Damping of subsynchronous resonance using excitation controllers and static VAr compensations: a comparative study
TL;DR: In this article, a comparative study on the application of two countermeasures, i.e., the excitation controller and the static VAr compensator (SVC), for damping of subsynchronous resonance (SSR) is presented.
Abstract: The results of a comparative study on the application of two countermeasures, i.e. the excitation controller and the static VAr compensator (SVC), for damping of subsynchronous resonance (SSR) are presented. To stabilize all the SSR modes, a unified approach based on modal control theory is proposed for the design of the excitation controller and the SVC, which are essentially dynamic output feedback compensators. The two damping schemes differ in the way they modulate the reactive power flow in the system to damp out the subsynchronous oscillations. To demonstrate the effectiveness of the proposed damping schemes under disturbance conditions, time-domain simulations based on a nonlinear system model are also performed. The relative merits of the two countermeasures are compared with respect to their validities under various loading conditions and different degrees of series compensations and their capabilities to expand the stable region on the real-capacitive reactance plane. >
Citations
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01 May 1990
TL;DR: A new type of power system stabiliser based on fuzzy set theory is proposed to improve the dynamic performance of a multimachine power system and is of decentralised output feedback form and is easy for practical implementation.
Abstract: A new type of power system stabiliser based on fuzzy set theory is proposed to improve the dynamic performance of a multimachine power system. To have good damping character istic over a wide range of operating conditions, speed deviation (δω) and acceleration (δω) of a machine are chosen as the input signals to the fuzzy stabiliser on that particular machine. These input signals are first characterised by a set of linguistic variables using fuzzy set notations. The fuzzy relation matrix, which gives the relationship between stabiliser inputs and stabiliser output, allows a set of fuzzy logic operations that are per formed on stabiliser inputs to obtain the desired stabiliser output. Since only local measurements are required by the fuzzy stabiliser on each generating unit, the proposed stabiliser is of decentralised output feedback form and is easy for practical implementation. The effectiveness of the proposed fuzzy stabiliser is demonstrated by a multimachine system example.
110 citations
TL;DR: In this paper, a countermeasure is developed by combining the supplementary excitation damping control (SEDC) and the torsional stress relay (TSR) to solve the multimodal subsynchronous resonance (SSR) problem.
Abstract: The Shangdu power plant has four 600-MW turbine-generators connected to the North-China Grid through two 500-kV transmissions, which are compensated with 45% fixed series capacitors. Extensive studies conducted on the system model indicate that the system suffers from multimodal subsynchronous resonance (SSR). To solve the problem, a countermeasure is developed by combining the supplementary excitation damping control (SEDC) and the torsional stress relay (TSR). In this paper, the characteristics of the SSR problem are investigated. Then the developed SEDC is presented. To validate the effectiveness of the proposed SEDC as well as the results of model studies, field tests were conducted under various operating conditions. The tests fully exposed the realistic threat of SSR in the system. Meanwhile, it is demonstrated that the developed SEDC can improve torsional damping significantly, and thus solve the multimodal SSR problem effectively. This is the first time in China that practical SEDCs have been developed and their ability to mitigate multimodal SSR has been verified in a real series-compensated system.
59 citations
Cites background from "Damping of subsynchronous resonance..."
...conducted in this area focuses on theoretical work [10]–[14]....
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TL;DR: The proposed subsynchronous resonance damping controller is based on reshaping the virtual output admittance of the interfacing VSC-based system to ensure positive damping in the vicinity of torsional modes.
Abstract: This paper presents a new technique to damp subsynchronous torsional oscillations in a series-compensated system with multimass synchronous generator by reshaping the output impedance of an electrically nearby voltage-source converter (VSC; e.g., interfacing a high-voltage dc transmission system or wind farm). The incremental output admittance of a VSC that is constructed by the circuit components and control parameters of a VSC is the key element for VSC-grid interactions. The proposed subsynchronous resonance damping controller is based on reshaping the virtual output admittance of the interfacing VSC-based system to ensure positive damping in the vicinity of torsional modes. The proposed reshaping technique uses the voltage at the point of common coupling in cascaded compensators to magnify the positive resistance without using generator or turbine speed and/or torque perturbations. Time-domain simulation results and laboratory-scale experimental results are presented to validate the theoretical analysis and show the effectiveness of the proposed approach.
45 citations
Cites methods from "Damping of subsynchronous resonance..."
...Such methods include tripping the generator [1], applying an SSR filter [2], using the excitation control [3], employing flexible ac transmis-...
