Gu Yuanpei

Bio: Gu Yuanpei is an academic researcher from North China Electric Power University. The author has contributed to research in topics: Oscillation & Dissipation. The author has an hindex of 1, co-authored 3 publications receiving 3 citations.

Stability Analysis of Power Grid Connected With Direct-Drive Wind Farm Containing Virtual Inertia Based on Integrated Dissipation Energy Model

Abstract: Concerning the difficulty in unified modeling of direct-drive wind farm with virtual inertia and the unknown cause of low frequency oscillation, a detailed model of integrated dissipation energy of direct-drive wind farm is built. First, the dissipation energy model of wind generator and the integrated dissipation energy model of direct-drive wind farm containing virtual inertia and PLL is derived and built. On this basis, according to different sources of integrated dissipation energy, it is decomposed into free dissipation energy, resonant dissipation energy and forced dissipation energy. These three components respectively characterize the contribution of inherent damping, generator-grid coupled resonance and generator-grid interaction to the stability of system. And then, how the variation of wind speed and generator location affects the stability of system is analyzed quantitatively using the integrated dissipation energy. Finally, the model of IEEE 10-machine 39-bus system connected with direct-drive wind farm is built in RTDS for hardware-in-the-loop tests. Simulation results verify that, the detailed model exhibits three different oscillation states, and each generator in the wind farm contributes differently to system oscillation. The traditional equivalent model of wind farm only exhibits one oscillation state and cannot reflect the difference in contributions of generators, thus it may wrongly identify the stability of system, even aggravate oscillation.

System and method for positioning oscillating source of wind power grid-connected system based on energy frequency spectrum

Abstract: The invention relates to a system and a method for positioning oscillating source of a wind power grid-connected system based on an energy frequency spectrum, belongs to the technical field of wind power generation systems, and solves the problem that an oscillating source unit cannot be accurately positioned under the condition that a system is interfered and a multi-oscillation mode is excited.The method comprises the following steps of 1, acquiring voltage and current information of an output port of each unit of a system, and obtaining a change curve of the dynamic energy of each generator set along with time; 2, taking the generator set corresponding to the curve with a rising trend as an alternative unit; 3, acquiring and processing energy spectra of a synchronous unit and a doubly-fed wind turbine generator with the phase-locked loop in the alternative unit and/or an energy-like frequency spectrum of a doubly-fed wind turbine generator with the virtual inertia, and taking the unit with the largest dominant oscillation mode as an oscillation source reference unit; and 4, calculating energy spectrum similarity coefficient of each other alternative unit and the oscillation source reference unit to determine an oscillation source unit. According to the system and the method, accurate positioning of the oscillation source unit can be realized under the condition that the system is interfered and the multi-oscillation mode is excited.

Stability evaluation method and system for doubly fed wind turbine

Abstract: The invention relates to a stability evaluation method and system for a doubly fed wind turbine, belonging to the technical field of wind power generation systems. The problem that the doubly fed windturbine in the prior art has poor stability and low safety coefficient and cannot be evaluated online in the full time domain is solved. First, the time-domain variations of the port voltage, current, active power and phase locking angle of a doubly fed wind turbine are measured, and then, the port energy of the doubly fed wind turbine is calculated, and the dissipation intensity of the doubly fed wind turbine is calculated. The stability of the system can be judged more quickly and effectively according to the dissipation intensity. Real-time monitoring of dynamic energy is realized, and theworking efficiency of the system is improved.

Dynamic synthetic inertial control method of wind turbines considering fatigue load

Abstract: This paper proposes a dynamic synthetic inertia control method, considering the fatigue loads of the wind turbine. The control objectives include reducing the rate of change of frequency and frequency nadir of the power system and the fatigue load of the shaft and tower of the wind turbine. A frequency regulation model of the power system containing the primary operating dynamics of the wind turbine is established. The dynamic synthetic inertia control method is proposed according to the relationship between fatigue load, wind velocity, and frequency. Case studies are conducted with a wind turbine fatigue load under a synthetic inertia control with different weights for different wind velocities and system loads. Therefore, the dynamic weights are obtained. Comparing the rate of change of frequency and frequency nadir and equivalent damage load, the efficacy of the proposed method is verified.

Wind power plant available inertia evaluation method

Abstract: The invention discloses a wind power plant available inertia evaluation method, which comprises the steps of constructing an instantaneous wind speed conditional probability distribution model under the influence of atmospheric turbulence by utilizing a hybrid Copula function based on the space-time distribution characteristic of the average wind speed of a wind field under the influence of physical factors; establishing an estimation model of available inertia kinetic energy and inertia power increment of a fan in an operation mode under virtual inertia control of a doubly-fed wind turbine generator, and obtaining an interval evaluation curve of available inertia of a whole wind field based on a certain confidence coefficient by additionally considering the operation condition of each fanin the wind field in actual operation. The confidence interval evaluation result provided by the invention is relatively small in error and relatively high in credibility.

Wind power grid-connected frequency response abnormity monitoring method and system

Abstract: The invention provides a wind power grid-connected frequency response abnormity monitoring method and a system. The method comprises the following steps: obtaining a frequency response curve of a windpower grid-connected system; according to a pre-trained frequency response anomaly identification model, identifying whether an anomaly exists in the frequency response curve or not; if the frequencyresponse curve is abnormal, performing anomaly detection on a plurality of wind driven generators of the wind turbine generator in sequence, recognizing the abnormal wind driven generators, executingthe system anomaly response emergency measures at the same time, and otherwise, continuously recognizing whether anomaly exists in the frequency response curve or not; and withdrawing the abnormal wind driven generator in the wind power grid-connected system. According to the invention, anomaly detection is carried out on the wind power grid-connected frequency response, specific fault equipmentis detected, the fault equipment is maintained, the anomaly detection efficiency is relatively high, and the abnormal frequency is regulated and controlled in time, so that the system frequency response returns to normal.

A novel AC chopper integrated with active measurement of wideband impedance for wind power system

Abstract: Large-scale wind farms are susceptible to oscillations like any other power systems with high penetration of power electronics, whose characteristics of wideband impedance hold the key to resolving this issue. However, due to the high cost of impedance measurements for power systems, computational modelling methods are usually used, accuracy of which is difficult to be verified. This paper proposes a novel AC chopper integrated with active measurement of wideband impedance (AIM-ACC), which can be slightly modified from the existing energy consuming devices in wind power systems. With the help of the proposed Reversed-phase Chirp Pulse Width Modulation (RC-PWM) signal, the AIM-ACC generates chopper current within a desired wide frequency band, avoiding the spectral shifting effects of sinusoidal voltages. Thus, the impedance characteristics of wind system are obtained by measuring the injected current and its corresponding voltage, with fast excitation time, good controllability and high accuracy. Finally, the verification of an experiment with single-phase branch and a simulation with the proposed AC chopper in wind power system was carried out for the effectiveness of the proposed method.