Life cycle economic viability analysis of battery storage in electricity market

Battery storage is essential to enhance the flexibility and reliability of electric power systems by providing auxiliary services and load shifting. Storage owners typically gains incentives from quick responses to auxiliary service prices, but frequent charging and discharging also reduce its lifetime. Therefore, this paper embeds the battery degradation cost into the operation simulation to avoid overestimated profits caused by an aggressive bidding strategy. Based on an operation simulation model, this paper conducts the economic viability analysis of whole life cycle using the internal rate of return(IRR). A clustering method and a typical day method are developed to reduce the huge computational burdens in the life-cycle simulation of battery storage. Our models and algorithms are validated by the case study of two mainstream technology routes currently: lithium nickel cobalt manganese oxide (NCM) batteries and lithium iron phosphate (LFP) batteries. Then a sensitivity analysis is presented to identify the critical factors that boost battery storage in the future. We evaluate the IRR results of different types of battery storage to provide guidance for investment portfolio.Comment: 17 pages, accepted by JP

Combined Edge- and Stixel-based Object Detection in 3D Point Cloud

Environment perception is critical for feasible path planning and safe driving for autonomous vehicles. Perception devices, such as camera, LiDAR (Light Detection and Ranging), IMU (Inertial Measurement Unit), etc., only provide raw sensing data with no identification of vital objects, which is insufficient for autonomous vehicles to perform safe and efficient self-driving operations. This study proposes an improved edge-oriented segmentation-based method to detect the objects from the sensed three-dimensional (3D) point cloud. The improved edge-oriented segmentation-based method consists of three main steps: First, the bounding areas of objects are identified by edge detection and stixel estimation in corresponding two-dimensional (2D) images taken by a stereo camera. Second, 3D sparse point clouds of objects are reconstructed in bounding areas. Finally, the dense point clouds of objects are segmented by matching the 3D sparse point clouds of objects with the whole scene point cloud. After comparison with the existing methods of segmentation, the experimental results demonstrate that the proposed edge-oriented segmentation method improves the precision of 3D point cloud segmentation, and that the objects can be segmented accurately. Meanwhile, the visualization of output data in advanced driving assistance systems (ADAS) can be greatly facilitated due to the decrease in computational time and the decrease in the number of points in the object’s point cloud

A novel torque sensor based on the angle of magnetization vector

Abstract Torque is an important parameter of a mechanical power system, which reflects transmission efficiency, transmission reliability, and operating conditions of equipment. Torque monitoring is very important for real-time control and fault diagnosis of mechanical equipment. A torque measurement method based on the theory of magnetic effect is proposed for multipoint torque monitoring in shafting. A model of the deflection angle of the magnetization vector and torque is established based on the theory of magnetic equivalent. A non-contact signal extraction circuit based on hall sensor is designed, a torque loading experimental device is set up, and the torque calibration experiment is completed. The experimental results show that the sensitivity of the torque measurement system is 17.7 mV/Nm, and the maximum nonlinear error is 0.77% full scale. The deflection angle of the magnetization vector has a good linear relation with the torque, which can be measured indirectly by the deflection angle. This method has the advantages of a simple device, strong anti-interference ability, and non-contact measurement. Because it is not necessary to do special treatment to the elastic shaft, it is convenient to form a non-contact torque sensing node, which can realize real-time monitoring of multipoint torque of shafting

Robust control strategy of VSC-HVDC systems based on feedback linearization and disturbance compensation method

The Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) technology has become the development direction of new energy grid-connected, DC power transmission and island power supply technology in the future due to its superior characteristics. The effective and reliable control method is important to realize the stable operation of VSC-HVDC system during disturbances. However, the common adopted control scheme for VSC-HVDC system lacks of superior dynamic response when system suffers external disturbances. Although some relatively new control methods have been continuously proposed and applied to the VSC-HVDC system, such as no-beat control, fuzzy control, sliding mode control and repetitive control, etc., they usually depend on detailed and exact system model. This paper focuses on the feedback linearization and disturbance compensation methods in VSC-HVDC system. Firstly, the mathematical model of VSC-HVDC system in dq coordinate system with modeling errors and external disturbances is derived. Secondly, in order to improve the dynamic response and robustness of the control, the feedback linearization and disturbance compensation method is used and designed to realize the decoupling control of the VSC-HVDC system. Finally, the VSC-HVDC system with conventional control and the proposed control is compared and analyzed on the PSCAD/EMTDC simulation platform. The results show that the proposed controller based on feedback linearization and disturbance compensation principle has better dynamic performance and higher robustness of regulation performance

