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In this paper, an analytical solution is solved for a piezoelectric energy harvester using a first order plate theory. Analytical formulas and a numerical example are presented for the electric current, voltage, output power and efficiency. The results are helpful to understand the effect of the geometry parameter, end mass and circuit impedance. The presented method may provide some guidance for the analysis and design of energy harvester with complex structure.

There are two synchronous compensators (SCs) with the capacity of 300 MW in Hunan network. At present, a SC is normally controlled within ± 50 Mvar and the other one operates in spare. There are rarely participates in regional voltage control. However, the problem of high voltage occurs frequently in the central Hunan during low load periods. Under the voltage safety premise of the most serious three phase fault, the SC participating in the regional voltage control method will improve the grid operating characteristics, and improve the safety and economics of the grid operation. In addition, this paper analyzes the relationship between the SC output reactive power and the number of thermal powers must on and its rotation reserve. By replacing the thermal power units and its rotation reserve which are the requirements for system stable operation, the SC in leading-phase operation can therefore improve the operation flexibility of power grid, increase the maximum transmission power of DC and the power supply capacity of Hunan power grid.

This paper proposes an optimal allocation method of synchronous condensers in weak received power grids with ultra-high voltage direct current (UHVDC) systems. Taking an actual weak received power grid with an UHVDC system as an example, the transient voltage stability is introduced and a certain scale of spinning reserve has to be retained to keep the voltage stability. And then, an optimal allocation model of synchronous condensers is established to minimize the spinning reserve for voltage stability during peak load periods. Using the sensitivity of spinning reserve deviation and the reactive power injection deviation, the effective buses for synchronous condenser allocation is determined. At last, the optimal number and capacity of synchronous condensers is solved step by step. The actual weak received power grid is used to validate the effectiveness of the proposed method.

Block chain is a newly emerging technology for data sharing and application. It can exchange de-centralized information in distributed systems without mutual trust by means of data encryption, timestamp and distributed consensus, so as to improve the efficiency of data sharing and application. This technology can be fully utilized in the large data remote sensing image system, and the multi-system shared node storage system can be managed efficiently and uniformly, so as to improve the economic efficiency of the system. This paper designs the shared architecture based on block chain technology, proposes key research technologies, and provides theoretical basis for nonengineering practice.

In order to resolve the problem that the power industry is with a rigid expectation of energy storage, higher requirement is put forward for intelligent and precise dispatch control of energy storage. The historical abandonment scenarios of power grids is analyzed to explore the pain points of current renewable energy consumption, where the principle and technical scheme is proposed of precise control of energy storage power stations. The precise control system of pumped storage power stations is applied to the actual grid data of a province. From the perspective of "source-network-loadstorage", the precise regulation of energy storage is used to promote the effect of renewable energy consumption. Through the intelligent and precise energy storage precision control system, the energy storage up and down adjustment flexibility is fully utilized to help the power system reach a balance, which not only promotes the consumption of renewable energy, but also makes the system more flexible and resilient.

Dynamical stability of power system is the periodical divergence caused by insufficient damping in the dynamical process. The dynamical stability level which is affected largely by the parameter change of power system stabilizer (PSS) is found in the actual power grid operation. Influence of PSS parameter optimization on dynamic stability level and its influencing factors is introduced to optimize the PSS parameter. The effectiveness and correctness of the method are verified by the application of the proposed method in regional power network.

It can avoid low frequency oscillation in power grid if we can detect the oscillation mode with low damping ratio and identify the source in early stage. This paper presents the Frequency Domain Decomposition (FDD) method, which can extract the low frequency oscillation modes from measurements of Phasor Measurement Units (PMU) in normal operation condition. The damping ratio, modal frequency and the mode shape of poorly damped oscillatory modes can be directly determined from ambient PMU measurements. After the oscillation modes are identified by FCC method, the next step is to identify the source of oscillation modes and the Pearson correlation coefficient (PCC) method is proposed. Combined with FDD and PCC from status data in energy management system (EMS) and the oscillation mode results, we can identify the source of oscillation mode with high correlations. The case study shows that the combination of FDD and PCC is a very efficient way to process large volume of WAMS data and EMS data, identifying low frequency oscillation mode source, and provide possible way to take early actions preventing low frequency oscillation in power system.

From a mathematical point of view, the evaluation of the open loop scheme of electromagnetic loop network is a multi-objective optimization problem. This paper combines subjective and objective weighting methods and takes fully into account the evaluation elements of electromagnetic loop network open-loop, and proposes an evaluation method based on comprehensive weighting for open-loop schemes of electromagnetic loop network. Firstly, the opening principle and mechanism of electromagnetic loop network are analyzed. On this basis, the comprehensive evaluation index system of the open loop scheme of the electromagnetic loop network is established by taking into account safety and stability of the system, current limiting effect and economic operation and so on. Then, in order to calculate the subjective and objective weight coefficient by using the analytic hierarchy process (AHP) and the coefficient of variation method and through the comprehensive evaluation calculation to obtain a comprehensive index to evaluate the advantages and disadvantages of the open-loop scheme. The rationality and validity of the method presented in this paper are verified through the example analysis of an actual grid in one province and the simulation analysis by using PSASP.

