Bu Guangquan

A frequency-domain parallel eigenvalue search algorithm of power systems based on multi-processing

With the rapid development of large-scale interconnected power systems, inter-area low frequency oscillation phenomena occasionally occur; thus, the small signal stability problem has become a serious issue affecting power system stability. When analyzing the small signal stability of a large-scale power grid (in particular, on-line dynamic security early warning systems), given the high rank of the differential algebra equations (DAEs), the serial eigenvalue algorithm cannot meet the requirements of computation speed. In recent years, the development of multi-core CPU technology has been very rapid. By fully using the hardware resources of multi-core CPU computers, the small signal stability calculation speed problem can be effectively solved in parallel computing technology. In this paper, a frequency-domain parallel eigenvalue search algorithm of power systems based on multi-processing is described, with the algorithm realized in the PSD-SSAP system, which is widely used in China. The calculation is accurate, the realization of the algorithm is simple, and the parallel computing efficiency is very high. Numerical simulation results of actual large-scale power systems show that the proposed algorithm is correct and efficient.

Voltage stability analysis of multi-infeed AC/DC power system based on multi-infeed short circuit ratio

The definitions of multi-infeed short circuit ratio (MSCR) were analyzed in the paper, which were proved to be equal. The relation between MSCR and traditional short circuit ratio (SCR) was discussed, and it came to a conclusion that the traditional SCR is the particular case of MSCR. Then, the decoupled model of MSCR system was presented in the paper, and based on it, the index of multi-infeed critical short circuit ratio (MCSCR) was given, which could be used as a criteria for weighing the strength of the system. Simulation results show that it is effective to use MSCR for denoting the level of voltage stability.

Discussion on cascade-connected multiterminal UHVDC system and its application

According to the development of UHVDC and MTDC technology, the cascade-connected MT-UHVDC system is presented. This paper introduces characteristics of this kind of MTDC system, including electric structure and requirements for equipments and control system and its application in the power system. Based on this new transmission solution, and with the UHVDC planning projects in China in the future, the MT-UHVDC demonstration project is selected by system analysis and comparison, which considering the problems of load distribution and short circuit current level and system stability and engineering cost and so on.

Study of the short circuit current contributed by a DC system with a three-phase fault on the AC side of an inverter

Currently, the standards used to calculate the short circuit (SC) current ignore the contribution of DC systems to the SC current when short-circuit faults occur in an AC systems. With the rapid development of High Voltage Direct Current systems (HVDC), it has become important to determine whether the contribution of the HVDC system can be ignored when calculating the SC current. This study investigates the transient processes of a line-commutated converter HVDC (LCC-HVDC) system with a three-phase fault on the AC side of an inverter. The mechanism of the SC current contributed by LCC-HVDC is analyzed, and a practical method for calculating the SC current is proposed. Simulation results verify the proposed mechanism and the accuracy of the method.

Operation rule extracting based on time series association analysis in transient stability study

A robust operation rule extracting algorithm is proposed based on adaptive time series association analysis here. It is applied to extract association knowledge among the accumulating massive operation data. A data model describing the system state and topological structure before/after fault happening is built up at first. The initial abstract features are independent of the scale of a power system. A recursive principal component analysis method is employed to yield the reduced-size feature space. The extract features are then fed into the associative analysis. For considering temporal constraint, the generated associative rules not only reflect the relationship between power system operating condition and transient stability, but also reveal some valuable information about operating characteristics. Simulation results on on IEEE 39-bus test system demonstrate the feasibility and efficiency of the proposed method.

Accuracy analysis of fixed voltage setpoint indices for voltage stability

There are many voltage stability indices for voltage security assessment and calculating stable margins from operating points to voltage instability at each load bus. Among them, one type of indices based on fixed voltage setpoint is applied in practice. Previous research has proved inaccuracy of these indices with the P-V curve method. This paper aims to verify the accuracy of these indices by theoretical analysis with a first-order induction motor model and dynamic time domain simulation using a third-order induction motor model. It briefly reviews the accuracy analysis of voltage stability indices based on fixed voltage setpoint by the P-V curve method. Then theoretical analysis and dynamic time domain simulation are performed on a simple system to verify these indices based results. Results obtained from both theoretical calculation and dynamic simulation reveal that fixed voltage setpoint indices are neither accurate nor adequate, just as the P-V curve method suggests.