In-Situ Measuring Campaign at the Hydropower Plant ‘‘Perućica’’, Montenegro - Part 1: Open Channel System

 Danica Starinac1, Radomir Kapor2, Budo Zindović2, Dragiša Žugić1 and Predrag Vojt1

 


1 Jaroslav Černi Institute for the Development of Water Resources, 80 Jaroslav Černi Str., 11226 Pinosava - Belgrade, Serbia; e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 University of Belgrade - Faculty of Civil Engineering, Bulevar Kralja Aleksandra 73, 11000 Belgrade, Serbia, e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

Abstract

The Hydraulic Department of the ’’Jaroslav Černi’’ Institute for the Development of Water Resources carried out an important measuring campaign within the Project of Modernization and Revitalization of HPP ‘‘Perućica’’. The campaign included in-situ measurements (water levels, discharges, pressures, displacements, stresses and vibrations) at different locations throughout the HPP system. All measurements were carried out concomitantly, with the aim of being used as the basis for the calibration of a mathematical model. With respect to the boundary conditions, all measurements were divided into three groups: with unsteady boundary conditions, with steady boundary conditions, and with unsteady downstream boundary conditions. The measuring campaign provided valuable data for the calibration of a mathematical model, as well as an insight into the operation of particular parts of the system.

Keywords: hydropower plant, in-situ measurements, measuring campaign, Perućica, open channel flow

 

Introduction

 

 

During June 2010, the Hydraulic Department of the ''Jaroslav Černi'' Institute for the Development of Water Resources carried out an important measuring campaign within the Project of Modernization and Revitalization of the ''Perućica'' hydropower plant (HPP) (Starinac et al., 2011).

During the entire exploitation period, the HPP has never operated at the maximum power of 307 MW (total installed capacity). Many studies and analyses, such as in-situ measurements, mathematical simulations, observations etc., (Djonin et al. 1984; Petrović and Djonin, 1986) have been undertaken with the objective to determine the origins of the problems and to identify the measures best suited to eliminate or, at least, alleviate them. Based on these results, the operating level has been increased to 285 MW. The main reasons for this limitation were inadmissible mechanical vibrations of the turbine housing as well as load fluctuations, especially in the tailrace system, particularly during load change, load rejection and shut down operation (Gajić et al. 1998).

The Project of Modernization and Revitalization of HPP ''Perućica'' is aimed at increasing the operating capacity up to the installed level as a first step and, after analyzing the possibilities for installing a new, eighth generating unit, increasing the capacity further. For that purpose, it is necessary to carry out detailed analyses of the whole system, including mathematical modeling. For the model calibration, parameter values based on in-situ measurements are required.

The measuring campaign included in-situ measurements of water level, discharge, pressure, displacement, stresses and vibrations, on different locations throughout the whole system of HPP ''Perućica'', in order to identify the origin of the existing problems and to define the basis for its rehabilitation. All measurements were continuous and simultaneous, due to the requirement to obtain real information on the system behavior in different conditions and to provide adequate data for the mathematical model calibration.

Considering different hydraulic characteristics, the system could be divided into two parts – an open channel system (upstream of the power intake ''Marin krst") and a pressurized system (downstream of the power intake). In this paper, the measurements carried out in the open channel system are presented through an explanation of the applied methodology, followed by the results and conclusions.

 

 

 

Description of the System
The hydropower plant ‘‘Perućica’’ is located on the Zeta River, in the central part of Montenegro, near the town of Nikšić. The hydropower plant comprises seven generating units with a total installed capacity of 307 MW. The system makes use of the energy potential (gross head 550 m) of the Zeta River, between its upper part (the Gornja Zeta River) at Nikšić polje and its lower part (the Donja Zeta River) close to Glava Zete.
Hydropower plant scheme
The hydropower plant scheme was planned and designed as a run-of-the river hydropower plant, in combination with three reservoirs for water storage purposes (Figure 1).

 

01

Figure 1: System of canals and reservoirs of the “Perućica” Hydropower Plant

 

 

According to this scheme, the use of the Zeta River (in Nikšić polje) was planned as a main source for the HPP ''Perućica''. The initial design foresaw the impounding of water from the Zeta River by the Vrtac Dam, for its controlled release and use for power generation following the power demand. In addition to the Zeta River, it was further planned to utilize the Moštanica River and the Opačica River, by impounding water by the Krupac Dam and the Slano Dam respectively. This concept anticipated that both reservoirs, Krupac and Slano, would contribute to power generation by releasing water into the Vrtac reservoir as a regulating structure for the headwater of the HPP ''Perućica''.

From the Vrtac Dam, water is conducted by the feeder canal Zeta I, to the compensation basin and to the power intake at "Marin Krst". The compensation basin has sufficient capacity for providing water during the startup of the power plant or when additional units are initiated. Similarly, the compensation basin preserves water when units are shut down. The settling basin, upstream of the intake structure, prevents coarse and heavy particles from entering the penstocks and the units.

A system of open canals

Water for the HPP is collected from several rivers such as the Zeta River, the Moštanica River, and the Slanska River. The water is collected by headworks in the case of the Zeta River and dams in the case of the Moštanica and Slanska Rivers, and conveyed through a system of open canals, to the power intake (Figure 1).

The system comprises the following headraces:

  • The Zeta River headwater (headworks, Zeta II Canal, Vrtac Dam, Zeta I Canal, Compensation basin, Power intake structure)
  • The Moštanica River headwater (Krupac Dam and Reservoir, Moštanica Canal)
  • The Slanska River headwater (Slano Dam and Reservoir, Opačica Canal)

The characteristics of the reservoirs, dams, bottom outlets and spillways are summarized in Table 1, while Table 2 summarizes the main characteristics of the existing canals.