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Abstract
Aiming at studying the regulation quality of isolated turbine regulating systems under load disturbance and different regulation modes, the complete mathematical model of a turbine regulating system under three regulation modes is established. Then, based on dominant poles and null points, the method of order reduction for a high-order system of time response of the frequency is proposed. By this method, the complete high-order systems are solved and the regulation quality for time response of the frequency is studied. The results indicate that (1) the tail wave, which is the main body of time response of the frequency and the principal factor that determines the regulation quality, is mainly determined by the dominant poles; (2) for the three regulation modes, by deleting the high-order terms, the three equivalent overall transfer functions are fourth order, third order, and third order, respectively, and can be solved; (3) the analytical fluctuation equations of time response of the frequency solved from low-order equivalent overall transfer functions accurately simulate the fluctuation characteristics of time response; and (4) based on damped vibrations decomposed from analytical fluctuation equations, the regulation qualities of three regulation modes are analyzed.
Nomenclature
| ΔZ | = | change of surge tank water level (positive direction is downward) |
| Qy | = | headrace tunnel discharge |
| n | = | unit frequency |
| Mt | = | kinetic moment |
| Pt | = | actual power of unit |
| Ly | = | length of headrace tunnel |
| fy | = | sectional area of headrace tunnel |
| hy0 | = | head loss of headrace tunnel |
| Twy | = | water inertia time constant of headrace tunnel |
| F | = | sectional area of surge tank |
| Fth | = | critical stable sectional area of surge tank |
| eh, ex, ey | = | moment transfer coefficients of turbine |
| Ta | = | unit inertia time constant |
| bt | = | temporary droop |
| Tn | = | accelerated speed time constant |
| ep | = | speed droop |
| H | = | net head |
| Qt | = | penstock discharge |
| Y | = | guide vane opening |
| Mg | = | resisting moment |
| Pg | = | given power of unit |
| Lt | = | length of penstock |
| ft | = | sectional area of penstock |
| ht0 | = | head loss of penstock |
| Twt | = | water inertia time constant of penstock |
| TF | = | time constant of surge tank |
| nf | = | amplification coefficient of sectional area of surge tank |
| eqh, eqx, eqy | = | discharge transfer coefficients of turbine |
| eg | = | load self-regulation coefficient |
| Td | = | damping device time constant |
| Ty | = | response time constant |
Additional information
Notes on contributors
Wencheng Guo
Wencheng Guo received his master's degree from the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University, Wuhan, China, in 2013. He is currently a doctoral candidate at the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University. His research interests are in the safe operation and control of hydroelectric power plants; transient processes for hydraulic, mechanical, and power coupling systems, hydraulic turbine regulation, and power system stability and control.
Jiandong Yang
Jiandong Yang received the Ph.D. from Wuhan University of Hydraulic and Electrical Engineering, Wuhan, China, in 1988. He is currently a professor at the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University. His research interests are in transient process and control of hydroelectric power plants and pumped storage power stations, and model testing of transient processes.
Jieping Chen
Jieping Chen received the bachelor's degree from the School of Water Resources and Hydropower Engineering Science of Hohai University, Nanjing, China, in 2013. She is currently a master degree candidate at the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University. Her research interests include transient processes and control of hydroelectric power plants.
Weijia Yang
Weijia Yang received his B.S. and M.S. from the School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan, China, in 2011 and 2013, respectively. He is currently pursuing his Ph.D. at the Division of Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden. His research interests include transient process and stability of HPPs and interactions between HPPs and power systems.
Yi Teng
Yi Teng received his bachelor's degree from the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University, Wuhan, China, in 2013. He is currently a master degree candidate at the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University. His research interest is in the transient process and control of hydroelectric power plants.
Wei Zeng
Wei Zeng received his bachelor's degree from the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University, Wuhan, China, in 2013. He is currently a master degree candidate at the State Key Laboratory of Water Resources and Hydropower Engineering Science of Wuhan University. His research interest is in the transient process and control of pumped storage power station.