Jianxun Dong

Demand Side Frequency Control Scheme in an Isolated Wind Power System for Industrial Aluminum Smelting Production

Reducing the fossil fuel consumption of aluminum smelting production, which consumes around 8% of electricity annually, is of great significance for Chinas energy sector. One possible solution is to integrate wind power as supply for aluminum smelter loads. Based on this background, this paper studies an actual industrial case-an isolated power system for aluminum production with integrated wind penetration levels as high as 30%. However, due to the integration of wind power, frequency stability issues become critical in such a system. Therefore, a demand-side frequency control scheme responding to frequency deviations of the system is proposed in this paper to control the load power of aluminum smelters. The scheme is designed based on the relationship between the DC voltage supply for aluminum smelting loads and the commutation voltage drop which can be adjusted by changing the inductance value of the saturable reactors. Finally, simulations under both N-1 and N-2 contingency scenarios demonstrate the effectiveness of the proposed control scheme considering various wind power outputs.

An Isolated Industrial Power System Driven by Wind-Coal Power for Aluminum Productions: A Case Study of Frequency Control

Summary form only given. Due to the uneven geographical distribution between load and wind power, currently it is difficult to integrate the large-scale wind power into the State Grid in China. There are significant wind curtailments for wind farms due to system restrictions. This paper proposes a new way of utilizing wind power, i.e. in-situ consumption, as an alternative to the costly development of long-distance transmission of large-scale wind power. Electrolytic aluminum load, which is one of the most typical high energy consuming loads, is employed to absorb the excess wind power in western China. An actual isolated industrial power system for aluminum production driven by wind power and coal-fired power is described. The penetration level of wind power in the isolated power system is up to 48.8%. The power imbalance between generation and load demand caused by wind power fluctuation or the tripping of coal-fired generators can dramatically impact the frequency stability of the isolated power system, which is of small inertia. An on-line identification method of power imbalance based on Wide Area Measurement System (WAMS) is presented. According to the characteristics of the electrolytic aluminum load, a system frequency control method by regulating the bus voltages of aluminum loads to eliminate the power imbalance is introduced. The simulation is done in Real Time Digital Simulator (RTDS) and the results verify the validity of the proposed frequency control method.

Load-Damping Characteristic Control Method in an Isolated Power System With Industrial Voltage-Sensitive Load

Load-damping characteristic models the load response to the frequency deviation, which has important impact on system frequency response. The load-damping coefficient is normally considered as a constant, obtained from operational experiences in large-scale power systems or from detailed load models in isolated power systems. An industrial isolated power system for aluminum production driven by coal-fired power and large scale wind power is studied in this paper. Since the electrolytic aluminum load is driven by direct current, it is one type of voltage-sensitive load and does not respond to the frequency deviation. This paper proposes a load-damping characteristic control method for such isolated industrial power system with voltage-sensitive load. To decrease the maximum frequency deviation during transient process, a time-varying load-damping coefficient control scheme is presented. Simulation is done on real-time digital simulator (RTDS) and the results verify the effectiveness of the proposed control method.

An isolated industrial power system driven by wind-coal power for aluminum productions: A case study of frequency control

Due to the uneven geographical distribution between load and wind power, currently it is difficult to integrate the large-scale wind power into the State Grid in China. There are significant wind curtailments for wind farms due to system restrictions. This paper proposes a new way of utilizing wind power, i.e., in-situ consumption, as an alternative to the costly development of long-distance transmission of large-scale wind power. Electrolytic aluminum load, which is one of the most typical high energy consuming loads, is employed to absorb the excess wind power in western China. An actual isolated industrial power system for aluminum production driven by wind power and coal-fired power is described. The penetration level of wind power in the isolated power system is up to 48.8%. The power imbalance between generation and load demand caused by wind power fluctuation or the tripping of coal-fired generators can dramatically impact the frequency stability of the isolated power system, which is of small inertia. An online identification method of power imbalance based on Wide Area Measurement System (WAMS) is presented. According to the characteristics of the electrolytic aluminum load, a system frequency control method by regulating the bus voltages of aluminum loads to eliminate the power imbalance is introduced. The simulation is done in Real Time Digital Simulator (RTDS) and the results verify the validity of the proposed frequency control method.

Demand side frequency control scheme in an isolated wind power system for industrial aluminum smelting production

Reducing the fossil fuel consumption of aluminum smelting production, which consumes around 8% of electricity annually, is of great significance for Chinas energy sector. One possible solution is to integrate wind power as supply for aluminum smelter loads. Based on this background, this paper studies an actual industrial case-an isolated power system for aluminum production with integrated wind penetration levels as high as 30%. However, due to the integration of wind power, frequency stability issues become critical in such a system. Therefore, a demand-side frequency control scheme responding to frequency deviations of the system is proposed in this paper to control the load power of aluminum smelters. The scheme is designed based on the relationship between the DC voltage supply for aluminum smelting loads and the commutation voltage drop which can be adjusted by changing the inductance value of the saturable reactors. Finally, simulations under both N-1 and N-2 contingency scenarios demonstrate the effectiveness of the proposed control scheme considering various wind power outputs.

Frequency control by aluminum smelter load response in an isolated wind power system: A study for an industrial case

Reducing fossil consumptions of aluminum smelting productions, which consumes around 8% electricity annually in China, is of significantly meaningful for Chinas energy section. One possible solution is by integrating wind power to supply for part of aluminum smelter loads. Based on this background, the paper studies an actual industrial case which is an isolated power system with as high as 30% wind penetration level integrated for aluminum production. After the integration of wind power, frequency stability issues become critical in such a system. This paper hence proposes a demand-side frequency control scheme, which uses self-saturable reactors to control load power of aluminum smelters responding to frequency deviations of this system. The scheme is designed based on the relationship between the input DC voltage of smelting loads and the commutation voltage drop which can be adjusted by self-saturable reactors. A numerical case study demonstrates the effectiveness of the proposed control scheme under the scenario considering with wind power outputs.

Placement of PMUs in power systems with multiple operation scenarios

This paper proposes an optimal PMU placement (OPP) model to make power system observable for normal operation condition as well as controlled islanding scenario. The optimization objective of proposed model is to minimize the number of installed PMUs and then maximize the measurement redundancy. To take advantage of the power network topology, the effect of zero-injection bus is incorporated into the model. Furthermore, additional observability constraints for single PMU or line loss are also derived. At last, test results on IEEE 118-bus system are presented to demonstrate the effectiveness of the proposed method.