This paper put forward to an interactive flexible SCADA system in which information shared, on the basis of analyzing and summarizing the defections of former SCADA. It not only solves the interaction of data and func...
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Distribution network planning is a multi-goal and multi-restricted problem that involves the geographical condition of power line route, constructing and maintenance expenses, power line losses, power flow and securit...
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ISBN:
(纸本)0863416381
Distribution network planning is a multi-goal and multi-restricted problem that involves the geographical condition of power line route, constructing and maintenance expenses, power line losses, power flow and security constraint. Computer aided planning is an important studying direction now. However, automatic line routing can not be made now. A model is advanced in this paper to minimize the work of planner and to simplify the network planning procedure. In this paper, an improved particle swarm optimization (PSO) is used to escape the locally point by adopting the probability distribution feature and controlling the flying speed automatically. By using this method in Jinan power network, found that the speed of network-planning can be improved by adopting the improved PSO and geographical feature pretreatment.
HVDC transmission lines system has some advantages, but it can generate an effect on the environment nearby due to the corona, especially the ionized field. Based on the electromagnetic field theory, a simple method t...
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ISBN:
(纸本)3952299049
HVDC transmission lines system has some advantages, but it can generate an effect on the environment nearby due to the corona, especially the ionized field. Based on the electromagnetic field theory, a simple method to analyze the ionized field generated from the bundled conductors of bipolar lines is proposed. And then, after the validity of the method is testified, some examples are analyzed and some conclusions are drawn finally. The results have been used in the design of ±800kV HVDC transmission lines system in China.
In this paper, a global control scheme for improving transient stability of powersystems by thyristor controlled braking resistor is proposed. According to the hierarchical control theory of large-scale system princi...
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ISBN:
(纸本)0863412467
In this paper, a global control scheme for improving transient stability of powersystems by thyristor controlled braking resistor is proposed. According to the hierarchical control theory of large-scale system principle, the control structure is organized into a two-layer controller. Two-level co- state prediction algorithm is used during optimization of parameters of the controller. The lower layer is composed of decentralized local feedback controllers, each of which takes local feedback signal and controls its connected generator. In the upper layer a global controller is designed to enhance the effectiveness of decentralized local controllers. The global controller coordinates local controllers by generating remote feedback signals which ensuring the global optimal solution of the overall system transient performance. The proposed control scheme can guarantee fast and accurate control actions of local controllers when a powersystem is subjected to large disturbances. Simulation results show the effectiveness of the proposed control scheme.
The paper presents the dynamic model of doubly fed induction generator (DFIG) including the mechanical model, the generator model and the PWM voltage source converter model. The mechanical model uses two-mass model, a...
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A detailed user-defined (UD) reactive powercontrol (RPC) model of HVDC has been developed in powersystem Analysis Software Package (PSASP). The UD RPC model, as one part of UD HVDC models which have been set up base...
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ISBN:
(纸本)0863412467
A detailed user-defined (UD) reactive powercontrol (RPC) model of HVDC has been developed in powersystem Analysis Software Package (PSASP). The UD RPC model, as one part of UD HVDC models which have been set up based on the controlsystem of Three Gorges-Changzhou project, includes reactive power generation calculation, reactive power consumption calculation, reactive powercontrol strategies and converter reactive power regulator strategies. Each part of the UD RPC model and its guidelines are presented in this paper. Case studies are carried out on the WEPRI-7 system whose embedded HVDC models are replaced by the UD HVDC models. The simulation results show the correctness and necessity of the UD RPC model for AC/DC hybrid system interaction and stability analysis.
Both static and dynamic electric load characteristics have considerable effect on short circuit ratio (SCR) or effective short circuit ratio (ESCR). This paper gives emphasis on the relationship between static/dynamic...
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Both static and dynamic electric load characteristics have considerable effect on short circuit ratio (SCR) or effective short circuit ratio (ESCR). This paper gives emphasis on the relationship between static/dynamic load characteristics and SCR (ESCR). Different power level with different power factor is considered for the impacts on SCR or ESCR of static load characteristics. Three-phase short-circuit current of induction motors is qualitative analyzed and simulation of the feeding current is carried out for the dynamic process of induction motor in the consideration of dynamic load characteristics. Case studies are carried out on WEPRI-36 system and Hunan power grid. Simulation results with powersystem analysis software package (PSASP) illustrates that load should be considered in calculating SCR.
Secondary voltage controlsystem is a significant segment of the hierarchical voltage control in powersystems. Though voltage controller has both constant voltage regulators, such as generators and static reactive po...
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Secondary voltage controlsystem is a significant segment of the hierarchical voltage control in powersystems. Though voltage controller has both constant voltage regulators, such as generators and static reactive power compensators, and discrete voltage regulators, such as OLTC and shunt capacitors/reactors, traditional secondary voltage control (SVC) only consider constant voltage regulators. A few of the papers consider discrete voltage regulators, but they are also treated as constant variable. In this paper, Considering the trait of continuous and discrete devices in secondary voltage control co-existing, a mixed secondary voltage control optimal model including continuous and discrete variables is established. The solution is gained by multi-agent particle swarm optimization algorithm. This method concerned with the advantages of multi-agent system and particle swarm optimization algorithm can get every setting value of regulator exactly and quickly. The proposed method is applied to the New England 39 nodes system. It is shown that by contrast to the traditional secondary voltage control, this method can achieve satisfactory controlling effort involved both constant and discrete controllers at the same time.
When relays trip a faulted line in powersystem, the flow on the faulted line will be transferred to the other lines. Those lines might be overloaded and then cascading tripped by the backup relays, which worsen the s...
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When relays trip a faulted line in powersystem, the flow on the faulted line will be transferred to the other lines. Those lines might be overloaded and then cascading tripped by the backup relays, which worsen the system state and even cause blackout. Generally, these kind of cascading trips are the origins of a lot of well-known blackouts. In this paper, by analyzing the defects of traditional backup protections, a new wide area backup protection scheme based on WAMS is presented to identify flow transferring. A new concept of flow transferring relativity factor (FTRF) is proposed to estimate the flow distribution after flow transferring occurs; and the method of calculating FTRF matrix online is also deduced. The simulation of 10-unit and 39-bus New England network shows that the proposed wide area backup protection scheme can identify flow transferring successfully and hence be superior to the traditional backup protection.
Conventional HVDC has the advantages of mature state of art and lower cost and the disadvantages of absorbing large reactive power and the danger of commutation fault. Voltage source converter (VSC) based HVDC (VSC-HV...
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Conventional HVDC has the advantages of mature state of art and lower cost and the disadvantages of absorbing large reactive power and the danger of commutation fault. Voltage source converter (VSC) based HVDC (VSC-HVDC) has the advantages of flexible operation and control and the disadvantages of high cost. Combining the advantages of the two kinds of transmissions, a novel hybrid HVDC transmission type is analyzed in this paper, which the sending terminal adopts phase control converter (PCC) and the receiving terminal adopts VSC. The hybrid HVDC system can supply to passive network, supply reactive power to AC system and expediently extend to two bi-terminal or multi-terminal systems from conventional HVDC system. The expressions of voltage, current and power in rectifier and inverter sides are deduced. The relationship between the operational variables and control variables is analyzed. The basic regulation characteristics are gotten. The simulation model is founded based on the simulation software PSCAD/EMTDC. Simulation results show that the hybrid HVDC system could be operated steadily when the system active power changes slowly and quickly. It has the application prospect in scope of long distance small load supplying, multi-terminal DC system connection and system black-start etc.
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