System of 7 SHPPs on Nišava River downstream from Pirot - Preliminary Design, Serbia

Client: PIROT ENERGO d.o.o, Serbia

Name of partner(s): N/A

Start/Completion Date: April 2009 - November 2009

Project description: SHPPs Pirot I-VII are unified cascade small hydropower plants on the stretch of the Nišava river, downstream of the HPP Pirot to the border with the municipality of Bela Palanka. Solution with cascading SHPPs was designed to maximally utilize the available head, which means that, wherever possible, tailwater level of the upstream facility represents the normal backwater level of the downstream step. Discharging of guaranteed discharge is not anticipated for these structures, since they are run-of-river plants, with no active volume in reservoirs. Energy effects of these facilities are realized on the water level difference (head), which is achieved by creating the backwater and decelerating the flow upstream and deepening of the riverbed downstream. System of SHPP Pirot includes a dam with appurtenant facilities, powerhouse with headrace within the dam body, dike with the lateral canal and deepened regulated Nišava riverbed. The basic characteristics of a representative SHPP:

• Average flow - 19,94 m3/s
• Spillway – rubber gates
• Gross head (Qi) – 5,3 m
• Installed power plant discharges – 40 m3/s
• Turbine type – Kaplan, 3 units
• Installed capacity - 1,66 MW
• Average annual output - 7,07 GWh/year.