Review on Reactive Power and Voltage Optimization of Active Distribution Network with Renewable Distributed Generation and Time-Varying Loads

With a high proportion of renewable distributed generation and time-varying load connected to the distribution network, great challenges have appeared in the reactive power optimization control of the active distribution networks. This paper first introduces the characteristics of active distribution networks, the mechanism and research status of wind power, photovoltaic, and other renewable distributed generators, and time-varying loads participating in reactive power and voltage optimization. Then, the paper summarizes the methods of reactive power optimization and voltage regulation of active distribution network, including multi-timescale voltage optimization, coordinated optimization of network reconfiguration and reactive power optimization, coordinated optimization of active and reactive power optimization based on model predictive control, hierarchical and zoning control of reactive power, and voltage and power electronic switch voltage regulation. The pros and cons of the reactive power optimization algorithms mentioned above are summarized. Finally, combined with the development trend of the energy Internet, the future directions of reactive power and voltage control technology in the active distribution network are discussed.

Renewable Distributed Generations Optimal Penetration in the Distribution Network for Clean and Green Energy

For raising the initiatives to supply clean and green energy globally, many renewable distributed generations are attached to the network. Power losses, voltage profile maintenance and environmental pollution are the most significant restrictions, which hinder the existing power system. Random penetration of the distributed generation in the existing network can cause severe problems like voltage instability, increase in power losses, system islanding, reverse power flows, environment pollution, etc. Therefore, for clean and green energy, optimal penetration of eco-friendly renewable distributed generation is required for power loss minimisation and voltage profile enhancement. Optimal penetration of renewable distributed generation has to deal with constraints like size, location, number, power factor and type. Adaptive schemes are based on biogeography-based optimisation and particle swarm optimization methods to satisfy all the constraints related to the optimal penetration of renewable distributed generation systems in the IEEE 33 bus radial distribution network. The adaptive schemes have been applied for (real and reactive) power loss reduction and enhancing voltage profile.

A Distributionally Robust Power Dispatch Model for Active Distribution Network

The uncertainty of distribution network operation is increasing with the integration of large-scale renewable distributed generation (DG) units. To reduce the conservativeness of traditional robust optimization (RO) solutions, a data-driven robust optimal approach, which incorporates the superiority of both stochastic and robust approaches, is employed to solve the dispatch model in this paper. Firstly, a deterministic optimal dispatching model is established with the minimum total operation cost of distribution network; secondly, a two-stage distributed robust dispatching model is constructed based on the historical data of renewable-generators output available. The first stage of the model aims at finding optimal values under the basic prediction scenario. In the second stage, the uncertain probability distribution confidence sets with norm-1 and norm-∞ constraints are integrated to find the optimal solution under the worst probability distribution. The model is solved by column-and-constraint generation (CCG) algorithm. Numerical simulation on the IEEE 33-bus system has been performed. Comparisons with the traditional stochastic and robust approaches demonstrate the effectiveness of the proposal.