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TL;DR: In this paper, a simple lead-lag excitation controller using generator shaft speed deviation (Delta omega ) as a feedback signal to damp all of the IEEE Second Benchmark Model, system-1 torsional oscillations is presented.
Abstract: A simple lead-lag excitation controller using generator shaft speed deviation ( Delta omega ) as a feedback signal to damp all of the IEEE Second Benchmark Model, system-1 torsional oscillations is presented. In order to stabilize all the torsional modes, modal control theory is used to determine the parameters of the dynamic output feedback controller. Various degrees of series compensation, different loading conditions, and torsional mode shapes for a torsional oscillations study are also investigated. In addition, time-domain simulation using a nonlinear system model are examined to demonstrate the effectiveness of the proposed countermeasure under torque disturbance conditions. >
42 citations
01 Mar 1996
TL;DR: In this paper, a simple and novel strategy for damping subsynchronous resonant oscillations through control of converter firing angles of a superconducting magnetic energy storage system (SMES) is proposed.
Abstract: A simple and novel strategy for damping subsynchronous resonant oscillations through control of converter firing angles of a superconducting magnetic energy storage system (SMES) is proposed. The strategy is derived such that the current injected or drawn by the SMES compensates for any deviation in real and reactive power in the system. The proposed control has been tested on the IEEE second benchmark model for subsynchronous resonance studies. It has been found to eliminate the slowly growing transients resulting from the unstable modes very effectively. The control algorithm is simple and its realization will require very little hardware.
35 citations
References
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TL;DR: In this article, a new concept for controlling static VAr compensators (SVC) in power systems is presented, which allows thyristor controlled VAR compensators to effectively damp subsynchronous resonance (SSR) oscillations besides controlling the system voltage.
Abstract: This paper presents a new concept for controlling static VAr compensators (SVC) in power systems. It allows thyristor controlled VAr compensators to effectively damp subsynchronous resonance (SSR) oscillations besides controlling the system voltage. Eigenvalue analysis and digital time simulations for the IEEE SSR benchmark system are utilized to investigate the role of the main voltage regulator of the SVC in stabilizing the system and alleviating the SSR modal interactions that may be introduced by the auxiliary speed signal alone. Stability zones are identified to optimize the compensator parameters for economical application.
127 citations
TL;DR: In this paper, the application of static reactive compensators (SVCs) to power transmission systems is discussed, and it is shown that SVCs can provide significant benefits in terms of increased transient stabilty and improved damping for synchronizing power flow oscillations.
Abstract: This paper concerns the application of static reactive compensators (SVCs) to Power transmission systems. Emphasis is placed on stability, and it is shown that SVCs can provide significant benefits in terms of increased transient stabilty liisand improved damping for synchronizing power flow oscillations. The paper includes descriptions Of static VAR compensators, with technical and economic comparisons of different compensators. An SVC system study model is presented which includes provision for modulating reactive compensation in response to a variety of system functions. Study procedures are illustrated which relate sYstem stability objectives to general specifications of SVCs, indluding their locations, regulating slopes, peak reactive power requirements, and modulation control.
87 citations
TL;DR: In this paper, the authors demonstrate a method of damping subsynchronous resonance using a set of phase controlled reactors connected to the machine terminals, which can prevent one mode of instability by modulating the reactive power consumed by the reactors in proportion to the change in generator speed.
Abstract: The IEEE benchmark system is used to demonstrate a method of damping subsynchronous resonance using a set of phase controlled reactors connected to the machine terminals. It is possible to prevent one mode of instability by modulating the reactive power consumed by the reactors in proportion to the change in generator speed. However, it is shown that this previously Suggested method of control is ineffective in damping all possible modes of instability of the benchmark system due to subsynchronous resonance. Methods of control are established which can be used to damp all critical modes of instability using a set of phase controlled reactors
79 citations
61 citations
TL;DR: In this article, a Static Var System (SVS) was used to provide automatic, continuous voltage control on a 115 kV network in western Nebraska. But, the SVS was not designed for continuous voltage regulation.
Abstract: Basin Electric Power Cooperative will commission a Static Var System (SVS) in late 1977 to provide automatic, continuous voltage control on a 115 kV network in western Nebraska. This paper describes engineering studies which were conducted to select the SVS rating and site, determine harmonic filtering requirements, synthesize the SVS voltage regulator characteristics and to simulate the steady-state and dynamic performance of the SVS. The studies have shown that the SVS will perform as intended to regulate the steady-state voltage within ±0.5% and reduce post-fault voltage swings which otherwise might cause important motor loads to trip off line.
55 citations