This paper proposes a three levels cascade control topology for the VSC and DC/DC converters used in DC grids. The inner control level regulates local current as in all VSC converters. The middle control level uses PI feedback control of local DC voltage on all terminals. At the highest level, each station reference DC voltage is set based on desired power transfer and observing DC voltage limi...

The paper documents a new transformer model in ATPDraw called XFMR. This model handles 3-phase transformers with two or three windings. Autotransformers and all Wye and Delta couplings are supported. The model includes an inverse inductance matrix for the leakage description, optional frequency dependent winding resistance, capacitive coupling, and a topologically correct core model (3and 5-leg...

Fault location remains a challenging problem in order to restore power supply rapidly. In this paper, a novel single-terminal traveling wave fault location procedure is proposed in a radial distribution network. Firstly, the propagating speed of zero mode traveling wave is determined by BP neutral network method. Then the preliminary estimation of fault distance is calculated based on the diffe...

Voltage sags in the electric power system are mostly due to faults in the power system. Voltage sag is characterized by its magnitude (the retained voltage), phase-angle jump, unbalance in the sag in the three phases, and duration. Type of transformers in the electrical system is the important parameter influencing the characteristic of sag at the node where sensitive loads are connected. For s...

This paper addresses a multiagent-based distributed load shedding scheme to restore frequency for the microgrids during islanded operation. The objective of the proposed scheme is to realize a distributed load shedding considering its associated cost and the capacity of the flexible loads. There are two advantages of the proposed scheme: (1) it is a distributed scheme using average-consensus th...

Power quality (PQ) has become a key problem of urban power grid recently. Improving power quality is a technical problem being concerned by both power supply companies and the consumers. Shenzhen power grid, as a typical urban power grid, is exemplified in this paper. Through researches, typical PQ issues of a key region in urban power grid are discussed. Industrial feasibility study is carried...

In this paper, the dual heuristic programming (DHP) optimization algorithm is applied for the design of two LOCAL nonlinear optimal neuro-controllers on a practical multi-machine power system. One neuro-controller is designed to replace the conventional linear controllers, which are the automatic voltage regulator (AVR) and speed-governor (GOV), for a synchronous generator. The other is a new e...

Back-to-back static synchronous compensator (BtBSTATCOM) consists of two back-to-back voltage-source converters (VSC) with a common DC link in a substation. This configuration extends the capabilities of conventional STATCOM that bidirectional active power transfer from one bus to another is possible. In this paper, VSCs are designed in quasi multi-pulse form in which GTOs are triggered only on...

This paper represents mitigation scheme of wind farm output power fluctuation in micro-grid system during grid and islanded mode. The impact of mitigation technique using sodium sulphur battery energy storage system is investigated during grid and islanded mode of micro-grid system. A micro-grid system with wind farm and photovoltaic system is used for the investigation of the mitigation of win...

With the advance of insulated gate bipolar transistor (IGBT) converters, Multi-Terminal DC (MTDC) based on the voltage-source converter (VSC) has developed rapidly in renewable and electric power systems. To reduce the copper loss of large capacity and long distance DC transmission line, an improved droop control design based on optimal power sharing in VSC-MTDC integrating offshore wind farm i...