The Effects On Stable Running Of Power Grid Of The Distributed Network With Small Hydropower

As is widely used of all kinds of distributed generation, the effects brought topower system stability become wider and deeper. Generally speaking, in the powersystem simulation calculation, which is the basis of decision making for the powergrid planning design and electric power dispatching and controlling, load model is theequivalent description of the characteristics of the synthesis load of the substationbus(it’s usually the110kV bus of the220kV substation), and the distributedgeneration is naturally included in it. As is widely distributed of the geographicallocation, the characteristics of dynamic operation and the installed capacity of thesmall hydropower, the components and the characteristics of the synthesis loadbecome more and more complex, and also how to get the accurate model become moredifficulty.In this paper, the system structure, method of operation of small hydro wereintroduced. Based on field investigation, the basic forms of power interconnection andthe distributing features were known well. Although the theoretical research onmechanism model of single small hydropower system is already mature, the numberof small hydropower is very large, even in a regional power network, the number ofnodes in the simulation calculation is also huge after considering the smallhydropower model. In additional, the equipment of small hydro power station isrelatively pallet, and it’s not an easy work to obtain these parameters of the units, soto a certain extent, it is unfavorable for technicist to calculate and analyse. We need areasonable and practical methold to analyse the influence of the distributed smallhydropower.So far as the shortage of the existing model of the small hydropower inapplication, in this paper, the modeling method of clusters equivalent of smallhydropower was presented, in which statistics composite method and weightedaverage method were included, and the capacity and parameters that corresponds togenerator units were acquired by investigation and calculation. Finally, the result ofthe parameter sensitivity analysis also provided important reference for parameteradjusting. Considering the practical situation that the number of small hydropower isvery large, and the unit type and parameters couldn’t be acquired completely, severaltypical small hydro regions were selected as the investigation object. And then, the parameters of equivalent model were calculated by adopting the above method. In themeanwhile, these model parameters could be popularized to other similar smallhydropower region. Based on the above works, clusters equivalent model waspresented,whose parameters were calculated according to the equivalent principlefrom low voltage to high voltage. Simulation result in the real power grid verifies theeffectiveness and practicability of this method.In this following paper, the contrast analysis of transient stability on both Hunanpower grid and typical power grid was completed between the original model and theclusters equivalent model presented, and the contrast analysis of small disturbancevoltage stability on a single power grid was completed with the PSASP tools.Simulation result verifies that small hydropower can improve transient stability ofrelevant region and the stability level of voltage was improved when smallhydropower participated to regulate the voltage of relevant nodes. The results areavailable to power network planning and operation in practical work.