimal Power Flow (OPF) is one of most important aspect in power system operation and control. It is a non linear optimization problem based on minimization an objective function such as the active power losses, fuel cost, voltage deviation, voltage stability, reliability evaluation,…etc. Transient stability analysis is an important concept to determine whether the system is stable or not when a heavy disturbance such as the fault or loss of generation or a sudden large increased in the load,…etc occur in the system. In this article the transient stability according to the fault occurrence are used as a constraint in the optimal power flow, where minimization a three objective function of the active power losses, the fuel cost of thermal generation units and the voltage deviation at the load buses separately for each one can improve the transient stability and keep all the generators in the synchronization system. Particle Swarm Optimization PSO of an artificial intelligence optimization techniques has been used for this purpose. Minimization the objective function can be satisfied by choosing an optimal control variables from their constraints keeping the state variables in their limits. The control variables in this article are the generator voltage magnitude, the transformer tap changer and the generator active power except the slack generator while the state variables are the stability system based on increasing the clearing time of the circuit breaker, the slack generator active power, the generator reactive power and the magnitude of the load voltage. Increasing the clearing time of the circuit breaker leads to increase the maximum value of the generator rotor angle and go towards the instability system. The maximum clearing time that keep the system stable is called the Critical Clearing Time TCC. This article used the Optimal Power Flow with Transient Stability as a constraint to increase the Critical Clearing Time TCC with stable system. The proposed algorithm has been tested on the two systems of IEEE 9 bus and IEEE 30 bus and compare the result with other reference. The implementation of this work are programming by the author using matlab software.

Transient Stability Constrained Social Welfare Maximization with Demand Response in Smart Electrical Grid

“…The load curtailment is predicted by the price of electricity at supply -demand balance (figure 1). (10) The constraints however remain the same from (3)- (8).…”

“…Minimisation of active power loss incurring in the transmission lines, in some cases has been taken as objective function of the grid as shown in (11) (referred here as "LossMinWP"). The constraints however remain same as in (3)- (8).…”

“…Thus proper planning must be done to schedule the generators as well as demand, so that substantial stability margin can be inherent in the operating point of the grid [7]. In this context Optimal power flow (OPF) has always been an effective tool to obtain optimal schedule of the generation and demand adhering to the operational constraints [8]. The century old objective of OPF has been changing, however with the addition of new constraints in the grid in presence of RES and ICT technology.…”

Choosing PSO under Different Overloads to Provide Best Power Flow for IEEE - 57 Bus

“…The vector of independent variables comprises the slack real power output Pg1, slack bus voltage vector Vg, transformer tap settings vector T, and shunt compensation settings vector Qc. Common load flow analysis is represented by the equality constraints h (x, u) [12], [13]. The system operating restrictions are represented by the inequality constraint g (x, u), which may be constructed as follows.…”