Abstract
Nowadays, integration of new devices like Distributed Generation, small energy storage and smart meter, to distribution networks introduced new challenges that require more sophisticated control strategies. This paper proposes a new technique called Optimal Coordinated Voltage Control (OCVC) to solve a multi-objective optimization problem with the objective to minimize the voltage error at pilot buses, the reactive power deviation and the voltage error at the generators. OCVC uses Pareto optimization to find the optimal values of voltage of the generators and OLTC. It proposes an optimal participation of reactive power of all devices available in the network. OCVC is compared with the classical method of Coordinated Voltage Control and is tested on the IEEE 13 and 34 Node test feeders with unbalanced load. Some disturbances are investigated and the results show the effectiveness of the proposed technique.
Introduction
The climate changes and the new technologies have led to major changes in electricity generation and consumption patterns. The equipment connected to the distribution network is becoming more diversified including renewable energy that is known as Distributed Generation (DG), small energy storage, and smart meter. It consequently requires more advanced algorithms for voltage and VAR control.
The DGs may trigger variation of voltage and change the direction of power flow in the distribution network. The voltage rise depends on the amount of active and reactive power injected by the DGs. Some researches [1–3] have studied the impact on the voltage, the reduction of losses, and the determination the optimum size and location of the DGs. Also, improper DG size and inappropriate location may cause high power loss and problems in the voltage profile [3–5].
Conclusions
In this paper, a new technique based on the Pareto frontier has been presented and applied to Multi-Objective optimization voltage problem. It has been proposed as multilevel optimization with the participation of active and reactive power of the DG connected to the distribution network. For this purpose, we used the Pareto frontier to solve all the different objectives of the Multi-Objective problem separately with dynamic weights.
The modern power system requires the generation of a set of optimal solutions (instead of a single solution) that would allow the operator (Decision Maker) to choose. Then, this new technique may be adapted to particular strategies, operating points, objectives and constraints.
OCVC performances are better than those of OLTC and CVC techniques. OCVC eliminates the entire voltage problem, including the DG’s over-voltages. The voltage problem has been solved; the distribution network voltage profile stays in a fixed range around the set point values.
OCVC could be an interesting way to reduce or eliminate future investments in classical voltage and reactive power regulation. This paper shows that the optimal integration of DG in distribution network can help to maintain the voltage within the limits and reduce losses.
