Post-Cold War Democratic Experiment and Presidential Term Limits in Africa

The introduction of presidential term limits was one of the outcomes of the various negotiations that preceded the post-Cold War transition elections in Africa. With constitutional support for presidential term limits, which were often ratified in most African countries through a referendum, presidential term limits not only assumed a democratic principle, but were also expected to become both a ＂process and practice＂ in new African democracies.1 The constitution legitimizes term limits （years and tenures） as a democratic principle to regulate power and leadership transition within the context of democratic elections. Shinn （2009） argues that term limits for a country＇s most important political leader are an essential component of building democracy. Their importance adds value to the process, practice and constitutive feature of liberal democracy （Shinn, 2009）. Numerous studies show that presidential term limits are one of the most consistent predictors of power transition （Beetham, 1994; Linz, 1996a; Cheeseman, 2010）. Presidential term limits are also important in sustaining open-seat contests that ensure power alternation. However, this was not to be the case in African democratic experiment, where the process and practice of presidential term limits have become problematic. This paper focuses on how the removal of presidential term limits has worked against the consolidation of democracy in African post-Cold War democratic experiment, resulting in weak institutions, entrenchment and reconsolidation of power by long serving dictators, democratic hybridity and sometimes democratic reversal.

A Data-driven Method for Fast AC Optimal Power Flow Solutions via Deep Reinforcement Learning

With the increasing penetration of renewable energy,power grid operators are observing both fast and large fluctuations in power and voltage profiles on a daily basis.Fast and accurate control actions derived in real time are vital to ensure system security and economics.To this end,solving alternating current(AC)optimal power flow(OPF)with operational constraints remains an important yet challenging optimization problem for secure and economic operation of the power grid.This paper adopts a novel method to derive fast OPF solutions using state-of-the-art deep reinforcement learning(DRL)algorithm,which can greatly assist power grid operators in making rapid and effective decisions.The presented method adopts imitation learning to generate initial weights for the neural network(NN),and a proximal policy optimization algorithm to train and test stable and robust artificial intelligence(AI)agents.Training and testing procedures are conducted on the IEEE 14-bus and the Illinois 200-bus systems.The results show the effectiveness of the method with significant potential for assisting power grid operators in real-time operations.

Deep Reinforcement Learning Based Real-time AC Optimal Power Flow Considering Uncertainties

Modern power systems are experiencing larger fluctuations and more uncertainties caused by increased penetration of renewable energy sources(RESs) and power electronics equipment. Therefore, fast and accurate corrective control actions in real time are needed to ensure the system security and economics. This paper presents a novel method to derive realtime alternating current(AC) optimal power flow(OPF) solutions considering the uncertainties including varying renewable energy and topology changes by using state-of-the-art deep reinforcement learning(DRL) algorithm, which can effectively assist grid operators in making rapid and effective real-time decisions. The presented DRL-based approach first adopts a supervised-learning method from deep learning to generate good initial weights for neural networks, and then the proximal policy optimization(PPO) algorithm is applied to train and test the artificial intelligence(AI) agents for stable and robust performance. An ancillary classifier is designed to identify the feasibility of the AC OPF problem. Case studies conducted on the Illinois 200-bus system with wind generation variation and N-1 topology changes validate the effectiveness of the proposed method and demonstrate its great potential in promoting sustainable energy integration into the power system.