Volume 18, Issue 1 -

Due to the liberalization of electric power market, many power producers are entering into the power market. Most of electric power company have been introduced renewable energies that might increase the power system uncertainty. Therefore, it is expected that rise might the likelihood of voltage instability and voltage collapse. In addition, fluctuations in supply and demand are increased by the introduction of a renewable energies. However, by using the Energy storage systems (ESS), the power fluctuations can be reduced. On account of this, we suggest the optimal operation method of the generator and the ESS by considering the voltage stability in this paper. The effectiveness of the proposed method is verified by simulation results in the Matlab/simulink.

Abstract: A new photovoltaic (PV) farm is proposed to be integrated in GHARDAIA bus distribution network (Gh-17 bus), this paper studies the optimal location of this PV farm in the distribution network. The study is done in IEEE-14 bus then it is validated in Gh-17 bus network, the constraints considered for the choice of the optimal location are the stability margin, power loss and critical clearing time (CCT) in case of line fault. The simulation results are given using the PSAT.

Elimination of harmonics by the use of power filters is required for power quality improvement; provides a wide area for the researchers to develop efficient power filters with improved control platforms. This paper motivates the implementation of the embedded control platform for better control of the power filters for faster elimination of harmonics. Although many embedded processors fascinates the implementation of the control techniques but finding the feasible platform is a great task. Software implementations are feasible for most of the power electronics converters but the hardware design with required digital hardware is a challenging task. The present paper deals with the development of the control technique for the Hybrid Active Power Filter with Xilinx System Generator Platform. The virtual FPGA (Field Programmable Gate Array) platform provided by the Xilinx System Generator has the ability to generate better switching signals for the control of the power filter to generate compensating signal for elimination of harmonics to maintain the power quality in the distribution lines. Experimental results obtained by the setup developed in the Power System Laboratory presents the effectiveness of the Embedded Platform. Various source voltage conditions also simulated and performance is verified for the developed Hybrid Active Power Filter.

Abstract: This paper presents a single-phase grid-connected photovoltaic power system with the capability of maximum power point tracking (MPPT) of photovoltaic (PV) array and reactive power compensation. The non linear characteristics of the proposed modified p-q theory have been improved with the help of maximum power point tracking (MPPT) controller. MPPT controller helps to feed the inverter with maximum power from the solar grid, for switching pattern generation hysteresis controller is used. The simulation results developed in MATLAB/Simulink software, verify the performance and advantages of the proposed system used to integrate the single phase grid to photovoltaic for enhancing the power quality. Also the proposed scheme has been verified in laboratory setup for its real time implementation.

This paper presents a hybrid islanding detection technique for grid connected Distributed Generations (DGs). The proposed scheme is based on three different decisive factors which are derived from negative sequence voltage (NSV) by applying Hilbert transform, Wavelet transform and standard normal distribution function. Different types of non-islanding and islanding events have been simulated by modeling IEEE 34-bus system using PSCAD/EMTDC software package. The performance of the proposed scheme has been evaluated on large number of cases which are generated by varying load and fault parameters. The simulation results indicate that the proposed scheme is able to detect islanding situation accurately even under perfect power balance condition. Moreover, the proposed scheme provides better stability in case of specific type of non-islanding event i. e. fault on adjacent feeder during which most of the existing scheme issues nuisance tripping. Furthermore, it provides satisfactorily results during change in network topology and also at different values of X/R ratio of DG. At the end performance of the proposed technique is also comprehensively compared with the schemes currently reported in the literature. This comparison apparently demonstrates the advantages of the proposed technique over existing schemes.

The electricity market is threatened by supply scarcity, which may lead to very sharp price spikes in the spot market. On the other hand, demand-side’s activities could effectively mitigate the supply scarcity and absorb most of these shocks and therefore smooth out the price volatility. In this paper, the positive effects of employing demand response programs on the spot market price are investigated. A demand-price elasticity based model is used to simulate the customer reaction function in the presence of a real time pricing. The demand achieve by DR program is used to adjust the spot market price by using a price regression model. SAS software is used to run the multiple linear regression model and MATLAB is used to simulate the demand response model. The approach is applied on one week data in summer 2014 of Connecticut in New England ISO. It could be concluded from the results of this study that applying DR program smooths out most of the price spikes in the electricity spot market and considerably reduces the customers’ electricity cost.

Abstract: The growing penetration levels of passive and rectifier interfaced active loads can cause instability in an islanded inverter based microgrid. This may be due to the dynamics associated with passive loads and interaction between the control loops of active loads and inverter-interfaced DGs. This paper proposes a decentralized supplementary control loop around each inverter-interfaced distributed generation (DG) unit to mitigate the instability caused by both the active as well as passive loads. The proposed control loop is based on a robust linear quadratic regulator with prescribed degree-of-stability (LQRPDS). In order to obtain the optimal values of the state and control weighting matrices of LQRPDS, a bi-objective optimization problem has been formulated and solved using a fast and elitist multi-objective non-dominated sorting genetic algorithm (NSGA-II). The proposed decentralized supplementary control loop does not interfere with the steady state performance and provides robust control performance under various load configurations as well as step load disturbances. Eigenvalue analysis and time-domain simulations have been used to validate the effectiveness of the proposed decentralized supplementary control loop.

This paper presents an approach to size the battery energy storage system (BESS) for the suppression of the output power fluctuations in a solar photovoltaic (PV)/Wind hybrid energy system. The strategy presented uses a dynamic averaging technique, with a different number of samples in order to produce different smoothing levels in the output power. The key advantage of the proposed strategy is that, apart from sizing the BESS, the same strategy can be implemented in real time to perform the energy management for the system. The gravitational search algorithm (GSA) has been used to find the optimum size of the BESS which will be able to produce the required level of smoothing. The effectiveness of the proposed strategy has been verified through a case study presented and the results indicate that the strategy is effectively able to size the BESS for reduced power fluctuations from the system. To verify the robustness of the proposed strategy, the uncertainty in the climatic conditions has also been considered and the results indicate that the proposed strategy works well even in the case of a change in the climatic conditions.

An industrial buyer, who can reschedule its production plan, may develop strategic bid by shifting its demand from high price period to low price period. Based on this concept, a new optimization formulation has been proposed to develop bidding strategy of such buyers considering Price Responsive Demand Shifting (PRDS). Since the bidding strategy of the buyer depends upon the market clearing price, which is volatile/uncertain due to various factors like gaming behavior of participants, demand forecasting error, transmission congestion etc, the proposed optimization problem is formulated as a stochastic linear problem, comprising of two sub-problems. The first sub-problem represents the market clearing process by the System Operator, which is formulated to maximize the social welfare of the market participants, while the second sub-problem aims at maximizing the purchase cost saving of the industrial buyer. The optimal bidding strategy has been obtained by solving these two sub-problems considering hourly market clearing for 24-hour scheduling period. The effectiveness of the proposed method has been tested on a 5-bus system and modified IEEE 30-bus system. Results obtained with the demand shifting based bidding strategy have been compared with those obtained with a Conventional Price Quantity (CPQ) bid strategy. It has been observed that the proposed approach leads to enhancement in the purchase cost saving as compared to the CPQ and meets the energy consumption targets of the industrial buyer.