Modeling and analysis of high renewable penetration in New York

Abstract

A basic market model uses an iterative commitment and dispatch engine that solves an AC power flow every 5 minutes, before compiling results back to 24-hour periods for analysis. The impact to ancillary service and generator performance requirements is quantified.

A more advanced market model consists of a day-ahead market, which clears transactions on an hourly basis, and a real-time market where commitment and dispatch processes occur every 15 and 5 minutes, respectively. The model uses Matpower and Most to calculate results for day-ahead and real-time scheduling. The results show that in two days with lower loads and higher availability of renewable resources, a fair amount of renewable output is curtailed during midday. Insights about the reasons for curtailment are provided along with the quantified impact to load cost, both of which can be helpful to system operators in designing future market dispatch programs. Perturbations to the market model include: 1) increasing steam unit ramp rates; 2) adding renewable generation credits; 3) elongating the RTC lookahead window; 4) adding dispatchable must-serve electric vehicle charging load; and 5) adding transmission interface flow constraints.

Analysis of the impact of high penetration on the dispatch of a power system is performed using a pair of market models on a 68-bus, 16-machine network model of the New York power system. Four market days are studied using both a Base Case at 2016 penetration levels and a 2030 Case with renewable penetration increased by a factor of 2.6, the amount needed to achieve New York's ``50-by-30" target (50% renewable energy by 2030).

A simplified voltage stability method is to use a static Thevenin equivalent to represent the electrical connection to a load center. Assuming fixed values of Thevenin voltage and reactance, a power-voltage (PV) curve analysis can be performed to find the voltage collapse point and stability margin. This dissertation proposes a method to compute the static Thevenin equivalent voltage and reactance of a power system using measured data. The method is validated with simulated PMU data and with 24-hour SCADA data at a wind hub on a medium voltage transmission system in the US western system. For the wind hub, the optimal Thevenin parameters are calculated and PV analysis is performed.

This dissertation investigates the curtailment of renewable generation which occurs in today's markets due to a number of circumstances. System operators may curtail output at a wind hub due to voltage stability concerns while market optimization software may reject renewable output to obtain an optimal economic dispatch and unit commitment solution. Investigation into both scenarios is presented.