Eco-Friendly Electric-Powered Hydraulic Fracturing Towards Shale-Gas Recovery: Efficiency, Economics and Field Application

The recovery of unconventional gas fields especially the shale gas is of great significance to clean energy supply. High productivity of shale gas is attributed to the large-scale hydraulic fracturing with high operating pressure (80-100MPa) and discharging rate (14-18m3/min). More high-horsepower fracturing vehicles driven by diesel engines result in higher CAPEX. The low operation efficiency and unexpected maintenance negatively affected the economics performance of operators due to unacceptable OPEX. The fully electric-powered hydraulic fracturing solution was proposed as the alternative to the diesel-engine fracturing vehicles in this article. The skid-based electric pumping units were newly developed with advantages of high power density (6000HP per unit), Variable Frequency Drive (VFD) modules integration, fuel cost saving, low maintenance expenditure and eco-friendly operation. The field application was conducted in one pad of N209 in shale gas field, Sichuan, China. The electric-powered system, consisting of pumping units and blenders with other facilities, was deployed on the operation site. One large-capacity electric power grid (35kV and 30000kVA) was constructed for both drilling and massive multistage fracturing. The operation team successfully performed all hydraulic fracturing jobs as required with 7.4×105 kWh of total power consumption. The system functioned reliably without large faults occurred. The electric-powered solution was comprehensively evaluated and compared to the diesel-engine fracturing solution in terms of CAPEX, operational efficiency, power consumption, maintenance and fleet crew cost. The novelty of the technology is the fully electric-powered hydraulic fracturing system with large-capacity electric power grid. It is concluded from the field application that the electric-powered fracturing technology is qualified for unconventional reservoirs development.

Primary Frequency Stability Support of a DFIG in Association With Pitch Angle Control

For an electric power grid that has large penetration levels of variable renewable energy including wind generation and photovoltaics, the system frequency stability is jeopardized, which is manifest in lowering frequency nadir and settling frequency. This paper suggests an enhanced primary frequency response strategy of a doubly-fed induction generator (DFIG) in association with pitch angle control. The DFIG works in de-loaded operation with a certain reserve power via pitch angle control prior to disturbances for frequency regulation. To address this, a function of the pitch angle is employed that decreases the pitch angle with time to slowly feed the active power to the power gird. The simulation results demonstrate the effectiveness and feasibility of the proposed primary frequency response strategy including the settling frequency and frequency nadir.

Smart Grid Technology Prospect of Implementation in Bangladesh

The term "smart grid" refers to the transformation of the traditional electric power grid into a modern grid. Modernization of the present electric power system is an important step to implement the Smart Grid technology. The structure of the existing power sector in Bangladesh is almost a hundred years old. Due to which the power sector of Bangladesh facing huge power wastage. A Smart Grid also ensures the efficient transmission and distribution of electric power. This paper gives a brief description of Smart Grid, the latest trends, challenges, prospects, cost analysis of smart grid equipment, and its facility. The spotlight of this paper is to implement the Smart Grid's perspective to Bangladesh. That’s included to have new distributed generation technology, smart meter, a pilot project, etc. Also, the main objective of this paper is the comprehensive development of transmission and distribution loss reduction, which will be saving a big amount of capital every year. And that will play a huge role in the economy of Bangladesh to move forward in global progress.

Research and Solution Proposals to Optimize Distribution Power Grids in Smart Grid Condition

Smart Grid is a concept for transforming the electric power grid by using advanced automaticcontrol and communications techniques and other forms of information technology. It integratesinnovative tools and technologies from: generation, transmission and distribution. This also includesconsumer appliances and equipment. This concept integrates energy infrastructure, processes, devices,information and markets into a coordinated and collaborative process. All allowing energy to be generated,distributed and consumed flexibly and efficiently. However, the Smart Grid with the integration ofdistributed generation itself also creates a several disadvantages. There can be problems with: stabilityand reliability, relay protection, isolation and operational isolation in which the problem is to create aburden on the distribution grid when transmitting electrical energy sources. Optimizing power flow andbringing high operating efficiency on Smart Grid conditions is an urgent issue. This paper focuses onresearching and proposing solutions for optimal calculation of power flow on Smart Grid. The paper hasresearched, and analyzed calculation solutions to optimize power flow and proposed to use the Lagrangemultiplier method. The study performed calculations for a typical Smart Grid model with three distributedgenerations. Calculation results have shown that the role of the method is to fully perform the optimalcalculation of the power flow on the grid. This is in order to reduce power loss and energy loss as well asincreasing operational efficiency while improving power quality in Smart Grid conditions.

Modelling of Electric Grid to Enhance Generated Power Evacuation

The study of evacuation of power from the power plants in Rivers State Nigeria, connecting to the 330kV transmission network of the Transmission Company of Nigeria (TCN). The Power World Simulator Educational version was used in the modelling and simulation of the electric power grid. The study of load flow analysis, short circuit, transient and N-1 contingency analysis and their effect on the 330 kV/132kV transmission bus connected to the existing power plants in Rivers State Nigeria namely; Rivers IPP (180MW), Afam III (265.6MW), Afam IV & V (351.00 MW) and Afam VI G. S (650.00 MW) was carried out. From the short circuit study, it is observed that when a bus is faulted with a 3-phase fault, the three-phase voltages of the system drastically become zero in all the phases. The other buses of the network experience an increase in voltage and all the buses fed have the same effect as the bus under fault, though the effect is felt more on the buses. However, with the introduction of substation splitting at Afam III and ongoing Afam IV substations, the short circuit level will be reduced by 15%; leading to improvement in the overall system stability.