Co-Optimization of Energy Losses and Transformer Operating Costs Based on Smart Charging Algorithm for Plug-in Electric Vehicle Parking Lots

The global transport sector has a significant share of greenhouse gas emissions. Thus, plug-in electric vehicles (PEVs) can play a vital role in the reduction of pollution. However, high penetration of PEVs can pose severe challenges to power systems, such as an increase in energy losses and a decrease in the transformers expected life. In this paper, a new day-ahead co-optimization algorithm is proposed to reduce the unwanted effects of PEVs on the power system. The aim of the proposed algorithm is minimizing the cost of energy losses as well as transformer operating cost by the management of active and reactive powers simultaneously. Moreover, the effect of harmonics, which are produced by the charger of PEVs, are considered in the proposed algorithm. Also, the transformer operating cost is obtained from a method that contains the purchase price, loading, and losses cost of the transformer. Another advantage of the proposed algorithm is that it can improve power quality parameters, e.g., voltage and power factor of the distribution network by managing the reactive power. Afterward, the proposed algorithm is applied to a real distribution network. The results show that the proposed algorithm optimizes the daily operating cost of the distribution network efficiently. Finally, the robustness of the proposed algorithm to the number and distribution of PEVs is verified by simulation results

Rate of Change of Direct-Axis Current Component Protection Scheme for Inverter-Based Islanded Microgrids

Rapid growth in the utilization of the inverter-interfaced distributed energy resources (IIDERs) in microgrids has brought new challenges in the network protection area. Microgrid protection specifically becomes a concern during operation in the islanded mode. There is a considerable reduction in fault current levels in this mode compared to when the microgrid is connected to the grid, which makes conventional algorithms operate with significant delay or, in many cases, not even pick up the fault. This paper proposes a protection algorithm based on the rate of change of direct-axis current component ( id ) to protect inverter-based microgrids (IBMGs). The proposed algorithm is applicable for microgrids with centralized protection as well as those deploying a decentralized approach equipped with the unit protection of the relevant lines. Photovoltaic (PV) systems and battery energy storage systems (BESS) are taken into account in this research and modeled precisely to capture the high-frequency effects of power-electronic converters and investigate the response of IIDERs in fault conditions. The effectiveness of the proposed protection method will be evaluated by applying symmetrical and asymmetrical faults in different locations with different resistances simulated on a test IBMG system in PSCAD/EMTDC environment. In addition, protection robustness against non-fault conditions such as a sudden increase in load levels, environmental uncertainties, and noisy measurement conditions will be scrutinized

A framework for day-ahead optimal charging scheduling of electric vehicles providing route mapping: Kowloon case study

With the ever-increasing growth of electric vehicles (EV)s in the power industry, their significance as a flexible load has increased drastically. On the other hand, uncontrolled charging of these vehicles can cause serious problems in the grid, such as a peak in demand, a decrease in the life expectancy of transformers and as a result, an increase in charging costs of EVs for the EV owners. In this paper, a framework for day-ahead optimal charging of EVs is proposed which through optimization of active and reactive power exchange at each time interval, could prevent the problems mentioned above and at the same time increase the benefit of EV owners and network operators simultaneously. Furthermore, taking into account the effective factors on electrical energy consumption of EVs and the driving pattern of their owners, a route mapping algorithm is developed based on the proposed framework, so as to provide the EV owners with better services. The simulations are carried out using a hybrid interior-point optimization approach, based on traffic and geographic data collected from the city of Kowloon and a standard IEEE 33 bus system is used. The simulation results show that integrating optimal charging of EVs with a route mapping algorithm into the proposed framework can reduce the loss costs of the network during the hours of EVs’ presence in the framework and the selling price of electricity to EV owners by 24.93% and 33.6%, respectively in comparison with the uncontrolled mode. Also, the average life expectancy of power transformers is increased by 2.97% in the optimal charging mode compared to the uncontrolled mode

Transmission Expansion Planning Using TLBO Algorithm in the Presence of Demand Response Resources

Transmission Expansion Planning (TEP) involves determining if and how transmission lines should be added to the power grid so that the operational and investment costs are minimized. TEP is a major issue in smart grid development, where demand response resources affect short- and long-term power system decisions, and these in turn, affect TEP. First, this paper discusses the effects of demand response programs on reducing the final costs of a system in TEP. Then, the TEP problem is solved using a Teaching Learning Based Optimization (TLBO) algorithm taking into consideration power generation costs, power loss, and line construction costs. Simulation results show the optimal effect of demand response programs on postponing the additional cost of investments for supplying peak load

A Model Predictive Control Based Virtual Active Power Filter Using V2G Technology

This paper presents a virtual active power filter (VAPF) using vehicle to grid (V2G) technology to maintain power quality requirements. The optimal discrete operation of the power converter of electric vehicle (EV) is based on recognizing desired switching states using the model predictive control (MPC) algorithm. A fast dynamic response, lower total harmonic distortion (THD) and good reference tracking performance are realized through the presented control strategy. The simulation results using MATLAB/Simulink validate the effectiveness of the scheme in improving power quality as well as good dynamic response in power transferring capability

Maximization of Wind Energy Utilization and Flicker Propagation Mitigation Using SC and STATCOM

This paper proposes a novel approach to maximize utilization of wind energy by using a combination of flexible AC transmission system (FACTS) devices, shunt capacitor (SC) and static synchronous compensator (STATCOM). The stochastic nature of wind power is considered through a set of scenarios. After running the real market, the proposed model must be applied by the independent system operator (ISO) to determine the parameters such as the value of the real reserve of each generator. The control procedure of the proposed model is easier and more accelerated due to using SC. Moreover, the proposed method improves the voltage flicker mitigation and power quality parameters due to using STATCOM. The proposed method is applied to IEEE RTS. It is shown that the proposed model affects the total flexibility of the energy system compared to the system without SC and STATCOM in order to enhance effective wind energy utilization

Fault ride through constrained protection scheme for distribution networks with DFIG-based wind parks

The main protection of distribution networks is based on overcurrent relays (OCRs). Due to the slow operation of these relays, some distributed generations (DGs), e.g. wind parks, may be unable to meet the fault ride through (FRT) requirements, which leads to unnecessary generation loss during faults. This paper proposes a new protection scheme for distribution networks that considers the FRT requirements of DFIG-Based wind parks. This is achieved by considering both the protection coordination constraints and FRT requirements in a single protection scheme. Considering the FRT requirements, the new method determines whether each overcurrent relay operates fast enough. If not, the proposed scheme determines a suitable solution for each relay to facilitate a faster operation. The proposed method is tested on the IEEE 33 bus test network and compared with conventional methods. Its superior impact on improving the FRT requirements and hence preventing unnecessary disconnection of DFIG-Based wind parks during short circuit faults is demonstrated through simulation results, proving by this its applicability and efficacy