Extended State Observer Based Adaptive Back-Stepping Sliding Mode Control of Electronic Throttle in Transportation Cyber-Physical Systems

Considering the high accuracy requirement of information exchange via vehicle-to-vehicle (V2V) communications, an extended state observer (ESO) is designed to estimate the opening angle change of an electronic throttle (ET), wherein the emphasis is placed on the nonlinear uncertainties of stick-slip friction and spring in the system as well as the existence of external disturbance. In addition, a back-stepping sliding mode controller incorporating an adaptive control law is presented, and the stability and robustness of the system are analyzed using Lyapunov technique. Finally, numerical experiments are conducted using simulation. The results show that, compared with back-stepping control (BSC), the proposed controller achieves superior performance in terms of the steady-state error and rising time

Study on frequency characteristics of receiving power system with large-scale offshore wind power generation

With the rapid development of offshore wind power and large-scale grid connection, the mechanical inertia and frequency regulation ability of the power system are greatly reduced, which seriously affects the frequency stability of the receiving end power grid. Aiming at the frequency stability analysis of large-scale offshore wind power connected to the receiving end power grid, this paper proposes a frequency response aggregation model which includes the frequency limiting controller (FLC) and the wind turbine generator (WTG) with frequency modulation (FM) capability. The rationality of model aggregation and the stability of transfer function are proved by theoretical analysis. Taking a southern province in China as an example, the effects of wind turbine generator access form and DC block capacity on different frequency response indexes are analyzed by using the proposed frequency response aggregation model. Through theoretical and simulation analysis, the correlation of system inertia, FM capacity and DC FLC capacity with frequency deviation nadir and quasi-steady state frequency index is obtained, and the relevant conclusions affecting frequency stability indexes are drawn. Finally, through the model simulation method, the improvement of the system frequency stability when the wind turbine provides inertia and primary FM support is analyzed. This paper concludes that when the wind power penetration is in the range of 10%∼40% and the wind power assisted frequency modulation capacity reaches 5% of the installed capacity, the minimum frequency of the system can be maintained above 49.5 Hz

Capacity optimization of hybrid energy storage systems for offshore wind power volatility smoothing

Energy storage devices are frequently included to stabilize the fluctuation of offshore wind power’s output power in order to lessen the effect of intermittency and fluctuation on the electrical grid but doing so will raise operators’ investment costs. To obtain the best economic benefits, this paper presents a hybrid energy storage system based on batteries and super-capacitors and its capacity configuration optimization method. First, the wind power output is divided using the wavelet packet decomposition method, and then power is distributed between the batteries and the super-capacitors. Then, the mathematical model of energy storage system optimization is established to optimize the capacity configuration of hybrid energy storage with the objective of minimizing the daily input cost of energy storage, and the configuration schemes of single energy storage and hybrid energy storage are compared. Finally, using the measured data of a domestic offshore wind farm for simulation, several energy storage schemes are compared to verify the feasibility and effectiveness of the proposed method, at the same time, using the hybrid energy storage devices to participate in the grid-connected stabilization task of offshore wind power is more advantageous than the single energy storage, the results show that the daily input cost of the hybrid energy storage scheme is 2.79% and 3.84% lower than that of the single energy storage scheme using only battery or super-capacitor

System value assessment method of energy storage system for multi‐services of power system considering battery degradation

Abstract The energy storage system (ESS) is a promising technology to address issues caused by the large‐scale deployment of renewable energy. Deploying ESS is a business decision that requires potential revenue assessment. Current value assessment methods focus on the energy storage owner or the electricity utility. The system value of the ESS needs to be fully considered to gain a broad understanding of benefits across the whole power system. Thus, this study proposes a system value assessment method of grid‐integrated ESS to quantify the total system value‐avoided cost based on an improved DC power flow model considering transmission losses. Four typical applications (production cost saving, upgrade deferral, environmental benefit, and transmission loss saving) are chosen to represent the system value of the ESS across the whole power system. In addition, the co‐optimisation model considering the “source‐grid‐storage” coordination operation and battery capacity degradation, is proposed for peak shaving and frequency regulation based on the Chinese power market rule. The proposed method is tested in simulation and experimental studies