The dynamic voltage stability, which often occurs in the load center, is a key factor that restricts the economic operation of power systems and threatens the development and safe operation of power systems. Comparing to the power electronic devices, traditional reactive power compensations such as synchronous condenser, low-voltage capacitor and reactance have less technical and economic advantages and hard to support systems rapid development. Therefore, it is of great significance to study the application of new dynamic reactive power compensation technology, namely static var generator (SVG), in practical power systems. Developing distributed SVGs for grid dynamic voltage support is of great technical and economic value. Therefore, this paper takes Hunan network as an example to investigate the effect of SVGs location and capacity on transient voltage recovery characteristics. Time-domain simulation results are carried out from the PSASP. From the simulation cases, it is shown that the case with distributed SVGs has a better effect on the voltage recovery than the centralized SVG. However, the simulation results also show that different SVG capacity, location and the load level will lead to different optimal configuration of distributed SVG. A further research is needed in the following future.

In this paper, the safety, efficiency and cost (SEC) concept of asset life management are introduced into distribution network planning, and a multi-objective programming model considering safety, efficiency and cost is established. Subsequently, Strength Pareto Evolutionary Algorithm (SPEA2) is employed to seek the Pareto optimal frontier. At the same time, the original grid and the corridor information of distribution network are considered in the solving process. Afterwards, the planning program set of SEC of the grid structure is obtained, and the comprehensive benefit index is used to sort the Pareto non-inferior solution set in the second-level optimization decision-making so as to solve and select the optimal decision-making scheme. The simulation results based on the IEEE 33-bus system demonstrate the correctness and effectiveness of the proposed method.

At present, with the rapid development of satellite remote sensing platform, the quality of acquired satellite images has been greatly improved, and the amount of image data has also increased geometrically. For users, how to get useful image information quickly and accurately from massive remote sensing image data is the primary issue to improve the application efficiency of satellite data. The existing remote sensing data sharing platform has already done "what to do", but there is still a certain gap from what the user needs "what to give", and cannot truly realize the service on demand. Based on this, this paper adopts the concept of user portrait (User Profile) in large data analysis, and designs a remote sensing user information description method, which uses "user identification + time + behavior type + contact point" as the allocation weight model of information elements, describes user tags, and then uses the "foreground" in image processing field. The concept of "background" uses the LDA model to accurately define the user's portrait content. In the experiment, we used the actual data sharing platform user behavior information, detailedly enumerated the quantitative data of user portrait, and gave the follow-up application direction. Experiments show that the feasibility of the algorithm has certain application prospects.

This paper proposes a voltage regulation of synchronous condensers and switching capacitors in the power grids with a ultra-high voltage (UHV) DC/AC system. The control is able to regulate the system voltages in permitted range, reduce the times of switching capacitors, and improve the system dynamic voltage stability. Firstly, the influences of the UHV DC/AC system, switching capacitors, and synchronous condensers on system dynamic voltage stability are estimated. And then, the sensitivity of bus voltages and reactive power is used to select the switching capacitors. A voltage control model with synchronous condensers and switching capacitors is established. Finally, an improved interior point method is applied to solve the voltage control model. An actual power grid with a UHV DC/AC system is used to validate the effectiveness of the proposed scheme.

The precise control system of the pumped storage power station developed in this paper is based on the analysis of the large amount of historical operation scenes of “source-network-load-storage”. It fully excavates the characteristics and occurrence rules of the abandoned wind/water period, and breaks the contradiction between peak load regulation of the power grid and the problem that the regulating capacity of the pumped storage power station has reached its limit. The energy stratified filling method for pumped storage power station precise control is proposed to cope with the contradiction between the increasing fluctuating power supply and the increasing user terminal load, and to realize the coordination and optimization of various resources such as hydropower, thermal power, wind power, pumped storage power, tie line and short-term load forecasting curve in the energy internet. Enhance the overall capacity to absorb and flexibility.

The state of health (SOH) of the power batteries is one of the most important performances of the electric vehicle power batteries system. In order to comprehensively evaluate the health of the batteries, the stereoscopic cross compound matter element is used in parameters of batteries charging and discharging, the joint weight of the evaluation index is determined by the analytic hierarchy process(AHP) and the maximum entropy method, and the matter element-maximum information entropy is used to carry out the quantitative calculation analysis for the health index of the lithium batteries. Parameter-optimizing Support Vector Machine is used to predict the health index of lithium batteries. The experimental results show that this method has a good guiding function for the state of health analysis, it provides a theoretical basis for the use of the power batteries.